3 Water Based Muds

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Agip KCO Well Area Operations

Drilling Supervisors Training CourseDrilling Muds 1RPW2021A

WATER-BASED DRILLING FLUIDS

(NON INHIBITING)

WATER-BASED MUDS





DRILL-IN FLUIDS………………14

PROCEDURES AND

LABORATORY EQUIPMENT…27

WATER-BASED DRILLING

FLUIDS (non-inhibiting)………03

INDEX





NON INHIBITING FLUIDS

• Fresh waters

• Muds prepared with formation clays

• Water-bentonite Spud Mud

• Guar-Gum suspension

• Bentonite and CMC based fluids

• Lignite/lignosulfonate muds (deflocculant) (FW/SW-LS)

• Contaminants: effects and remedial actions in non-inhibiting muds





Fresh Waters

Fresh water is not frequently used as continuous drilling fluid during start up drilling

because of inability to have thyxotropics properties and carrying capacity.

Sea Water

It is used as intitial drilling fluid in start up drilling off-shore every 10-15 mt drilled . It is

recommended to displace a viscous pill in order to sweep the drilled hole.

Mud prepared with formation clays

Frequently used as spud mud off-shore when the phase to drill is not deep and the

formation is clay prevalent. In this case, the mud is also called S.W.-native clay and only

caustic soda is added to help building up of the mud.






Water-Bentonite Spud Mud

Fresh water is suggested.

In case of shortage of F.W., prehydrate the bentonite in 25-30% of the volume in fresh water,

then add sea water and dilute to total volume.

Characteristics

Range of Density: 1.15 – 1.30 kg/l

Viscosity= 40-60 sec.

PV= 6-10 cps

YP= 5-10 gr/100 m2

(10-20 lbs/100 ft2

)

API Filter= 12-20 cc/30‘

pH= 8.5 – 9.5

Easily convertible to more complex system (after dilution).



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Well Area Operations


Formulation

Fresh Water or FW/SW

Bentonite 50/80 kg/m3 (17.5/ 28 ppb)

Caustic Soda ½ kg/m3 (0.35/0.7 ppb)

Limitations

Very sensitive to contaminants.

Non adequate for long section drilling.

Low solids tolerance






Guar Gum Suspension

• To be used off-shore

• Need sea water to enhance the viscosity

• It is often alternate to sea water. In this option, it is used as viscous pill, 8 to 20 MC

(depending on the bit size) every 10-15 mt drilled

• The Funnel viscosity suggested is over 100 sec/lt

• Easy and fast to mix. Low concentration of product is requested

• It reduces logistic problem for large initial volumes of mud.






Fomulation

Sea Water Guar-Gum 8-12 kg/l (2.8 – 4.2 ppb)

Bactericide As needed

Limitations

• Poblems of fermentation

• Degradation in presence of caustic agents

• Formation of “Fish Eyes” if not mixed adequately






Bentonite and CMC based fluids

• Used when FW-GE characteristics are not sufficient• Used in non reactive formations

• Not easy to weight it up

• Low cost

Characterisitcs

• Range of Density: 1.03 – 1,15 kg/l

• Funnel Viscosity: 50-80 sec/l• PV: 5-15 cps

• YP: 6-15 gr/100 cm2 12-30 lbs/100 ft2

• API Filter: 6-10 cc/30 min.

• PH: 8,5 – 9,5






Formulation

Fresh Water Bentonite 20-60 kg/m3 (7-21 ppb)

Caustic Soda 1-2 “ (0.3 – 0.7 ppb)

CMC HV 0-5 “ (0-1.8 ppb)

CMC LV 3-10 “ (1-3.5 ppb)

Limitations

• High sensitive to contaminants

• Low solid tolerance






Remove ions Ca++ content with soda ash.

Add lignosulfonate and/or convert into gypsum mud.

Drill speed variation. Yield point, Marsh viscosity, hardness

increase. pH, PM, PF decrease.Gypsum /anhydride

Reduce low density solids and MBT.

Use a thermal stable deflocculant.

Test mud to identify possible carbonates contamination.

Pump pressure increasing to break the circulation out . Viscous

bottom cushions after the tripsFreezing Temperature

If possible, increase the density to remove the flow.

Dilute with fresh water. Increase caustic soda and filtrate, chlorides.

