Drilling Fluids Manual Handbook

7/21/2019 Drilling Fluids Manual Handbook

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health, safety and environment (hse)

section 1


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your health & safety is primarily your

own responsibility

your actions will directly impact the

health & safety of others

we all have a duty to support and

promote the health and safety of

others


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Introduction 2

drilling fluid engineer - roles and responsibilities 2

hazard and risk assessment 2

hazardous materials 3

Personal Protective Equipment (PPE) 4material safety data sheet msds 5

chemical wallcharts 5

mixing guidelines 5

hydrogen sulphide 6

non aqueous fluids 9

potential hazards and risks 9

miscellaneous rig hazards 11

trips and falls 11

falling objects 11

hand injuries 12

fire 12

stepback 5 x 5 12

section 1 Scomi Oiltools


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2

Section

1 health, safety and environment

introductionThe purpose of this section is to provide general guidelines for prudent work practices and procedures

for the use of chemicals, and to protect Drilling Fluids Engineers and Rig Personnel from the potentialhealth hazards of the chemicals they encounter in the workplace.

All personnel must be made aware of the guidelines. New employees should receive safety training

before beginning work with hazardous chemicals.

drilling fluid engineer - roles and responsibilities Attend Operators/Contractors safety meetings and advise on all HSE matters pertaining to Scomi

Oiltoolsproducts. The requirement for Drilling Fluids Engineers is to not only attend, but to contribute,

to safety meetings onsite, including giving presentations about the fluids and chemicals being used.

Give toolbox / pre-tour talks on chemical safety.

Take part in risk assessments relevant to fluids, in particular for the first use of new systems e.g. SBM /

OBM etc.,

Follow all procedures related to HSE and follow all wellsite directives issued by the operator and / or

drilling contractor.

Ensure correct and updated safety posters are in place in the mud and sack rooms or mixing areas for

land rigs.

Ensure MSDS are up to date and easy to locate.

Use engineering controls and personal protective equipment, as appropriate.

Use rig specific HSE Observation system e.g. STOP.

hazard and risk assessmentThe use of chemicals in the workplace presents hazards and risks to personnel involved in their handlingand application. In order to minimise these hazards risk assessments are performed and HSE control

measures and management systems are established to achieve the following:-

Identify hazards

Safely manage those hazards.

Identify risks

Where possible, eliminate those risks through control / engineering measures e.g. ventilation and

collection of dust. Where not possible, manage those risks through processes including the use of PPE.

Provide training and awareness systems designed to achieve the above and promote continuous

improvement.

A health Hazard is defined as:

The potentialof a chemical or substance to cause harm to the health of personnel or the environment.

A health Risk is defined as:

The likelihood that a chemical or substance will cause harm to personnel or the environment in the

actual circumstances of exposure.

RISK = Hazard x Exposure

health, safety and environment


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hazardous materialsThe effect on a person of a hazardous material depends on:

The nature of the hazardous material.

The site of the action.

The amount of the hazardous material involved (dose). The reaction of the individual (susceptibility).

Hazardous Material Effects

Local effects:

Skin and eye irritation & burns.

Skin defatting leading to dermatitis.

Systemic effects:

Central nervous system (headaches, nausea, dizziness).

Cardiovascular system (CO poisoning).

Sensitisation (allergy) and asthma.

Teratogenic and carcinogenic.

Chemical hazardous effects may be:

Acute - effects lasting minutes, hours or days e.g. irritation i.e. generally short term recoverable effects.

Chronic - effects lasting weeks, months or years e.g. occupational asthma generally long and possibly

permanent effects.

Effects may be reversible or irreversible.

Routes of Entry to the Body

EYES

INGESTIONSKIN ADSORPTION

INHALATION

Injection

Inhalation

Ingestion

(swallowing)

Skin and eye contact

Chemical Injuries to the Skin

One of the bodys biggest organs

one major function is protection.

Composed of the outer

(epidermal) and inner (dermal)

layer.

Major protection provided by the

outer layer.

Irritant contact dermatitis -

a common skin disease which

results from direct contact with

a chemical.

Effects occur only where contactoccurs and can range from

a redness to blistering and

formation of pustules.

Layer & Structures of the Skin

(Epidermis raisedto show papillae)

EPIDERMIS

DERMIS

SUBCUTANEOUS

FAT

TYTISSUE

Hair shaftCornified layer (dead cells)

Pigment layer

Spiny (Prickle cell layer)

Germinating layer

Dermal papilla

Capillary tuft

Oil (sebum)

Sebacecous (oil) glands

Sensory nerve endings for touch(Ruffinis corpuscles)

Erector muscle for hair follicle

Hair follicle

Sweat gland

Papilla of hair follicle

Sensory nerve endings for pressure

(Pacinis corpuscles)Fat

Blood vesselsBeck

SKIN-PROTECTION AND TOUCH


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Section

1 health, safety and environmentBurn 1

A caustic burn at the back of the ankle.

Burn 2

The same caustic burn one week later.

Personal Protective Equipment (PPE)

Hard Hat

Gloves, long rubber gloves

for handling hazardous

materials.

Eye Protection, glasses,

goggles or full face mask (as

appropriate).

Coveralls, i.e. long sleeved,

fire resistant, to cover as

much body skin as possible,

rubber apron when handling

hazardous material.

Boots recommended

rubber or treated leather.

Dust mask, particulate

filter mask, respirator (as

appropriate).

PPE should be checked before use each time and examined on a regular basis if not in regular use.

Remember PPE requires care and maintenance.

Ensure PPE being worn is in good condition and provides the desired protection !!


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material safety data sheet msdsAn assessment is made of the physical and health hazards of each chemical supplied by Scomi Oiltools.

This information is included in a Material Safety Data Sheet (MSDS) and, in part, on container labels.

Material Safety Data Sheets contain the following information:

1 Product Identification

2 Composition, information on ingredients

3 Hazard identification

4 First aid measures

5 Fire fighting measures

6 Accidental release measures

7 Handling and storage measures

8 Exposure controls, personal protection

9 Physical and chemical properties

10 Stability and reactivity

Ensure that the following practices are followed regarding MSDS information at the workplace:

Provide active up-to-date MSDS files covering all drilling fluid chemicals on location either on CD or

paper copies. This must also include the laboratory testing chemicals.

Distribute the MSDS files to the Wellsite Manager / OIM, Medic (or designate) and sack storage /

mixing areas.

Update the MSDS file list whenever a new item is received.

chemical wallchartsDisplay wallchart with basic safety information in key areas, laboratory, sack

room and mixing areas.

The wallchart should include short information covering immediate actions

in case of exposure of personnel or spill.

mixing guidelinespre-job Select the chemicals to be mixed.

Review MSDS (Material Safety Data Sheets).

Review the wall charts.

Obtain appropriate tools, e.g. barrel pump.

Inspect the condition of the chemicals to be mixed.

Obtain appropriate PPE and WEAR IT.

Ensure mixing personnel have clear written instructions.

Perform a Job Hazard Analysis for any new chemicals or personnel.

mixing Check that hopper is running and that the correct lines valves and pits have been selected.

Ensure sufficient extraction and ventilation in hopper area.

Ensure that sacks and drums are conveniently positioned and use correct lifting procedures.

Be aware of any forklift operations.

Clean up spills as soon as possible.

Close the hopper any time chemicals are not being mixed.

PromotionsCommittee

Kwok Kian Hai(Chairman)

Tan Sri Datuk DrYusofBasiron

DatoHaji SabriAhmad

Haji Nasrullah Khan

Er Kok Leong

Carl Bek-Nielsen

Zubir Abdul Aziz

Kwok Kian HaiChairman,AsiaPacific

Chairman,Sub-Continent

DatoHaji SabriAhmadChairman,Africa

Zubir Abdul AzizChairman,MiddleEast

Haji Nasrullah Khan

Financial andGeneralAffairs Committee

Mohd Zain Omar

DatoMamat Salleh

Er Kok Leong


Er Kok Leong

Carl Bek-Nielsen

PromotionsCommittee

Kwok Kian Hai(Chairman)


DatoHaji SabriAhmad

Haji Nasrullah Khan

Er Kok Leong

Carl Bek-Nielsen

Zubir Abdul Aziz

Kwok Kian HaiChairman,AsiaPacific


DatoHaji SabriAhmadChairman,Africa


Haji Nasrullah Khan

Financial andGeneralAffairs Committee

Mohd Zain Omar

DatoMamat Salleh

Er Kok Leong


Er Kok Leong

Carl Bek-Nielsen

Promotions Committee

Kwok Kian Hai (Chairman)

Tan Sri Datuk Dr YusofBasiron

DatoHaji Sabri Ahmad

Haji Nasrullah Khan

Er Kok Leong

Carl Bek-Nielsen

Zubir Abdul Aziz

Regiona l Market Committee

Kwok Kian HaiChairman,Asia Pacific



Chairman,Africa


Carl Bek-NielsenChairman,Europe

Haji Nasrullah Khan

Financial and GeneralAffairs Committee

DatoLow MongHua

Mohd Zain Omar

DatoMamat Salleh

Er Kok Leong



Haji Nasrullah Khan Neazullah

Er Kok Leong

Carl Bek-Nielsen

Promotions Committee

Kwok Kian Hai (Chairman)



Haji Nasrullah Khan

Er Kok Leong

Carl Bek-Nielsen

Zubir Abdul Aziz

Regiona l Market Committee

Kwok Kian HaiChairman,Asia Pacific



Chairman,Africa


Carl Bek-NielsenChairman,Europe

Haji Nasrullah Khan

Financial and GeneralAffairs Committee

DatoLow MongHua

Mohd Zain Omar

DatoMamat Salleh

Er Kok Leong



Haji Nasrullah Khan Neazullah

Er Kok Leong

Carl Bek-Nielsen


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6

Section

1 health, safety and environmentcleaning up Inform derrickman, pump man or supervisor that job is complete.

