阅读说明：本技术 一种油井井筒胶囊阻垢颗粒对碳酸钙垢阻垢性能评价方法 (Evaluation method for calcium carbonate scale inhibition performance of oil well shaft capsule scale inhibition particles ) 是由 刘爱华 周志平 李琼玮 苑慧莹 刘宁 姜毅 董俊 于 2019-11-06 设计创作，主要内容包括：本发明提供了一种油井井筒胶囊阻垢颗粒对碳酸钙垢阻垢性能评价方法,通过模拟油田地层水的组成,在模拟地层条件下分别测定加入胶囊阻垢颗粒待测样中钙离子浓度、不加胶囊阻垢颗粒的待测样和不加胶囊阻垢颗粒和B溶液的空白待测样中的钙离子浓度,得到碳酸钙垢阻垢率。本发明通过沉淀法或scale结垢预测软件对A溶液与B溶液的混合比例进行确定,符合油田生产的实际情况,按照该比例评价出防垢剂可以用于整个井筒或者集输站点不同的开发时期,该方法更科学的指导油井井筒胶囊阻垢颗粒加注工艺,方法操作简单、对检测人员要求低、检测成本低、采油生产单位操作性强、利于推广。(The invention provides a method for evaluating the calcium carbonate scale inhibition performance of oil well shaft capsule scale inhibition particles, which comprises the steps of respectively measuring the calcium ion concentration in a sample to be measured in which the capsule scale inhibition particles are added, the calcium ion concentration in a sample to be measured in which the capsule scale inhibition particles are not added, the calcium ion concentration in a blank sample to be measured in which the capsule scale inhibition particles are not added and a solution B are not added under the condition of simulating a stratum, and obtaining the calcium carbonate scale inhibition rate. The method determines the mixing ratio of the solution A and the solution B through a precipitation method or scale scaling prediction software, accords with the actual situation of oil field production, evaluates that the antiscaling agent can be used in different development periods of the whole shaft or gathering and transportation sites according to the ratio, scientifically guides the oil well shaft capsule antiscaling particle filling process, and has the advantages of simple operation, low requirement on detection personnel, low detection cost, strong operability of oil production units and contribution to popularization.)

1. A method for evaluating the calcium carbonate scale inhibition performance of oil well shaft capsule scale inhibition particles is characterized by comprising the following steps: the method comprises the following steps:

step 1) determining the mineralization degree, the calcium ion content and the bicarbonate ion content of formation water of an oil field;

step 2) preparing solution A: preparing a solution with the same content of calcium ions as the oil field formation water by using anhydrous calcium chloride, and adding sodium chloride to ensure that the mineralization degrees of the solution A and the oil field formation water are the same;

preparing a solution B: preparing a solution with the bicarbonate content same as that of the oil field formation water by using sodium bicarbonate, and adding sodium chloride to ensure that the mineralization degree of the solution B is the same as that of the oil field formation water;

step 3) determining the mixing ratio of the solution A and the solution B;

step 4) adding a certain volume of the solution A into a conical flask, adding a certain mass of the capsule scale inhibition particles C to form an A + C solution, shaking uniformly, simulating the production temperature, keeping the temperature for 24 hours and simultaneously keeping the temperatureStirring at the stirring speed of 100-; wherein the effective concentration of the added capsule scale inhibition particles is c₁；

Step 5) adding a borax buffer solution into the conical flask according to the mixing ratio of the solution A and the solution B determined in the step 2), and then adding the solution B to obtain an A + B + C solution with the pH value of 9;

step 6), pouring the solution A, B and C into a special conical flask, shaking uniformly, putting into a constant-temperature oven or a water bath, and keeping the temperature at 80 ℃ for 24 hours under normal pressure;

step 7), taking out the special conical flask, placing the special conical flask to room temperature, taking supernatant, and filtering the supernatant to obtain a solution to be detected;

step 8) taking a certain volume V₁Placing the solution to be detected in a container, adding 5.0mL of potassium hydroxide, adding 2-3 drops of calcium-carboxylic acid indicator test solution, titrating with EDTA standard solution, and consuming volume V of the EDTA standard solution when the solution color is changed from purple pink red to bright blue₂Calculating the calcium ion concentration c_{Sample application}；

