Water Base Muds

Water Base Mud Systems

Many types of water-base systems.

Basic systems are usually converted to complex systems as a well is deepened, as wellbore temperatures and/or pressures increase and formations dictate.

More than one system is typically used when drilling the same well.

Un-weighted clay water suspensions

Deflocculated, weighted clay-water suspensions

Calcium treated, weighted deflocculated clay-water suspensions

Salt water systems

HTHP Deflocculated Systems

Polymer Systems with/without salts

HTHP Polymer Systems

Cationic Systems

Classification of Water Base Muds

Factors Affecting Choice

Application:

Drilling surface intervalDrilling intermediate intervalDrilling production interval

Completion Method Production Type

GeologyShale TypeSand Type – Permeability

Other Formation Types– Carbonate Rock

Limestone Dolomite

– Salts


Make-Up Water

Type of water

Chloride concentration

Hardness (Calcium / Magnesium) concentration


Drilling Data

Water Depth -- Hole Size

Hole Angle -- Torque/Drag

Drilling Rate -- Mud Weight

Maximum Temperature


Potential Problems

Shale Problems -- Bit/BHA Balling

Stuck Pipe -- Loss Circulation

Depleted Sands


Rig/Drilling Equipment

Remote Location

Limited Surface Capacity

Good Mixing Capacities

Good Mud Pumps

Good Solids Control Equipment


Contamination:

Solids Cement

Salt Anhydrite's/Gyp

Acid Gases CO2

H2S


Solids Content v. Mud Density

0

10

20

30

40

50

60

9 10 11 12 13 14 15 16 17 18 19 20 21 22

Mud Weight, lbs/gal

Volu

me P

erc

en

t S

olid

s Barite

Hematite

Low Gravity Solids

+ 10% LGS+ 5% LGS

+ 5% LGS+ 10% LGS

Solids Content vs Density

PV & YP v. Mud Wt, lbs/gal

0

5

10

15

20

25

30

35

40

45

50

9 10 11 12 13 14 15 16 17 18 19 20 21

Mud Weight, lbs/gal

Pla

stic V

isco

sity,

Yie

ld P

oin

t &

MB

T

Max Recommended PV

Max Recommended YP

Max Recommended MBT

PV, YP vs Density

Basically composed of bentonite and water.

Used to spud (begin) a well

Native Mud (Bentonite incorporated with drilled solids from the formation as some formations are bentonitic in nature and increase viscosity)

Spud Muds

Low Solids System due to no added weight materials

Low in cost and high penetration rate

Extremely shear thinning

Spud Muds

Lignosulphonate Systems

This used to be the most common drilling fluid system used in the industry.

Primary product -lignosulfonate – may contain chrome, an organic acid which supplies anions (negative ions) which reduce the YP and Gel strengths by neutralizing the cations (positive ions) on the clay particles.

System requires an alkaline environment to solubilize the lignosulphonate. Caustic Soda or Lime should be used to increase the pH to a minimum of 9.5 Old technology

System can tolerate high solids and contamination - by increasing the concentration of lignosulphonate

Lignite can be used as a supplementary product and, like lignosulfonate, is an organic acid that supplies anions which reduce the YP and Gels by neutralizing the clay particles.


Typical Properties:

Density >10.0 ppgFV (3.5)(MW)+/-PV/YP see PV/YP GraphGels 1-5 / 1-10pH 9.0 - 11.5FL as requiredLGS 5 - 7 percent


Calcium Treated Systems

Calcium added to a clay-water slurry causes flocculation - an increase in yield point and gel strengths. This is caused by the Ca2+ cation having higher bonding energy than the Na+ cation on the clays, thus converting them to Ca2+ clays.This results in partial dehydration of the hydrated clay particles, causing a reduction in the size of the water envelope around the clay particle. This reduction of the water envelope allows closer proximity of the clay particles to each other, resulting in flocculation.

If a deflocculant is not present or utilized, the size of the flocks of clay will increase and precipitate out, resulting in decreased PV’s.

As calcium is added when sufficient deflocculant is present, partial dehydration will still occur and the water envelope will be reduced causing a increase in the YP and Gels initially. This is called a viscosity hump.

Shear, time and temperature causes the clay flocks to break apart and the anionic deflocculants neutralize the cationic clay charges, reducing the YP.


Advantages:

Effective inhibiting system. Low costs. Can be used where salts are not permitted.

Tolerant of CO2 and H2S contamination

Disadvantages:

Calcium is not tolerant to certain polymers.


Potassium Systems

Potassium is an effective ion that minimizes (inhibits) clay hydration. This is achieved by the ionic base exchange of potassium for sodium and/or calcium ions on clay platelets.