Decrease the lignosulfonate to control rheological properties; when

they’re stabilized, add PAC for the filtrate control. If the chlorides

concentration is higher than 35,000 mg/L, to convert into salt mud

Well flow, yield point, Marsh viscosity, hardness and pH, , PM, PF

increase.Salt/salt water

Document the history of the product through the Supplier. Arrange

sampling and regular analysis.

Pilot test to be develop on good materials

Packing product changes.

Quantity increasing the treatment.

Impossibility of controlling mud properties through standard

treatments

Low-quality product

Increase the pH to 10.7 with NaOH o KOH.

Treat with gypsum and/or lime to remove carbonates (avoid

overtreating).Minor dilution.

Gel, yield point, and MF increase.

Viscous bottom cushions after the round trips

Carbonates

Remove cement content (Ca++) with bicarbonate and/or SAPP and

lignosulfonate.

Minor dilution.

Increase the PF to limit the Ca++ solubility.

If necessary convert into lime mud.

PM, P

F, pH, yield point and Marsh viscosity increase. Hardness

increase.Cement

Greater dilution.

Improve solids removal use of the centrifuges to treat the mud.Gels, solids content, plastic viscosity increaseHigh density solids

Treatment StrategyIndicatorsContaminants

Contaminats treating for bentonite-cmc and lignite/lignosulfonite muds

NON INHIBITING FLUIDSCONTAMINANTS: Effects and remedial actions in non inhibiting muds





DRILL-IN FLUIDS





INTRODUCTION

Drill-in fluids are non damaging fluids. They are used to drill mineralized formation

(reservoir). They are formulated to optimize the drilling performance and minimize

the damages to the reservoir, preserving the productive potential of the well.

Normally, the conventional muds can’t be converted in drill-in fluids.

Drill-in fluids are chosen to reduce the damaging effects (as fluid invasion) and to

obtain a good hole cleaning (clean-up) especially for open-hole completion.





Many well drilled with D.I.F. are completesd without programming “cemented casings” in

the productive area. The following steps are the recommended practice for a correct

D.I.F programme:

1. Identification type of formation and permeability.

2. Select the competion type.

3. Select the D.I.F.

4. Select the clean-up method (remove from the well cake and mud).

Drill-in fluids are particularly important in horizontal wells where clean-up practices are

more difficult.

INTRODUCTION





The damaging of the formation can be quantified with several means.

In laboratory:

• measures of return of permeability,

• solubility of the filter cake

• lift-off pressure

They are used to compare the performance of a fluid supporting the specific

formation in the well. The Skin Effect calculation and the Productivity rate are used to

measure the damaging.

INTRODUCTION





CONTROL OF THE FORMATION DAMAGING:

• The Drilling-in fluid must not contain clay or weighting material insoluble in

acid as barite which can enter in the formation and cause the blocking of the

porosities.

• It has to be formulate with acid soluble viscosifiers or “BREAKABLE” additivesfor the filtrate control and blocking agents with controlled granulometry (in

relationship to the values of porosity of the formation), that can be removed

from the well during the purging phase.

• The filtrate should be formulated to prevent hydration of the clay layers

INTRODUCTION





CONTROL OF THE FORMATION DAMAGING:

• In the filtrate there must not be salts that in reaction with the formation fluids can

precipitate the insoluble elements.

• The mud and filtrate must not change the wettability characteristics of the

formation either from Water-Wet to Oil-Wet or from Oil-Wet to Water-Wet.

• The filtrate mustn’t form emulsions with the formation fluids and cause blocking of

the same formation.

INTRODUCTION





DURING DRILLING

a) The D.I.F. has to guarantee a good cuttings transport (hole

cleaning, lubrication and inhibition on the formation clays.

b) It has to minimise cavings and ensure the hole stability.

INTRODUCTION





COMPATIBILITY WITH PROCEDURES AND COMPLETION EQUIPMENT

• The size (granulometries of product) of the D.I.F. additives has to allow the

formation of bridges in the cake and therefore not to penetrate deeply in the

formation. The size must be small enough to pass through completion

equipment.

• The D.I.F. must be formulated with materials: solubles in acid, soluble in

water, degradable with oxygenation or soluble with solvents but without

producing emulsions or precipitate.

• Breaker must be compatible with the formation fluids and the D.I.F. filtrate.

INTRODUCTION





To select an appropriate D.I.F. the following items must be studied in detail:

- Type of formation

- Permeability/porosity

- Pore pressure

- Mineralogy

- Composition of the formation fluid.

