6 Inhibiting Water Based Muds

INHIBITING WATER BASED MUDS

Agip KCO

Well Area Operations Drilling Supervisors Training Course

Drilling Muds

RPW2021A

1

INTRODUCTION

Fluids classification :

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•

Calcium base

•

Salt base

•

Potassium base


Drilling Muds

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CALCIUM BASED MUD • •

Lime Muds –Ca(OH)2 Gyp Muds -CaSO4.2H2O

FW/SW-LI FW/SW-GY

Calcium absorption from clays

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Drilling Muds

RPW2021A

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CALCIUM BASED MUD

Reduction water hydration for sodium clay during base exchange with calcium.

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Drilling Muds

RPW2021A

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CALCIUM BASED MUD

Effect of solids concentration on viscosity with calcium additions.

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Drilling Muds

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CALCIUM BASED MUD

Line A - Soluble calcium vs. lime concentration; Line B - Soluble calcium of 4 lb/bbl of lime added to caustic solutions.

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RPW2021A

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CALCIUM BASED MUDS

Solubility of calcium vs. chlorides.

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Drilling Muds

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LIME BASED MUD Description and application

•

This system is used to drill in reactive shale formation, even at high temperature

•

It is a dispersed, lignosulfonate base fluid where lime is apporting source of Ca++.

•

Two basic formulations: low lime (5-8 kg/m3 – 1.75 – 2.8 ppb excess of lime) and high lime content (20 kg/m3 – 7 ppb excess of lime)

•

The tolerance to high solids is acceptable

•

It is possible to weight up to over 2.1 kg/l (17.5 ppg)

•

Low cost

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Drilling Muds

RPW2021A

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LIME BASED MUDS

Limitations •

The system needs more dilution than other inhibitive systems.

•

The high value of the pH (up to 12) reduces the inhibitive action of the Ca++ due to the dispersing action.

•

At temperature over 120°C gelation problems may occur.

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Drilling Muds

RPW2021A

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LIME MUD (FW/SW-LI)

Lime muds classification versus alkalinity values

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Low Lime

Intermediate

High Lime

PF

0.8 - 2

2-5

5 - 10

Pm

4-9

9 - 15

15 - 25


Drilling Muds

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LIME MUD (FW/SW-LI) Lime Muds main additives Additive

Concentration, kg/mc

Function

Bentonite

60 - 80

Viscosity, filtrate control

Lignosulfonate

0,5- 1,5

Deflocculant

Lime Ca(OH)2

5 - 30

Soda or caustic potash

for pH 10.5 - 12.5

Inhibitor, alkalinity control pH Control

Lignite

0,5 – 1,2

Filtration Control

*(Starch)

0,6 – 1,2

Filtration Control

0.5 - 3

Filtration Control

PAC *Antifermentant treatment needed

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Drilling Muds

RPW2021A

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LIME MUD (FW/SW-LI) Typical Properties of a Low and High Lime Mud Plastic Viscosit y (cPs)

Yield Point (gr/100 cm2)

Low Lime 1,20

15 - 18

3–5

0-1

0-2

5 - 10

High Lime 1,20

15 - 18

3-5

0-1

0- 2

12 - 18

Density (Kg/lt))

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Gels 10 sec/10 min (gr/100 cm2)


pH

Eccess Lime (Kg/m3)

API Filtrate (cm3/3 0 min)

1-2

10.5 -12.5

3-6

6 - 12

5 - 10

12.0 -12.5

15 - 45

6 - 12

PM cc

PF cc

H2SO4

H2SO4

n/50

n/50

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LIME MUD (FW/SW-LI)

Filtrate alkalinity due to Caustic Soda additions (NaOH)

NaOH, lb/bbl

Kg/mc

PF, cm3 H2SO4 - N/50

1

2,8

1.0

2

5,6

3.0

3

7,8

5.0

4

11,3

7.0

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Drilling Muds

RPW2021A

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LIME MUD (FW/SW-LI) Treatment Ranges for Lime Mud Conversions

Additive

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Concentration, lb/bbl Kg/mc

Soda/ Caustic potash

2–3

5–8

Lime

4–8

10 – 20

Thinning Agent

2–5

5 - 15


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LIME MUD (FW/SW-LI) Lime Muds contaminants treatments Contaminants

Indicators

Treatments

Increase of solids in the mud

Increase in solids content in retort test. Increase in PV, Gels, MBT.

