A ULTRADRIL Engineering Guidelines DJ!!!

Confidential – Internal Use Only

ULTRADRIL A Highly Inhibitive Water-Base Fluid for Drilling Reactive Shales

Best Practices and Engineering Guidelines

M-I Technology Center (HTC) 5950 North Course Dr. Houston, TX 77072 Tel: 281-561-1440 Fax: 281-561-1441


ULTRADRIL Best Practices & Engineering Guidelines (Draft Revision 004) INDEX I. II. III.

Introduction ULTRADRIL Performance Goals Qualification Testing Shale Inhibition Dispersion Swelling Hardness Accretion Lubricity Toxicity Cement Contamination ULTRADRIL System Components Primary Inhibitor Secondary Inhibitor/Encapsulator Fluid Loss Control Agent Viscosifier Anticrete/Lubricant Mud Formulation and Properties ULTRADRIL Engineering Building the System System Maintenance    

IV.

V. VI.

Appendix A: Procedures for Determination of U LTRAHIB and ULTRACAP Concentrations Appendix B: Additional Reading

ULTRADRIL Engineering Guidelines June 2002 Page 2 of 15


Introduction Continuing interest in deepwater exploration and development, increasing environmental regulations imposed on the discharge of cuttings and the biodegradation of non-aqueous-base drilling fluids (NAF), and limited performance of water-base fluids in deepwater environments have driven the development of M-I’s high-performance water-base ULTRADRIL mud system. Existing WBM systems have limited performance when compared to NAF systems relative to inhibition, ROP and fluid maintenance. A water-base drilling fluid with superior shale inhibition, will not only improve the drilling of upper-well sections, but also will have applications throughout the deepwater operation. The ULTRADRIL system represents a leap forward in water-base technology by addressing the limitations and disadvantages of current high-performance fluid applications, allowing the ULTRADRIL system to effectively compete with NAF systems in drilling performance. Designed for both global offshore and land applications, the ULTRADRIL system was developed to be a water-base fluid with improved deepwater drilling performance. Research and development, facilitated by M-I’s technical centers in Houston, Stavanger and Aberdeen, insured that the resulting system would consider drilling challenges from various regions o f the world by focusing on specific performance goals for the system design.

ULTRADRIL Performance Goals The ULTRADRIL drilling fluid system is a highly inhibitive water-base mud developed for optimized stability and drillability of reactive and dispersible shale formations. The ULTRADRIL system was developed with a total system approach concept: designed to provide maximum shale inhibition and wellbore stability; to provide low accretion and bit balling tendencies; to have good, stable and easy to maintain properties; to offer flexibility in density and base brine selection; and application potential in a variety of drilling environments for global utilization. The performance goals and design criteria for ULTRADRIL are based on addressing specific limitations and performance issues such as toxicity, shale inhibition (dispersion, swelling), density limitations, accretion, and engineering aspects associated with non-aqueous drilling fluids and various water-base systems.

Qualification Testing Shale Inhibition

A significant number of laboratory tests have been conducted to verify and optimize the shale inhibition provided by the ULTRADRIL system. A comprehensive range of native outcrop clays and drilled shales from different regions of the world, bentonite, Oxford, Arne, Foss Eikeland, Trinidad Red Mango, and Gulf of Mexico “gumbo,” were used to develop and test the ULTRADRIL system. A full suite of thorough testing procedures designed to address performance goals focused on: ULTRADRIL Engineering Guidelines June 2002 Page 3 of 15


• • • • •

Cuttings dispersion tests – standard hot rolling and slake durability dispersion Swelling – clay hydration and swell meter tests Hardness – bulk hardness via shale extruder Accretion – Shell-type rolling bar accretion Wellbore stability – Shale Membrane Tester and Teratek Wellbore Simulator

Following are some of the more relevant results of these tests:

Fig. 1 - Dispersion – Comparison of ULTRADRIL and 20% NaCl/PHPA system Hot Roll Dispersion Shell Field Cuttings 10 lb/gal –No drill solids