INTRODUCTION





Actions which damage the productive formation. They can occur during the execution

of the well and cause lower productivity values (daily production) and a minor

recovery of the reservoir reserves. Some of these harmful effects are reported as

follows with techniques of prevention.

DAMAGING MECHANISM OF THE FORMATION





Solids blocking

Hydration of the layer of clays

Emulsion block

Scaling

DAMAGING MECHANISM OF THE FORMATION





DRILLING FLUIDS TYPES AND APPLICATION

Clear fluids with viscous sweeps.

Fluids with HEC. (Hydroxyethilcellulose)

Sized-Salt System (NaCl)

The cleaning procedure is carried out in two phases:

– Acid soap to destroy polymers

– Low salinity water to dissolve the salt particles (they are in the cake with

starch).





PROCEDURES AND

LABORATORY EQUIPMENT





INTRODUCTION

• The American Petroleum Institute (API) recommends standardized methods for

laboratory and rig site tests which can be found in their publications.

• Recommended Practice: Standard Procedure for Field Testing Water-Based (Oil-

Based)

• Drilling Fluids, API RP 13B-1, 13 B2.





FLUID DENSITY (or MUD DENSITY)

INSTRUMENTS

The density, commonly called “mud weight” is checked with a mud balance whose

precision has a margin of error of 0.1 lb/gal. (10 gr/l).

The density is defined as weight per unit of volume.

The weight of mud may be expressed as density in: lb/gal or lb/ft3 or Specific Gravity

(SG)

litre

kg

or cm

g

or 62.3

lb/ft

or 8.345

lb/gal3

3

=

SG





MUD BALANCE

Description

Balance for mud





PROCEDURE

1. Fill the vessel with a sample of mud to check its weight.

2. Put the cap on again, rotate it several times to ensure that no solids are in its seat.

3. Rinse all and dry with a cloth.

4. Put the graduated bar of the balance down with care in equilibrium on the fulcrum.

5. Move the slider until the bubble of air is in the centre.

6. Read, near the cursor, the weight (or density) of the mud.

7. Write the weight, according to the system of measure desired, both in lb/gal, lb/ft3,

psi/1,000 ft of depth or Specific Gravity (SG).

8. If the balance in use does not have the system desired, the following equations

may be used.





MUD GRADIENT

psi/ft = 0.052 x lb/gal

= 0.4333 x SG

= 0.00695 x lb/ft3

kg/cm2/m = SG / 10

SG a 60°F (15.6°C) = (141.5) / (131.5 + °API)

Where: °API = American Petroleum Institute gravity





VISCOSITY

INSTRUMENTS

The Marsh Funnel is used in the rig site to measure the viscosity. The Fann V-G

viscosimeter is used when complete information on rheology is necessary(Plasticviscosity, yield point and gels).

Marsh Funnel and graduated cup





MARSH FUNNEL

Description

The Marsh Funnel is 6 inch. In diameter at the top and 12 inch long. At the bottom is has

a 2 inch smooth-bore tube having an insider diameter of 3/16 inch.

CalibrationFill the funnel till the bottom of the screen (1,500 cm3) with fresh water at

70±5°F. The time to flow of 1 qt (946 ml) should be 26 sec ±0.5 sec.





Procedure

Collect a fresh mud sample

Hold the funnel erect with a finger over the outlet tube, and pour the mud into the

funnel through the screen until the mud level reaches the bottom of the screen (The

screen will filter out the larger particles that could clog the outlet tube)

Quickly remove the finger from the outlet tube, and at the same time, begin timing themud outflow

Allow one quart of gallon (946 cc) of mud to drain from the Marsh Funnel into a

graduated container

Record the number of seconds it takes for the quart of mud to flow out of the funnel,

and report this value as the Marsh Funnel Viscosity. Also record the temperature of

the mud sample in degrees F or C.

MARSH FUNNEL





ROTATIONAL VISCOSIMETER

With a Rotational Viscosimeter it is possible to

measure the rate/shear stress of a drilling fluid

and you can calculate the Bingham PV and YP

parameters. With the same data it is possible to

use other rheological models. The Rotational

Viscosimeter is also used to measure the

thyxotropic properties and gel strength

Description

The Rotational Viscosimeter offers a direct

reading and functions electrically.

SPECIFICATIONS DIRECT READING





SPECIFICATIONS: DIRECT READING

VISCOSIMETER.