More dilution. Improve the solids removal. Centrifuges use.

Salt/Salt water

Chlorides, Visc.Marsh , yield point, gel 10” / 10’ , filtrate increase. PM, PF, pH decrease.

Increase density (if the level increases), to dilute with fresh water. Add fluidizing and caustic soda to control the rheology then treat with starch or PAC for the filtrate control. If salt presence is high, transform the system saturated with salt. Or replace with oil based mud.

Carbonates/CO2

MF, Gel10-min increase . PM, pH decrease. If the CO2 inlet is continuous, normal treatments with lime cause a thin solids increase (CaCO3).

Add lime for PM control and KOH for PF.control. Check solids content optimal conditions ( Low)

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Drilling Muds

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LIME MUD (FW/SW-LI) Contaminants

Indicators

Treatments

Low quality products

Packaging variations. Treatment quantities increasing. Mud properties anomalous state.

Shipping documents and specifications control. Organize sampling and analysis. Cooperation with the Supplier

Foam

Foam in the tanks. Trapped air . Decrease pressure pumps if possible

Add a non toxic antifoam. Detect the foaming causes and remove them

Gelation due temperature

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to

high Pressure peaks after round trip. Bottom cushion very viscous. High viscosity in the mud at the flow line


Reduce Low Gravity solids. Add lignosulfonate if bottomhole temperature is <300°F (150°C). Add polymeric deflocculant for high temperature, for values higher than 150°C.

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GYPSUM MUD (FW-GY) Main Gypsum Mud additives Additives

Concentration,Kg/mc

Function

Bentonite

60 - 70

Viscosity, filtrate control

Lignosulfonate

10 - 25

Deflocculant

Gypsum

10 - 25

Inhibition, alkalinity control

Caustic Soda

pH 9.5 - 11.0

Alkalinity control,Inhib.I

Caustic Potash

pH 9,5 - 11

Inhibition

Tannin Sulphonated

5 - 10

Deflocculant

Starch

5 - 18

Filtrate Control

PAC

0.7 – 4,5

Viscosity, Filtrate control

Barite

Programmed Density

Weighting Material

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GYPSUM MUD (FW-GY)

Gypsum mud typical characteristics API Filtrate (cm3/30 min)

Density (Kg/lt)

Plastic Viscosity (cPs)

Yield Point (gr 100 cm2)

Gels 10 sec/10 min (gr100 cm2

Exceeding Gypsum (Kg/mc)

PF

pH

1,08

12 - 15

3– 5

1-2

4- 6

30- 40

0.2 - 2.7

9.5 - 11.0

600-1200

8 - 12

1,44

15 - 20

1- 7,5

0 -2,5

1- 7,5

30- 40

2-3

11.0 12.0

200-600

6-8

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Drilling Muds

Ca++ (mg/L)

RPW2021A

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GYPSUM MUD (FW-GY) Advantages/Disadvantages of Gyp Mud Advantages

Disadvantages

Low Viscosity and Gel strengths.

High pressure peaks (pressure loss) during conversion can cause “Hole Damages”.

Solids content tolerance.

Gelation phenomena with temperature higher than 300°F (150°c)

Weighting facility up to 2,16 Kg/lt. It inhibits clay sands and clays hydration. It resists to contaminations: Cement, Anhydrite and Salt (Up to50000mg/lt Cl-) It stabilizes the hole (regular section)

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Drilling Muds

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GYPSUM MUD (FW-GY) Contaminant Treating of Gyp Muds Contaminant High content of gravity solid

Indicators low

Salt/Salt Water

Carbonates/CO2 problem for lime muds.)