Clean up mixing area.

Dispose correctly of empty sacks, drums and pallet waste, e.g. banding, wood & plastic wrapping in

the correct manner.

Ensure forklift is parked in designated area with forks lowered.

housekeeping rules for drilling fluids

Immediately clean-up all chemical spills, dry or liquid.

Immediately clean-up all drilling fluid spills.

Have a dedicated storage area for hazardous chemicals this may require a bunded area to prevent

leakage of any liquid spillage.

Ensure that pallets are labelled on all four sides and the top to allow easy and correct identification

of chemicals.

Maintain fume and dust extraction equipment over mixing hoppers, shale shakers and mud pit area.

Ensure adequate supply of masks for dust protection.

Provide particulate filters and respirators as necessary.

Rotate personnel working in high risk areas to minimise exposure.

hydrogen sulphide

Hydrogen Sulphide (H2S) hydrogen sulphide

is highly poisonous as well as corrosive. Small

concentrations in air may be fatal in minutes.

Hydrogen sulphide (H2S) is a colourless poisonous gas that smells like rotten eggs. Often referred

to as sewer gas it occurs naturally in the earth in crude petroleum, natural gas reservoirs, volcanic

gases and hot springs. As well as being found downhole in sour gas reservoirs hydrogen sulphide can

be produced by the action of sulphur reducing bacteria and the break down of a number of products

anerobically, particularly in fluids left behind casing.

It can be detected by smell at concentrations ranging from as low as 0.01 - 0.3 parts per million

(ppm). However, relying solely on its odour is dangerous because at concentrations above 100 ppm it

deadens a persons sense of smell within a few minutes. The pure gas is heavier than air and can collect

in low areas on rigs such as pits, storage areas and accommodation units.

The presence of hydrogen sulphide in a drilling fluid, [if not treated with caution], can be lethal to

personnel, apart from the corrosive impact of even low concentrations on the drilling fluid and rig

equipment.

Shortterm (acute) exposure to hydrogen sulphide can cause irritation to the nose, throat, eyes and

lungs and exposure to higher concentrations can cause very serious health effects, and even death as

detailed in Table 1.


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proactive actions for the mud engineer

On wells where there is a high likelihood of encountering hydrogen sulphide it is recommended thatbeards are shaved. This is to ensure that breathing sets are sealed tightly against the face.

It is imperative that all personnel be aware of the hydrogen sulphide alarm, as well as the designated

safe area to evacuate to. It must be stressed that the safe area, unless in a positive pressure environment,

must be upwind at a higher elevation than the gas source.

Even on wells that are unlikely to have hydrogen sulphide it is recommended that a contingency stock of

sulphide scavengers is kept at the rig site.

When the presence of H2S is suspected the mud engineer is asked to confirm the presence and

concentration of the gas. Never ever enter an area where any acid gas is suspected unless specifically

trained and wearing the appropriate personal protective equipment.

During displacements if the mud engineer has to be at the flow line ensure that there are at least two

means of gas detection and available PPE as well as being aware of the nearest escape route.

first aid Immediately remove the victim from further exposure. Designated rescuers must wear properly

fitting, positive pressure self-contained breathing apparatus (SCBA) and other required safety

equipment appropriate to the work site.

If the worker is not breathing, apply cardio-pulmonary resuscitation in the nearest safe area.

Remove contaminated clothing, but keep the individual warm. Keep conscious individuals at rest.

Be aware of possible accompanying injuries (e.g. the victim may have fallen when they were overcome)and treat them accordingly.

If the victims eyes are red and painful, flush with large amounts of clean water for at least 15 minutes.

Ensure the worker receives medical care as soon as possible. The worker must not be allowed to return

to work or other activities.

h2s testsOn rigs where H2S is expected, there are fixed hydrogen sulphide detectors placed in strategic locations,

shale shakers, pit room, rig floor and flow-line. In addition portable detectors should be available and are

to be used when entering enclosed spaces or as personal monitors when contamination is suspected.

There are 2 common tests for H2S in drilling fluids, a qualitative test and a quantitative test. The

qualitative test should only be used as a quick method to confirm the presence of H 2S in the mud. Inorder to effectively treat and remove sulphides it is essential to perform the qualitative test, Garret Gas

Train, and determine the concentration in the system.

Concentration Health effect(ppm)

0.01 - 0.3 Odour threshold

1 - 20 Offensive odour, possible nausea, tearing of the eyes or headaches with prolonged

exposure

20 - 50 Nose, throat and lung irritation; digestive upset and loss of appetite; sense of smell starts

to become fatigued; acute conjunctivitis may occur (pain, tearing and light sensitivity)100 - 200 Severe nose, throat and lung irritation; ability to smell odour completely disappears.

250 - 500 Pulmonary oedema (build up of fluid in the lungs)

500 Severe lung irritation, excitement, headache, dizziness, staggering, sudden collapse

(knockdown), unconsciousness and death within a few hours, loss of memory for the

period of exposure

500 -1000 Respiratory paralysis, irregular heart beat collapse and death without rescue.

>1000 Rapid collapse and death

Table 1. Hydrogen sulphide toxicity to man


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Section

1 health, safety and environmentqualitative testLead acetate (Hach test): An alka-seltzer tablet drives hydrogen sulphide gas from solution and the

hydrogen sulphide reacts with lead acetate soaked in a filter paper. The degree of colour change is a

measure of hydrogen sulphide concentration in the mud.

quantitative testThe Garrett Gas train is an instrument used for quantitative analyses of sulphides and carbonates.

Specific test methods have been published by API. The oil-mud procedure analyzes active sulphides

and uses whole mud samples, whereas the water-base mud procedure tests filtrate.

The Garrett Gas Train method for sulphides is detailed in Section 3, mud testing procedures for both

WBM and NAF.

drilling fluid treatmentA common field approach is to neutralise H2S by the addition of caustic soda and or lime. At pH 12 and

above the sulphides are soluble and the H2S is dissociated.

H2S + H20

H+

+ HS-

2H+

+ S=

This reaction is reversible and as the pH drops the hydrogen and the sulphide re-associate and H2S

may be released from mud.

Ionic Distribution of H2S with pH

0.0001

0.001

0.01

0.1

1

1 2 3 4 5 6 7 8 9 1 0 11 12 13 14 15

pH

HS-

H2SS

-

Fractio

n

This treatment is only recommended to treat very minor amounts of H2S such as that associated with

pore space gas. It does not remove the H2S from the drilling fluid. This treatment will only sequester

the H2S. Continued exposure of the liquid to H

2S will reduce the pH of the system and will eventually

begin to release the gaseous H2S once the pH has fallen below pH 7.

In order to effectively deal with an influx of H2S it is essential to use a sulphide scavenger which is

an additive that reacts with sulphides to convert them to an inert form e.g. zinc sulphide and is an

irreversible reaction.

Zinc or iron compounds are the products of choice e.g. Zinc Carbonate andZinc Oxide.

It is estimated that 0.002 lb/bbl (0.0057 kg/m3)of Zinc Carbonate will precipitate 1 mg/ l of sulphide.

Zinc carbonate is used primarily in water based muds but caution must be taken as continuous

treatments may produce undesirable zinc or carbonate concentrations which can adversely effectdrilling fluid rheology and fluid loss.

Zinc oxide is primarily used in NAF (Non Aqueous Fluids) but may also be used in water based systems.


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zinc carbonate

2ZnCO3+ 3Zn(OH)2+ 5H2S = 5ZnS + 2CO2+ 8H20

zinc oxide (contains more zinc than zinc carbonate)

H2S + ZnOZnS + H2O.