Rotor sleeve (external cylinder)

Internal diameter 1.450 in. (36.83 mm)

Total length 3.425 in. (87.00 mm)

Reference line 2.30 in. (58.4 mm) above the bottom of the cylinder.

Two rows of 1.8-in. (3.18-mm) holes spaced of 120 degrees (2.09 radiants)

around the rotor just below the reference line.

Bob (internal cylinder)

Diameter 1.358 in. (34.49 mm)

Cylinder length 1.496 in. (38.00 mm)

The BOB is closed with a flat base.





PROCEDURE TO DETERMINE APPARENT VISCOSITY,

PLASTIC VISCOSITY AND YIELD POINT

• Plastic Viscosity in centipoise = Reading at 600 RPM – Reading at 300 RPM (see

figure below)

• Yield Point in lb/100 ft2 = reading at 300 RPM less the plastic viscosity in

centipoise.

• Apparent Viscosity in centipoise = reading at 600 RPM divided by 2.

Typical “ flow curve” of a drilling fluid.





FILTRATION

DESCRIPTION

The filtration, or capacity of a mud to constitute a filter cake is determined by the filter

press. The test defines the Ratio with which a fluid is forced through the filter press.

This API Fluid Loss test must be carried out in specific conditions of duration,

temperature and pressure that according to the API Recommended Practice are

surface temperature, 100 psi and recorded as the number of millimeters lost in 30

minutes.





API FLUID LOSS

Procedure

1. Pressure availability at 100 psi with gas or air.(7 Kg/cm2).

2. Remove the cap from the bottom of the cleaned and dried cell. Install the O-ring to

check that its seat is not damaged, then turn the cell upside down for the filling.

Any mechanical imperfection can compromise the seal. Close the inlet hole with a

finger.

3. Fill the cell with mud up to ¼ inch from the housing of the O-ring. Put the filter

paper (Whatman No. 50 or equivalent) over the O ring. Put the cap on the filter

paper with its flanges between those of the cell, then turn in a clockwise direction

and close by hand. Turn the cell upside down and insert the cell body into the

bottom of the mud chamber of the filter press and turn in either direction to lock

the closure.





API FLUID LOSS

4. Put a graduated cylinder under the drain tube.

5. Open the valve to pressurize the cell. You will immediately notice a fluctuation of

the needle of the manometer which will indicate higher pressures during the

pressurization and then, it stabilizes at 100 psi.

6. The API duration for this test is 30 minutes. When the test is finished, close the

valve to stop the pressure at the source. The purge will occur automatically.

Remove the cell.





HIGH-TEMPERATURE, HIGH-PRESSURE (HTHP)

FILTRATION (High Pressure High Temperature)

HTHP Filter Press

MB style (API #II) HTHP fil ter pressDescription

The instrument consists of a heating

jacket with thermostat, cell plate

assembly, primary pressure assembly

and back-pressure receiver. The

capacity of the mud cell is 160 ml with

a filter area of 3.5 in.2.

Filtrate receiver holds 15 ml, and up to

100 psi backpressure can use a glass

tube. If a higher back pressure is to be

used, a stainless-steel tube should

replace the glass.

A routine test can be conducted at300°F and 500 psi differential pressure.

High-temperature fluid loss is recorded

as double the number of milliliters lost

in 30 min.







Procedure

1. Turn on the heating and wait for the instrument to reach the pre-heating

temperature. Put the thermometer in its housing and control the thermostat to

reach a temperature higher than the desired one of 10 °F.

2. Close the inlet valve of the cell and invert the cell.

3. Take the mud from the flow line. Pour it inside the vessel up to 0.2” below the

housing of the O-ring and wait for the expansion.

4. Put a filter of paper in the appropriate housing and put over it the O-ring. Use a

Watman filter No. 50 or equivalent.

5. Put the cover above the filter of paper and block it.

6. Shut the caps with strength and close the bleeding valve.

HIGH TEMPERATURE HIGH PRESSURE (HTHP)







7. With the cap of the cell at the bottom, put the cell inside the heater making sure

that all valves are closed. Transfer the thermometer to its location.

8. Install the cylinder of CO2 in its seat and turn it clockwise until the cover is opened.

The controller and the purge valve must be closed.

9. Keeping the lock ring raised, insert the primary unit of pressure in the upper

housing, and turn the lock ring to close.

10. Introduce a pressure of 100 psi against the valve, then open it to pressurize the

unit. This pressure will minimize the boiling during the heating of the sample.