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(no

Treatments

Values at Mud Still, PV,gel at 10-minute , MBT.

Higher dilution, improve solids discard, use the centrifuges to treat the mud

Chlorides, viscosity, yield point, Gel 10”/10’ and filtrate increase. PM, PF, pH decrease

Increase the density if water flows from well. Treat with deflocculant and soda for rheology, starch or PAC for the filtrate. Transform the mud saturated with salt or oil base mud, in presence of salt dome.

Increase MF,Gel 10-min . PM, pH decrease. To control the CO2 need Ca (OH)2 treatment- that causes thin solids increase (CaCO3)

Add lime for PM and KOH for PF control. Keep solids control to the lowest possible level


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GYPSUM MUD (FW-GY) Contaminant

Indicators

Treatments


Different packing, minor product performance. Mud characteristics not conform to the programmed values

Supplier documents. Sample and analyse. Collaborate with the Supplier and detect the trouble (do not change the supplier)

Foam

Foam in the tanks, air incorporated Treat with non toxic antifoam. in the mud, irregular pump pressure Identify the foam origin and operate.

Temperature gelation

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Pressure peaks at the pump (when the circulation restarts) after the round trip. Very viscous bottom cushions and high viscosity mud at the flow line


Reduce low gravity solids, treat with lignosulfonate if BHT<300°F Treat with polymeric deflocculant with temperature higher than 300°F (150°C).

Drilling Muds

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SALT BASED MUDS

•

Mainly used to drill salt formations. Sometimes also used as inhibitive fluid in shale formations. It’s better when saturated

•

It is possible to use the system with suitable viscosity as work-over fluid

•

Lower cost referred to other competitor system

•

The basic product, (NaCl) is readily available

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Drilling Muds

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SALT BASED MUDS

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Salt Muds Classification

NaCl, mg/L

Salt saturated (NaCl)

315,000

Sea Water

25,000-35,000

Brackish Water

10,000-25,000


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SALT BASED MUDS Salt saturated mud The pH control, changes widely and it is not a fundamental function pf the system. Many low Solids Mud with starch are formulated without caustic soda. In other areas the pH=11 – 11,5 is maintained, with NaOH addition. The S.S. mud, needs a major quantity of soda to keep a high PH. To maintain the pH = 11 – 11,5 gives several advantages : •

More efficient fluidizing

•

Reduced Corrosion

•

To reduce the filtrate, minor quantities of additives, are needed when the solubility from Ca++ and Mg++ is reduced.

•

Minimizes foaming tendency

•

Mud is generally more stable

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Drilling Muds

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SALT BASED MUDS Principal Additives of Salt Saturated Muds Additive

Concentration, Kg/mc

Function

Pre-hydrated Bentonite

30 - 70

Viscosity, Filtrate control

STARCH

10 - 20

Filtrate control

Caustic Soda

pH 9.0 - 11.0

Soda Ash (Na2CO3) PAC

Salt (NaCl)

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3-8

Ca++ Removal

0.7 - 4.2

Filtrate control, Viscosity Inhibition, Weighting

350


Alkalinity control

Drilling Muds

RPW2021A

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SALT BASED MUDS Typical Properties of Salt Saturated Muds

Density (Kg/lt) (ppg)


Yield Point (gr/100 cm2) (lbs/100 ft2)

1.26 – 10.5

8 - 12

4-6/8-12

2-4/4-8

6-8/12-16

8 - 12

2.1-17.5

45-50

10-14/20-28

3-5/6-10

15-18/30-36

6-8

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Gels 10 sec/10min (gr/100cm2) (lbs/100 ft2)


Drilling Muds

API Filtrate (cm3/30 min)

RPW2021A

pH

8.59. 5

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SALT BASED MUDS Advantages/Disadvantages of Saturated salt Muds Advantages

Disadvantages

Inhibiting (clays)

Filtrate control more difficult (starches or polymers efficiency)

Contaminations resistant: cement, anhydrite, salt and salt water.