Swelling clays are selective toward potassium and will adsorb potassium ion over the sodium ion.

This exchange of potassium ions occurs when the potassium-to-sodium ratio exceeds 3 : 1.

The low hydration energy of the potassium ion contributes to inter-layer dehydration, resulting in a compact, tightly held structure.

When ion fixation occurs, the clay platelet loses its water within the inter-layer space and the platelet becomes stable.

Potassium Systems

KCL PHPA MUD

Developed to stabilize water sensitive shales by means of potassium ion inhibition.

Minimizes the hydration of shales, which minimizes hole enlargement, bit and stabilizer balling, sloughing shale and reduction of permeability in productive zones.

Uses potassium chloride (KCL) as the primary source of potassium

Potassium Systems

Concentration of KCL required to inhibit the shale being drilled depends on the shales’ sensitivity to water.

Shale cuttings should be monitored for inhibition during drilling operations. Insufficient concentrations will cause the shale to be soft and mushy. If there is a sufficient concentration of KCL, the shale will retain its integrity.

Concentration of KCL required:Older Shales: 10 - 15 ppb (3.5 - 5.0 %)Younger Shales: 30 - 40 ppb (8.5 - 12.5%)

KCL PHPA MUD The Potassium

Component

In some areas potassium salts are not permitted. However, other chemicals can be used to provide a source of potassium without using a salt.

Potassium lignites

Potassium Acetates

Are usually more expensive.

The Potassium Component

The PHPA component

PHPA SYSTEMS - designed to provide shale stabilization (inhibition) and viscosity control in water-base muds.

PHPA - is a high molecular weight anionic polymer which has multiple applications and benefits.

PHPA is used in many applications:

PHPA: Used primarily for shale stabilization

Shale stabilization is achieved through encapsulation, through viscosifying the water phase, and by the polymer adsorbing free water.

Encapsulation - is the process by which PHPA wraps around the clay platelets, preventing water from entering the interlayer structure of the clays.

By viscosifying the water phase, fluid movement into the interlayer structure of the clay is slowed.

KCL PHPA MUD The PHPA

component

The stability of the system depends on maintaining the polymer concentration at the proper range and controlling the clay content to less than 6.0 percent.

If the polymer concentration is not maintained and the solids concentration is allowed to increase above the proper range, the viscosity will increase and anionic deflocculants (thinners) will be required to stabilize fluid properties.

The PHPA component

MAINTAINING a PHPA SYSTEM

Monitor and maintain proper polymer concentration.

Control solids and MBT in the proper range.

Maintain Calcium at <300 mg/l.

Control pH below 10.0.

The PHPA component

KCL PHPA MUD The Glycol component

A polymer system may use glycol technology to provide additional shale inhibition, wellbore stability, lubricity and good fluid loss. Other benefits include enhanced cuttings integrity, improved filter cake, lower dilution rates, less hole enlargement, greater solids tolerance, reduced bit balling and increased ROP.

Glycols are environmentally acceptable due to their low toxicity.

CLOUD-POINT PHENOMENON:This is the primary mechanism for inhibition and stabilization.CLOUD-POINT is the temperature at which polyglycol changes from being totally soluble to insoluble.****At temperatures above the cloud point, poly-glycols form colloidal droplets or micelles which results in a micro-emulsion. “Thermally Activated Mud Emulsion” (TAME).

The Glycol component

At temperatures above the cloud point, poly-glycols form colloidal droplets or micelles which results in a micro-emulsion.

This is referred to as “Thermally Activated Mud Emulsion” (TAME).

Glycol Mud Systems

The TAME provides wellbore stability in three distinct ways:

Through chemical adsorption

Through micro-emulsion and precipitate pore plugging

By providing a thinner, less porous filter/wall cake


The adsorption of insoluble poly-glycols into the filter/wall cake on permeable formations reduces the thickness of the filter/wall cake and fluid loss rates.

The poly-glycols provide lubrication and resists balling since insoluble poly-glycols have an affinity to solids and can coat solids and other surfaces.


Most poly-glycol systems are designed to become totally soluble as it cools while being pumped up the annulus to the surface. But some systems are designed to keep the poly-glycol insoluble at all times.


There are several glycols available with a wide range of cloud points. Systems are usually designed to find the proper glycol required prior to drilling. Only the proper glycol will be sent to the drill-site.

These poly-glycols are:

•Broad range clouding PAG blend•Low salinity clouding,<30,000 mg/l Cl•Moderate salinity clouding, 30-90,000 mg/l Cl•High salinity clouding, >90,000 mg/l Cl•Soluble poly-propylene


Silicate Mud Systems

Silicate System:

A salt polymer system with added SODIUM SILICATE.