11. Always use a container to prevent the vaporization of the filtrate if the test

temperature will reach or exceed the boiling temperature. Install and activate the

cylinder of CO2 in the purge unit.

12. Install the purge unit in the proper housing.

HIGH-TEMPERATURE HIGH-PRESSURE (HTHP)







13. Apply a pressure of 100 psi. at the lower unit while the valve is still closed.

14. Once you have reached the desired temperature (300°F), as indicated by the

thermometer, increase the pressure of the controller in the upper cell from 100 to

600 psi to make the pressure increase, keeping 100 psi with the lower controller.

Open the lower cell valve by one turn and start the test.

15. Keep a pressure of 100 psi on the receiver during the test. If the pressure raises,

discharge some of the filtrate and keep a differential of 500 psi. Keep the

temperature at ±5°F.








16. After 30 min., close the valve of the lower cell and then the higher one.17. Loosen either T-screws in the controller and discharge the pressure from either

controllers.

18. Discharge the filtrate in the graduated cylinder and read the volume. Double the

reading in the ratio. Remove the receiver.








19. Disconnect the primary unit of pressure raising the blocking ring and taking off the

unit. ATTENTION: The cell is pressurized.

20. Hold the cell erect and leave cooling at ambient temperature, then discharge the

pressure; the mud must not pass through the valve

21. Invert the cell, then loosen the screen of the cup. (If necessary, use an hexagonal

key) and disassemble. Clean and dry the various parts.

22. Visually observe and note the condition of the filter cake. It can be measured in

1/32 of an inch.



API #I Filterpress HTHP





API #I Filterpress HTHP

Tests at 300°F (149°C) or lower temperatures

TEST AT TEMPERATURE BETWEEN 300 AND





TEST AT TEMPERATURE BETWEEN 300 AND

400°F (149 to 233°C)

The same procedures are used, except the following cases, where the 500-ml cell is

suggested, manifold pressurization with azote:

1. During the heating of the sample, pressurize either units with 450 psi. At the

beginning of the test, the higher pressure raises at 950 psi while the lower pressure

is kept at 450 psi.

2. With temperatures between 350 and 400°F, a porous stainless steel disk (Dynalloy

X5 or equivalent) is preferred . (see API RP 13B-1 and 13B-2).

3. Heating time should not exceed 1 hour.





FILTER-CAKE COMPRESSIBILITY

For this test, the same procedure compared to 300°F (149°C) is applied, but there’s

a difference infact, 200 psi are applied to the cell and 100 psi to the receiver at the

bottom. The differential values regarding 100 and 500 psi are then compared.





SAND CONTENT

INSTRUMENTS

KIT FOR SAND CONTENT

The Sand Content Kit determines the volume percent of sand-sized particles in the

drilling fluid. API defines sand-sized particles as any material larger than 74 microns

(200 mesh) in size. This test can be performed on low solids fluids as well as on

weighted fluids. The kit consists of a glass tube graduated to read percent (%) by

volume, a funnel, and a 200-mesh sieve contained in a cylindrical-shaped holder.





SAND CONTENT

Procedure

1. Fill the glass vessel to the indicated mark with mud. Add water to the next mark.

Close the mouth of the vessel and shake vigorously

2. Pour the mixture onto the screen, add more water to the vessel shake and again

pour onto the screen. Repeat until water will be clear. Wash the sand remained on

the screen

3. Put the funnel over the mouth of the vessel. Insert the tip of the funnel into the

mouth of the glass vessel. Wash the sand on the screen by spraying a fine spray

of water. Allow the sand to settle, from the graduate on the tube, read the volumepercent of the sand.





SOLIDS AND LIQUIDS CONTENT

INSTRUMENTS

The distillation of the mud through the heating can define the quantity of liquids and

solids in the mud. A sample of mud (distillers available 10, 20 or 50 cm3), is placed

in the cup and it is heated until the liquid components have been vaporized. Then,

they are pressed through a condenser and collected in a percent graduated cylinder.

The volume of liquid (oil and water) is measured directly in percent. The solids, both

suspended and dissolved, are determined by subtracting from 100%. The distiller is

also called Ministil and/or Retort.





