A preparation method of a solid scale inhibitor for oilfield downhole

Abstract

The present invention belongs to the technical field of oil exploitation, and specifically relates to a preparation method of a solid scale inhibitor for oil wells underground, which is as follows: Add 5 parts of polyvinyl alcohol and 90 parts of deionized water into a reactor, start stirring, raise the temperature to 85 °C until the polyvinyl alcohol is completely dissolved, then cool down to 55 °C, add 20 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 20 parts of potassium hydroxyethylidene diphosphonate, 1 part of Tween 80, and 5 parts of OP-10. After stirring evenly, add 1 part of potassium persulfate and 30 parts of vinyl acetate. After raising the temperature to 80 °C and reacting for 3 hours, cool down to 35 °C, put the material into a mold, then place it in a heating box and heat it to 115 °C, and continue heating for 12 hours. Then raise the temperature of the heating box to 210 °C again and continue heating for 8 hours. Finally, cool and demold to obtain the solid scale inhibitor. The corrosion inhibition rate of the scale inhibitor in the oil well > 90%; the scale inhibition rate > 96%. It has the characteristics of long anti-scaling time, high anti-scaling rate, and good corrosion inhibition performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil exploitation, and particularly relates to a preparation method of a downhole solid scale inhibitor for oil fields. Background Art

[0002] As the oil production in Daqing Oilfield enters the high water cut stage, the widespread application of various enhanced oil recovery technologies has caused serious scaling in the reservoir environment and the produced fluid system. These scales block the pores of the oil layer, reduce the sweep efficiency of the displacing agent, and increase the damage to the oil layer. In particular, after scaling occurs in the produced fluid system, rod sticking and pump leakage occur, which not only affects the normal production of oil wells but also affects the comprehensive economic benefits of various enhanced oil recovery technologies. Therefore, it is necessary to adopt a scale inhibition measure of adding chemicals to such oil wells. After continuous addition of common liquid scale inhibitors, the scaling rate can be effectively slowed down, but it is necessary to frequently inject into oil wells, which consumes a large amount, has a high cost, and has problems such as high construction intensity. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a preparation method of a downhole solid scale inhibitor for oil fields. The scale inhibitor prepared by this method has a corrosion inhibition rate > 90% in oil wells; a scale inhibition rate > 96%. It has the characteristics of long scale inhibition time, high scale inhibition rate, and good corrosion inhibition performance.

[0004] The technical solution adopted by the present invention is as follows: A preparation method of a downhole solid scale inhibitor for oil fields is as follows: Add 5 - 10 parts of polyvinyl alcohol and 90 - 150 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and sequentially add 20 - 35 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 20 - 30 parts of potassium hydroxyethylidene diphosphonate, 1 - 3 parts of Tween 80, 5 - 10 parts of OP - 10. After stirring evenly, add 1 - 3 parts of potassium persulfate and 30 - 50 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; after the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C, and continuously heat for 12 hours. Then, raise the temperature of the heating box to 200°C - 220°C and continuously heat for 8 hours. Finally, cool and demold to obtain the solid scale inhibitor.

[0005] Further, the preparation method of the downhole solid scale inhibitor for oil fields is as follows: Add 5 parts of polyvinyl alcohol and 90 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 20 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 20 parts of potassium hydroxyethane diphosphonate, 1 part of Tween 80, and 5 parts of OP-10. After stirring evenly, add 1 part of potassium persulfate and 30 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; After the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C, and continuously heat it for 12 hours. Then, raise the temperature of the heating box to 200°C - 220°C again and continuously heat it for 8 hours. Finally, cool and demold to obtain the solid scale inhibitor.

[0006] Further, the preparation method of the downhole solid scale inhibitor for oil fields is as follows: Add 7 parts of polyvinyl alcohol and 120 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 27.5 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 25 parts of potassium hydroxyethane diphosphonate, 1.5 parts of Tween 80, and 7.5 parts of OP-10. After stirring evenly, add 1.5 parts of potassium persulfate and 40 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; After the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C, and continuously heat it for 12 hours. Then, raise the temperature of the heating box to 200°C - 220°C again and continuously heat it for 8 hours. Finally, cool and demold to obtain the solid scale inhibitor.

[0007] Further, the preparation method of the downhole solid scale inhibitor for oil fields is as follows: Add 10 parts of polyvinyl alcohol and 150 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 35 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 30 parts of potassium hydroxyethane diphosphonate, 3 parts of Tween 80, and 10 parts of OP-10. After stirring evenly, add 3 parts of potassium persulfate and 50 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; After the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C, and continuously heat it for 12 hours. Then, raise the temperature of the heating box to 200°C - 220°C again and continuously heat it for 8 hours. Finally, cool and demold to obtain the solid scale inhibitor.