It should be noted that there may be environmental restrictions preventing the use of zinc based

H2S scavengers. If this is the case alternative iron based treatments should be used.

pre-treatmentTo ensure a high level of protection against H2S influxes, zinc oxide should be added to the active

mud system before drilling out the last casing shoe above a potentially H 2S bearing zone. Add slowly

and evenly through the hopper to achieve good distribution and any new volume mixed or added

should be similarly treated.

Note that pre-treatment might mask small influxes as they react with the zinc oxide in the system and

detection may not occur until all the zinc has reacted.

Hydrogen sulphide treatment of drilling fluids, along with proper pH control, should be used to reduce

the amount of hydrogen sulphide that is recirculated. Caution is needed when handling drilling fluid

that has been exposed to hydrogen sulphide because hydrogen sulphide can move from the liquid into

the vapour space of the storage tank and will be released when the tank is opened.

non aqueous fluidsInvert emulsion muds (Non Aqueous Fluids) are generally a brine water phase emulsified in a hydrocarbon

base fluid along with other chemicals to provide a stable drilling fluid with the required drilling

properties.

The components and properties of these fluids are detailed in section 8, NAF Fundamentals.

From an HSE perspective these fluids present significantly more challenges in their use as the impacts

of personnel exposure and environmental discharge are greater than with the majority of water base

systems.

potential hazards and risksPersonnel may come into direct or indirect contact these fluids in the following areas on the rig:

The drill floor.

The mud pit area and the mud pump room.

The sack room and mixing area.

The shale shaker and solids process area.

The laundry.

It is imperative that any exposure is dealt with immediately and personnel do not continue to

work with wet clothing as this can lead to long term health issues.

The following exposure effects may occur.

eye / skin contactDue to the higher salinity and oil content of invert systems, irritation to both the skin and eyes can

occur if they come into contact with the fluids.

Calcium chloride accentuates the tendency to irritate by removing the natural oils in the skin and

weakening the skins tolerance to other components in the NAF such as the base fluids. Untreated

exposure may lead to dermatitis and or eczema.


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Section

1 health, safety and environmentUse barrier creams to reduce this effect and if skin becomes dry use a good lanolin based moisturising

cream to replenish removed natural oils.

dust, mist & vapour inhalationRig personnel may inhale dust, vapours or mists which are at their highest concentration in the shaker

house, pit room and mixing area. Vapours are generally generated by higher temperatures driving off

water vapour which will contain some of the organic components in the system. Mists are normally

generated when using pressure wash down equipment.

Dust is generated when powders become released into air. During the mixing of sacked and bulk

powders, dust will be generated. Ensure that there is adequate ventilation and extraction available at

the mixing hopper.

All flowlines / mud ditches should be fully enclosed. Shale Shakers and solids control equipment should

be enclosed in extraction hoods to contain and remove mists and vapours.

Areas where vapours or mists are generated must be well ventilated and personnel should minimise

their exposure time in these areas, and be rotated if there is a need to spend extensive periods workingon equipment such as shale shakers whilst drilling.

slippery floorsOBM / SBM fluids are usually lubricious and any spillage will produce a very slippery surface creating a

significant safety hazard to personnel. All spills must be cleaned up immediately.

Minor spills should be squeegeed or mopped up or covered with an absorbent material such as

sawdust, barite or dedicated spill absorbency materials which should be disposed of correctly. NB.

Barite used to adsorb spills can be recycled into the mud system.

Larger spills should be vacuumed with a diaphragm pump or dedicated vacuum system.

noiseLoud and continuous noises will gradually degrade hearing. When in high noise environments such as

the Shakers, Pump Room and Rig floor ensure that hearing protection is used.

laundryOne of the main sources of skin problems is incorrect laundering. OBM and SBM are difficult to clean

from clothing.

It is recommended that a dedicated washing machine is used to wash coveralls, slicker suits, gloves

etc. separately from personal clothing, Detergent specifically manufactured for cleaning oily clothing

should be used. If possible a pre-wash then wash cycle should be introduced in the washing

programme to ensure maximum cleanliness of all clothing worn close to the skin. Incorrectly washedclothes may cause skin irritation.

ppeIt is recommend that PPE as specified elsewhere in this section is used at all times and in particular

the following points are noted:-

Coveralls should cover as much skin as possible with full length sleeves which can be sealed at the

wrist. Coveralls should be made from flame resistant materials.

All buttons or zips should remain closed when exposed to chemicals.

Gloves and footwear should overlap where the coveralls end.

Use barrier creams in those areas that cannot be covered by some form of PPE. These areas includeportions of the face, neck and arms where one piece of PPE may not meet another. A barrier cream

for protection against Organic / Water emulsions is recommended.


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immediate first aidIn the event of personnel becoming exposed to any chemical and the chemical is known then refer to

the MSDS or Wallchart for the appropriate action to be taken. If the chemical is not known then the

following general first aid measures apply.

EYE Immediately flood the eye with water for at least 15 minutes while holding the eye

open. Then obtain medical attention.

INHALED Remove from exposure, keep warm and at rest. If breathing difficulty develops,

ensure airways are clear and give Oxygen through a face mask. If breathing has stopped

apply artificial respiration immediately. Seek urgent medical assistance.

SKIN Remove contaminated clothing. Remove any mud with medicated degreaser, then

wash with soap and water. Obtain medical attention if irritation develops.

SWALLOWED Wash out the mouth. Give water to drink, DO NOT INDUCE VOMMITING unless

specifically recommended in the MSDS. Obtain medical attention.

If any medical condition, however minor, occurs seek medical attention immediately.

All incidents and unsafe conditions must be reported to the rig medic and / or rig

safety representative.

miscellaneous rig hazardsMost engineers work at the rig site of the clients, it is imperative that they follow the clients HSE

requirements and systems. The engineers should be aware of the rig safety systems including the alarms

and emergency responses.

The engineer must actively participate in any and all preventative systems. All accidents and or near

miss incidents should be reported through the STOP card or equivalent systems.

Engineers work for a number of different clients and are a crucial element in the transfer of HSEexperience between operators.

A number of rig specific risks exist some are detailed below:

trips and fallsThere are numerous trip hazards on a rig site. In order to prevent tripping good house keeping is

essential. The following actions are suggested

Ensure that waste material is tidied away as soon as possible.

When rigging up temporary hoses ensure that they are clearly sign posted.

The most common tripping occurrence is while climbing stairs. Ensure that while climbing stairs at

least one hand is on the rails. Ensure that guard rails around tanks are in place and in good condition.

Ensure that tops of pits are covered an if opened they are barriered off with clear signs.

Obey all rig-site signs and barriers.

Never work at heights without appropriate training and equipment.

falling objectsMud Engineers rarely work at heights but on occasion due the rig layout it may prove necessary e.g.

during displacements the flow line may be at height. However if working at heights do not work

without an approved platform and wear inertia protection.

While at a rig site be aware that other personnel may be working atheights and using hand held toolswhich can fall and cause severe injuries. Always be conscious of the need to identify and avoid such

potential hazards. Also note that cranes may be shifting loads overhead; never stand or walk under a

load.


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Section

1 health, safety and environmenthand injuriesHand injuries are the most common injuries on rigs. Always be aware of potential squeeze points and

assess all activities carefully before commencing the work.

fireThe mud engineer should be aware of the specific fire fighting systems of the rig, location of the muster

points and evacuation procedures.

Ensure that all heating and electrical equipment in the mud lab is in good condition and can be

operated in a safe manner. Ensure that the lab has two exits and is equipped with an appropriate fire

extinguisher.

Ensure that materials are stored as per MSDS instructions to minimise the danger of fire and that the

required fire fighting equipment available and operational. Not only is fire lethal, but it may generate

toxic smoke from drilling fluid products.

If a fire is found raise the alarm, and only attempt to fight the fire with the available fire fighting equip-

ment, if you have been trained in its use and as long as this will not result in personal injury.

stepback 5 x 5Before you start any job take 5 steps back from the work area and invest a few minutes to step through

the work in your mind.

Before the Job:

Stop and think.

Observe the work area and surroundings.

Think through the steps of what you will be doing. Identify what is happening today in your area.

Identify any hazards.

Develop methods for eliminating and controlling these hazards.

Satisfy yourself that the hazards are controlled before starting the job.

During the Job:

Do you feel safe doing the job?

Are others around you working safely?

Repeat the steps above if you encounter an unexpected problem.

After the job:

Observe the work area.

Take action to control any hazards that may have been created because of the job.

Reflect on the job performed.

Can any improvements be made?

Discuss these improvements at tour and safety meetings.

STOP AND THINK BEFORE YOU ACT


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drilling fluid functions

section 2


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Introduction 2

primary functions 2

control formation pressure 2

transport cuttings 3

maintain stable wellbore 4

secondary functions 10

support weight of tubulars 10

cool and lubricate bit and drill string 10

transmit hydraulic horsepower to bit 10

provide medium for wireline logging 10assist in formation evaluation 10

section 2 Scomi Oiltools


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2

Section

2 drilling fluid functions

introductionThe objective of a drilling operation is to drill, evaluate and complete a well that will produce oil and/or

gas efficiently. Drilling fluids perform numerous essential functions that help make this possible.