Foaming and air entrap tendence

Low solids content. The dissolved salt helps density.

Corrosive, with salinity lower than saturation

Good hole cleaning (cuttings transport).

Temperature max limit = 280°F (140°C).

Stabilizing action on-open hole.

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Drilling Muds

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SALT BASED MUDS

Contaminant Treating of Saturated Salt Muds Contaminant

High Solid Contents

Low Quality Products

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Indicators

Treatment

PV, YP, gels , viscosity, filtrate, MBT. Increases. Foaming, trapped air

Dilution. Use the centrifuges and improve solids removal

Lower material efficiency. Product Package change

Ask for data regarding package process. Sample and carry out efficiency test + complete analysis


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SALT BASED MUDS Sea Water Muds

Principal Additives of Saltwater Muds Additives


Function


40 - 70

Control Filtrate, Viscosity

Soda /Caustic potash

1,5 – 4,5

Starch

9 – 18

Filtrate Control

PAC

1,5 – 3.0

Filtrate Control

Lignosulfonate

9 – 18

Deflocculant

Lignite

5 - 10

Filtr. Control HP/HT

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Drilling Muds

Control alkalinity/corrosion

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SALT BASED MUDS Sea Water Based Mud Advantages and Disadvantages

Advantages/Disadvantages of Saltwater Muds Advantages

Disadvantages

Inhibiting Material (clay layer)

Increasing of the quantity of additives used because of lower performance

Reduced fresh water consumptions.

Difficult to control filtration

Contaminants negative aspects; anhydrite, cement, salt and layer salt water

Pre-hydrated bentonite is required

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Drilling Muds

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SALT BASED MUDS Problems and Contaminations – Sea Water Muds Contaminations are more evident compared to S.S. mud. The sea water mud has higher quantities of additives. The salinity and hardness range affect the fluid performances Contaminant Treating of Saltwater Muds Contaminants

Indicators

Treatments

High Solid Contents

Increase % solids , PV, YP, gel, viscous mud cushions from bottomhole to surface

Salt /Salt Water

Increase density in case of inlet from formation water. YP, Filtrate and chlorides Treat with fluidizing to control increase. the rheology. Control filtrated In case of formation water, loss of with starch or Pac. Add density and PH decrease caustic soda to repristinate correct PH

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Massive dilutions, use of centrifuges and other equipment to remove solids.

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SALT BASED MUDS Contaminant Treating of Saltwater Muds Contaminants

Indicators

Treatments

Increase the quantity of treating. Different packaging

Know the production methodology. Sample and analyse the product

Cement

PV, YP, pH, PM, PF, gel and filtrate increase. Ca++ increase.

Add sodium bicarbonate or SAPP. Dilute with water (fresh or sea). Treat with fluidizing, starch or PAC (Rheology and filtrate control)

Carbonates

Increase gels, YP. Rheology not correct. Bottom cushion with high viscosity.

Increase pH at 10.7 or more to convert the bicarbonate in carbonate, treat with lime or gypsum to remove carbonates.

Low quality product

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SALT BASED MUDS

Brackish-Water Muds In many areas, for economical reasons or for fresh water shortage, Brackish waters are often used to prepare mud. They have a salinity (NaCl) between 10000 and 15000 mg/lt. These areas are near the sea a/o in marshy zones.

Main additives (Brackish-Water Muds) They are essentially the same additives of the sea water mud; they have lower salinity. Because of brackish-water (bacterium and organic products), the use of chemicals is always high to reduce the bacterium degradation

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Drilling Muds

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SALT BASED MUDS

Principal Additives of Brackish Water Muds

Additives


Pre-hydrated bentonite

40 - 70

Soda / Caustic potash

1,5 – 4,5

Function Viscosity and Filtrate, Control Pf corrosion control

Starch

9 – 18

Filtrate control

PAC

1,5 – 3

Filtrate control

Lignosulfonate

9 – 18

Deflocculant

Lignite

6 - 10

HP/HT Filtrate control.