[0008] Advantages of the present invention: A preparation method of a solid scale inhibitor for oilfield downhole is provided. The scale inhibitor prepared by this method has a corrosion inhibition rate > 90% in oil wells; the scale inhibition rate > 96%. It has the characteristics of long scale inhibition time, high scale inhibition rate, good corrosion inhibition performance, etc. Specific embodiments

[0009] Example 1

[0010] A preparation method of a solid scale inhibitor for oilfield downhole is as follows: Add 5 parts of polyvinyl alcohol and 90 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 20 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 20 parts of potassium hydroxyethylidene diphosphonate, 1 part of Tween 80, and 5 parts of OP - 10. After stirring evenly, add 1 part of potassium persulfate and 30 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; after the material is loaded into a mold, put it into a heating box and heat it to 110°C - 120°C and continuously heat for 12 hours, then raise the temperature of the heating box to 200°C - 220°C and continuously heat for 8 hours, and finally cool and demold to obtain the solid scale inhibitor.

[0011] Example 2

[0012] A preparation method of a solid scale inhibitor for oilfield downhole is as follows: Add 7 parts of polyvinyl alcohol and 120 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 27.5 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 25 parts of potassium hydroxyethylidene diphosphonate, 1.5 parts of Tween 80, and 7.5 parts of OP - 10. After stirring evenly, add 1.5 parts of potassium persulfate and 40 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; after the material is loaded into a mold, put it into a heating box and heat it to 110°C - 120°C and continuously heat for 12 hours, then raise the temperature of the heating box to 200°C - 220°C and continuously heat for 8 hours, and finally cool and demold to obtain the solid scale inhibitor.

[0013] Example 3

[0014] A preparation method of a solid scale inhibitor for oilfield downhole is as follows: Add 10 parts of polyvinyl alcohol and 150 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and sequentially add 35 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 30 parts of potassium hydroxyethane diphosphonate, 3 parts of Tween 80, and 10 parts of OP - 10. After stirring evenly, add 3 parts of potassium persulfate and 50 parts of vinyl acetate. Heat the reactor to 70°C - 85°C and react for 3 hours, then cool down to 30°C - 40°C and discharge the material; After loading the material into a mold, place it in a heating box and heat it to 110°C - 120°C and continuously heat for 12 hours, then raise the temperature of the heating box to 200°C - 220°C again and continuously heat for 8 hours, and finally cool and demold to obtain the solid scale inhibitor.

[0015] Performance evaluation of the solid scale inhibitor:

[0016] (1) Determination of scale inhibition rate

[0017] First, filter the produced fluid from a single oilfield well through filter paper for later use;

[0018] Use a pipette to transfer 190 mL of the filtered produced fluid from a single well into a 250 mL stoppered conical flask, add 10 mL of distilled water, tighten the flask stopper, and shake well. This solution is the blank solution;

[0019] Use a pipette to transfer 190 mL of the filtered produced fluid from a single well into a 250 mL stoppered conical flask, add 10 mL of a 1% concentration solid scale inhibitor solution, tighten the flask stopper, and shake well. This solution is the dosed solution;

[0020] Place the above conical flasks in an electrothermal constant temperature water bath at 70°C ± 1°C and keep them at a constant temperature for 24 hours, then take them out and cool them to room temperature for 1 hour, and immediately perform the following operations;

[0021] Use a pipette to separately take 10 mL of the filtered blank solution and the dosed solution, adjust the pH value to 12 - 13 with a 2 mol / L NaOH aqueous solution, and add a little calcium indicator reagent. Titrate with an EDTA solution to the end point (the solution changes from red to bright blue), and record the volume of the consumed EDTA solution.

[0022] The scale inhibition rate is calculated according to the following formula:

[0023] E f = [(V1 - V0) ÷ (V - V0)] × 100%

[0024] Among them, E fThe scale inhibition rate is expressed in percentage (%), V1 is the volume of EDTA consumed by the chemical dosing solution, in milliliters (mL), V0 is the volume of EDTA consumed by the blank solution, in milliliters (mL), and V is the volume of EDTA consumed by the original aqueous solution, in milliliters (mL).

[0025] (2) Determination of corrosion inhibition rate

[0026] Use a measuring cylinder to measure 250 mL of the single-well produced fluid filtered through filter paper into a test bottle. Put the weighed test rod into the test bottle, tighten the bottle cap to fix the test rod, and shake well.