KIT FOR OIL AND MUD DISTILLATION

Retort Cody

Steel Wool

Lid

Retort Cup Liquid

Receiver

Condenser

Discharge

Retort Stem

Retort Condenser

R e t o r t A

s s e m b l y





DISTILLER DESCRIPTION

Procedure

1. Allow the mud to cool down to ambient temperature.

2. Disassemble the distiller and lubricate the threads of the cup with grease for high

temperature. Fill in the sample cup with the mud till the edge. Put on the cap, make

a firm rotation and let pour out the fluid in excess. The correct volume of mud, which

can be 10, 20 or 50 cm3, is defined. Dry any possible trace of mud.






3. Fill the upper expansion chamber with a steel wool which will trap the boiling

solids. Hold all erect so that the mud cannot flow into the drain tube.

4. Insert, or screw the drain tube in the hole situated at the end of the

condenser. The graduated cylinder, which is calibrated in order to allow the

reading of the percentage, will be then arranged in the condenser.

5. Connect to the electrical network and keep the current till the completion of the

distillation. This could require 25 minutes, according to the characteristics of

the oil, water and the content of solids.






6. Allow the distillate to cool down to ambient temperature

7. Read the % of water, oil and solids. A couple of drops of aerosol solution will help

the definition of the oil-water interface, after the reading of the solids percentage.

8. Once you have finished the test, cool the distiller then clean and dry it .

9. Run a pipe cleaner through condenser hole and retort drain tube to maintain full

openings.





METHYLENE BLUE CAPACITY

Equipment

1. Syringe, 3 cm3, burette 10 cm3.

2. Micropipette, 0.5- cm3.

3. Erlenmeyer flask (graduated), 250- cm3 with a gum plug.

4. Burette or pipette, 10- cm3.

5. Graduated cylinder, 50- cm3.

6. Mixer vane.

7. Hot plate.

8. Filter paper: diametre 11 cm, Whatman No. 1 or equivalent.

It is the field procedure to define cation exchange capacity (for Shales)





Reagents

1. Methylene blue solution:

1 cm3 = 0.01 milliequivalents

3.74 g of methylene blue, USP degree

(C16H18N3SCl•3H2O) per litre.

2. Hydrogen peroxide, solution at 3%.

3. Sulphuric acid solution 5 N.






PROCEDURE

1) Add 2 ml of muds to 10 ml of water in the E. Flask. Add 15 ml of 3% hydr.

Peroxide and 0.5 ml of 5N sulfuric acid solution and mix. Boil gently for 10 min.(this initial treatment is to remove the organic materials like CMC,

lignosulfonate…). Dilute to about 50 ml with water.

2) Add Methylene Blue Solution 0,5 ml at time, and shake for 30 sec. after each

addition. While the solids are still suspended, remove 1 drop from the flask with a

glass rod and place on filter paper. The end point of the titration is needed when

the dye appears as a greenish-blue ring surrounding the dyed solids.

3) Record the ml of methylene blue solution used. MBC of mud in lbs/bbl = (cm3 of

methylene blue/cm3 of mud used) x 5

MBC of mud in kg/m3 (cm2 of methylene blue/cm3 of mud used) x 14






pH INDICATOR STICKS

Description

These pH indicators sticks are coated with indicators whose colour is dependent on the

ph of the fluid in which the stick is placed. Standard colour charts are supplied for

comparison with the test stick, allowing estimation of pH to 0.5 pH units. (from 0 to 14).





pH METERS

Description

The pH meter, equipped with a glass electronic electrode is the recommended method

for measuring the pH in drilling fluids. Surveys are highly accurate, easy and auto-

adapting to the temperature variations.





pH METER

The recommended procedure to detect the pH is as follows:

Measurements consist of:

Instrument calibration.

pH survey from a sample.

Cleaning and storage of the probe.





Alkalinity (Pf , Pm, Mf and lime content)

Equipment

The following materials and products are necessary in order to define the alkalinity of

the mud and lime:

1. Standard acid solution, 0.02 N (N/50); nitric or sulphuric acid (as an alternative, It is

also possible to use an acid solution 0.1N(N/10). However, it must be converted to

the equivalent of ml 0.02 N multiplied 5).

2. Phenolphtalein indicator solution.

3. Methyl orange indicator solution.

CHEMICAL ANALYSIS OF WATER IN THE MUD

CHEMICAL ANALYSIS OF WATER





4. Vessel for titration, from 100 to 150 cm3

, preferably white.

