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OFI Testing Equipment – 146-00 Instructions – Workover and Completion Fluids Test Kit Page 1 of 17 

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INSTRUCTIONS 

WORKOVER AND COMPLETION FLUIDS TEST KIT 

PART No. 146-00 

Individual Test Procedures for the OFITE Workover Kit are listed below: 

Instructions 

ALKALINITY and LIME CONTENT 

WATER BASED DRILLING FLUIDS 

Alkalinity is the acid neutralizing power of a substance. Alkalinity measurements in drilling fluid testing may be made 

on the whole mud (designated with a subscript m) or on the filtrate (designated with a subscript f). The data collected 

can also be used to estimate the concentrations of hydroxyl (OH – ), carbonate (CO 3 -2 ) and bicarbonate (HCO 3 ) ions in 

the drilling fluid. Knowledge of the mud and filtrate alkalinity is important in many drilling operations. Mud additives, 

particularly some organic deflocculants, require an alkaline environment in order to function properly. Alkalinity 

arising from hydroxyl ions is generally accepted as being beneficial while alkalinities resulting from carbonates or 

bicarbonates may be detrimental to mud performance. 

The ions that are primarily responsible for filtrate alkalinity are the hydroxyl (OH – ), carbonate (CO 3 -2 ) and bicarbonate 

(HCO 3 

– ) ions. The carbonates can change from one form to another by changing the pH of the solution. Other 

inorganic ions such as borate's, silicates, sulfides and phosphates may also contribute to the alkalinity. It is important to 

realize the following calculations are only estimates of the concentrations of the reported ionic species based on 

theoretical chemical equilibrium reactions. The composition of mud filtrates is often so complex that the interpretation 

of alkalinities may be misleading. Any particular alkalinity value represents all of the ions which will react with the acid 

within the pH range over which that particular value was tested. Anionic organic thinners and filtrate reducers 

contribute to a large portion of the M f alkalinity value and may also mask the endpoint color change and render the test 

highly inaccurate in muds treated with organic thinners. For simple bentonite-based mud systems containing no organic 

thinners, the Phenolphthalein (P f ) and the methyl orange (M f ) alkalinities may be used as guidelines to determine the 

presence of carbonate/bicarbonate contamination and the treatment necessary to alleviate the problem. If organic 

thinners are present in large amounts, the conventional P f /M f test is suspect, and the P 1 /P 2 method should be used 

instead. 

OFITE • 11302 Steeplecrest Dr. • Houston, TX 77065 USA • Phone (832) 320-7300 • http://www.ofite.com 

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Equipment - Water Based Drilling Fluids: 

#147-16 Pocket pH Sensor (Optional) 

#153-26 Titration Dish, Polyethylene 

#153-28 Stirring Rod, Polyethylene 

#153-29 Syringe, glass tip, 2 ml 

#153-34 Pipette, Serological, 1 ml x 1/100 ml, glass 

#153-40 Pipette, Serological, 10 ml x 1/10 ml, glass 

Reagents: 

#220-01 Phenolphthalein Indicator sol'n, 8 oz 

#230-08 Sulfuric Acid sol'n, N/50, 8 oz 

#240-02 Methyl Orange Indicator sol'n, 8 oz 

Procedure - Filtrate Alkalinity, P f, M f 

1. Measure one or more milliliters of filtrate into the titration dish. 

2. Add two or more drops of Phenolphthalein Indicator solution. If the solution turns pink, add N/50 

Sulfuric Acid, drop by drop from the pipette, while stirring, until the pink color just disappears. If the 

filtrate is so colored that the end point cannot be seen, use a pH meter and titrate until the pH of the 

solution drops to pH 8.3, and this will be the end point. 

3. Report the Phenolphthalein Alkalinity of the filtrate, P f , as the number of milliliters of N/50 Sulfuric Acid 

required per milliliters of filtrate. 

4. To the same sample which was titrated to the P f endpoint, add two or three drops of Methyl Orange Indicator 

solution. Add the N/50 Sulfuric Acid drop by drop from the pipette while stirring until the color of the indicator 

changes from yellow to pink. The end point may also be taken when the pH of the sample drops to pH 4.3 as 

measured with a pH meter (more accurate). 

5. Report the Methyl Orange Alkalinity of the filtrate, M f , as the total milliliters of N/50 Sulfuric Acid per 

milliliters of filtrate required to reach the Methyl-Orange end-point. This also includes the amount of acid used 

to reach the Phenolphthalein, P f , end-point. 