[0027] Use a measuring cylinder to measure 250 mL of the single-well produced fluid filtered through filter paper into a test bottle, add 10 mL of 1% concentration solid scale inhibitor solution, put the weighed test rod into the test bottle, tighten the bottle cap to fix the test rod, and shake well.

[0028] Install the above test bottle on a rotary tester, run it for 24 hours at a temperature of 70 °C and a rotation speed of 28 r / min, then remove the test bottle and take out the test rod from the test bottle.

[0029] The corrosion inhibition rate is calculated according to the following formula:

[0030] R = [(Δm0 - Δm1) ÷ Δm0] × 100%

[0031] Wherein, R is the corrosion inhibition rate, expressed in percentage (%), Δm0 is the mass reduction of the test rod in the test bottle without chemical dosing, in grams (g), and Δm1 is the mass reduction of the test rod in the test bottle with chemical dosing, in grams (g).

[0032] Table 1 shows the determination results of the scale inhibition rate and corrosion inhibition rate of Examples 1 - 3;

[0033] Table 1

[0034] Sample Scale inhibition rate, % Corrosion inhibition rate, % Example 1 91.73 96.58 Example 2 94.26 98.91 Example 3 92.38 98.17

[0035] The data shows that the scale inhibition rate of the solid scale inhibitor obtained in Examples 1 - 3 is over 90%, and the scale inhibition effect is good; the corrosion inhibition rate of the solid scale inhibitor is over 96%, and the corrosion inhibition effect is good, and the effect of Example 2 is the most obvious.

Claims

1. A preparation method of a solid scale inhibitor for oilfield downhole, characterized in that: The preparation method is as follows: Add 5 - 10 parts of polyvinyl alcohol and 90 - 150 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 20 - 35 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 20 - 30 parts of potassium hydroxyethylidene diphosphonate, 1 - 3 parts of Tween 80, and 5 - 10 parts of OP - 10. After stirring evenly, add 1 - 3 parts of potassium persulfate and 30 - 50 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; after the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C and continuously heat for 12 hours, then raise the temperature of the heating box to 200°C - 220°C again and continuously heat for 8 hours, and finally cool and demold to obtain the solid scale inhibitor.

2. The preparation method of a downhole solid scale inhibitor for oil fields according to claim 1, characterized in that: The preparation method is as follows: Add 5 parts of polyvinyl alcohol and 90 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 20 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 20 parts of potassium hydroxyethylidene diphosphonate, 1 part of Tween 80, and 5 parts of OP - 10. After stirring evenly, add 1 part of potassium persulfate and 30 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; after the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C and continuously heat for 12 hours, then raise the temperature of the heating box to 200°C - 220°C again and continuously heat for 8 hours, and finally cool and demold to obtain the solid scale inhibitor.

3. The preparation method of a solid scale inhibitor for oilfield downhole according to claim 1, characterized in that: The preparation method is as follows: Add 7 parts of polyvinyl alcohol and 120 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 27.5 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 25 parts of potassium hydroxyethylidene diphosphonate, 1.5 parts of Tween 80, and 7.5 parts of OP - 10. After stirring evenly, add 1.5 parts of potassium persulfate and 40 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; after the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C and continuously heat for 12 hours, then raise the temperature of the heating box to 200°C - 220°C again and continuously heat for 8 hours, and finally cool and demold to obtain the solid scale inhibitor.

4. The preparation method of a solid scale inhibitor for oilfield downhole according to claim 1, characterized in that: The preparation method is as follows: Add 10 parts of polyvinyl alcohol and 150 parts of deionized water into a reactor, start stirring, raise the temperature in the reactor to 80°C - 90°C until the polyvinyl alcohol is completely dissolved, then cool down to 50°C - 60°C, and successively add 35 parts of pentasodium diethylenetriamine pentamethylene phosphonate, 30 parts of potassium hydroxyethane diphosphonate, 3 parts of Tween 80, and 10 parts of OP-10. After stirring evenly, add 3 parts of potassium persulfate and 50 parts of vinyl acetate. After the reactor is heated to 70°C - 85°C and reacts for 3 hours, cool down to 30°C - 40°C and discharge the material; after the material is loaded into a mold, place it in a heating box and heat it to 110°C - 120°C and continue heating for 12 hours, then raise the temperature of the heating box to 200°C - 220°C again and continue heating for 8 hours, and finally cool and demold to obtain the solid scale inhibitor.