A properly designed drilling fluid will enable an operator to reach the desired geological objectiveat the lowest overall cost. A fluid should enhance penetration rates, reduce hole problems andminimise formation damage.

Removing cuttings from the well, maintaining wellbore stability and controlling formation pressuresare of primary importance on every well. Though the order of importance is determined by well design,conditions and current operations, the most common drilling fluid functions are:

1 Transport cuttings from the well2 Control formation pressures3 Maintain stable wellbore4 Seal permeable formations5 Suspend cuttings downhole and release them on surface6 Minimise reservoir damage7 Cool, lubricate, and support the bit and drilling assembly8 Transmit hydraulic energy to tools and bit9 Ensure good data recovery10 Control corrosion11 Facilitate cementing and completion12 Minimise HSE risk

primary functionsDrilling fluids are designed and formulated to perform three prime functions:

Control Formation Pressure Transport Cuttings Maintain Stable Wellbore

control formation pressureA drilling fluid controls the subsurface pressure by its hydrostatic pressure. Hydrostatic pressure isthe force exerted by a fluid column and depends on the mud density and true vertical depth (T VD).

Borehole instability is a natural result of the unequal mechanical stresses and physico-chemicalinteractions and pressures created when surfaces are exposed in the process of drilling a well. Thedrilling fluid must overcome both the tendency for the hole to collapse from mechanical failureand/or from chemical interaction of the formation with the drilling fluid.

Normal formation pressures vary from a pressure gradient of 0.433 psi/ft (9.79 kPa/m) (equivalentto 8.33 lb/gal or SG 0.99 freshwater) in inland areas to 0.465 psi/ft (10.51 kPa/m) (equivalent to8.95 lb/gal or SG 1.07) in marine basins. Elevation, location, and various geological processes andhistories create conditions where formation pressures depart considerably from these normal values.The density of drilling fluid may range from that of air (essentially 0 psi/ft or 0 kPa/m), to in excessof 20.0 lb/gal (1.04 psi/ft) or SG 2.40 (23.51 kPa/m).

drilling fluid functions


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In most drilling areas, a fresh water fluid which includes the solids incorporated into the water fromdrilling subsurface formations is sufficient to balance formation pressures. However, abnormallypressured formations may be encountered requiring higher density drilling fluids to control theformation pressures. Failure to control downhole pressures may result in an influx of formation fluids,resulting in a kick, or blowout.

Hydrostatic pressure also controls stresses adjacent to the wellbore other than those exerted byformation fluids. In geologically active regions, tectonic forces impose stresses in formations and maymake wellbores unstable even when formation fluid pressure is balanced. Wellbores in tectonicallystressed formations can be stabilised by balancing these stresses with hydrostatic pressure. Similarly,the orientation of the wellbore in high-angle and horizontal intervals can cause decreased wellborestability, which can also be controlled with hydrostatic pressure.

transport cuttingsAs drilled cuttings are generated by the bit, they must be removed from the wellbore. To do so,drilling fluid is circulated down the drillstring and through the bit, transporting the cuttings up theannulus to the surface. Cuttings removal is a function of cuttings size, shape and density combined

with Rate of Penetration (ROP), drillstring rotation, plus the viscosity, density and annular velocity ofthe drilling fluid.

Cleaning the hole is an essential function of the mud. This function is also the most abused andmisinterpreted. The drill solids generally have a specific gravity of 2.3 - 3.0 SG; an average of 2.5 willnormally be assumed. When these solids are heavier than the mud being used to drill the hole, theyslip downward through the mud.

The rate at which a cutting settles in a fluid is called the slip velocity. The slip velocity of a cuttingis a function of its density, size and shape, plus the viscosity, density and velocity of the drilling fluid.If the annular velocity of the drilling fluid is greater than the slip velocity of the cutting, the cutting willbe transported to the surface

While the fluid is in laminar flow, the slip velocity of cuttings is affected directly by the viscosity orshear characteristics of the mud. Thus, when the annular mud velocity is limited by pump volume orenlarged hole sections, it often is necessary to viscosify the mud to reduce the slip velocity of theformation cuttings to keep the hole clean.

Sometimes the decision to increase the lifting capacity of the mud is complicated by the factthat any viscosifying of the mud may adversely affect other drilling conditions. For example, if themud is viscosified, circulating pressure losses increase and the danger of lost circulation increases.Small batches of viscous mud can be used to lift cuttings and to minimise the requirement forviscosifying all of the mud.

Fluid flowing from the bit nozzles exerts a jetting action to clear cuttings from the bottom of the holeand the bit, and carries these cuttings to the surface. Several factors influence cuttings transport.

If the cuttings generated at the bit face are not immediately removed and carried towards the surface,they will be ground very fine, stick to the bit and retard effective penetration.

Velocity - Increasing annular velocity generally improves cuttings transport. Variables include pumpoutput, borehole size and drill string size.

Density - Increasing mud density increases the carrying capacity through the buoyant effect on

cuttings.


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4

Section

2 drilling fluid functionsViscosity - Increasing viscosity often improves cuttings removal.

Pipe Rotation - Rotation tends to throw cuttings into areas of high fluid velocity from low velocityareas next to the borehole wall and drill string.

Hole Angle -Increasing hole angle generally makes cuttings transportation more difficult.

Drilling fluids must have the capacity to suspend weight materials and drilled solids duringconnections, bit trips, and logging runs. Otherwise they will settle to the low side or bottom of thehole. Failure to suspend weight materials can result in a reduction in the drilling fluid density, whichin turn can lead to kicks and a potential blowout.

The drilling fluid must also be capable of transporting cuttings out of the hole at a reasonablevelocity that minimises their disintegration and incorporation as a fine solid into the drilling fluidsystem. At the surface, the drilling fluid must release the cuttings for efficient removal. Failure toadequately clean the hole or suspend drilled solids are contributing factors to hole problems such asfill on bottom after a trip, hole pack-off, lost returns, differentially stuck pipe, and inability to reach

bottom with logging tools.

maintain stable wellboreWellbore instability during drilling causes

Packoffs Excessive trip and reaming time Mud losses Stuck pipe & BHAs Loss of equipment Sidetracks Inability to land casing Poor logging and cementing conditions

There are 3 stresses acting on the formation

sv Vertical Stress Weight of rock and water abovesH Maximum Horizontal Stress Regional Stresssh Minimum Horizontal Stress Regional Stress

Overburdenstress

Maximumhorizontalstress

Manimumhorizontal

stress


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5

The following diagram illustrates how the earth stresses adapt to the borehole as mud pressuresubstitutes for the load bearing capacity of the drilled rock

Earth stresses Borehole stresses

SV

SH

Sh

Sr

So

So

Wellbore failure problems can be categorised in two groups;

Tensile failure: where the well pressure is too high for the wellbore at a given trajectory, losses occurthrough opening pre-existing natural fractures and initiation of new (induced) fractures occurs if thewell pressure exceeds the fracture gradient e.g. when mud weight overcomes borehole stresses androck strength.

Compressive failure: when the well pressure is too low for a particular well trajectory, wellborestress builds up and the wellbore wall tries to contract and close. This can occur at high or low mudweights. The mode of failure depends on mechanical properties of the rock, varying from creepclosure in weak and soft ductile formations like salt to while in competent and brittle rocks, this leads tocavings and overgauge holes, when the cavings fall into the wellbore.

These generalised failure types are illustrated below and overleaf

Tensile failure

Circulation lostthroughinduced fractures

Mud pressure


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6

Section


Compressional failure

Elastic formations such assandstones and shales

Hole enlargementthroughbreakouts

Hole reductionDuctile formationssuch as salt

OVERGAUGE HOLE

Breakout

OVERGAUGE HOLE

Washout Shale(Brittle)

HOLE CLOSURE

Creep

LOST CIRCULATION

Induced fractures

Limestone

Sandstone

Salt

Friablesandstone/sand

Shale/mudstone


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7

The following diagram illustrates the safe mud weight window for trouble-free drilling in a conventionallystressed earth in which V>Hh. The blue curves show the compressional failure limits while thered curve shows the tensile fracture limit. The window narrows as well deviation increases

2 4 6 8 10 12 14 16 18 20

80

60

40

20

0

Borehole

deviation,

degree

Safe window

Tensile failure

Compressionalfailure

Mud weight, lbm/gal (SG)

(0.24) (0.48) (0.72) (0.96) (1.20) (1.45) (1.69) (1.93) (2.17) (2.4)

When we drill the wellbore we replace a cylinder of rock with a cylinder of mud. The first criticalstep towards designing a drilling fluid is to establish the mud weight required to provide the correctlevel of bore hole pressure support.