ULTRADRIL

10-lb/gal mud

ULTRADRIL

100% 90% 80% 70% 60% PHPA ULTRADRIL

50% 40% 30% 20% 10% 0% Hot Rolling

Slake Durability



Fig. 2 - Accretion – Comparison of U LTRADRIL and 20% NaCl/PHPA systems

PHPA

ULTRADRI L 10 lb/gal Mud

80%

ULTRADRIL

70% 60% 50% 40% 30% 20% 10% 0% Amount Adhered

Fig. 3 – Hydration – Chemical stabilization of Oxford clay (Tertiary-Jurassic Era)

120

Gel/ Lignosulphonate

111

KCl/ PHPA 88

100 74

CALDRIL

75

Sea water/glycol/PHPA

80

n o i t a r 60 d y H 40 %

KCl/glycol/PHPA

51

ULTRADRIL (sea water only)

39 33 27

ULTRADRIL (20% NaCl) 15

ULTRADRIL (KCl)

20

SILDRIL 0 -16

Invert OBM

-20



Lubricity

The ULTRADRIL system exhibits good natural lubricity in laboratory testing, however, the addition of ULTRAFREE ROP enhancer, enhances lubricity in addition to minimizing accretion. In a higher density system (14 lb/gal), the addition of the U LTRAFREE additive lowered the coefficient of friction below 0.25, a good value for WBMs at such a mud weight. Toxicity

The individual components in the ULTRADRIL system have been tested for their effect on toxicity. All formulations had good LC50 values, higher than 140,000 ppm. The table below shows the aquatic toxicity test results (LC50) for a wide range of ULTRADRIL formulations:

Fluid Type

LC50, 96-hr RF

5% ULTRAHIB, 4-lb/bbl U LTRACAP, 0% ULTRAFREE

142,200

10.3-lb/gal Field U LTRADRIL (20% NaCl) 3% ULTRAHIB, 2.5-lb/bbl U LTRACAP, 3% ULTRAFREE

162,400

16-lb/gal Lab U LTRADRIL (20% NaCl) 3% ULTRAHIB, 1-lb/bbl U LTRACAP, 3% ULTRAFREE

374,000

11-lb/gal Lab U LTRADRIL (Seawater) 3% ULTRAHIB, 3-lb/bbl U LTRACAP, 3% ULTRAFREE

221,500

Table 1: ULTRADRIL LC50 data Cement contamination

The ULTRADRIL system should be pre-treated with citric or acetic acid and sodium bicarbonate prior to drilling cement. Although the system is tolerant to high levels of calcium / hardness, the high alkalinity associated with cement is detrimental to the ULTRACAP polymer. At pH > 10.0 this polymer hydrolyzes, which will not only deplete the concentration, but will also generate ammonia. Pre-treat the system with 0.4 lb/bbl citric acid and 0.5 lb/bbl sodium bicarbonate and continue adding the two products while drilling cement. Monitor the pH and ensure that the final pH is below 9.5. Example: Laboratory tests with a 14-lb/gal ULTRADRIL system were run to determine the effect of cement contamination and the best treatment method. The test matrix included 5 lb/bbl of class G cement as the contaminant to compare fluid properties of untreated, cement-contaminated mud, and with citric acid and sodium bicarbonate treatments. Before running the contamination test, a cement titration was performed to measure excess lime generated by 5 lb/bbl of cement in ULTRADRIL Engineering Guidelines June 2002 Page 6 of 15


20% NaCl brine. The result (2.6 lb/bbl) was used in the basic formulas recommended for cement contamination treatment: • •

Citric acid (lb/bbl) = lb/bbl excess lime x 1.893 = 4.92 lb/bbl Sodium bicarbonate = lb/bbl excess lime x 1.135 = 2.95 lb/bbl

Based on the above calculations, fluid samples were treated with 5-lb/bbl citric acid and 3lb/bbl sodium bicarbonate. Fluid loss and rheology had minimal variation compared to the base mud.