Calculation, P f , M f (Estimation of Hydroxide (OH – ), Carbonate (CO 3 

–2 ) & Bicarbonate (HCO3 – ) ions) 

Test Results 

Calculation, Concentration mg/liter 

P f = 0 M f x 1220 = mg/L HCO 3 

– (Indicates Bicarbonate ion only) 

P f = M f P f x 340 = mg/L OH – (Indicates Hydroxide ion only) 

2P f < M f 2P f x 600 = mg/L CO 3 

–2 (Indicates Carbonate ion) 

(M f – 2P f ) x 1220 = mg/L HCO 3 

– (Indicates Bicarbonate ion) 

2P f = M f M f x 600 = mg/L CO 3 

–2 (Indicates Carbonate ion only) 

2P f > M f (2P f – M f ) x 340 = mg/L OH – (Indicates Hydroxide ion) 

(M f – P f ) x 1200 = mg/L CO 3 

–2 (Indicates Carbonate ion) 


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Procedure - Whole Mud Alkalinity, P m 

1. Measure 1 ml of drilling mud into the titration dish and dilute with 25 to 50 ml of distilled water. 

2. Add four or five drops of Phenolphthalein Indicator solution and while stirring, titrate with N/50 Sulfuric acid 

solution until the pink color just disappears. If the end point color change cannot be seen, it can be taken when 

the pH drops to pH 8.3 as measured on a pH meter. If cement contamination is suspected, the titration must be 

performed as rapidly as possible and the end-point is reported as the first disappearance of the pink color. 

3. Report the Phenolphthalein alkalinity of the whole mud, P m , as the number of milliliters of N/50 Sulfuric acid 

required per milliliter of mud. 

Procedure - Lime Content, Estimated 

1. Determine the P f and P m of the filtrate and whole mud as described in the Alkalinity test. 

2. Determine the volume fraction of water F w , using the percent of water from the liquid and solids as 

determined in a Retort analysis. 

F w = % Water by Volume 

100 

3. Report the Lime Content of the Fluid: 

Alternate Alkalinity Procedure 

Estimated Lime, lb/bbl = 0.26 (P m - F w x P f ) 

Estimated Lime, kg/m 3 = 0.742 (P m - F w x P f ) 

The P1/P2 Back Titration method is used to overcome some limitations of the P f /M f alkalinity method. A serious 

problem arises with anionic organic thinners, filtrate reducers and their degradation products which may contribute to a 

large portion of the alkalinity value, as well as masking the end point color change. These organic materials make a 

particularly large contribution to the M f alkalinity and thus render the test highly inaccurate in treated with organic 

thinners. If organic thinners are present in large amounts, the P1/P2 method should be used, but it also has its 

limitations. See the table below: 

Method Advantages Disadvantages 

P f /M f Traditional Method Interference with the M f titration 

2 Titrations, 1 Sample Bicarbonate result normally too high 

P1/P2 Eliminates interference 3 Titrations with 3 samples 

in M f titrations 

Caustic measurement critical 

Uses a toxic material - BaCl 2 


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Equipment - P1/P2 Alkalinity Method 

#147-16 Pocket pH Meter (Optional) 

#147-54 pH paper strips, range 7 - 14 pH 

#153-16 Graduate Cylinder, 25 ml x 2/10 ml, glass 



#153-26 Titration Dish, polyethylene 

#153-34 Pipette, 1 ml x 1/100 ml, glass 


#168-05 Stirring Rod, polyethylene 

Reagents: 

#206-02 Distilled Water, 16 oz 


#260-01 Sodium Hydroxide sol'n, 16 oz 

#275-04 Hydrochloric Acid sol'n, 0.02N, 8 oz 

#285-07 Barium Chloride, 10 % sol'n, 8 oz 

Procedure - P1/P2 Alkalinity 

1. Determine the P f alkalinity as described above. 

2. Measure and add 1.0 ml of Filtrate to the titration dish, then add 25 ml of distilled water. 

3. Using a pipette add 2.0 ml of Sodium Hydroxide, 0.1N and stir well. 

4. Measure the pH of the solution with the pH paper or the pH meter. 

If the pH is 11.4 or greater proceed to the next step. 

If the pH is less than 11.4 add 2.0 ml more of 0.1N Sodium Hydroxide solution and then proceed. Exact 

measurements of Sodium Hydroxide is necessary to avoid serious errors. 

5. Using the 5 ml Graduate Cylinder, measure 3 ml of Barium Chloride and add to the titration dish. 

Caution: Do not use your mouth to pipette Barium Chloride as it is extremely poisonous. 

6. Add 2 to 4 drops of Phenolphthalein Indicator solution while stirring. 

7. Immediately titrate the mixture with the standard 0.02 normal Hydrochloric Acid to the first disappearance of 

the pink color - or to a pH of 8.3 with a pH meter. The color may reappear after a short time but do not continue 

the titration. 

8. Report the Alternate Alkalinity, P1, as the total ml of 0.02 normal Hydrochloric acid required to reach the 

phenolphthalein end point. 

9. Determine the Blank Alkalinity, P2. Omit the Filtrate, but repeat the above procedure from item 1 through 8 for 

determining the P1. Use exactly the same quantities of water and reagents in preparing the sample. 

10. Report the Blank Alkalinity, P2, as the total ml of 0.02 normal Hydrochloric acid required to titrate the 

reagent mixture to the phenolphthalein end point. 