Borehole Pressure Support

Pore pressure prediction involves the full cooperation of several different engineering disciplines,i.e. Petrophysical, Geology, Reservoir & Geomechanics.

It is crucial that rigorous seismic and / or geological well data interpretation is done to determine theanticipated pore pressure regimes in order to identify any pressure reversals and therefore facilitateappropriate casing design.

Mud weight planning is based on the predicted pore pressure gradient plus, typically, 200 to 500 psi(1379 3449 kPa).

It is crucial that the drilling engineers thoroughly review all available offset well data with a specialemphasis on procuring offset leak off and / or F.I.T. test data.

One of the key elements to successfully drilling a stable, near gauge wellbore depends upon planning

the correct mud weight.

Maintaining Borehole Support

Wellbore stability is a complex balance of mechanical (pressure and stress) and chemical factors.The chemical composition and mud properties must combine to provide a stable wellbore untilcasing can be run and cemented. Regardless of the chemical composition of the fluid and otherfactors, the weight of the mud must be within the necessary range to balance the mechanical forcesacting on the wellbore (formation pressure, wellbore stresses related to orientation and tectonics).Wellbore instability is most often identified by a sloughing formation, which causes tight holeconditions, bridges and fill on trips.

Fluid hydrostatic pressure acts as a confining force on the wellbore. This confining force acting across

a filter cake will assist in physically stabilising a formation.


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8

Section


STABLE WINDOW

+/- 200 psi (1379 kPa)to 500 psi (3449 kPa)

overbalanceFracture gradientPore pressure gradient

Wellbore stability is greatest when the hole maintains its original size and cylindrical shape. Oncethe hole is eroded or enlarged in any way, it becomes weaker and more difficult to stabilise. Holeenlargement leads to a number of problems, including low annular velocity, poor hole cleaning,increased solids loading, fill, increased treating costs, poor formation evaluation, higher cementingcosts and inadequate cementing.

Borehole stability is also maintained or enhanced by controlling the loss of filtrate to permeableformations and by careful control of the chemical composition of the drilling fluid. Most permeableformations have pore space openings too small to allow the passage of whole mud into the formation;however, filtrate from the drilling fluid can enter the pore spaces. The rate at which the filtrate entersthe formation is dependent on the pressure differential between the formation and the column of

drilling fluid, and the quality of the filter cake deposited on the formation face.

Large volumes of drilling fluid filtrate, and filtrates that are incompatible with the formation orformation fluids, may de-stabilise the formation through hydration of shale and/or chemical interactionsbetween components of the drilling fluid and the wellbore. Drilling fluids, which produce low qualityor thick filter cakes, may also cause tight hole conditions including stuck pipe, difficulty in runningcasing and poor cement jobs.

Chemical wellbore instability is due to chemical interaction between the formation being drilledand the drilling fluid. This occurs primarily in shales and salt formations. In both cases, it is aninteraction with water that causes instability. Thus, chemical instability is always minimised by usingoil-base muds.

In shales, if the mud weight is sufficient to balance formation stresses, wells are usually stable - at first.With water-base muds, chemical differences cause interactions between the drilling fluid and shale,and these can lead (over time) to swelling or softening. This causes other problems, such as sloughingand tight hole conditions. Highly fractured, dry, brittle shales, with high dip angles, can be extremelyunstable when drilled. The failure of these dry, brittle formations is mostly mechanical and not normallyrelated to water or chemical forces.

When shales react with water, they can soften, disperse, swell, and crack. These effects can cause a widerange of operational problems, as shown in the table below.

Stable Mud Weight Window


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9

Shale Type

Soft(shallow)

Firm(deeper)

Hard(deep)

Brittle(very deep)

Typical Hole Problems

Tight hole due to swelling Hole enlargement due to washout

Ledges if interbedded with sandstones Bit balling, mud rings, blocked flowlines Tight hole due to swelling Possible washout Prone to bit balling Occasional cavings Cavings Cuttings beds causing packing off Tight hole in stressed formations Possible stuck pipe Cavings Hole collapse

Table 1

MBT*

(meq/100g)

20-40

10-20

3-10

0-3

Clay Types

smectite+ illite

illite + mixedlayer

illite + poss.smectite

illite kaolinitechlorite

* MBT = methylene blue test - a measure of cation exchange capacity; high MBT equates to smectiterich shale.

Various chemical inhibitors or additives can be added to help control mud/shale interactions.Systems with high levels of calcium, potassium or other chemical inhibitors are best for drilling intowater-sensitive formations. Salts, polymers, asphaltic materials, glycols, oils, surfactants and other shaleinhibitors can be used in water-base drilling fluids to inhibit shale swelling and prevent sloughing.Shale exhibits such a wide range of composition and sensitivity that no single additive is universallyapplicable.

Oil or synthetic-base drilling fluids are often used to drill the most water sensitive shales in areaswith difficult drilling conditions. These fluids provide better shale inhibition than water-base drillingfluids. Clays and shales do not hydrate or swell in the continuous oil phase, and additional inhibitionis provided by the emulsified brine phase (usually calcium chloride) of these fluids. The emulsifiedbrine reduces the water activity and creates osmotic forces that prevent adsorption of water by theshales.

In salt formations, chemical instability occurs if the formation is soluble in water. Using an incorrectly

formulated fluid will lead to uncontrollable washouts in these formations. Formation types which

exhibit this behaviour are:

Halite (NaCl) Carnallite (KMgCl3.6H2O) Bischofite (MgCl2.6H2O) Sylvite (KCl) Polyhalite (K2Ca2Mg(SO4)4.2H2O)

Salt beds are usually drilled using salt saturated water phase fluids, the salt selected is usually the sameas the salt being drilled.


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10

Section

2 drilling fluid functionssecondary functionsSecondary functions of a drilling fluid include:

Support weight of tubulars Cool and lubricate the bit and drill string

Transmit hydraulic horsepower to bit Provide medium for wireline logging Assist in the gathering of subsurface geological data and formation evaluation

support weight of tubularsDrilling fluid buoyancy supports part of the weight of the drill string or casing. The buoyancy factoris used to relate the density of the mud displaced to the density of the material in the tubulars;therefore, any increase in mud density results in an increase in buoyancy.

cool and lubricate bit and drill stringConsiderable heat and friction is generated at the bit and between the drill string and wellboreduring drilling operations. Contact between the drill string and wellbore can also create considerable

torque during rotation, and drag during trips. Circulating drilling fluid transports heat away from thesefrictional sites, reducing the chance of pre-mature bit failure and pipe damage.

The drilling fluid also lubricates the bit tooth penetration through rock and serves as a lubricant betweenthe wellbore and drill string thus reducing torque and drag.

An additional source of heat is derived from the increasing thermal energy stored in formations withdepth, geothermal gradient. The circulating fluid not only serves as a lubricant helping to reduce thefriction between the drilling components in contact with the formation, but also helps conduct heataway from the friction points and formation.

transmit hydraulic horsepower to bitHydraulic horsepower generated at the bit is the result of flow volume and pressure drop through thebit nozzles. This energy is converted into mechanical energy which removes cuttings from the bottomof the hole and improves the rate of penetration.

provide medium for wireline loggingAir/gas-based, water-based, and oil-based fluids have differing physical characteristics which influencelog suite selection. Log response may be enhanced through selection of specific fluids and conversely,use of a given fluid may eliminate a log from use. Drilling fluids must be evaluated to assure compatibilitywith the logging program.

assist in formation evaluationThe gathering and interpretation of sub-surface geological data from drilled cuttings, cores andelectrical logs is used to determine the commercial value of the zones penetrated. Invasion of thesezones by the fluid or its filtrate, whether it is oil or water, may mask or interfere with the interpretationof the data retrieved and/or prevent full commercial recovery of hydrocarbon.


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mud testing procedures

section 3


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section 3a - wbm testing procedures

section

section 3b - naf testing procedures


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health, safety and environmentMud Engineers will be responsible for ensuring that all mud testing activities are carried out in a safe

and responsible manner, especially those involving high pressures, high temperatures and dangerouschemicals. Be aware of the hazards and ensure that all risks are well managed.

Mud Engineers will be responsible for ensuring that all hazardous testing chemicals are correctly

labelled, and safely stored and handled. They will also ensure that testing chemicals sent off the rig are

correctly packaged and labelled.

MSDS sheets for all the mud testing chemicals should be available in the mud lab. Copies should also be

distributed to the Medic, client representative and the contractor representative.

Empty bottles of testing chemicals should be thoroughly flushed out with water and then returned to

the Mud Company for re-cycling or disposal.

A Hazchem poster should be posted in the lab, detailing all the mud testing chemicals:

Product Name

Colour Code

UN Code

First Aid Treatment

Fire Fighting Media

Action for Spillage

Personal Protection Recommended

It is recommended to have a pair of oven gloves available for handling hot testing equipment, eg. retort

and HTHP.