ULTRADRIL System Components The primary shale inhibitor in the ULTRADRIL system is ULTRAHIB polyamine, which also provides gas-hydrate inhibition for deepwater operations. The ULTRACAP polymer, a mildly cationic acrylamide, provides secondary shale inhibition and cuttings stability. Shale inhibition is achieved by preventing water uptake by clays, and by providing superior cuttings integrity. Secondary shale inhibition can be achieved by cation substitution with formation clays using potassium and/or calcium ions in the formulation. The system also contains the ULTRAFREE anti-accretion/ROP enhancer. Primary Inhibitor

The ULTRADRIL system has a multiple-inhibition mechanism, provided by the primary ULTRAHIB and secondary ULTRACAP shale inhibitors. The ULTRAHIB inhibitor is a liquid additive that acts as a clay hydration suppressant, by intercalating and reducing the space between the clay platelets so that water molecules will not penetrate and cause shale swelling. Recommended concentrations are 2–4% v/v, depending on shale reactivity. ULTRAHIB chemistry additionally provides alkalinity. Proper concentration of the ULTRAHIB additive will insure a pH in the 9.0– 9.5 range, eliminating any additions of caustic soda (NaOH) or potassium hydroxide (KOH). Secondary Inhibitor

The ULTRACAP polymer, a mildly cationic acrylamide, provides cuttings encapsulation and 3 shale stabilization. A system concentration of 2-3 lb/bbl (5.7-8.56 kg/m ) provides a protective polymer sheath that gives cuttings good integrity and prevents sticking to the shaker or each other. Fluid Loss Control Agent

Although other cellulose materials may be used on certain applications, the POLYPAC UL or POLYPAC ELV agent is the preferred fluid loss additive. The POLYPAC UL/ELV additive provides very effective fluid loss control with minimum or no effect on rheology. A 3 concentration of 2–4 lb/bbl (5.7-11.4 kg/m ) of the POLYPAC UL/ELV agent should insure a low fluid loss (<6.0 mL/30min). ULTRADRIL Engineering Guidelines June 2002 Page 7 of 15


Viscosifier

The optimum rheology profile of the ULTRADRIL system is achieved using xanthan gum biopolymers such as DUO-VIS or XCD. Concentrations ranging from 0.5 – 1.5 lb/bbl (1.42-4.28 3 kg/m ) are required, depending on hole diameter and well profile. Anti-accretion/Lubricant

The ULTRAFREE ROP enhancer is a blend of surfactants that minimizes accretion, adh erence of shale cuttings to metal surfaces (e.g., BHA or bit). The ULTRAFREE additive also provides additional lubricity. It is recommended to add the ULTRAFREE agent last in the mixing order and to mix vigorously for good and uniform incorporation. Optimum concentration is 1-3% v/v, depending on mud weight and solids content.

Mud Formulation and Properties The ULTRADRIL system can be built with a variety of base brines, ranging from seawater to high-concentration NaCl brine to KCl brine. In deepwater operations, a much higher salinity (e.g., 20% NaCl) is often required to provide additional gas hydrate suppression or to increase the shale inhibition quality. The following table lists typical concentrations. Additives Additive

Material

Function

Drill Water

Base Fluid

Seawater

Base Fluid

Typical concentration

NaCl

Sodium chloride

Inhibition/Density

Up to Saturation %wt

KCl

Potassium chloride

Inhibition

As Required

ULTRAHIB

Polyamine

Shale inhibitor

2.0-4.0 % v/v

ULTRACAP

Acrylamide polymer

Shale encapsulator

2.0-3.0 lb/bbl

POLYPAC UL/ELV

Cellulose polymer

Fluid loss control

2.0-4.0 lb/bbl

DUO-VIS/XCD

Xanthan gum

Viscosifier

0.5-1.5 lb/bbl

ULTRAFREE

Surfactant blend

Anti-accretion/lubricant

1.0-3.0 % v/v

M-I BAR

Barite

Density control

As required

Table 2: Typical concentrations and functions



Table 3 lists the low to high mud property ranges for a 20% w/w NaCl ULTRADRIL system field application. Property Hole size, in. Density, lb/gal Funnel Viscosity, s/qt R600/R300 R200/R100 R6/R3 PV, cP 2 YP, lb/100 ft 2 Gels, 10s/10m, lb/100 ft

Value 17.0-22.0 9.9-10.3 56-75 41-90/28-65 23-53/16-36 5-12/4-10 13-30 15-35 5-10/6-14