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Calculation - P1/P2 Alkalinity Method 

When P1 > P2: 

When P1 < P2: 

OH – , mg/L = 340 (P1 – P2) 

CO 3 

–2 , mg/L = 1200 [Pf – (P1–P2)] 

HCO 3 

– , mg/L = 1220 (P2 – P1) 

CO 3 

-2 , mg/L = 1200 Pf 

WHOLE MUD ALKALINITY - OIL BASED DRILLING FLUID 

Procedure: 

1. Add 100 ml of Arcosolv PNP solvent to the 400 ml beaker 

2. Fill the 5 ml syringe with at least 3 ml of whole mud and discharge 2 ml into the beaker. Swirl the 

mixture until it is homogenous. 

3. Add 200 ml of distilled water. 

4. Add 15 drops of Phenolphthalein Indicator solution. 

5. While stirring with the magnetic stirrer, slowly titrate with N/10 Sulfuric Acid until the pink color just 

disappears. Continue stirring for one more minute, and if no pink color reappears, discontinue stirring. It may 

be necessary to stop the stirring to allow separation of the two phases in order to more clearly see the color in 

the aqueous phase. 

6. Let the sample stand for 5 minutes and if no pink color reappears, the Alkalinity end point has been reached. If 

the pink color returns, titrate a second time with the Sulfuric Acid solution. If the pink color still returns 

titrate a third time, but if the color returns after this third titration, call this the end point. 

7. Use the total ml of N/10 Sulfuric acid solution required to reach the end point to calculate the whole mud 

Alkalinity, V sa . 

Calculation: 

Alkalinity (Whole Mud), V sa = 

N/10 Sulfuric Acid, ml 

Mud Sample, ml 


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TOTAL HARDNESS TITRATION 

(Calcium and Magnesium) 

Kit Part No. 145-10 

INSTRUCTIONS: 

This test measures the amount of soluble calcium and magnesium ions in a mud filtrate. When measured 

simultaneously, the result is called total hardness. The calcium ion concentration can be determined separately and 

when it is subtracted from the total hardness, the magnesium ion concentration can then be determined. Different 

buffer-indicator combinations may be used for these determinations. It is imperative however not to intermix the 

various buffers and indicators. 

Procedure: 

Components: 



#153-34 Pipette, glass, 1 ml x 1/100 ml 

#153-40 Pipette, glass, 10 ml x 1/10 ml 

Reagents: 

#205-02 Indicator sol’n, (Calmagite), Versenate Hardness, 2 oz 

#205-04 *Buffer sol’n., (Ammonium), 2 oz (UN2672) 

#205-06 Titration sol’n., (EDTA), 40 mg/L, 2 EPM, 8 oz 

#205-10 Titration sol’n., (EDTA), 400 mg/L, 20 EPM, 8 oz 

#206-02 Deionized Water, 16 oz 

• Hazardous Chemical – Must be specially packaged, and hazardous shipping charges will apply. 

1. Add 50 mls of deionized water to a titration dish. 

2. Add 20 to 40 drops (1 – 2 mls) of hardness buffer solution to the dish. 

3. Add 10 to 15 drops (0.5 – 0.75 mls) of hardness indicator solution to the mixture. 

4. If a wine-red to a purple color develops, the deionized water used in step 1, contains hardness. If there is a 

color change, add total hardness titrating solution drop wise while stirring until the water turns to a bright 

blue color. 

5. Using the pipette, add 1 ml of filtrate into the titration dish and stir. A wine red to purple color will again 

develop if calcium and/or magnesium is present in the filtrate solution. 

6. Add total hardness titrating solution, stirring continuously, until the sample again turns a bright blue color. 

Calculation: 


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epm Calcium and Magnesium = mls of Hardness Titrating solution used x 2 

(If the solution strength is 1 ml = 2 epm Hardness) 

epm Calcium and Magnesium = mls of Hardness Titrating solution used x 20 

(If the solution strength is 1 ml = 20 epm Hardness) 

Usually the magnesium ion content is negligible, so the total Hardness is reported as being all Calcium. 

Therefore: 

mg/L Calcium = epm Total Hardness x 20 

More or less sample can be used to obtain a titration between 1 and 10 mls, in which case the results obtained above 

should be divided by the ml of sample used. 

epm = equivalent parts per million 

Sometimes the test is erratic at low temperatures due to the change in solubility of the ingredients. 

If desired, separate test may be performed for Calcium and Magnesium individually using Calcium Buffer 

solution and Calver II Indicator powder. See separate instructions. 

Various Buffer Indicator Combinations: 

1. Versenate Buffer solution (#205-04, Ammonium Hydroxide, pH = 12 –13) with Versenate Indicator (#205-02, 

Calmagite). 

2. Manver Indicator (#205-27) with Ammonium Hydroxide Buffer (#205-04, pH = 12 –13) 

3. Eriochrome Black T indicator (#205-28) with Ammonium Hydroxide Buffer 

(#205-04 pH = 12 –13) 

Water Based Drilling Fluids 

All of these combinations may be used to determine Total Hardness. 