Safety glasses are mandatory when conducting any mud test. This will help protect the eyes from

broken glass, or being splashed with chemicals, mud or mud filtrate.

Pipette filling devices are recommended for titrating, as they will prevent any dangerous chemicals

being swallowed.

Mud engineers should ensure that the mud lab has an adequate method of extracting fumes from

chemicals or retorts. Either a strong extractor or a fume cupboard is recommended. If fume extraction is not

adequate then recommendations for its improvement should be submitted to the client representative.

If the mud lab is sited in a designated hazardous area the mud engineers should ensure that the mudlab is suitably pressurised. If pressurisation is inadequate then recommendations for its improvement

should be submitted to the client representative.

An adequate number of power points of the correct voltage should be available in the mud lab.

Power points that have too many appliances running off them are a common source of fire. If there are

not enough power points often a request to the rig electrician can resolve the matter. If that is not

successful then the client representative should be consulted.

Any base oil, or synthetic or ester based mud samples that are used for testing should be kept and

disposed of in the active mud system. It should not be flushed down the sink.

If practical, the surfactant mixtures that have already been used for testing non water base muds shouldbe kept in a suitable container and later sent to shore for appropriate disposal.

Surgical gloves should be available for handling dangerous testing chemicals or non water base fluids.

mud testing procedures

Section

3


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Section

3 mud testing proceduresgood laboratory practices

Regularly calibrate mud balances, pH, electrical stability and K+ meters.

Ensure that all testing equipment is kept clean, working properly and that spare parts are available.

This is particularly important in reference to O rings, batteries, gaskets, pressure regulators, HTHPvalves, and meter probes.

For critical instruments like the 6 speed Viscometer, it is necessary to have a back up 6 speed Viscometer,

or handcrank available.

All bottles of titrating chemicals must have a manufactured date on them. The date will indicate

whether the chemical is still fresh enough to return accurate results. Ensure that a good supply of

fresh testing chemicals is available. If there is any uncertainty about the accuracy and/or age of a

particular chemical compare results obtained using a fresh sample of the same chemical. Ensure, where

applicable, that all testing chemicals, including Drger tubes and stick chemical testers, eg. nitrates and

sulphites are within their use by date.

Always use a dedicated, labelled pipette for each testing chemical. This prevents cross contamination

of testing chemicals and erroneous test results.

After use the WBM filtrate sample pipette should be flushed with distilled water and allowed to dry

before re-use. This prevents salt crystals forming on the tip of the pipette.

Use 50 ml glass beakers stirred with a small magnetic bead on a hot plate/stirrer in preference to the

traditional ceramic or plastic titration dish and a glass rod stirrer. This method is far simpler and will

lead to more consistent results.

Wash all glassware with distilled water after use and drain dry or dry off with a clean paper towel.

Keep the mud lab clean and tidy.


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section 3a

wbm testing procedures


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mud density 2

funnel viscosity 3

rheology 4

retort analysis 7

api filtrate 10

hthp filtration 11sand content 13

pH 14

filtrate alkalinity Pfand Mf 16

filtrate hardness Ca++and Mg++ 18

filtrate chlorides 20

phpa content 22

potassium ion direct reading potassium ion meter 25

potassium ion sodium perchlorate method

(steiger method) 26

mbt test 27

glycol cloud point and % by vol concentration 29

garrett gas train - sulphides 30

garrett gas train - carbonates 34

silicate testing 37

section 3a Scomi Oiltools


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2

Section

3a wbm testing procedures

mud density

discussionThe Mud Balance is used for mud weight determinations and is the

recommended equipment in the API 13B standard procedures for testing

drilling fluids. The mud balance is accurate to within +/- 0,1 lb/gal (or 0.5

lb/cu.ft, 0.01 g/ml, 10 g/l). It is designed such that the mud cup, at one end

of the beam, is balanced by a fixed counterweight at the other end, with a

sliding weight rider free to move along the graduated scale. A level bubble is

mounted on the beam to allow accurate balancing.

This, most basic, of mud properties is often reported incorrectly due to the

use of an inaccurately calibrated mud balance. The time to check the balance

is not when a well control situation develops but on a routine daily basis.

The mud test kit will contain both standard mud balances and a pressurised

Halliburton mud balance. Both types are calibrated by weighing distilled

water at 70 F (21.1 C) and obtaining a reading of 1.00 SG / 8.345 lb/gal. If

this is not the case adjust the balance by adding or removing lead shot as

required.

Experience has shown that, under normal drilling conditions, the standard

balance gives the same reading as the pressurised balance. For ease of use,

therefore, the standard balance may be routinely used to measure mud

density.

At the first indication of gas or air entrapment in the mud only the pressurised

balance should be used.

On a per tour basis the pressurised balance will be used to confirm it is reading

the same as the standard balance

equipment Standard Mud Balance

Pressurised Mud Balance

procedure standard balance1) Instrument base must be set on a flat level surface.2) Measure and record the mud temperature.

3) Fill the mud cup with the mud to be tested. Gently tap the cup to encourage

any entrapped gas to break out.

4) Replace cap and rotate until it is firmly seated, ensuring some of the mud

is expelled through the hole on top, to free any trapped gas.

5) Holding cap firmly (with cap hole covered

with thumb) wipe the outside of the cup

until it is clean and dry.

6) Place the beam on the base support and

balance it by using the rider along the

graduated scale. Balance is achieved

when the bubble is directly under the

centre line.

wbm testing procedures

Have you

checked the

mud balance

lately?

Example of standard mud balance


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3

procedure pressurised balanceA problem with many drilling fluids is that they contain considerable amounts

of entrained gas, leading to inaccurate mud weight measurements on the

standard mud balance. By pressurising the mud cup the entrained air volume

can be decreased to a minimum. The balance operates in much the same way

as standard mud balance except the lid of the mud cup has a check valve.

1) Follow steps 1 - 5 as for the standard mud balance procedure.

2) Place the lid on the cup, with the valve in the open position, wipe the

outside of the cup clean and dry.

3) The pressurising plunger is similar to operating a syringe. The plunger is

filled by submersing the nose of the plunger in the drilling fluid with the

piston rod in the completely inward position. The piston rod is then drawn

up, thereby filling the plunger with fluid.

4) The nose of the plunger is then placed into the female O ring on top of

the cap. The sample is pressurised by maintaining a downward force on

the cylinder housing in order to hold the check valve open, whilst at the

same time forcing the piston rod inwards. Approximately 50 pounds of

force or greater should be maintained on the piston rod.

5) The check valve in the lid is pressure actuated, i.e. closing as pressure is

applied. The valve is therefore closed by gradually easing up on the cylinder

housing while maintaining pressure on the piston rod.

6) Having applied pressure to the sample with the pump there should be no

indication of fluid leaking back through the nipple. It should not be possible

to depress the nipple by hand if the nipple can be easily depressed it

is a sign that pressure is not being held and a true weight is not being

obtained. Change the O ring and repeat the test.

7) Once the check valve is closed, disconnect the plunger and weigh the fluid

as in step 6 of the standard mud balance procedure.

interpretationThe density of WBM does not vary greatly with temperature. However, it is still

a requirement to report the density at flowline and ambient temperatures.

Water based muds can be prone to air entrapment and foaming. It is important

to ensure that the density reported is as accurate as possible. The reason for

this is that under downhole conditions the mud is compressed and thus the

effective mud weight at the bottom can be much higher than indicated by a

gas cut surface sample.

Do not weigh up mud to compensate for an aerated or gas cut surface sample

Ensure you have a true mud weight beforedoing anything.

For density control purposes the mud weight will always relate to what is

being measured at flowline temperatures as this is the best indicator of what is

actually in the hole at any particular time.

funnel viscosity

discussionThe Marsh Funnel Viscometer is used for routine viscosity measurements. The

results obtained are greatly influenced by rate of gelation and density. The

latter varies the hydrostatic head of the column of mud in the funnel. Becauseof these variations, the viscosities obtained cannot be correlated directly with

those obtained using the rotational viscometers, and therefore can ONLY be

used as an indicator of mud stability, or relative changes to mud properties.


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4

Section

3a wbm testing proceduresThe funnel viscosity will be measured in seconds per quart.

The funnel must be calibrated on a regular basis. The viscosity of fresh water

at 70 F (21.1 C) is 26 secs/qt (27.6 sec/l) and any reading above this would

indicate that the spout of the funnel required cleaning. The diameter of the

spout is 3/16 and a hand held drill bit of this diameter should be used to clear

any deposits/cake.

equipment Thermometer: 32 220 F (0 105 C)

Stopwatch

Graduated cup: one quart / litre

Marsh funnel

procedures1) Cover the orifice with a finger and pour a freshly agitated fluid sample

through the screen into the clean, dry and upright funnel until the liquid

level reaches the bottom of the screen.2) Quickly remove the finger and measure the time required for the fluid to

fill the receiving vessel to the one quart (946 ml).

