Clay Control IN DRILLING AND COMPLETION

Clay minerals, generally crystalline in nature, typically have a flaky structure. Clay flakes are made up of a number ofcrystal platelets stacked face-to-face in layers held in placeby weak attractive forces. Water invasion of clay depositscauses swelling, a process by which water molecules are

adsorbed onto crystal surfaces and drawn by osmosis between thelayers of clay flakes, forcing them apart.

Shale is a type of sedimentary rock composed chiefly of silt andclay. There are many different types — bituminous shale, oil shale andgas shale — all of which are important sources of fossil hydrocarbons.Clay swelling in shale formations during drilling or well completion can have a tremendously adverse impact on oil and gas operations.

Traditionally, preventing clay swelling in oilfield operations by aque-ous liquids has been achieved using large concentrations of inorganicsalts, mainly potassium chloride (KCl). However, effective clay controlrequires high concentrations, which can be difficult to apply.

Current methods of clay control involve both polymers and ammonium compounds. Polymers stabilize clays by reducing the rate of water penetration into the shale, while amines and ammoniumcompounds inhibit swelling by chemical means.

One effective way to isolate clays from water inflow involves the use of water-soluble polyol compounds to achieve cloud point underdown-hole conditions. At temperatures above the cloud point, the precipitated polymer forms a barrier that not only protects the forma-tion from water, but also reduces its fluid loss. The same polymeric additives act as lubricants and suspending agents for drill cuttings.

Amines/quaternary compounds inhibit swelling by changing theionic strength and the transport behavior of fluids into clays, thus preventing clay platelets from moving further apart.

In field operations, both types of inhibitors are often used in conjunction with minimal concentrations of KCl to provide maximumclay control. Fluid design compatible with formation minerals and othercomponents under site-specific work conditions is a key element ofsuccess.

Huntsman’s leadership position comes from its range of technologies, world-scale integrated manufacturing capabilities, and

global distribution network.

Clay Control Basics

Huntsman Clay Control Chemicals

SURFONIC OFS 300

SURFONIC OFS 500

SURFONIC OFS 600

SURFONIC L4-1

SURFONIC L4-2

SURFONIC L4-3

SURFONIC L4-4

SURFONIC OFS 124

SURFONIC OFS 125

SURFONIC OFS 126

SURFONIC OFS 127

SURFONIC OFS 781

Amine/Quaternary Shale Inhibitors

By use of the proper concentration of SURFONIC® OFS 500 or SURFONIC® OFS 600 with a SURFONIC® L4 series solvent and KCl, the cloud point of the clay control fluid can be adjusted to a particular downhole environment. Amine compounds are often more effective when applied as ammonium salts.

Several laboratory methods of evaluating shale inhibitor efficiency are being used industry wide. Huntsman clay controlagents and their acetate salts have been rigorously tested in accordance with published protocols.

Capillary Suction Test (CST): Often used as a preliminary screening method. Slurries of bentonite clay, silicaflower and inhibitor in water were filtered through a specialty paper filter while the instrument measured the speed of filtration. Faster filtrate flow indicates less swelling and improved performance.

Dispersion Test (Hot Rolling): Shale pieces between 4.75 and 6.7 mm size were tumbled in water base drillingmud formulations for 16 hours at 90°C (194°F) in a rolling oven and screened through a 0.85 mm sieve. Survivingchips were washed and dried. Higher retained weights of shale indicate improved shale stablization.

Product Chemistry Mode of Action Lubricant Applications

NO INHIBITOR

SURFONIC OFS 124

SURFONIC OFS 125

SURFONIC OFS 126

SURFONIC OFS 127

SURFONIC OFS 781

>1000

9.0

-3.0

3.6

9.4

0.6

33

50

85

84

97

94

11

< 46

49

73

91

67

Clay Inhibitor

Polyols

Ethoxylated butanol

Ether polyamines

Etheramine

Yes

No

No

No

• Blocks H2O access to clay, cloud point inhibitor

• Partial KCl replacement• Combination with KCl and co-solventsleads to desired cloud point of drilling mud

• Co-solvent

• Add 5 - 20% to OFS 124-125 inhibitors

• Cloud point modifiers

• Binds clay platelets

• Partial or total KCl replacement

• Inhibitor for dispersed clays • Effective over Wide pH range• Also functions as anti-balling agent• Effective in high pH (> 10) muds

• Shale inhibitor performance booster

Dispersion Test, Clay Retained,** % Dispersion Test, Clay Retained,** %pH < 10 pH > 10

* Negative number indicates performance better than 5% KCl, amines tested at 0.5% concentration.**Tested on Khvalynsky brown “chocolate” clay from Volgograd region in Russia, 3% shale inhibitor. Different clays may produce different results.

