FIELD TESTING OF DRILLING FLUIDS Water Base Drilling

FIELD TESTING OF DRILLING FLUIDS

Water Base Drilling Fluids Marsh funnel viscosity- Cup and Funnel Procedure 1. 2. 3. 4. 5. Hold one finger over tip of funnel; pour the mud through funnel screen until the funnel is filled to the bottom of the screen (1, 500 cm 3). Begin the flow of mud into the mud cup by removing the finger. Start a stop watch at exactly the same time. Stop the watch when the mud level reaches the one quart mark. Note the number of seconds recorded by the stop watch and enter on API Drilling Mud Report as “Funnel Viscosity (sec/qt) API. ” Record temperature of mud at flow line.

Mud Density- Mud Balance Procedure 1. 2. 3. 4. Using the sample of mud, completely fill the mud balance cup. Place lid on cup with a rotating motion, expelling some mud through the hole in the lid, and wash mud from outside of cup. Wipe the excess water from mud balance with towel or rag. Place balance arm on the base with knife edge on the fulcrum and move the rider along the balance arm until balance indicates the arm is level. Note the Density (weight of the mud at the left hand edge of the rider and enter on API drilling mud report as “weight (lb/g, lb/cu ft, or specific gravity, SG). ”

Plastic Viscosity, Yield Point, Apparent Viscosity 1. 2. 3. 4. As quickly as possible within 10° F from original temperature, start the viscometer test. Fill viscometer cup with mud to approximately two inches from the top. Immerse the rotor sleeve to the scribed line. Place a thermometer in the mud, but do not lay it against the rotor sleeve. Record temperature. Run rotary speed at 600 rpm until dial stabilizes. Record the reading.

Plastic Viscosity, Yield Point, Apparent Viscosity Change speed to 300 rpm. Let dial stabilize and record the reading. 5. A. Plastic viscosity (PV) recorded in centipoises (cp): PV= 600 rpm reading – 300 rpm reading. B. Yield Point (YP) in lbs/100 ft 2. = 300 rpm reading – PV C. Apparent Viscosity AV in centipoise: AV= 600 rpm reading 2

Gel Strengths 1. 2. 3. After running the PV and YP, stir mud at 600 rpm for 10 seconds. Put viscometer in the 3 rpm position. Wait 10 seconds, and then manually turn the knurled hand wheel (on top of viscometer) very slowly to produce a positive reading. As the rotary sleeve is being moved very slowly, a reading will produced on dial. Once the reading records its maximum measurement, it will begin to decline. The highest reading will be the initial gel strength and this is the reading at should be recorded.

Gel Strengths 4. 5. 6. 7. 8. Again stir sample at 600 rpm for 10 seconds, go to the 3 rpm setting, and turn off viscometer. Set timer and keep mud in static state for 10 minutes. Repeat procedure in step 3. Record the highest reading as the 10 -minute gel strength. The initial and 10 minute gel strength will both be recorded in lb/100 ft 2. NOTE: A 30 minute gel strength can be run as well. Repeat from step 4, allowing sample to set for 30 minutes before checking and recording deflection at 3 rpm.

Filtration & Cake Thickness 1. 2. 3. Remove bottom of filter cell and fill to ½ inch from gasket ledge with mud. Be sure cell is clean and o-ring is in place before placing filter paper and locking bottom of cell in position with moderate hand pressure on locking screw. Engage coupling at top of cylinder with coupling on filter press rack. Place 25 cc graduated cylinder under filter press. Pressurize the cell to 100 psi by opening the valve at top of press until pressure can be heard entering filter cell. (This should take one or two complete turns. Be careful do not turn too far. Start timer immediately.

Filtration & Cake Thickness 4. 5. 6. 7. 8. Read and record 7 -1/2 minute and 30 minute fluid loss in cubic centimeters (cm 3). After 30 minutes, shut off and release by turning valve clockwise. (Save filtrate for Chemical tests. ) Save filter paper and use extreme caution to prevent minimum disturbance of filter cake. With a gentle flow of water, wash excess mud from filter cake. Measure thickness of filter cake and record in 32 nds if an inch. Record the physical properties of the cake. Record filtrate loss as # of cc’s collected in 30 minutes.

p. H Test p. H Strip Method: 1. 2. 3. Place one-inch strip of indicator paper on surface of mud or place into filtrate. Allow it to remain until liquid gas wetted the surface of the paper and the color has stabilized (usually about 30 seconds). Compare the color of the paper with the color standards provided with the paper dispenser and estimate p. H. Note the ph to the nearest 0. 5 or 0. 2 units depending upon the scale of the color chart. Enter in proper space on the mud report.