Step 9) preparing a sample to be tested without the capsule anti-scaling particles C according to the steps 4) to 8), and recording the volume V of the consumed EDTA standard solution₃Calculating the calcium ion concentration c_{Without sample application}；

Wherein, the capsule scale inhibition particles C are not added in the step 4);

preparing blank sample according to the steps 4) to 8), and recording the volume V of the EDTA standard solution consumed₄Calculating the calcium ion concentration c_{Blank space}；

Wherein, the capsule scale inhibition particles C are not added in the step 4), and the solution B is replaced by distilled water;

step 10) based on the calcium ion concentration c_{Sample application}Calcium ion concentration c_{Without sample application}And calcium ion concentration c_{Blank space}And (3) calculating to obtain the calcium carbonate scale inhibition rate, and evaluating that the capsule scale inhibition particles C can effectively inhibit scale when the calcium carbonate scale inhibition rate is not less than 85%.

2. The method for evaluating the calcium carbonate scale inhibition performance of the oil well shaft capsule scale inhibition particles as claimed in claim 1, wherein the mixing ratio of the solution A and the solution B in the step 3) is determined as follows:

inputting the content of each ion, pH value, temperature and pressure in the solution A and the solution B by scale scaling prediction software, and according to the weight ratio of the solution A: and (3) predicting the scaling amount of the solution B according to the volume ratio of 1:9 to 2:8 to 3:7 to 4:6 to 5:5 to 6:4 to 7:3 to 8:2 to 9:1, wherein the mixing ratio corresponding to the maximum scaling amount is the mixing ratio of the solution A to the solution B.

3. The method for evaluating the calcium carbonate scale inhibition performance of the oil well shaft capsule scale inhibition particles as claimed in claim 1, wherein the mixing ratio of the solution A and the solution B in the step 3) is determined as follows:

(1) respectively preparing 50ml, 100ml, 150ml, 200ml, 250ml, 300ml, 350ml, 400ml and 450ml of solution A;

(2) respectively preparing 450ml, 400ml, 350ml, 300ml, 250ml, 200ml, 150ml, 100ml and 50ml of solution B;

(3) respectively mixing the solution A and the solution B according to the corresponding sequence under the temperature and the pressure of the simulated oil field stratum to obtain 9 groups of mixed liquor;

(4) taking a plurality of pieces of quantitative filter paper, drying to constant weight, recording the mass G1 of each piece of filter paper, filtering each mixed solution in the quantitative filter paper, placing the mixed solution in a 105-degree oven to dry to constant weight, recording the mass G2, calculating the mass G of precipitates in each mixed solution, wherein G is G2-G1, selecting one group with the largest mass of precipitates from 9 groups of mixed solutions, and determining the mixed ratio of the solution A and the solution B.

4. The method for evaluating the calcium carbonate scale inhibition performance of the oil well wellbore capsule scale inhibition particles as claimed in claim 1, is characterized in that: the mass of the capsule scale inhibition particles C added in the step 4) is determined by adding the effective concentration C of the capsule scale inhibition particles₁To determine that the user has taken a particular task,

c₁＝ν×c×1，

in the formula, c₁The effective concentration of the scale inhibition particles added into the capsule is mg/L; v is the average release rate of the capsule scale inhibiting particles C, mg/L ∙ d; c is the effective wrapping rate of the capsule scale inhibition particles C,%; 1 means reaction time 1 day, d.