Developed to provide shale inhibition and hole stability in areas where oil or synthetic fluid systems would normally be used.

Formations like micro-fractured shale, chalk, or inter-bedded dispersive clays are applications for a Silicate System.

Inhibition and hole stability is achieved as soluble silicates precipitate to form an insoluble silicate film in the hole to prevent water contact with the shale (clay), or invasion into permeable formations.


As soluble silicates contact the low pH shales (clays) of formations, a reduction in pH and a reaction with divalent cations (Ca2+, Mg2+) on/in the shale (clay) form a calcium and/or magnesium silicate coating.


Soluble silicates are stable only at pH values > 11.0 or in the absence of cations.

Silicates will precipitate out at pH <11.0 or in the presence of cations.

Therefore, the pH should be controlled at 11.0 or greater and cations treated out with Soda Ash.


Monitor the concentration of silicate, since the silicate is depleted at high rates when drilling reactive shale. This is necessary for the system to provide good inhibition. The optimum concentration of 50% active silicate in a system is approximately 30 ppb.Greater concentrations result in unstable flow properties.


The silica-to-sodium ratio is important for shale inhibition. Research indicates that ratio ranges of 2.0-1 to 2.65-1 are best. Higher ratios do not improve inhibition and may viscosity instability

Inhibition levels of the Silicate system is comparable to oil and synthetic base systems.


Further shale inhibition can be achieved with additions of Glycol and NaCl or KCL.

Glycol added to the system reduces the coefficient of friction and extends the thermal stability of the system to 250°F. Therefore, glycol is recommended once the BHT reaches 190 °F or as needed to reduce torque and drag.


• Reservoir damage may occur when drilling reservoirs which contain hard water.

• Damage may occur due to precipitation of calcium silicate (cement) or solidification of sodium silicate into the pore throat of the rock matrix.

• The same reservoir damage may also occur if the pH of the invaded filtrate is reduced over time.


This system is not as solids tolerant as most inhibitive systems and not recommend where densities above 13.5 ppg are needed.

Temperature limitation: 275°F

A silicate system is a high cost, high performance system and is only recommended for difficult wells containing water sensitive shales


Coeficient of Friction (COF) value Silicate fluids vs other mud systems

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

SILICATE Silicate/Glycol PHPA Glycol OBM

Mud system

Co

efi

cie

nt

Of

Fri

cti

on


Products and their Applications

CHEMICAL COMMON NAME PRIMARY APPLICATIONS

1. Caustic Soda (NaOH) Caustic Soda Increase pH

2. Caustic Potash (KOH) Caustic Potash Increase pH and K+

3. Lime (CaOH2) Lime Increase pH & treat CO3

4. Gypsum / Anhydrite (CaSO4) Gypsum Increase Ca2+ treat CO3

5. Sodium Bicarbonate (NaHCO3) Sodium Bicarbonate Treat Cement

6. Soda Ash Na2CO3) Soda Ash Treat Hardness

(Ca2+, Mg2+)


7. Sodium Acid Pyrophosphate SAPP Treat cement & thin mud

8. Citric Acid Citric Acid Decrease Ph

9. Sodium Chloride (NaCl) Sodium Chloride Increase Cl- (WBM)

10. Calcium Chloride (CaCl2) Calcium Chloride Increase Cl- (OBM / SBM)

11. Potassium Chloride (KCl) Potassium Chloride Increase Cl- and K+

12. Zinc Oxide (ZnO) Zinc Oxide Scavenge H2S



WEIGHTING MATERIALS: 1. BARITE BAR Increase Mud Density Barium Sulfate (BaSO4)

2. HEMATITE Increase Mud Density Ferris Oxide (Fe2O3)

3. CALCIUM CARBONATE (CaCO3) Calcium carb Increase Mud Density, LCM


CLAYS: 1. BENTONITE GEL Increase Viscosity, Decrease FL

2. BENTONITE GEL Increase Viscosity, Decrease FL (Non-Treated)

3. ATTAPULGITE SALT GEL Increase Viscosity




THINNER / DEFLOCCULANTS AND FLC PRODUCTS: 1. Lignite LIGNITE Decrease FL, deflocculate mud

2. Chrome Lignosulfonate Deflocculate mud

3. Lignosulfonate Deflocculate mud (Chrome Free)

4. Causticised Chrome Lignite Decrease HT FL, deflocculate mud

5. Resin treated Lignite Decrease HT FL

6. Synthetic Resin (liquid) Decrease HT FL (env)

7. Potassium Lignite Decrease FL & add K+

8. Sodium Polyacrylate Decrease HT FL

9. Polyacrylate (Low MW) Deflocculate mud



POLYMERS: 1. PHPA PHPA Encapsulate clays (Partially Hydrolyzed Polyacrylamide)