Class Electrode p. H Meter 1. 2. 3. Standardized the glass electrode ph meter with suitable buffer solutions according to directions supplied with the instrument. Make the necessary adjustments to put the meter into operation. Wash the tips of he electrodes, gently wipe dry, and insert them into the mud. Rotate the container to stir the mud around the electrode. After the meter reading becomes constant (30 seconds to several minutes), record the p. H to the nearest 0. 1 unit, and enter in proper place on the mud report.

Sand Content Test 1. 2. 3. 4. 5. 6. Fill glass measuring tube to indicated mark with mud. Add water to next mark, close mouth of bulb, and shake vigorously. Pour mixture onto a clean, wet 200 mesh screen. Add wash water to the tube and pour this on screen. Repeat washing until tube is clean. Fit funnel on top of sieve. Insert tip of funnel into glass bulb and wash sand back into bulb with water. Allow sand to settle and read sand content percent on graduations of bulb. Record percent sand by volume, estimating to the nearest tenth of one percent. * *There may be particles other than sand that may have been captured. Note the presence of these solids (for example, lost circulation materials, shale cuttings, and barite).

Retort-Liquid and Solid Content 1. 2. 3. 4. 5. 6. Disassemble retort unit and check for cleanliness. De-aerate mud before attempting retort test. Place a measured volume of mud in cylinder cup and place lid on top, expelling excess mud. Insert fine steel wool in heating probe. Assemble the retort and place on condensing chamber. Put a clean 100% graduated cylinder under the condenser discharge.

Retort-Liquid and Solid Content 7. 8. 9. 10. Plug into proper voltage to begin heating retort. Continue 10 minutes after no more condensate is collected. Add wetting agent to separate oil and water. Read oil and water percent directly from graduate. 100 %-( oil% +H 2 O %) = solids% This reading incorrect if salt is present in the water phase. Volume of salt in mud can be estimated from chloride analysis of filtrate. Consider the percent of salt as part of the continuous liquid phase. The same percent amount should be subtracted from solids percent. Record the corrected oil, water, and solids percent by volume.

Chemical Analysis Alkalinity of mud (Pm) 1. 2. Using syringe, measure one milliliter (ml) of mud into titrating vessel. Dilute with 25 to 50 ml distilled water. Add 4 or 5 drops of phenolphthalein. While stirring, titrate rapidly with 0. 02 N sulfuric acid until pink color disappears. Report Pm as the number of ml of 0. 02 N acid used.

Chemical Analysis Alkalinity of filtrate (Pf) 1. 2. Measure one ml of filtrate into titration vessel; add two drops phenolphthalein. If no color appears, the alkalinity is zero. If indicator turns pink, titrate with 0. 02 N sulfuric acid until color disappears. (If the sample is so colored that a color change cannot be detected, the endpoint is taken when the p. H drops to 8. 3 as measured with the p. H meter. ) Report Pf as the number of ml of 0. 02 N acid used.

Chemical Analysis Alkalinity of filtrate (Pf) 3. 4. Add two drops of bromcresol green-methyl orange to the sample and continue titrating with 0. 02 N acid until color changes to yellow. Report Mf as the total number of ml of 0. 02 N acid used. NOTE: Mf alkalinity is not part of the API Code, but some operators use it to determine carbonates, bicarbonates, and hydroxides in the mud.

Chemical Analysis Alkalinity of filtrate (Pf) 5. Calculate the lime content of the mud: Lbs/bbl lime= 0. 26(Pm-Fw. Pf). Fw is the water fraction of the mud as determined from the liquid-solids test: Fw = % water by vol. 100 6. Report lime content lbs/bbl in one of the blank spaces provided on the mud report.

Chemical Analysis Chloride Determination (Salt Content) 1. 2. Measure one ml of filtrate in titration dish. Add 2 drops phenolphthalein. If indicator turns pink, add 0. 02 n sulfuric acid drop by drop while stirring until pink color disappears. Add 25 to 50 ml distilled water and 5 to 10 drops potassium chromate. Titrate with 0. 0282 N silver nitrate while stirring until color changes from yellow to brick red and persists for 30 seconds.

Chemical Analysis Chloride Determination (Salt Content) Chloride (mg /1000 cm³) = (cm³ of silver nitrate) (strength) Cm³ of filtrate used Salt na. Cl mg/l= (1. 65) (chlorides mg/l) Grains per gallon = (0. 0583) (salt) mg/l)

Chemical Analysis Total Hardness- calcium (Quantitative Determination) 1. To approximately 50 ml distilled water in titration vessel, add approximately two ml of hardness buffer solution and sufficient hardness indicator solution to give a strong color (two to six drops). If red color develops, and Versenate drop by drop until color turns blue. Do not record this amount to calculate Ca. CO 3 mg/100 cm³.