CALCIUM ANALYSIS 

INSTRUCTIONS 

When Hardness Titration solution (EDTA) is added to water or mud filtrate that contains both Calcium and Magnesium, 

the EDTA first combines with the Calcium. Calcium alone can be determined with EDTA when the pH of the sample is 

sufficiently high so that magnesium is precipitated out as the Hydroxide, and an indicator specific to Calcium is used. 

Several indicators will give color changes when all of the Calcium has been complexed by the EDTA at a pH in the 

range of 12 to 13. An end point obscured by dark organic components may be treated by oxidizing with Sodium 

Hypochlorite. 

Equipment: 

#153-14 Graduated Cylinder, 50 ml x 1.0 ml, glass 

#153-34 Pipette, 1.0 ml x 1/100 ml, glass 


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#153-51 Beaker, 250 ml, glass 

#168-01 Hot Plate, with Thermostat, 115 volt (Optional) 

(Required if the filtrate is colored) 

or 

#168-01-1 Hot Plate, with Thermostat, 230 volt (Optional) 

Reagents: 

#205-12 Titration sol'n (EDTA), Ver. Hard., 0.01M, 400 Mg/L, 16 oz 

#205-14 Calcium Buffer sol'n (NaOH), 1N, 2 oz 

#206-02 Deionized Water, 16 oz 

#210-00 Calver ® II Indicator Powder, 10 gram 

#230-25 Acetic Acid, Glacial, 8 oz (UN2789) (Optional) 

#261-00 Sodium Hypochlorite sol'n, 8 oz (UN1791) (Optional) 

#261-50 Masking Agent, 1:1:2 mixture by volume of 

Triethanolamine: Tetraethylenepentamine : Water, 16 oz 

(Optional) 

Procedure: 

WORK IN AN ADEQUATELY VENTILATED AREA. 

1. Using a pipette add at least 1.0 mL of sample to the Beaker. This volume will be used in the calculation 

formula below. 

If the filtrate is colorless or is only slightly colored, omit steps 2 - 5. 

2. Add 10.0 ml of Sodium Hypochlorite solution and mix. 

3. Add 1.0 ml of Glacial Acetic Acid and mix. 

4. Boil the sample for 5 minutes and maintain the sample volume by adding deionized water as required during 

boiling. Boiling removes excess Chlorine and this may be verified by immersing a strip of pH paper in the 

sample. If the paper is bleached white, continue boiling. A sufficiently boiled sample will have a pH of 5.0. 

5. Cool the sample and wash the sides of the beaker with deionized water. 

6. Using deionized water, dilute the sample to approximately 50 ml. 

7. Add 10 to 15 ml of Calcium Buffer solution, or sufficient Buffer solution to produce a pH of 12 - 13. 

Note: The presence of soluble Iron may interfere with the endpoint determination. If this is suspected, a mixture of 

Triethanolamine: Tetraethylenepentamine: Water (1:1:2 by volume) is a suitable masking agent. 

Add 1 ml of the mixture at this point. 

8. Add sufficient Calver ® II Indicator powder (0.1 to 0.2 grams) to produce a pink to wine-red color if 

Calcium is present. Too much indicator will obscure the endpoint. Note: Adding several drops of 

Methyl Orange Indicator solution may improve the visibility of the endpoint. 

9. While stirring, titrate with Hardness Titration solution (EDTA), to the end point. Calcium indicators produce a 

Red-to-Blue change and the endpoint is best described as that point where additional Titration solution will 


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produce no further Red-to-Blue color change. The Titration solution volume will be used in the calculation 

procedure. 

Calculation: 

Calcium, mg/L = 400 (Titration sol'n, ml3 ) 

Sample Volume, ml 3 

Oil Based Drilling Fluids: 


#153-53 Magnetic Stirrer, with Stirring Bar 

#153-64 Syringe, 5 ml, disposable, 

#154-75 Scoop, brass, 4 inch length 

#297-05 Mason Jar, with Lid, 16 oz 

Reagents: 

#205-17-3 Titration sol'n. (EDTA), 4000 mg/L Ca +2 , 0.1M, 200 EPM, 16 oz 

#206-04 Distilled Water, gal 

#210-00-1 Calver ® II Indicator powder, 100 gram 

#260-05 Sodium Hydroxide Buffer sol'n, 1.0 N, 8 oz (UN1824) 

#280-30 Arcosolv PNP, gal. (UN1993) 

Procedure: 

1. Add 100 mls of Arcosolv PNP solvent to a 16 oz jar 

2. Fill a new 5 ml syringe with whole mud past the 3 ml mark. 

3. Displace 2.0 mls of oil mud into the jar with the Arcosolv solution. 

4. Cap the jar and shake vigorously by hand for 1 minute. 

5. Add 200 mls of distilled water to the jar. 

6. Add *6.0 mls of Sodium Hydroxide Buffer sol'n, 1 N, to the mixture. 

7. Add *0.7 to 1.0 gram of Calver ® II Indicator powder. (Note: 5 scoops = 0.7 grams) 

Recap the jar tightly and shake vigorously again for 2 minutes. Set the jar aside for a few seconds to allow the 

upper and lower phases to separate. If a reddish color appears in the aqueous (lower) phase, this indicates that 

calcium is present. 