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Drilling Muds

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SALT BASED MUDS Typical Properties of Brackish-Water Muds

Yield Gels Point Plastic 10 sec/10min Density Viscosity (gr/100 (gr/100cm2) (Kg/lt) 2 cm ) (cPs) Lbs/100ft2 2 lbs/100ft

pH

Chlorides mg/L


1,10

16

4–5 8 – 10

1–2 2–4

2–5 4-10

10.5 –11

10,000 -25,000

6 - 10

1,45

22

6–8 12 – 16

2–3 4–6

3–5 6 –10

10.5 - 11 10,000 -25,000

6-8

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SALT BASED MUDS

Advantages/Disadvantages of Brackish-WaterMuds

Advantages

Give moderate inhibition degree

Reduced fresh water consumption (Brackish water is used).

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Disadvantages

Use of chemical products increasing, (because of minor efficiency)

Pre-hydrated bentonite (in fresh water) is required

Drilling Muds

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SALT BASED MUDS

Problems and Muds Contaminations - Brackish-Water Muds Contaminations and problems are the same of the sea water system

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POTASSIUM MUDS – (FW/SW-KC)

There are three potassium based muds:

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•

KCl-Polimers (KCl-PHPA)

•

KOH-Lignite

•

KOH-Lime


Drilling Muds

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POTASSIUM MUDS – (FW/SW-KC) KCl-Polimers (KCl-PHPA) =FW/SW-KC

Principal Additives of KCL-Polymer Muds Additive

Concentration,Kg/mc

Function


15 - 45

Control Visc. and filtrate

Potassium Chloride

15 - 170

Inhibiting source K+

Caustic Potash

0.7 – 2

Gives ions K+ and controls alkalinity

Starch

8 – 16

Filtrate control

PAC

1.5 – 3

Filtrate control

Lignosolfonate

8 - 16-

Fluidifizing

Lignite

5 - 10

Filtrate control HP/HT

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POTASSIUM MUDS – (FW/SW-KC) Typical Properties of KCL-Polymer Muds Density (Kg/lt)


Yield Point (gr/100cm2)

1,10-1,20

12 – 25

5 – 10

3–4

4 - 10

10 - 12

1,20–1,32

15 – 25

5 – 10

1–4

4–8

5–8

1,32–1,44

15 – 35

3–8

1–4

2–8

3–6

1,44–1,68

20 – 40

3–8

1–3

2–8

2–4

1,68–1,92

25 - 45

3–8

1–3

2–6

2–4

1,92-2,16

30 - 45

3-4

1-3

2-5

1-3

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Gels 10 sec/10min (gr/100cm2)

Drilling Muds


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POTASSIUM MUDS – (FW/SW-KC) Typical Material Concentrations for KCl-Polymer Muds CONCENTRATION , Kg/mc Density KG/Lt

Water (lt)

Bentonite

Caustic Potash

KCl

Xanthan

Gum LV

PAC

Reg Starch

Barite

PHPA Active

1,20

937

40

0,7

100

2,8

--

4

12

0

2,8

1,44

812

40

0,7

90

2,8

--

4

12

350

2,8

1,68

750

36

1,4

85

2,2

4

--

12

670

2,8

1,92

718

28

1,4

80

1,5

3

--

9

830

2,8

2,16

687

20

1,4

75

1,5

3

--

9

1080

2,8

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Contaminant Treating of Brackish-Water Muds Contaminants

Indicators

Treatments

Increase: solids, PV, YP, gels. Viscous bottom cushions after the round trip

Large dilutions. Use centrifuges and improve the efficiency of solids control equipment .

Cement

Increase: PM, PF, pH, YP, Filtrate, and Marsh viscosity

Minor dilution. To treat with bicarbonate a/o SAPP. When rheology becomes stable treat with starch or PAC to reduce filtrate.