Property Value API Fluid Loss, mL/30m <5.0 MBT, lb/gal <10 pH 9.5-10.0 Pm 5.0-7.9 Pf /Mf 5.0-6.8/6.9-8.1 Chlorides, mg/L 121000-128000 ++ Hardness (Ca ) 360-1200 ULTRAHIB 2.7-3.1 ULTRACAP 2.3-2.8

Table 3: Typical mud properties

ULTRADRIL Engineering Building the System

One of the main advantages of the ULTRADRIL system is the simplicity of the mixing process. The products can be added relatively quickly, and the fact that two products are liquids saves even more time. Shearing and shaker screen testing has demonstrated that for proper polymer hydration and maximum fluid performance, a shearing unit such as a Poly Shear 140 or Halco is required, and a Vortex Venture Lobestar hopper is recommended. Screenability is greatly enhanced and rheological properties improved by shearing at least one complete circulation through the units after initially blending the ULTRACAP additive with the Lobestar hopper. Tables 4 and 5 are examples of an actual field trial application for mixing 1,000 bbl of 10 lb/gal ULTRADRIL fluid and 1,000 bbl of dilution premix with 3% ULTRAHIB inhibitor and 2.5-lb/bbl ULTRACAP encapsulator . The order of addition proved to be the most effective. The addition of the ULTRAFREE additive before adding the DUO-VIS viscosifier resulted in foaming, suggesting that the ULTRAFREE additive should not be added in the dilution premix (which does not contain DUO-VIS). A Lobestar hopper has improved the time required for mixing. If a Lobestar is not available, allow at least twice the mixing time when adding polymers.



Recommended Order of Mixing (1,000 bbl volume)

Quantity to Add

Estimated Mixing Time

1. Add freshwater/drill water to a clean pit

261 bbl

15 min

2. Add NaCl brine to blend with the water

678 bbl

35 min

3. Add ULTRAHIB inhibitor

23 drums

20 min

4. Add ULTRACAP agent through the hopper at 1 sk/min.

50 sx

50 min

5. Add POLYPAC UL polymer through the hopper at 2 sk/min.

40 sx

20 min

6. Add DUO-VIS viscosifier through the hopper at 1 sk/min

50 sx

50 min

7. Add ULTRAFREE enhancer

11.5 drums

10 min

12. Weight up system to 10 lb/gal with barite

~23,500 lb

30 min

13. Circulate the mud through a shear unit to storage

60 – 120min

Comments

Minor foaming may develop. Treat with D EFOAM-X.

If foaming is not a problem, can add full concentration. Check mud properties before and after shearing the fluid and compare with properties below Time depends on maximum flow rate through the shear unit.

Table 4: Example: 1,000 bbl 10.0 lb/gal ULTRADRIL system. Expected rheology at 80°F: PV = 17-20; YP = 16-21; Gels = 5-7/6-8; API = 4-5; pH = 9.5-10 Recommended Order of Mixing (1,000 bbl volume)

Quantity to Add

Estimated Mixing Time

1. Add freshwater/drill water to a clean pit

261 bbl

15 min

2. Add NaCl brine to blend with the water

678 bbl

35 min

3. Add ULTRAHIB inhibitor

23 drums

20 min

4. Add ULTRACAP encapsulator through the hopper at 1 sk/min.

50 sx

50 min

5. Add POLYPAC UL polymer through the hopper at 2 sk/min.

40 sx

20 min

13. Circulate the mud through a shear unit to storage

Comments

Minor foaming may develop. Treat with D EFOAM-X defoamer.

60 – 120min

Time depends on maximum flow rate through the shear unit.

Table 5: Example: 1,000 bbl 9.5 lb/gal dilution premix with 3% ULTRAHIB & 2.5-lb/bbl ULTRACAP additives. System Maintenance 1. Solids Control – Make full and effective use of all solids control equipment. Run the finest ULTRADRIL Engineering Guidelines June 2002 Page 10 of 15


screens possible at all times on the shale shakers. The mud cleaners should be run with screens not coarser than 250 mesh to limit the build up of sand in the system. Prior to weight-up, or if MBT values are high, the desilters/desander should be run with discharge overboard. The mud cleaner should then be used as an extra shaker for increased flow capacity. Maintain the system in such manner that the MBT value is less than 15 lb/bbl. Ensure that all equipment is operating at the maximum efficiency. It is exceptionally important to maintain the absolute minimum of drilled solids in the active system and to maintain the drilling fluid system according to the program parameters. 2. Displacement – Follow the standard displacement guidelines found in the M-I Drilling