8. Agitate by placing the jar on a magnetic stirrer and drop in a stirring bar. 

9. Titrate very slowly, adding Titration solution (EDTA) drop by drop from a pipette, while stirring only fast 

enough to agitate the aqueous (lower) phase without remixing the upper and lower phases. A distinct color 

change from the reddish color to a blue-green occurs at the end point. Note the volume of Titration solution 

added. 

10. Use the mls of titration solution required to reach the end point to calculate the whole mud calcum. 

Calculation: 

Ca oil mud = Ca, mg = 4000 (0.1 M EDTA, mls) 

oil mud sample, L 

2.0 mls 

*Quantities have been revised since the last API issue - "R.P. 13B-2", Third Edition, Dated Feb 

Water Based Fluids 

CHLORIDE ION KIT 

PART NO. 144-40 


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This test measures the total soluble Chloride ion concentrations in the mud Filtrate. These Chlorides can come from 

Sodium Chloride, Calcium Chloride or Potassium Chloride. For the titration to work correctly, the pH of the filtrate 

needs to be slightly basic, around pH = 8.3, etc. Two chemical reactions take place simultaneously during the titration 

procedure. 

1. Ag + + Cl¯ ——————» AgCl 

2. 2Ag + + CrO 4 

–2 ————» Ag2 CrO 4 

The first reaction, the formation of Silver Chloride, accounts for the appearance of the white specs or milky appearance 

during the titration. The formation of Silver Chromate, which is red in color, will not start until all of the Chloride Ions 

are tied up as Silver Chloride. The Silver Nitrate will then react with the chromate from the Potassium Chromate 

Indicator to form Silver Chromate. So, for the above two reactions to occur, the filtrate needs to be weakly basic. (pH = 

8.3). High pH will precipitate out Silver Oxide. 

EQUIPMENT: 





Reagents: 


#215-00 *Potassium Chromate Indicator sol'n, 2 oz (UN3082) 


#230-08 Sulfuric Acid, 0.02N (N/50), 8 oz 

#265-02 Silver Nitrate sol'n, 0.001G, 0.0282N, 16 oz 

#265-06 Silver Nitrate sol'n, 0.01G, 0.282N, 8 oz 

#285-00 Calcium Carbonate, precipitated. 35 grams 

Case: 

#144-35 Multi Kit Case, Diagonal design, Stainless Steel 

PROCEDURE - Water Based Muds: 

1. Pipette one or more milliliters (cm 3 ) of filtrate into the titration dish. 

2. Add 2 - 3 drops of Phenolphthalein Indicator sol'n to the filtrate. 

If a pink color appears - Titrate with N/50 Sulfuric acid until the color is discharged. 

If the filtrate is deeply colored - Add an additional 2 ml of N/50 Sulfuric Acid and stir. 

Then add 1 gram of Calcium Carbonate and stir. 

3. Add 25 - 50 ml of distilled water. If any water other than distilled water is used, the chlorides in it must be 

accounted for by titration before adding the filtrate to it. 

4. Add 5 - 10 drops of Potassium Chromate Indicator sol'n. 

5. Add Silver Nitrate sol'n drop-by-drop from the pipette while stirring continuously with the stirring rod, until the 

color changes from yellow to orange-red and persists for 30 seconds. Record the number of milliliters (cm 3 ) of 

Silver Nitrate sol'n required to reach the end point. 

A. If the chloride ion concentration of the filtrate exceeds 10,000 milli grams (mg/l) per liter use the 


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0.1 gram chloride-ion per cubic centimeter (0.282N) strength solution. 

B. If over 10 milliliters (cm 3 ) of Silver Nitrate is used, repeat the test with a smaller amount of filtrate. 

CALCULATION: 

To Convert Units: 

Chloride, mg/L = 

*1000 x mls of Silver Nitrate titrated) 

Filtrate Sample, mls 

Chloride, ppm = Chloride, mg/L 

Specific Gravity of Filtrate 

Salt (NaCl), mg/L = (1.65) Chloride, mg/L 

* Use 1000 as the multiplier for 0.0282N (.001gram) Chloride Ion solution, and 10,000 for the 0.282N (.01 gram) AgNO 3 

REMARKS: 

1. Avoid contact with Silver Nitrate and wash immediately with water if Silver Nitrate gets on skin or 

clothing. 

2. The end point of the reaction is when the Silver Chromate is first formed and it is reddish in color. When using 

the weak, or 0.001 gram sol'n, the end point is approached very gradually. Therefore the formation of the Silver 

Chromate can be seen by a color change from yellow to orange-red. If the strong (.01gram) solution is used the 

end point is reached much more rapidly and may go from yellow to red. As soon as the red color is seen, the titration 

procedure is complete. 

3. White lumps of Silver Chloride form when titrating high concentrations of salt. This should not be taken for 

the end point of the titration. 