Low-quality products

The product packaging changes. Higher quantity of the product used

Product documentation Supplier quality history. Sample and analyse.

High % solids

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Drilling Muds

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Contaminant Treating of Brackish-Water Muds Contaminants

Indicators

Treatments

Salt Water/salt

Increase:Chlorides, Marsh viscosity, YP, Gels, Filtrate.

Increase density if the well flows salt water. Convert in a mud saturated with salt

Gypsum/ Anhydrite

Increase: Ca++, YP, gels, filtrate. Decrease: pH, PM, PF.

Treat with SAPP, soda ash or potassium carbonate. When necessary, treat with fluidizing

Carbonates

Increase: MF, YP, gels. Decrease: pH, PM, PF. Viscous bottom cushions and also high viscosity to the mud comes from flow Line

Carry out GGT analysis. Raise pH>10,7 with KOH. Add lime and guarantee the value of the solids within acceptable limits.

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Drilling Muds

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POTASSIUM MUDS – (FW/SW-KC) KOH-Lignite (system)

Principal Additives of KOH-Lignite Muds Additives

Concentrations, kg/mc

Functions

Bentonite

45 - 75

Viscosity and filtrate control.

Lignite

15 - 23

Fluidizing and filtrate control

Caustic Potash PAC/CMC Barite

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Alkalinity and K+ control

1,5 – 4,5 1,5 – 3

Viscosity and filtrate control

Add the amount needed to reach a programmed value of density


Weighting material

Drilling Muds

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Typical Properties of KOH-Lignite Muds

Density Kg/l



1,08

12 - 14

4-6

1–2

1,44

16 - 20

5–9

1-3

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pH


2–4

10.0

10 - 12

3-5

10.0

6–8

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POTASSIUM MUDS – (FW/SW-KC) Advantages/Disadvantages of KOH-Lignite Muds Advantages

Disadvantages

Inhibiting system

Contaminants intolerance such as, salt, Ca++, cement, carbonates and anhydrite

Economical. Control filtrate with lignite and bentonite

Clay solids (L.G.) must be kept very low

Simple. Limitated product numbers Thermic stability up to 400°F(240°C).

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POTASSIUM MUDS – (FW/SW-KC) Contaminant Treating of KOH-Lignite Muds Contaminant High solid contents

Cement

Low quality product

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Indicators

Treatments

Increases:solids, PV, YP, and gels. Viscous bottom cushions. High additives consumption

Dilute and use centrifuge, improve solids removal.

Increases PM, PF, pH, YP, gel and filtrate.

Deflocculate with bicarbonate a/o SAPP. Dilute with water. Increase PF to limit the Ca++. Fluidify to reduce rheology. Transform in FW-LI if necessary.

Increases treatment quantity. (consumptions)

Production documents. Make sample and analysis. Pilot test with good quality materials. (comparison)


Drilling Muds

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POTASSIUM MUDS – (FW/SW-KC) Contaminant Treating of KOH-Lignite Muds Contaminant

Salt Water/Salt

Anhydrite/Gypsum

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Indicators

Treatments

Well lows, viscosity, chlorides, YP, filtrate increases. Density decreases

Increase density, (Kill Flow) Treat with water and fluidizing for rheology control, then PAC/CMC for filtrate. Convert in mud SS when there’s much salt.

Change drilling speed (metres/hour) . Increases: Ca++ , Decrease: pH, PM, PF.

Increase pH with KOH to reduce Ca++. Treat with bicarbonate and soda Ash. Add fluidizing or convert in FWGY.


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Contaminant Treating of KOH-Lignite Muds Contaminant

Indicators

Treatments

Carbonates

Increase: MF, YP, gels. False rheological results. Decreases: pH, PM, PF. Viscous bottom cushions after round trips, high viscosity mud at the Flow line

Carry out GGT analysis. Raise the pH over 10,7 with KOH. Add lime a/o gypsum to settle carbonates (avoid overtreatments). Keep drilled solids contents (L.G.) within recommended limits

Gelation for High temperature

High pressure peaks at the pump to restart circulation after breaks. Bottomhole viscous cushions after trips.