Fluids Engineering Manual, Chapter 20C, Displacements and Cementing, for spacer recommendations and design. A typical spacer design to displace an existing water-base mud or seawater with the ULTRADRIL system might be: ±100 bbl of seawater followed by 50 bbl of weighted DUO-VIS sweep with YP >50 (from 2.5-3-lb/bbl DUO-VIS viscosifier). To assist in reducing accretion tendencies, add 15% ULTRAFREE enhancer to the seawater spacer, allowing the surfaces to be coated prior to contact with the ULTRADRIL fluid. 3. Dilution – Premix dilution fluids should be built based on expected depletion rates and the

rate of dilution needed to maintain the proper concentrations of the major constituents, ULTRAHIB inhibitor and ULTRACAP encapsulator, in the system. A standard dilution fluid should have a minimum of 3.5% v/v ULTRAHIB, 3.0-lb/bbl ULTRACAP and 2-lb/bbl POLYPAC UL or ELV additives. Dilution rates can range from 3.0 to 5.0 bbl of dilution per bbl of hole drilled, also depending on formation reactivity and depletion rates. 4. Rheology – Control drilling fluid rheology by the addition of DUO-VIS viscosifier and

dilution with pre-mixed drilling fluid, together with optimum use of all solids control equipment. Maintain low gravity solids at a minimum. As a guide, LGS content should be less than 50 lb/bbl. Increasing LGS content of the mud may cause the rheology profile to deviate from the desired, exhibiting increased PV and YP. Two of the most important rheology parameters are the 3-rpm reading which defines the lifting capacity at very low flow rates, and the 10-sec gel strength which defines the suspension capability of the system. It is important that these two parameters are within the specifications to ensure that hole cleaning is optimum and that the build-up of cuttings is reduced to a minimum. 5. Inhibition – Monitor cutting conditions at the shakers. Cuttings should be firm and dry

inside. Sticky and balled-up cuttings may indicate insufficient inhibition from a low ULTRAHIB concentration and/or too low ULTRACAP level. The initial mixture should contain more ULTRAHIB inhibitor than specified in the mud program to act as a buffer for high consumption rates. Cuttings that appear dry inside, but ball or stick to shakers may indicate low ULTRACAP levels. The addition of ULTRACAP polymer to maintain the programmed levels should improve solids-removal efficiency. Maintain the ULTRAHIB concentration of the mud system. The ULTRAHIB concentration is expected to exhibit a slow depletion, as the ULTRAHIB agent is mainly lost from the system through depletion. Add the ULTRAHIB agent as appropriate to maintain the concentration between 3-4%. If the formation drilled seems less reactive, i.e., the depletion rate of the ULTRAHIB additive is much slower than normal, the concentration can be gradually reduced to 2 – 2.5% v/v. ULTRADRIL Engineering Guidelines June 2002 Page 11 of 15


6. Bit balling/ROP – The system is designed to optimize ROP and minimize bit balling

potential. Any indications of bit balling, or poor ROP as a result, can be alleviated by addition of 1.0-3.0% v/v ULTRAFREE ROP enhancer, which can be added directly to the system or maintained through premix addition. ®

7. Hole cleaning – Run VIRTUAL HYDRAULICS CLEANPRO prior to drilling a new interval.

The low-shear rheology should be adjusted accordingly with the DUO-VIS viscosifier. If needed, pump a high viscosity sweep containing 0.75 lb/bbl DUO-VIS additive, and 10 sacks of NUT PLUG hulls every other stand. Be prepared when the pill comes around to the surface to dump or collect that volume. Controlled drilling is strongly recommended for proper hole cleaning. Cuttings should be circulated up above the BHA prior to connections. Reaming each connection should also be considered. This will minimize the potential of cuttings settling during connections, causing packing off and stuck pipe. Prior to trips, the hole should be circulated for a period of at least 1 ½ x bottoms-up. This will prevent tight hole on the way out and bridges, fill, etc., on the way back in. 8. Density – Cuttings at the shale shakers should be monitored for signs of cavings that may