3) Report the result to the nearest second as Marsh Funnel viscosity and the

temperature to the nearest degree.

interpretationThe funnel viscosity is a good quick guide to whether a water based mud

is thickening or thinning. However further analysis of rheology and solids

content will be required before embarking on any treatment program.

The result is temperature dependent but not to the same degree as SBM.

The funnel viscosity is, therefore, a more relevant indicator of trends in a

WBM.

rheology

discussionThe rheology will be determined using a Motor Driven Fann 6 speed

Viscometer. Ensure that the Viscometer motor runs at the same electrical

cycles (either 50 hertz or 60 hertz) as the rig power, otherwise erroneous

readings will be obtained. Offshore rigs usually operate on 60 hertz.

All Viscometers sent to the rig site must have been recently calibrated and

carry a label noting the date of the last calibration.

Drilling fluid is contained in the annular space between two concentric

cylinders. The outer cylinder or rotor sleeve is driven at a constant rotational

velocity. The rotation of the rotor sleeve in the fluid produces a torque on

the inner cylinder or bob, and the dial attached to the bob indicates

displacement of the bob. This is the standard procedure recommended by

API 13B for field testing water based drilling fluids.

Instrument constants have been adjusted so that the Bingham plastic

viscosity and yield point can be obtained by using the readings at 300 rpm

and 600 rpm.

When checking oil

base mud systems it is

recommended to insert

the thermometer in the

actual fluid to ensure

the correct testing

temperature has been

reached


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5

The six readings will be taken at 120 F (48.9 C). A heated cup will be

used for this purpose. Water Based Muds exhibit thinning tendencies with

temperature and so it is still necessary to standardise this test by taking the

readings at the same temperature on each occasion.

The thermometer used must be calibrated against a mercury or alcohol

type thermometer to confirm its accuracy. To adjust the thermometer

simply use a small spanner to turn the nut on the back of the dial so that

the thermometer reads the same temperature as the mercury or alcohol

thermometer.

The rheometer readings may be taken at a higher temperature, to reflect flow

line temperatures, if required. However, to avoid confusion and to allow

comparisons between wells, usually only the 120 F (48.9 C) readings will be

entered in the mud check columns on the mud report. If necessary, readings

taken at higher temperatures can be noted in the comment section.

Note: Maximum operating temperature is200 F (93 C). If fluids above 200 F

(93 C) are to be tested, a solid metal

bob or a hollow metal bob, with

completely dry interior, should be

used. Liquid trapped inside a hollow

bob may vaporise when immersed in

high temperature fluid and cause the

bob to explode.

The gelling characteristics of the fluid can

be determined from taking a 10 second

and a 10 minute gel reading. Consequently

there is no requirement to take a 30 minute

gel under normal circumstances. However

if increasing rheology is becoming a

problem a 30 min gel should also be taken

in order to determine the effectiveness of

the treatment programme.

equipment Fann 35, 110 volt or 120 volt, powered by a two speed synchronous motor

to obtain speeds of 3, 6, 100, 200, 300 and 600.

Mud cup Stopwatch

Thermometer 32 220 F (0 104 C)

procedures1) Stir the sample at 600 rpm while the sample is heating, or cooling, to 120 F

(48.9 C). Ensure the dial reading has stabilized at this speed before noting

the result and proceeding to the 300, 200, 100, 6 and 3 RPM speeds.

2) Having taken the 3-RPM reading stir the sample at 600 RPM for 30 secs

before taking the 10-second gel at 3 rpm.

3) Restir the sample at 600 rpm for 30 seconds and leave undisturbed for

10 minutes, ensuring the temperature stays at 120 F (48.9 C). Take the10 minute gel reading at 3 rpm.

Example of 6 Speed

Rheometer


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6

Section

3a wbm testing procedurescalculationsApparent Viscosity (AV) in = 600 reading 2

Centipoise (cps)

Yield Stress = 2 x 3 reading 6 reading

Plastic Viscosity (PV) in = 600 reading - 300 readingCentipoise (cps)

Yield Point (YP)

Yield Point (YP) in Ib/100 ft2 = 300 reading PV

Yield Point (YP) in Pa = (300 reading PV) x 0.48

Power Law Index (n) = 3.32 log (600 reading / 300 reading)

Consistency Index (K):

Consistency Index (K) in Ib/100 ft2 = 600 reading / 1022n

Consistency Index (K) in Pa = (600 reading / 1022n

) x 0.48

Gels:

Gels in Ib/100 ft2 = As per 10 sec & 10 min reading

Gels in Pa = (As per 10 sec & 10 min reading) x 0.48

Note: If the 600 rpm reading is off scale then the PV and YP can be calculated

as follows;

YP in Ib/100 ft2 = (2 X 100 rpm reading) 200 rpm reading

YP in Pa = [(2 X 100 rpm reading) 200 rpm reading] x 0.48

PV = 300 rpm YP

PV (S.I units) =

interpretationThe main focus of attention, with regards to mud rheology, is the 6 rpm reading.

Mud programs will specify a range for the 6 rpm reading and so the other

indicators of rheological properties, i.e. yield point, apparent viscosity, plastic

viscosity and initial gel strengths, become a function of what is required to meet

this low end specification.

Experience has shown that the initial gel strength will be more or less the same

as the 6-rpm reading.

10 minute gels that show an increasing trend and a widening divergence from

the initial gel are a good indicator of a colloidal solids build up that may not be

detected by solids analysis. This is due to the fact that while the solids percent

may remain the same the actual size of the particles, and hence the surface area

they present to the liquid phase, will decrease as degradation occurs.

If the colloidal solids increase is not due to reactive claystones then the MBT

test may not reveal the true nature of what is happening. The 10 minute gel

in a WBM will always react to increasing fines and can often be the best indicatorof solids related changes to mud properties.

Increasing PV values are also generally a good indicator of a solids build up.

300 rpm reading YP

0.48


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It is important to identify increasing trends at an early stage so that timely

measures may be taken before they reach problem levels.

retort analysis

discussionThe accuratedetermination of the high gravity solids and low gravity solids

in a WBM mud relies on the correct usage of the 50 ml retort and the correct

interpretation of the results.

A retort is used to determine the quantity of liquids and solids in a drilling fluid.

A carefully measured sample of mud is placed in a steel cell and then heated

until it vaporises. The vapours are then passed through a condenser and

collected in a calibrated cylinder. The volume of liquid, water and oil can then be

calculated in percent. The percent solids value, both suspended and dissolved,

is determined by subtraction of the total liquid from 100%.

Small errors in the measurement of the solids percentage can result in seriously

erroneous reporting of the drilled solids content. It is apparent that inaccurate

retort results can lead to unnecessary mud treatments aimed at reducing an

apparently out of spec LGS concentration.

It is essential that the retort be run at a high enough temperature to burn off

the heavier fractions of any liquid additives such as glycol or lubricants.

It is absolutely critical that the correct mud weight is used in the calculation

to determine the relative concentrations of HGS and LGS. Using the flowline

mud weight when the sample to be retorted has in fact cooled considerably,

and hence increased in density, will give a much higher LGS content than

is actually the case. The retort mud weight, i.e. the actual density of the mud

in the retort as opposed to the flow line mud weight, will, therefore, be utilised

in all calculations.

The volume of the retort will be confirmed by filling the cell with distilled

water (at ambient temperature) and checking that 50 ccs is in fact received in

the test tube. If 50 ccs is not consistently obtained with distilled water (it might

be necessary to repeat the check with distilled water to ensure the error is

genuine) then, either the 50 cc retort cell must be replaced with an accurate

one, or, a correction factor must be applied to the volume of distillate actually

obtained, as per the following formula:

50

Volume of distilled water obtained ccsx Volume of distil late ccs

Any smoke emerging from the heating jacket is an indication that vapour is

escaping through the threads connecting the upper and lower parts of the

retort cell. If this is noted it is an indication that the tube to the condenser is, or

has been, blocked. A blocked tube will result in the bottom of the upper part

of the retort cell flaring to allow an escape route for increasing pressure. Even

if the tube is subsequently cleaned the flaring will remain and is still an

escape route for a proportion of the vapour. This will obviously result in aninaccurate solids measurement. Any hint of smoke from the heating jacket

is an indication that the top part of the retort cell is damaged and should be

discarded.