Reduce L.G: E MBT solids. Use thermostable fluidizing. Analysis for carbonate contamination (GGT).

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Drilling Muds

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POTASSIUM MUDS – (FW/SW-KC) KOH-Lime Mud KOH-Lime Muds main additives Additives

Concentration,Kg/mc

Function

Bentonite

45 - 75

Control viscosity and filtrate

Lignosulfonate

12 - 24

Fluidizing and controls filtrate

Lime

12 - 30

High pH and Ca++ source

Caustic potash (KOH)

6-9

Pf control and K+ source

Tannin sulfonate

6-9

Deflocculant

PAC /Starch

3-6

Filtrate control

Barite

Agip KCO

Add the amount needed to reach a programmed value of density Well Area Operations Drilling Supervisors Training Course

Weighting material

Drilling Muds

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POTASSIUM MUDS– (FW/SW-KC)

Typical Properties of KOH-Lime Muds

Gels 10 sec/10.min (gr/100cm2)


Density (Kg/l)

Plastic Visc. (cPs)

Yield Point (gr/100 m2)

1,08

10 - 12

4–6

2–3

3-5

6-9

1,44

16 - 18

8 – 10

2-3

3–6

4-6

Agip KCO


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Advantages/Disadvantages of KOH-Lime Muds Advantages

Disadvantages

Inhibiting (Ca++ e K+)

Non dispersed fluid

Solids Tolerance

Decreasing ROP in hard formation

Contaminations resistance : Anhydride, Cement, Carbonates and salt.

Complex, many additives Gelation at high temperature Bentonite must be pre-hydrated

Agip KCO


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Contaminant Treating of KOH-Lime Muds Contaminants

Indicators

Treatments Strong dilution, use centrifuge and improve solids removal.

High solid contents

Increase: % solids, PV, YP, Gel 10’-

Salt and salt water

Increase Kill Flow denisty. Dilute with fresh water. Treat with fluidizing and KOH for Increase: Chlorides, Viscosity, YP, rheology and then PAC or gel and filtrate. Decreases: PM, PF, starch for the filtrate. With pH, and density (salt water). large quantities of salt, convert it in saturated salt or replace with oil base mud.

Agip KCO


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Contaminant

Carbonates / CO2


Agip KCO

Contaminant Treating of KOH-Lime Muds Indicators Treatments Increase: MF, gels10’, rheology difficult to control. Decreases : Pm,PH

Add Ca(OH)2 for the PM e and KOH for PF.. Check clay solids at the planned range lower limit.

Package product changes. Product quantity increasing, to obtain the same results. Muds characteristics not reliable

Supplier documents on production mehtods and quality control. Sample and analyse through comparison with standard products as well.


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Contaminant Treating of KOH-Lime Muds Contaminant

Indicators

Treatments

Temperature Gelation

Viscous bottom cushion after round trip. Viscous mud at the flow line (not at the sump pit). Pressure peaks at the pump after a break.

Reduce L.G. solids. Increase lignosulfonate concentration if the temperature is lower than 160°C. If the temperature is higher, use high temperature deflocculant.

Foaming

Presence of foam to the tank and shaker The mud incorporates/absorbs air, pump pressure drop.

Treat with non toxic anti-foam. Detect the cause of the trouble and remove it.