2. PAC PAC REGULAR Decrease FL increase viscosity (Poly Anionic Cellulose)

3. PAC LV PAC Low vis Decrease FL

4. PAC (extra low viscosity) PAC ELV Decrease FL

5. CMC CMC Decrease FL & increase viscosity Carboxy Methyl Cellulose

6. Corn Starch Corn starch Decrease FL

7. Potato Starch Drilling starch Decrease FL


8. Carboxy Methyl Starch Decrease FL

9. XCD (Biopolymer) XCD Increase LSRV

10. Starch derivative FLO-TROL Decrease FL

11. Clarified Biopolymer FLO-VIS Increase LSRV

12. Bentonite extender Increase Viscosity

13. Clay Flocculent Selectively Flocculate Clays



CHEMICAL M-I PRODUCT NAME PRIMARY APPLICATIONS

SHALE CONTROL:

1. Shale Inhibitor ASPHASOL Inhibit shale, reduce FL

2. Shale Inhibitor STABLE HOLE Inhibit shale, reduce FL

3. Shale Control GLYDRIL-(GP,LC,MC,HC) Inhibit shale, reduce FL

4. Shale Control SHALE CHEK Control shale

5. Shale Control K-52 Provide K+ for inhibition

6. Shale Control KLA CURE Control shale

7. Shale Control KLA GARD Control shale

8. Shale Control (Cl- free) KLA GARD-B Control shale



CORROSION INHIBITORS: 1. Water dispersible blended amine Reduce corr. In FW Packer fluids

2. Persistent filming amine Reduce Corr. on pipe

3. Brine soluble filming amine Reduce corr. in clear brines

4. Phosphorus based Corr. inhibitor Reduce corr. in Drilling Fluids

5. 55% Ammonium Bisulfide Oxtgen scavenger Scavenge Oxygen

6. Scale Inhibitor Inhibit scale formation

7. 12% Zn (liquid) Zinc chelate Scavenge low Conc. of H2S

8. Zinc Oxide ZnO Scavenge H2S

9. 25% Gluteraldehyde Biocide Kill Bacteria



OIL / SYNTHETIC MUD PRODUCTS:

1. Clay Viscosifier Organoclay Increase Viscosity, Gel Strength

2. Premium Clay Viscosifier Organoclay Increase Viscosity, Gel Strength

3. Sag-Reducing Additive Reduce Sag Potential in NAF

4. High temperature Clay Organoclay HT Maintain HT Viscosity in NAF

5. OBM Emulsifier PRIMARY Emulsify Conventional OBM

6. OBM Emulsifier / Wetter SECONDARY Oil wet Conv/ Emulsify Relaxed

7. OBM Wetting Agent Oil wet relaxed OBM

8. Amine Treated Lignite Reduce HTHP FL in OBM

9. Asphaltic Resin Reduce HTHP FL in OBM



OIL / SYNTHETIC MUD PRODUCTS:

10. OBM Thinner VERSATHIN Thin OBM

11. Rheological Modifier Increase LSRV of OBM

13. Calcium Chloride CaCl2 Reduce Water Activity

14. Olefin based SBM Wetting Agent Oil wet SBM

15. SBM Rheological Modifier Rheology modifier Inc. LSRV in Olefin based SBM



SPECIALTY PRODUCTS:

1. Detergent for clean-up OBM/SBM CLEAN-UP Clean-up Rig OBM/SBM

2. Drilling Detergent D.D. Reduce surface tension

3. Alcohol-base de-foamer De-foam Mud

4. Silicone-base de-foamer De-foam Mud

5. Low toxicity detergent additive Prevent Bit and BHA balling

6. Low toxicity Lubricant Lubricate well, reduce HTHP FL

7. All purpose lubricant (ENV) Decrease COF, reduce torque/drag

8. Graphite plugging agent Cure LC, (torque/drag/FLC)

9. LCM Blend Cure Lost Circulation



SPECIALTY PRODUCTS:

10. Ground Mica MICA (F,C) Cure lost Circulation

11. Fibrous plugging and bridging agent Fibre (F,M,C) Plug and Bridge perm. form.

12. Ground nut hulls NUT PLUG (F,M,C) Cure Lost Circulation

13. OB-Stuck Pipe freeing surfactant Free Stuck Pipe

14. ENV-Stuck Pipe spotting fluid Free Stuck Pipe (ENV)

15. One Drum Stuck Pipe Spotting fluid Free Stuck Pipe


Water Base Muds

Engineering

Transcript of Water Base Muds