5. Graduated pipettes: one 1 cm3 and one 10 cm3.

6. Stirring rod.

7. One syringe from 1 cm3.

8. pH meter with glass electrode. (optional but suggested)

IN THE MUD



PROCEDURE FOR THE ALKALINITY





5. To the same sample used to measure the Pf , add 3 to 4 drops of Methyl orange.

The reaction will give a green colour

6. Titrate with 0.02 N acid until a yellow colour is obtained. This will happen when a

pH = 4.3. is reached

7. The Mf is reported as the number of millilitre of acid used for the Pf plus this last

titration.

Example:

If you use 0.5 cm3 of acid to titrate the final point of the phenolphtalein the Pf is 0.5.

OF THE FILTRATE (Pf and Mf )





CHLORIDES (Cl –)

Aim

Chloride test is very important in those areas where salt can contaminate the mud.

The content of the chloride ion is an excellent detector for example, when

stratigraphic levels of salt and salt water areas are crossed during the drilling,

Moreover, the chloride test check the quality of industrial water.





CHLORIDES (Cl –)

PROCEDURE

1. Measure 1 cm3 into the titration dish.

2. Add the amount of acid required in the Pf titration.

3. Add 25 ml of distilled water and 10 drops of potassium chromate solution. Stir

continuously and titrate with standard silver nitrate solution, drop by drop until the

colour changes from yellow to orange-red and persists for 1 minute.



CALCIUM QUALITATIVE





CALCIUM - QUALITATIVE

Aim

When water has a high content of mineral salts in particular calcium and magnesium,

is called “hard water”. The evidence of hardness in water at home is the difficulty in

producing a lather with soap.

When the water used to mix the mud is hard, drilling clays have low yields. Bentonite

must be used in greater amount to make a satisfactory thixotropy.

It is often economical to treat the water to reduce the hardness.

Calcium may also arrive from drilling out cement or gypsum or anhydrite levels.

Calcium contamination can increase gels and filtrate valve. The high hardness in the

mud reduces the effectiveness of the majority of the polymeric products.



CALCIUM AND MAGNESIUM TOGETHER –





7. Distilled water.

8. Stirring rod.

9. NaOH, 8N solution or KOH.

10. Calcon Indicator Calver II

11. Porcelain Spatula.

12. Masking Agent: tritalonamine mixture at 1:1:2

QUANTITATIVE


QUANTITATIVE





QUANTITATIVE

Procedure (total hardness)

Add 50 cm3 of deionized water to the titration dish; add 2 cm3 (20 drops) of

versenate buffer solution (base NH4OH).

Add 10 drops of Versenate Hardness Indicator Solution (nero eriocromo t). If

calcium and/or Magnesium is present in the deionized water, a wine red-colour will

develop otherwise the solution will keep the blue colour.

During the stirring titrate with standard versenate (EDTA) unitl the colour turns

from red-wine to blue. Do not pass the colour change point.

Note: The steps 1-3 remove hardness from deionized water.






QUANTITATIVE

Procedure (total hardness)

Add to the deionized water 1 cm3 of filtrate. If there’s calcium and/or magnesium

a red-wine colour will develop. During the stirring, titrate (drop by drop) until the

colour turns from red-wine to blue.

Note the number of cm3 of versenate used (if magnesium is measured according

to procedures report the value as “A” cm3.) and calculate the hardness in mg/l.

A = total hardness; B = calcium hardness ;A-B = magnesium hardness.






QUANTITATIVE

Calculation

Total Hardness as Ca++ (mg/l) = (cm3 versenate x 400) / (cm3 sample)

CaCO3 (mg/l) = (cm3 versenate x 1,000) / (cm3 sample)

Occasionally, the dark colour filtrate could not be easily visible at the end point as a consequence,

it is difficult to define the total hardness. For a better definition of the end point, the following

mehtod is suggested.

TOTAL HARDNESS TITRATION



Pass to column 2Note:

(cm3 of versenate x 400)/ (cm3 of

the sample)NoRecord

Wine-red colour to blue

Red-wine to blue

Do not pass the end pointChange Colour

Standard VersenateStandard VersenateTitrate with:

No10 gocce Versenate Hardness indicator Colour Indicator

No2 cm3

Buffer Versenate hardnessBuffer

No50 cm3Deionized Water

1 cm3 of filtrateNoSample

Column 2Column 1

Total Hardness

Chemical analysis

Total Hardness – Titration

Table 6

TOTAL HARDNESS TITRATION

3 Water Based Muds

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