Oil Based Fluids - Whole Mud Chloride 

The whole mud chloride test procedure for oil muds is a titration procedure which measures the volume of a standard 

Silver Nitrate required to react with the Chloride ions to form insoluble Silver Chloride salts. The Chloride value 

reported for the whole mud may be assigned to the water phase of the solution up to the saturation point. The water 

soluble salt concentration indicates how effective an oil mud is in controlling shale through the "aqueous phase activity" 

concept. The water phase salinity value is also needed to adjust the retort value to obtain a corrected solids content for 

the oil mud. The test procedure uses the same sample as used in the whole mud Alkalinity test provided the sample is 

acidic (pH < 7). 

Equipment - Oil Based Fluids: 

#153-29-1 Syringe, glass tip, 5 ml 

#153-51-1 Beaker, 400 ml, glass 

#153-53 Magnetic Stirrer, with Stir Bars 


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Reagents: 


#215-02 Potassium Chromate sol'n, 8 oz (UN3082) 


#230-10 Sulfuric Acid sol'n, N/10, 8 oz 

#265-08 Silver Nitrate sol'n, 0.01g, 0.282N, 16 oz 

#280-30 Arcosolv PNP, gal. 

Procedure - Oil Based Fluids 

Perform the whole mud alkalinity test first as follows: 

1. Add 100 ml of Arcosolv PNP solvent to the 400 ml beaker. 

2. Fill the 5 ml syringe with at least 3 mls of whole mud and discharge 2 ml into the beaker. Swirl the 

mixture until it is homogenous. 

3. Add 200 ml of distilled water. 

4. Add 15 drops of Phenolphthalein Indicator solution. 

5. While stirring with the magnetic stirrer, slowly titrate with N/10 Sulfuric Acid until the pink color just 

disappears. Continue stirring for one more minute, and if no pink color reappears, discontinue stirring. It may 

be necessary to stop the stirring to allow separation of the two phases in order to more clearly see the color in 

the aqueous phase. 

6. Let the sample stand for 5 minutes and if no pink color reappears, the Alkalinity end point has been reached. If 

thepink color returns, titrate a second time with the Sulfuric Acid solution. If the pink color still returns titrate a 

third time, but if the color returns after this third titration, call this the end point. 

7. After running the Alkalinity test make sure the mixture to be titrated for Chlorides is acidic (pH < 7) by 

adding 10 - 20 drops of N/10 Sulfuric Acid. 

8. Add *3.0 mls of Potassium Chromate Indicator solution. 

9. While stirring with a Magnetic Stirrer, slowly titrate with 0.282N Silver Nitrate solution until a salmon pink 

color remains stable for at least one minute. It may be necessary to stop the stirring of the mixture and allow 

separation of the two phases to occur in order to more clearly see the color in the aqueous phase. 

10. Note the total milliliters of 0.282N Silver Nitrate required to reach the end point to calculate the whole mud 

Chloride. 

Calculation: 

Chloride, Whole Mud (Cl om ) Mg/l = 10,000 ( ml Silver Nitrate titrated) 

ml of sample 

*Quantity has been revised since the last API issue - "R.P. 13B-2", Third Edition, Dated Feb. 1998. 


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CALCIUM SULFATE ANALYSIS 

INSTRUCTIONS 

The Calcium Sulfate content of a drilling fluid is determined by using EDTA Titration solution to determine the total 

Calcium in both mud filtrate and in whole mud. The total and undissolved Calcium Sulfate content of the drilling fluid 

can then be calculated. 


#147-53 pH paper, range 1 - 14 

#153-14 Cylinder, graduated, 50 ml x 1 ml, glass 

#153-26 Titration Dish, Polyethylene 





#168-01 Hot Plate, 115 volt (Required if filtrate is colored) 

Reagents: 

#205-12 Tittration solution, EDTA, 400 mg/L Ca +2 , 20 EPM, 16 oz 


#210-00 Calver ® II Indicator powder, 10 gram 

#230-20 *Glacial Acetic Acid, 8 oz (UN2789) 

#260-05 *Sodium Hydroxide, 1N, 8 oz (UN1824) 

#261-00 Sodium Hypochlorite sol'n, 8 oz (UN1791) 

#261-50 Triethanolamine masking agent, 16 oz 

Note: Also necessary will be the following items: 

#140-30 Filter Press, API, full area, with CO 2 Pressuring assembly 

#165-00-1 Retort Kit, 10 ml, with stainless steel case, 115 volt 

or 

#165-10-1 Retort Kit, 10 ml, with stainless steel case, 220 volt 

Procedure: 

1. Add 5 ml of whole mud to 245 ml of distilled water. 

2. Stir the mixture for 15 minutes and filter the diluted mixture through a standard API Filter Press, collecting only 

clear filtrate. Also filter the undiluted whole mud through the standard API Filter Press. 