5. The method for evaluating the calcium carbonate scale inhibition performance of the oil well wellbore capsule scale inhibition particles as claimed in claim 1, is characterized in that: and step 6) the special conical bottle comprises a conical bottle, a rubber plug and two glass tubes, wherein the rubber plug is plugged at the opening of the conical bottle, the two glass tubes penetrate through the rubber plug and then go deep into the conical bottle, one glass tube is on the liquid level, and the other glass tube is under the liquid level.

6. The method for evaluating the calcium carbonate scale inhibition performance of the oil well shaft capsule scale inhibition particles as claimed in claim 1, wherein when the effective concentration of the capsule scale inhibition particles is c₁The calculation formula of the calcium ion concentration is as follows:

in the formula, M is the molar concentration of an EDTA standard solution, mol/L; v is the volume of EDTA standard solution consumed in titration, ml; v₁Is the volume of the solution to be measured, ml; c is calcium ion concentration, mg/L.

7. The method for evaluating the calcium carbonate scale inhibition performance of the oil well wellbore capsule scale inhibition particles as claimed in claim 1, wherein the calcium carbonate scale inhibition rate calculation formula is as follows:

in the formula, c_{Sample application}The calcium ion concentration in the solution after the capsule scale inhibition particles are added is mg/L; c. C_{Without sample application}The concentration of calcium ions in the solution is mg/L after the capsule scale inhibition particles are not added; c. C_{Blank space}The concentration of calcium ions in the blank solution is mg/L; x is the number of₃The scale inhibition rate of the calcium carbonate scale is percent.

8. The method for evaluating the calcium carbonate scale inhibition performance of the oil well wellbore capsule scale inhibition particles as claimed in claim 1, is characterized in that: and 7), filtering the supernatant in the step 7) by using a 0.45um acetate fiber filter membrane.

9. The method for evaluating the calcium carbonate scale inhibition performance of the oil well wellbore capsule scale inhibition particles as claimed in claim 5, is characterized in that: the distance between the glass tube on the liquid surface and the liquid surface is 3-4 cm.

10. The method for evaluating the calcium carbonate scale inhibition performance of the oil well wellbore capsule scale inhibition particles as claimed in claim 5, is characterized in that: the two glass tubes are 10mm in diameter and 300mm in length.

Technical Field

The invention belongs to the technical field of chemical scale inhibition of oil well shafts, and particularly relates to a method for evaluating the scale inhibition performance of oil well shaft capsule scale inhibition particles on calcium carbonate scale.

Background

When the injected water of the oil field is rich in HCO3^-Formation water rich in Ca²⁺Due to the incompatibility of the two components and the factors such as temperature, pressure and the like, a large amount of calcium carbonate scale is generated in a shaft of an oil well, so that the perforation section of the oil well is blocked, a pump valve fails, a pump is frequently detected and the like, and the normal production of the oil field is seriously influenced.

The traditional method for solving the problem of shaft scaling is to directly inject liquid scale inhibitors into a well from a well head, but the scale inhibitors quickly flow away with produced liquid or are adhered to the wall of the pipe and cannot completely reach the well bottom, so that continuous and frequent injection is needed, and a lot of troubles are brought to production and management.

At present, long-acting scale inhibition is carried out on oil wells at home and abroad by adding capsule scale inhibition particles into a well bottom pocket, wherein the capsule scale inhibition particles take an organic phosphorus chemical scale inhibitor as a capsule core, are wrapped by different capsule wall materials through adsorption impregnation or cementing adhesion or high-temperature melting and the like, and are extruded into granules. However, at present, no evaluation method for the calcium carbonate scale inhibition performance of the capsule scale inhibition particles for the oil well shaft is published in China.

Disclosure of Invention

The invention aims to provide a method for evaluating the calcium carbonate scale inhibition performance of oil well shaft capsule scale inhibition particles, which can scientifically guide the filling process of the oil well shaft capsule scale inhibition particles.