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Section

3a wbm testing proceduresIt can be appreciated that a combination of all, or some of the factors

mentioned above, i.e. insufficient retort temperature, incorrect mud weight

used in calculations, volume being retorted not in fact 50 ccs, partial escape

of vapour through flared threaded area, can result in wildly inaccurate

determinations of the drilled solids content.

equipmentThree retort sizes are available to the industry, 10 ml, 20 ml and 50 ml. The

latter is recommended for drilling operations, due to its greater precision and

accuracy. Each unit consists of;

Sample cup

Thermostatically controlled heating element

Liquid condenser

Pyrex measuring cylinder (50 ml)

Fine steel wool

Pipe cleaner

High temperature silicone grease Defoaming agent

Spatula

procedures1) Ensure retort assembly to be used is clean

and dry. It is vital that all traces of previously

retorted solids are removed from the retort

cup to guarantee 50 ml of fluid is actually

retorted. Remove all traces of previously

used steel wool. Water can be retained in

steel wool when the upper retort body

is washed / cleaned. Failure to change

the steel wool can result in inaccurate

measurements, as this extraneous water

will become included in the total water content.

2) Weigh the clean and dry retort cup and lid on the triple beam balance.

3) Add the mud, which has been allowed to cool to ambient temperature,

to the retort cup, gently tap the cup to remove any air bubbles and place

the lid with a rotational movement to obtain a proper fit. Be sure an excess

of fluid flows out of the hole in the lid.

4) Carefully clean the cup and lid of excess fluid and reweigh on the triple

beam balance. The retort mud weight SG is determined as the difference

between the empty and full weights, in grams, divided by 50 (the volume ofmud).

5) Pack the retort body with new steel wool, apply NeverSeez, to the threads

and assemble top and bottom parts. Ensure that the two parts are fully

screwed together. If it is not possible to fully screw together the two parts it

will be necessary to clean the threads and repeat the above steps. Failure to

get a good seal could result in leakage that will lead to an inaccurate result.

6) Attach the condenser and place the retort assembly in the heating jacket

and close the insulating lid.

7) Place clean, dry liquid receiver below condenser outlet and turn on heating

jacket.

8) The temperature control should be adjusted so that the retort cell glowsdull red at the end of the distillation. Ultimately smoke will emerge from

the retort and the distillation is only complete when the smoke stops.

Example of Retort


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calculations SG of drilled solids (LGS) = 2.60

SG of Barite (HGS) = 4.25

SG of oil additive = SGo

Input Data

SG of mud in retort = SGm

Retort % oil = Of

Retort % water = Wf

Retort % solids = Sf

Salinity mg/l =

SG of Brine = SGb (Look up Salinity in

specific brine table)

Correction factor = CF (From brine table)

Brine fraction = Bf (Correction factor x Wf) Corrected Solids = CS [Sf - Salt content (Bf - Wf)]

Then

Average SG of Solids =

(AVSG)

% LGS =

=

% HGS = CS - % LGS lb/bbl LGS = %LGSx 3.5 x 2.6

= %LGSx 9.1

lb/bbl LGS = %HGSx 3.5 x 4.25

= %HGSx 14.87

kg/m3LGS = %LGSx (9.1 x 6.2897) 2.205

= %LGS x 25.96

kg/m3HGS = %HGSx (14.87 x 6.2897) 2.205

= %HGSx 42.42

interpretationThe control of the low gravity solids content of a WBM system will trigger

the use of centrifuges or dilutions. If mud costs were broken down and assignedto a particular reason then the control of LGS would probably account for the

bulk of expenditure on most wells. For this reason very careful attention must

be paid to the points outlined in the Discussion section above.

This test is a reliable indication of the condition of a drilling fluid on a one

off basis. The results of other tests may change, for example, with shear and

temperature i.e. the rheology may increase, the API filter loss may decrease

without any additions being made to the mud. The LGS content, however, is

something that can be assessed, and tackled if required, without waiting for

trends to be established from further tests.

The calculations are extremely sensitive and a 0.5% difference in total solids

content will have a large affect on the LGS fraction. For this reason it is

important to be meticulous when taking the volumes of oil, water and solids.

mls of 0.282NAgNO3 x 10,000

%Water 100

SGm x 100 - [(Of x SGo)+(Bf x SGb)]

CS

CSx (4.25 -AVSG)

4.25 - 2.6

CSx (4.25 -AVSG) 1.65


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Section

3a wbm testing proceduresapi filtrate

discussionFiltration control is one of the primary characteristics of a drilling fluid and

fulfils a variety of functions from the prevention of differential sticking to

minimisation of formation damage.

Filtrate control can be established at just about any level but the cost increases

almost exponentially as tighter and tighter properties are required. A fit for

purpose attitude must be adopted when programming fluid loss levels to

avoid non-justifiable expense. No benefit may be gained, for example, from

having a fluid loss of 3 ml as opposed to 5 ml but mud costs will have doubled.

Further, over treatment with fluid loss polymers, especially PAC polymers,

can have a detrimental effect on the rheology by reducing the muds shear

thinning characteristics.

The API test for WBM is carried out at ambient temperature and with only

100 psi (690 kPa) of differential pressure. This quite patently does not mirror

downhole conditions. However experience has shown that this test is a reliable

way of measuring the performance of a drilling fluid at any given moment.

The results must be viewed in conjunction with the thickness of the filter

cake that has been formed by the end of the test. A low solids polymer mud

may have a relatively high fluid loss but the filter cake is almost non existent

whereas a high solids mud may have a lower fluid loss but a much thicker

filter cake.

equipment

Filtration Cell OFI specially Hardened Filter paper - Filtration Area 7.07 sq.in (Alternatively

- Whatman No 50 paper)

Low Pressure CO2supply 100 psi (690 kPa) (Soda stream cartridges)

Stop Clock

10 and 25 ml measuring cylinders

procedure1) Assemble the clean and dry components that form the cell of this piece of

equipment.

2) Ensure the filter paper is Whatman no 50 (or equivalent) and make sure

the screen is not damaged. A creased screen can result in weaknesses in

the filter cake that seem to result in higher results than would normally be

expected.

3) Pour the mud sample into the cell to 0.5 from the top, put the top in place

and position it in the support frame.

4) Place a dry graduated cylinder of suitable size (usually 10 ccs) under the

drain tube and apply 100 psi of pressure over 15 seconds.

5) Maintain a constant 100 psi (690 kPa) throughout the test period.

6) After 7.5 mins measure and record the amount of filtrate collected to the

nearest 0.1 ml.

7) After 30 mins measure and report the amount of filtrate collected to the

nearest 0.1 ml.

8) Having bled off the pressure, dismantle the equipment and examine thefilter cake. Report the thickness in 32nds of an inch (mm). Comments about

the quality of the cake should be noted in the comments section of the

mud report i.e. texture, colour, hardness, compressibil ity, flexibility etc.


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calculations API Fluid Loss = 30 min Reading

* Relative API Fluid Loss = (30 min Reading - 7.5 min reading) x 2

Spurt Loss = API Fluid Loss - Relative API Fluid Loss

* Relative API Fluid Loss is corrected for spurt loss prior to cake formation.

interpretationThe API fluid loss may not give an accurate representation of what is

happening under dynamic conditions at downhole temperatures and

pressures. Dynamic lab testing has shown solids content to be the key

influencing factor. Thus it could follow that a mud that has lower API fluid

loss than another may have a much higher dynamic loss.

However any change in fluid loss properties is a good indicator of general

mud health. Having established the required control any increasing trend must

be identified and treated as required.

Fluid loss can also decrease without any chemical additives as solids contentand particle size distribution optimises under drilling conditions.

Generally speaking, therefore, an increasing trend is bad and a decreasing trend

is good.

The results must be viewed in conjunction with the thickness of the filter cake

that has been formed by the end of the test. A low solids polymer mud may have

a relatively high fluid loss but the filter cake is almost non existent whereas a

high solids mud may have a lower fluid loss but a much thicker filter cake.

hthp filtration

discussionThe high pressure / high temperature filter press is a static filtration procedure

recommended by the API 13B standard procedures for testing drilling fluids

at elevated temperatures and pressures.

This test tends to be run at temperatures that reflect expected bottom hole

temperatures and thus there is no standardised temperature. However ensure

the test temperature is noted on the mud report.

These procedures are for temperatures up to 300 F (148.9 C). If higher testtemperatures are required a porous stainless steel disc will need to be utilized

instead of the normally used filter paper and higher top and bottom pressures

applied. When heating, apply 100 psi (690 kPa) to top and bottom, increase top

pressure to 600 psi (4138 kPa) for the test.

The thermometer used must be calibrated against a mercury or alcohol type

thermometer to confirm its accuracy. To adjust the thermometer, simply use a

small spanner to turn the nut on the back of the dial so that the thermometer

reads the same temperature as the mercury or alcohol thermometer.

Remember the screen and bomb are a matched pair. The use of unmatchedpieces of equipment may result in it being impossible to get a result as whole

mud breaches the seals at some point during the test. This is indicated when

the pressure gauge on the bottom pressure vess

Drilling Fluids Manual Handbook

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