Capillary Suction Test Efficiency vs. 5% KCl*, %

®

Cloud Point Shale Inhibition

SURFONIC OFS 500 Shale Stabilizing Agent for Cloud PointShale Control.

SURFONIC L4-3 as cloud point modifier when used in combination with SURFONIC OFS 500 Shale StabilizationAgent. Dosage: 1% total surfactant package in KCl.

n SURFONIC OFS 500: SURFONIC L4-3 (25:75)

n SURFONIC OFS 500: SURFONIC L4-3 (50:50)

30

40

50

60

70

80

90

100

0 5 10 15 20

n SURFONICOFS 500

KCI Solution (%)

Cloud Point (˚C)

15

25

35

45

55

65

75

85

95

0 2 4 6 8 10 12 14 16 18 20

0

5

10

15

20

25

30

35

40

45

50

0 6 12 18 24 30 36 42 48 54 60 66 72

0

20

40

60

80

100

120

0 25 50 75 100 125 150 175 200 225

n 1% Surfactant n 2% Surfactant n 5% Surfactant

KCI Solution (%)

Cloud Point (˚C)

n Drilling mud with OFS shale inhibitor n Drilling mud without OFS shale inhibitor

Time, hours

% Swelling

Dynamic Linear Swelling: The OFITE Swellmetermeasures clay swelling at wellbore conditions. Compressed pills of bentonite were submerged in adrilling mud at high temperature and the amount of vertical swelling recorded over time. Less swelling indicates improved clay inhibitor performance.

Mud Rheology: Bentonite was incrementally added to water base drilling muds (3% inhibitor) until the muds became too thick to measure their viscosities. The ability to absorb more bentonite indicates improved clay inhibitor performance. Baselines representing the uninhibited system and 5% KCl are added for reference.

Effect of Polyol Concentration on Cloud Point of KCI Solutions Adjustment of Cloud Point with SURFONIC L4-3 Solvent

Testing at 70°C, bentonite pill stopped swelling after 30 hours in mud formulatedwith OFS shale inhibitor while continued swelling was observed with a common reference shale control agent.

Water base drilling mud after incremental addition of bentonite. Viscosity measuredon Fann 35 at 3 rpm. A mixture of sodium hydrogen carbonate and sodium carbonate was used to adjust pH to9.

Different clays may produce different results.

Bentonite, lbs/barrel

Yield Point

n KCI 5% n SURFONIC OFS 124

n SURFONIC OFS 125n SURFONIC OFS 126

n SURFONIC OFS 127

• Partial replacement for KCl.

• Highly soluble in salt water. Should not give a sheen on surface water at temperatures below cloud point.

• Cuttings may be easily rinsed and recycled back into the mud.

• May be formulated with SURFONIC L4-3to give a wide range of system cloudpoints to match bottom hole circulatingtemperatures.

• “On the fly” adjustments may easily beconducted such to give suitable cloudpoints as drilling conditions change.

• Additional benefits include lubrication of the drill stem and cleaning of the drill bit.

SURFONIC OFS 600 as cloud point modifier when used in combination with SURFONIC OFS 500 Shale StabilizationAgent. Dosage: 1% total surfactant package in KCl.

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

n SURFONIC OFS 500 (1% in KCl)n SURFONIC OFS 500: SURFONIC OFS 600 (50:50)

KCI Solution (%)

Cloud Point (˚C)

Adjustment of Cloud Point with SURFONIC® OFS 600 Polyol

Bentonite Pills Shale Chips (4.75mm to 6.7mm)

Key Points inPolyols Applications

0

20

40

60

80

100

120

0 25 50 75 100 125 150 175 200 225

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Calculated Yield Point (lbs/100ft2) of water base drilling mud after incremental addition of bentonite at pH 9.

Viscosity and Yield Point (YP) of water base mud at pH 13 (NaOH). Comparing to pH9 experiments it is clear that high pH has a detrimental effect on the mud rheology.