indicate a need for an increased drilling fluid weight. Tight hole, fill on trips, and torque or drag on connections can also be good early indications of the possible need to increase the drilling fluid density to maintain stable hole conditions. 9. Gel strengths – Typically the lower the 10-minute gel strength can be maintained, the better

the condition of the drilling fluid. As ultra-fine and fine solids content builds up in conjunction with the polymer concentrations, the gel strengths will increase. Field 2 experience has shown that a 10-minute gel strength of 30 lb/100 ft in polymer drilling fluid systems is acceptable. However, it is essential to maintain the initial gel strength >6 to provide a thixotropic fluid that will support cuttings. 10. pH – A pH range of 9.0 to 9.5 should be maintained in this system. This pH will be

provided by the proper ULTRAHIB agent concentration, reducing the tendency of gumbo/claystone to hydrate and disperse. DO NOT add caustic soda or potassium hydroxide to the ULTRADRIL system, due to the potential to hydrolyze the ULTRACAP shale encapsulator and release ammonia. Treat with citric acid or acetic acid when necessary to reduce the pH to the prescribed range. 11. pf/Mf – As shown in Table 3, expect alkalinities to be higher than normal as seen in other

water-base mud systems. The higher alkalinities are a result of the intrinsic pH of the ULTRAHIB shale inhibitor and do not present a problem. 12. API fluid loss – A consistent API fluid loss, together with a thin and slick filtercake,

indicates a sufficient amount of free available polymer. Maintain the fluid loss in the range of 2 - 4 mL/30 min by adding POLYPAC UL polymer. 13. HTHP fluid loss – Depending on the degree of HTHP control required, POLYPAC UL

polymer can be supplemented with high-temperature fluid loss reducers such as R ESINEX resinated lignite and THERMPAC UL polymer. 14. Hardness – High hardness levels do not adversely affect the system.



Appendix A: Procedures for Determination of U LTRAHIB and ULTRACAP Concentrations LTRADRIL Filtrate Determination of Free U LTRAHIB in U

Scope and application:

This is a field method for determining free ULTRAHIB in ULTRADRIL filtrate by amine titration. Equipment and Reagents: 1. Beaker, 150 mL 2. Magnetic stir plate and stir bar 3. Pipette, graduate, two 5 mL 4. pH meter accurately calibrated 5. Phenolphthalein indicator, 1% in ethanol 6. 50/50 Mixture of Isopropyl alcohol (IPA), 99% and Deionized (DI) water 7. Potassium hydroxide (KOH), 0.1N in methanol 8. Hydrochloric acid (HCl), 0.1N Procedure: 1. Accurately measure 2 mL of filtrate into the 150-mL beaker. Add 50 mL of the DI water / IPA mixture and then 10 drops of phenolphthalein indicator. If the solution remains colorless, the fluid does not contain any free caustic (i.e., from cement contamination). 2. Insert the pH meter probe into the beaker and measure the initial pH. 3. Titrate with 0.1N hydrochloric acid (HCl) to pH = 3.5. Use 0.5 mL at a time until pH = 6 – 5.5. Continue adding 0.1 mL at a time until pH = 3.5. Record the mL of 0.1N hydrochloric acid (HCl) used. 4. Titrate with 0.1N potassium hydroxide (KOH) to pH = 10. Use the volume from the previous step as a guideline for the initial addition. Continue adding 0.1 mL at a time until pH = 10. Record the mL of 0.1N potassium hydroxide (KOH).

5. As an indication, the solution will turn pink near the end of titration. Calculation:

Free ULTRAHIB in filtrate % v/v = mL 0.1N KOH x 1.16 - 1.21 NOTE: The pH meter should be calibrated daily to ensure accurate readings. A back-up pH meter is recommended, due to the importance of this test in properly running the system.