3. Using the 10 ml pipette, add 10 ml of the clear filtrate to the titration dish. Titrate with EDTA titration solution 

to the calcium endpoint, and call this volume EDTA V t. The procedure is as follows: 


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A. Add at least 1.0 mL of sample to the Beaker. 

If the filtrate is colorless or is only slightly colored, omit steps B - E. 

B. Add 10.0 ml of Sodium Hypochlorite solution and mix. 

C. Add 1.0 ml of Glacial Acetic Acid and mix. 

D. Boil the sample for 5 minutes and maintain the sample volume by adding distilled water as required 

during boiling. Boiling removes excess Chlorine and this may be verified by immersing a strip of Ph 

paper in the sample. If the paper is bleached white, continue boiling. A sufficiently boiled sample will 

have a pH of 5.0. 

E. Cool the sample and wash the sides of the beaker with distilled water. 

F. With distilled water, dilute the sample to approximately 50 ml. 

G. Add 10 to 15 ml of Calcium Buffer solution, or sufficient Buffer solution to produce a pH of 12 - 13. 

H. Optional: The presence of soluble Iron may interfere with the endpoint determination. If this is 

suspected, a mixture of Triethanolamine: Tetraethylenepentamine : Water (1:1:2 by volume) is a 

suitable masking agent. 

I. Add sufficient Calver ® II Indicator powder (0.1 to 0.2 grams) to produce a pink to wine-red color if 

Calcium is present. Too much indicator will obscure the endpoint. Note: Adding several drops of 

Methyl Orange Indicator solution may improve the visibility of the endpoint. 

J. While stirring, titrate with Hardness Titration solution (EDTA), to the end point. Calcium indicators 

produce a Red-to-Blue change and the endpoint is best described as that point where additional Titration 

solution will produce no further Red-to-Blue color change. The Titration solution volume will be used 

in the calculation procedure. 

3. Using the 1 ml pipette, add 1.0 ml of the original undiluted mud filtrate to the titration dish. Titrate with 

EDTA titration solution to the calcium endpoint, as above. Call this volume EDTA V f . 

4. Retort the whole mud. Determine the volume fraction of water in the mud by using the volume percent of water 

from the liquid and solids determination based upon the following equation. 

Volume Fraction of Water, F w = 

Volume Percent Water 

100 

Calculation: 

Total Calcium Sulfate, lb/bbl = 2.38 ( EDTA V t ) 

The excess undissolved Calcium Sulfate content of the mud in pounds per barrel may be calculated as follows: 

Excess Calcium Sulfate, lb/bbl = 2.38 (EDTA V t) – 0.48 [EDTA V f x (F w )] 

Procedure: 

MAGNESIUM CONTENT 

The Hardness Titration test and the Calcium Titration test must be performed first. 

The total milliliters of Versenate Titration solution (EDTA), 1 mL = 400 mg/L Ca ++ used in the determination of total 

hardness, minus the milliliters of Versenate Titration solution (EDTA) used in the determination of calcium ion, times 

243 equals the mg/L of Magnesium. 


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Calculation: 

Mg ++ , mg/L = 

(mL EDTA, Total Hardness – mL EDTA, Ca++) x 243 

mL of Filtrate 

POTASSIUM & POTASSIUM CHLORIDE 

OFI Part No. 285-09 

Centrifuge Method: > 5000 Milligrams per Liter KCl (1% KCl) 

Potassium ion is used in drilling fluids to aid in the stabilization of shales and to control swelling clays. The accurate 

determination of the potassium ion content is necessary to control the properties of the drilling fluid. This procedure is 

used to measure the potassium ion content in mud filtrates at levels above 5000 milligrams per liter or 3.5 pounds per 

barrel KCl. The procedure is most accurate in the range between 10,000 mg/L (2%) and 40,000 mg/L (8%) KCl and is 

suspect below 10,000 mg/L (2%) KCl. Potassium is precipitated in a centrifuge tube as the perchlorate salt, and then the 

precipitate volume is measured. The potassium ion content is then read from a prepared standard curve. 


#153-21 Centrifuge Tube, Kolmer, 10 ml (2 supplied) 

#153-25-2 *Centrifuge, Hand Crank, with dual head and shields 


Reagents: 


#285-10 *Sodium Perchlorate sol'n, 16 oz (UN1502) 

#285-11 Potassium Chloride sol'n (standard), 4 oz 

Procedure - Generating a Standard Calibration Curve: 

1. A standard calibration curve is required for each type of centrifuge. A minimum of three points or test 

procedures (3.5, 10.5 & 17.5 pounds per barrel) is required to obtain an accurate graph. 

2. Samples can be prepared by using the standard potassium chloride solution where 0.5 ml of standard 

potassium chloride solution is equivalent to 3.5 pounds per barrel KCl. 

3.5 ppb KCl = 1 % KCL = 5000 mg/L ≅ 0.5 ml standard KCl solution. 