Unexposed Swollen Unexposed Well Inhibited Poorly Inhibited

n No inhibitor YP •• No inhibitor YP Vis. 3 rpm

n SURFONIC OFS 127 •• SURFONIC OFS 127 Vis. 3 rpm

Bentonite, lbs/barrel

Vis. @

3 rpm, Fann Units & YP

Bentonite, lbs/barrel

Vis. @

3 rpm, Fann Units

n KCI 5% n SURFONIC OFS 124

n SURFONIC OFS 125n SURFONIC OFS 126

n SURFONIC OFS 127

About Huntsman

Huntsman Corporation is a publicly traded global manufacturer and

marketer of differentiated chemicals with 2015 revenues of approxi-

mately $10 billion. Our chemical products number in the thousands

and are sold worldwide to manufacturers serving a broad and diverse

range of consumer and industrial end markets. We operate more than

100 manufacturing and R&D facilities in approximately 30 countries

and employ approximately 15,000 associates within our 5 distinct

business divisions. For more information about Huntsman, please

visit the company’s website at www.huntsman.com.

Huntsman Performance Products

Performance Products brings together innovation and world-leading

process technologies to produce more than 2,000 components used

to formulate products that enhance people’s lives:

Amines: Largest global producer of specialty amines used in

composites, coatings, fuel and lube additives, and gas treating

Maleic Anhydride: The leading global producer and supplier into

areas such as unsaturated polyester resins, food, oil additives

and coatings

Surfactants: Integrated producer of a wide range of products for

home and personal care, oilfield, agriculture, and process industries

Ethylene and Derivatives: Highly integrated manufacturer of

ethylene, ethylene oxide, ethylene glycol and other derivatives

The division has 17 manufacturing plants and had 2015 revenues of

more than US $ 2.5 billion.

Global headquartersHuntsman Corporation 10003 Woodloch Forest DriveThe Woodlands, Texas, 77380USATel : +1-281-719-6000Fax : +1-281-719-6055

South AmericaHuntsman Quimica Brasil Ltda.Av. Prof. Vicente Rao, 90Predio 122 - 2º andar04636-000São Paulo/SP BrazilTel : +55-11-5532-4278Tel : +55-11-5532-7307

Asia PacificHuntsman Performance Products No. 455 Wenjing RoadMinghang Economic & Technological Development ZoneShanghai 200245P. R. ChinaTel : +86-21-3357-6588Fax : +86-21-3357-6543

Australia61 Market Road Brooklyn Victoria 3012, Australia Tel : +61-3-9933-6696Fax : +61-3-9933-6656

Europe, Middle East & AfricaHuntsman Performance Products Everslaan 45 B-3078 EverbergBelgiumTel : +32-2-758-9544Fax : +32-2-758-9946

DisclaimerHuntsman Corporation warrants only that its products meet thespecifications stated in the sales contract. Typical properties,where stated, are to be considered as representative of currentproduction and should not be treated as specifications. While allthe information presented in this document is believed to be re-liable and to represent the best available data on these products,HUNTSMAN MAKES NO WARRANTY OR GUARANTEE OF ANYKIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITEDTO ANY WARRANTY OF MERCHANTABILITY OR FITNESS FORA PARTICULAR PURPOSE, NON-INFRINGEMENT OF ANY IN-TELLECTUAL PROPERTY RIGHT OF ANY THIRD PARTY, ORWARRANTIES AS TO QUALITY OR CORRESPONDENCE WITHPRIOR DESCRIPTION OR SAMPLE, AND ANY USER OF PROD-UCTS DESCRIBED HEREIN SHOULD CONDUCT A SUFFICIENTINVESTIGATION TO ESTABLISH THE SUITABILITY OF ANYPRODUCT FOR ITS INTENDED USE AND ASSUMES ALL RISKAND LIABILITY WHATSOEVER RESULTING FROM THE USE OFSUCH PRODUCT, WHETHER USED SINGLY OR IN COMBINA-TION WITH OTHER SUBSTANCES. Products may be toxic andrequire special precautions in handling. For all products describedherein, the user should obtain detailed information on toxicity, to-gether with proper shipping, handling, and storage procedures,and should comply with all applicable safety and environmentalstandards. The behavior, hazards and/or toxicity of the productsreferred to in this publication in manufacturing processes and theirsuitability in any given end-use environment are dependent uponvarious conditions such as chemical compatibility, temperature,and other variables, which may not be known to Huntsman. It isthe sole responsibility of the user of such products to evaluate themanufacturing circumstances and the final products under actualend-use requirements and to adequately advise and warn futurepurchasers and users thereof.

SURFONIC® is a registered trademark of Huntsman Corpora-tion or an affiliate thereof in one or more, but not all, countries.

Copyright © 2017 Huntsman Corporation or an affiliate thereof.All rights reserved.

www.huntsman.com/performance_products