LTRADRIL Drilling Fluid Determination of Free U LTRACAP in U

Equipment: (Modified PHPA test) 1. Hot plate/magnetic stirrer 2. 2, 125 mL Erlenmeyer Flasks 3. Magnetic Stirring Bar 4. Distilled Water 5. 2% by Weight Boric Acid Solution 6. Silicon Defoamer 7. 6N Sodium Hydroxide Solution 8. 2-3 Feet of Tygon Tubing 9. #6 Rubber Stopper with 1 ¼” hole 10. 0.1N Sulfuric Acid solution (N/10 Sulfuric Acid solution) 11. Methyl Red Indicator 12. ¼” O.D. Glass Tubing (e.g., Dow-Corning 84 AFC-78) (2 pcs about 3-4” long) Procedure: 1.

Attach the two glass tubes to the end of the Tygon tubing and fit one of the glass tubes into the rubber stopper so that the end of the tube just fits flush with the bottom of the rubber stopper.

CAUTION: Be careful while inserting the glass tube into the stopper; the tubing could break and produce a serious injury.

2. To one Erlenmeyer flask add 25 mL of boric acid solution and 3-6 drops of methyl red indicator. 3. To the other Erlenmeyer flask add 50 mL distilled water, 2 mL of silicon defoamer, and 10 mL of filtrate or whole mud.

4. Carefully drop the magnetic stirring bar into the flask containing the filtrate or whole mud, place the flask on the hot plate and begin stirring at a slow-to-moderate speed. Then, add 6.0 mL of the 6N sodium hydroxide solution and immediately fit the flask with the rubber stopper. 5. Submerse the other end of the tubing into the boric acid/methyl red solution and begin to heat the flask containing the filtrate or whole mud. 6. Heat for 60 minutes. Approximately 20-25 mL of distillate should collect during this time. 7. When the reaction has been completed, the boric acid solution should be yellow. Titrate the solution back to its original red or pink color with a 0.1N H2SO4 solution and record the amount of acid used. Calculation:

ULTRACAP, lb/bbl = mL 0.1N H2SO4 X 0.59 – 0.34



Additional Guidelines and Trouble Shooting:

1. It is important that the glass tubing be flush with the bottom of the rubber stopper. If the glass tube protrudes below the stopper, the caustic solution being distilled will collect around the exposed tube and be sucked up and over to the boric acid solution. This will give high erroneous values in the determination. 2. Be sure the indicator used is methyl red. This indicator will change from a pale amberyellow to a pink or pinkish-red when going from a high pH to a low pH. Also, the boric acid solution should turn the indicator pink and not yellow. If it does not, try to obtain a fresh batch of boric acid. If this is not possible, use some 0.02N sulfuric acid and add dropwise until the solution just turns pink. Use this solution to collect the distillate. This way, when the final titration with 0.02N sulfuric acid is done, only the amount of ammonia will be titrated and not any unconformity in the boric acid. 3. If your particular mud or filtrate foams a lot or bumps over, use more defoamer. 4. The temperature setting for distilling the solution should be below boiling, (which invalidates the test). Bring the solution to a slow gentle boil, which causes water (or distillate) to condense at the top of the glass tubing so the distillate isn’t boiled to the receiving flask but merely collects in the tubing and runs down to the boric acid solution. 5. Be sure that the free end of the glass tubing is below the surface of the boric acid solution. It is even better if a Pasteur pipette is used at this end instead of a glass tube. The opening is smaller and the chance of allowing ammonia to escape is reduced.

6. When the final titration is performed, be sure to titrate back to the original color of the boric acid solution. If a light pink was observed originally, don’t continue to titrate to a darker pink or reddish color. 7. Please remember that although testing was conducted under as many conditions as possible, there may still be untested conditions that may produce erroneous results. So be aware that there may be chemicals or combinations of chemicals that could interfere with this test. Appendix B: Additional Reading

1. M-I Drilling Fluids Engineering Manual, Chapter 4B Clay Chemistry; Chapter 20C Displacements & Cementing 2. “A New Generation of Shale Inhibitors for Water-Based Muds,” E. Stamatakis, C.J. Thaemlitz, G. Coffin, W. Reid, SPE/IADC 29406 3. “Highly Inhibitive Water-Based Fluid System Provides Superior Chemical Stabilization of Reactive Shale Formation,” A. Patel, E. Stamatakis, J.E. Friedheim, E. Davis; AADE…Draft 02-13-01


A ULTRADRIL Engineering Guidelines DJ!!!

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