Agip KCO


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POLYMERS FLUIDS

Low Solids PAC/CMC Muds: Main Additives Materials

Concentration Kg/mc

Bentonite

Viscosity and Filtrate control

15 - 30

Caustic Soda

Function

pH 9.0 – 9.5

Alkalinity

Ash Soda

0.75 – 1.5

Calcium removal

PAC/CMC Regular

1.5 – 4.5

Filtrate control

Barite

Agip KCO

Add the amount needed to reach a programmed value of density


Drilling Muds

Weighting material

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POLYMERS FLUIDS

Typical Properties of Low-Solids PAC/CMC Muds

Density (Kg/lt)


Yield Point (gr/10 0 cm2)

1,08

4-6

4-6


2-4

3-5

Chlorides mg/L


< 2000

10 – 12

pH

Hardnes s (mg/L)

< 200

9.0 – 9.5

< 200

9.0 – 9,5

6-8 1,44

8 - 10

Agip KCO

5-8

3-6

5-8


< 2000

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POLYMERS FLUIDS Low Solids PHPA Muds (polyacrilamide partially hydrated)

Principal Additives of Low Solids PHPA Muds Materials

Concentration Kg/lt

Bentonite

Filtrate and Viscosity Control

3 - 40

Soda /Caustic Potash

pH 9,0 – 9,5

PHPA

Function

Alkalinity Control Solids encapsulation, Borehole stability, Viscosity control

2,85

SPA

0,75 – 1,5

Filtrate control

Ash Soda

0,75 – 2,15

To settle ions Ca++

Agip KCO


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POLYMERS FLUIDS

Typical Properties of Low-Solids PHPA Muds

Density (Kg/lt)



1,08

4–6

5–7

2–4

3–5

10 - 12

1,44

8 - 10

6 – 10

4-6

5–8

6–8

Agip KCO



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POLYMERS FLUIDS Advantages/Disadvantages of Non-Dispersed Polymer Muds Advantages

Disadvantages

High ROP (m/hour) in hard formations

Limited use

Pressure drop low values/ ECD

Polymers absorption on clays is irreversible

Good borehole cleaning (Transport Capacity)

Low stabilit at temperatures.

Easy maintenance

Solids increase is not tolerated.

Easily convertible in a deflocculated/dispersed system

They need higher dilutions compared to the deflocculate system

It doesn’t disperse solids (inhibited system).

Filtrate control is expensive More corrosive than deflocculate system. Contaminants sensible. Carbonates contamination difficult to be treated Weighting difficulty Not very inhibiting.

Agip KCO


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POLYMERS FLUIDS Contaminant Treating of Non-Dispersed Polymer Muds Contaminant

High SolidContents

Cement

Agip KCO

Indicators

Treatment

Increases: solids %, PV, YP, gels, MBT. Viscous bottom cushions after round trip. High viscosity at the flow Line.

Higher dilution use the centrifuges To improve solids control

Marsh viscosity, pH, PM, PF, gels, filtrate increasing

Control (Ca++) contamination with bicarbonate a/o SAPP or Citric Acid Dilute with fresh water. Increase PF in order to limit the Ca++ solubility. Deflocculant could be necessary or convert mud into lime


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POLYMERS FLUIDS

Contaminant Treating of Non-Dispersed Polymer Muds Contaminant

Salt water/Salt

Gypsum/Anhydrite

Agip KCO

Indicators

Treatment

Well flowing. Increases: Marsh viscosity, YP, Gels, Filtrate. Surface water separation. Decreases: pH, PM, PF.density.

Increase density (if the well flows). Dilute with fresh water to reduce chlorides. Treat with deflocculant for PAC contamination and for the filtrate control. If necessary transform in SS. mud

Increase:Ca++, YP, Gels, and filtrate Decrease: pH, Pm, Pf.

Treat for Ca++ with ash soda, Bicarbonate a/o SAPP. Add fresh water. Deflocculant treatment can be required.


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POLYMERS FLUIDS

Contaminant Treating of Non-Dispersed Polymer Muds Contaminant

Carbonates / CO2 (Not very problematic)


Agip KCO

Indicators

Treatment

Increases: MF, gels 10’. Rheology difficult to be checked. Dercreases: PM, pH.

Add lime for the Pm and KOH for the Pf. Keep the content of clayey solids to the lowest possible value.

Treatment quantities increasing. Type of packaging changed. Poor results with standard treatments

Documentation of the productive process from supplier. Sample and analyze. Pilot test comparison with reliable products


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6 Inhibiting Water Based Muds

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