Chemical Analysis Total Hardness- calcium (Quantitative Determination) 2. Add 1 ml of filtrate to the vessel. If calcium or magnesium is present, a wine color will develop. Titrate with versenate while stirring until color turns blue. NOTE: Filtrate is colored red-brown by chemical thinners; the color change may be from brownish-purple to slate grey. Record ml of versenate and calculate Ca. Co 3 with the following formula.

Chemical Analysis Total Hardness- calcium (Quantitative Determination) Ca. Co 3 (mg/1) mg/1000 cm³ = cm³ standard versenate (1000) No. of cm³ filtrate used Ca++mg/1000 cm³= (0. 4) (Ca. CO 3 mg/1000 cm³) 3. Enter results as mg/1000 cm³ on mud report.

Cation Exchange Capacity (MBT) Equipment: The following materials are necessary to estimate the cation exchange capacity of drilling mud solids or clays using the methylene blue method. 1. Methylene blue Solution 3. 74 g USP grade 2. Hydrogen peroxide: three percent solution 3. Sulfuric acid: 5 N 4. One 1 cm³ serological pipette or one 1 cm³ syringe 5. Erlenmeyer Flask: 250 cm³ 6. Burette: 10 cm³ 7. Graduated cylinder: 50 cm³ 8. Stirring rod 9. Hot Plate 10. Filter paper

Cation Exchange Capacity (MBT) Procedure: 1. 2. 3. 4. 5. 6. Add two ml of the mud sample to the Erlenmeyer flask containing 10 cm³ of distilled water. Add 15 ml of 3% hydrogen peroxide. Add 0. 5 ml of sulfuric acid. Gently boil the mixture for 10 minutes. After boiling, bring the total volume to 50 ml using distilled water. Allow the liquid to cool. Add methylene blue solution in 0. 5 ml increments. After each addition swirl the contents for about 30 seconds. While the solids are suspended, remove one drop of liquid with a stirring rod and place the drop on the filter paper. The endpoint is reached when a greenish-blue ring surrounding the dyed solids appears.

Cation Exchange Capacity (MBT) Procedure: 7. 8. When the endpoint is reached, stir for two minutes and again place one drop on filter paper. If the greenish-blue ring is again evident, the endpoint has been reached. If the ring does not appear, continue adding methylene blue in. 5 ml increments until the endpoint is reached and remains (after stirring for an additional two minutes). Record ml of methylene blue used. The cation exchange of the mud should be reported as the methylene blue capacity, calculated as follows: Methylene Blue Capacity = ml of methylene blue ml mud

Cation Exchange Capacity (MBT) Procedure: NOTE: Bentonite is not the only substance in a drilling fluid that will absorb methylene blue. The addition of hydrogen peroxide is intended to remove the effect of organic materials such as CMC, polyacrylates, lignosulfonates and lignites. The use of hydrogen peroxide allows the bentonite content of the mud to be estimated with out interference of other absorptive materials. The calculation is made as follows: Bentonite, lb/bbl= 5 x methylene blue capacity

Cation Exchange Capacity (MBT) Procedure: NOTE: The cation exchange of clays can also be determined by the following method: 1. Weigh 100 grams of clay 2. Disperse the 100 grams into water using a high speed mixer. 3. Titrate, using the method above but delete the hydrogen peroxide. 4. The cation exchange capacity can be given as milliequivalents of methylene blue per 100 grams of clay.

High Temperature – High Pressure Filtration Test 1. 2. 3. 4. 5. 6. Connect the heating jacket to the correct line voltage. Place a thermometer (50°/500°) in thermometer well and preheat to 10° above selected temperature. Pour mud sample into cell and leave ½-inch from top to allow for expansion. Place filter paper. Tighten allen screws evenly and close bottom valve. Place cell in heating jacket and transfer thermometer to the cell thermometer well.

High Temperature – High Pressure Filtration Test 7. 8. Place pressure unit to top valve and lock into place. Place pressure unit to bottom valve and lock in place. Apply 100 psi to both pressure units with valves closed. Open the top valve and apply 100 psi to the mud while heating. When sample reaches the desired temperature, increase top pressure unit to 600 psi and open bottom valve to start filtration. (There should be 100 psi on bottom valve. )

High Temperature – High Pressure Filtration Test 9. 10. 11. Collect filtrate for 30 minutes maintaining 500°F. If back pressure increases above 100 psi, slowly relieve pressure by collecting filtrate. Record total volume by doubling filtrate ml. Close top and bottom valves and back-off pressures from both regulators. CAUTION: Pressure in the filter cell will be 500 psi. Maintain cell in upright position and cool to room temperature before disassembly.