Therefore - 

A. To obtain 3.5 ppb equivalent KCl or 1% KCl use 0.5 ml of standard potassium chloride. 

B. To obtain 10.5 ppb equivalent KCl or 3% KCl use 1.5 ml of standard potassium chloride. 

C. To obtain 17.5 ppb equivalent KCl or 5% KCl use 2.5 ml of standard potassium chloride 

3. Dilute the samples in the centrifuge tube to the 7.0 ml mark with distilled water and agitate the mixture. 

4. Add 3 ml of standard sodium perchlorate solution to each centrifuge tube and do not agitate. 

5. Centrifuge at a constant speed of approximately 1800 revolutions per minute for one minute and read the 

precipitate volume immediately. It will be necessary to counterbalance the centrifuge tube with another tube 

and 10 ml of liquid of the same weight. 

A fairly constant 1800 revolutions per minute can be obtained by determining the number of revolutions of the rotor per 

each turn of the crank. Move the crank very slowly and count the number of revolutions of the rotor head during one turn 

of the crank. For example, 15 revolutions of the rotor per one turn of the crank. Calculate the number of crank turns 

required to obtain 1800 revolutions of the rotor head. In the example to obtain 1800 revolutions of the head would require 

120 turns of the crank (1800/15). Thus the crank must be turned 120 times in one minute to obtain the rate of 1800 


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revolutions per minute. At this rate in 5 seconds the handle must be turned 10 times (120/60) (5). By counting the crank 

turns in 5 seconds and adjusting the rate to obtain the required number of turns, a constant 1800 revolutions per minute 

should be obtained in 15 to 20 seconds. The interval used to adjust to the 1800 revolutions per minute should be included 

in the centrifuge time of the sample. 

6. Clean the centrifuge tube immediately after use to facilitate ease of cleaning. 

7. Plot the volume of precipitate in milliliters versus pounds per barrel of KCl or milliliters of precipitate versus 

percent (%) potassium chloride using rectangular graph paper as shown below. 

Procedure - Sample Testing 

1. Measure the appropriate volume of filtrate into the centrifuge tube. See the table below for the volume: 

Filtrate Volumes to Be Used At Various KCL Concentrations 

Concentration 

Filtrate Volume 

Range KCl K + to use 

(lb/bbl (mg/L) (ml) 

3.5 - 18 5,250 - 27,000 7.0 

18 - 35 27,000 - 52,500 3.5 

35 - 70 52,500 - 105,000 2.0 

over 70 over 105,000 1.0 

2. Dilute to 7.0 ml if necessary with distilled water in the tube and agitate the mixture. 

3. Add 3.0 ml of standard sodium perchlorate solution and do not agitate. If potassium is present precipitation 

occurs at once. 

4. Centrifuge at a constant speed of approximately 1800 rpm for one minute. Read the precipitate volume 

immediately and then record it. 

5. Add 2 to 3 drops of the sodium perchlorate solution to the tube. If a precipitate still forms, the total 

amount of potassium has not been measured. Refer to the table above and use the next smaller filtrate 

volume. Repeat the procedure in items 1 - 5 above. 

6. Determine the potassium chloride concentration by comparing the precipitate volume measured with the 

standard calibration curve as prepared above. Report the potassium concentration as pounds per barrel KCl. 

The potassium concentration may also be reported as milligrams per liter potassium ion. If the filtrate potassium 

chloride concentration from the standard calibration curve exceeds an 18 pounds per barrel reading, accuracy of 

the results is reduced. For more accurate results, use the next smaller filtrate volume as noted in the table above, 

and repeat the steps 1 through 5 above. 

Calculation: 

KCl in filtrate, lb/bbl = 7 ( Value from standard curve) 


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filtrate used, ml 

K + in filtrate, mg/L = 1500 (KCl in filtrate, lb/bbl) 

High Potassium Chloride Concentrations 

If the potassium concentration of the filtrate is greater than 35,000 mg/L (7%) KCl, dilution may be accomplished as 

follows: 

1. Pipette 2.0, 3.0 or 4.0 ml of filtrate into the centrifuge tube and dilute with distilled water to the 7.0 ml mark. 

2. Correct the results by multiplying % KCl by 7, divided by the volume of filtrate used (2.0, 3.0 or 4.0 ml) 

Remarks 

1. The potassium ion test must be made with the same centrifuge used to construct the standard curve. Turn the 

centrifuge at a constant speed of 1800 rpm. 

2. Sodium and potassium perchlorates are explosive in the dry state if heated to a high temperature or allowed to 

contact organic reducing agents. The perchlorates are not hazardous if kept water wet. They will decompose 

harmlessly if dispersed in a bucket of water. 

3. Salts, lignosulfonates, polymers, clay and pH do not interfere with the test. 

4. The precipitate may become slightly discolored in high lignosulfonate concentrations, but the test is not 

adversely affected. 

5. Only the Kolmer-type clinical centrifuge tubes are satisfactory for the test. 

6. The calibration curve does not need to be remade for every potassium determination, however the validity of the 

curve should be rechecked regularly by re-running at least one standard. 

7. A new standard graph must be prepared if a different model of centrifuge is used. 


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Instructions - OFI Testing Equipment, Inc.

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