The technical scheme provided by the invention is as follows:

a method for evaluating the calcium carbonate scale inhibition performance of oil well shaft capsule scale inhibition particles comprises the following steps:

step 1) determining the mineralization degree, the calcium ion content and the bicarbonate ion content of formation water of an oil field;

step 2) preparing solution A: preparing a solution with the same content of calcium ions as the oil field formation water by using anhydrous calcium chloride, and adding sodium chloride to ensure that the mineralization degrees of the solution A and the oil field formation water are the same;

preparing a solution B: preparing a solution with the bicarbonate content same as that of the oil field formation water by using sodium bicarbonate, and adding sodium chloride to ensure that the mineralization degree of the solution B is the same as that of the oil field formation water;

step 3) determining the mixing ratio of the solution A and the solution B;

step 4) adding a certain volume of the solution A into a conical flask, adding a certain mass of the capsule scale inhibition particles C to form an A + C solution, shaking uniformly, simulating the production temperature, stirring at the constant temperature for 24 hours at the stirring speed of 100-200 r/min; wherein the effective concentration of the added capsule scale inhibition particles is c₁；

Step 5) adding a borax buffer solution into the conical flask according to the mixing ratio of the solution A and the solution B determined in the step 2), and then adding the solution B to obtain an A + B + C solution with the pH value of 9;

step 6), pouring the solution A, B and C into a special conical flask, shaking uniformly, putting into a constant-temperature oven or a water bath, and keeping the temperature at 80 ℃ for 24 hours under normal pressure;

step 7), taking out the special conical flask, placing the special conical flask to room temperature, taking supernatant, and filtering the supernatant to obtain a solution to be detected;

step 8) taking a certain volume V₁Placing the solution to be detected in a container, adding 5.0mL of potassium hydroxide, adding 2-3 drops of calcium-carboxylic acid indicator test solution, titrating with EDTA standard solution, and consuming volume V of the EDTA standard solution when the solution color is changed from purple pink red to bright blue₂Calculating the calcium ion concentration c_{Sample application}；

Step 9) preparing a sample to be tested without the capsule anti-scaling particles C according to the steps 4) to 8), and recording the volume V of the consumed EDTA standard solution₃；

Wherein, the capsule scale inhibition particles C are not added in the step 4), and the calcium ion concentration C is calculated_{Without sample application}；

Preparing blank sample according to steps 4) -8), and recording the volume V of consumed EDTA standard solution₄；

WhereinStep 4) replacing the solution without adding the capsule scale inhibition particles C and B with distilled water, and calculating the calcium ion concentration C_{Blank space}；

Step 10) based on the calcium ion concentration c_{Sample application}Calcium ion concentration c_{Without sample application}And calcium ion concentration c_{Blank space}And (3) calculating to obtain the calcium carbonate scale inhibition rate, and evaluating that the capsule scale inhibition particles C can effectively inhibit scale when the calcium carbonate scale inhibition rate is not less than 85%.

The process for determining the mixing ratio of the solution A and the solution B in the step 3) is as follows:

inputting the content of each ion, pH value, temperature and pressure in the solution A and the solution B by scale scaling prediction software, and according to the weight ratio of the solution A: and (3) predicting the scaling amount of the solution B according to the volume ratio of 1:9 to 2:8 to 3:7 to 4:6 to 5:5 to 6:4 to 7:3 to 8:2 to 9:1, wherein the mixing ratio corresponding to the maximum scaling amount is the mixing ratio of the solution A to the solution B.

The process for determining the mixing ratio of the solution A and the solution B in the step 3) is as follows:

(1) respectively preparing 50ml, 100ml, 150ml, 200ml, 250ml, 300ml, 350ml, 400ml and 450ml of solution A;

(2) respectively preparing 450ml, 400ml, 350ml, 300ml, 250ml, 200ml, 150ml, 100ml and 50ml of solution B;

(3) respectively mixing the solution A and the solution B according to the corresponding sequence under the temperature and the pressure of the simulated oil field stratum to obtain 9 groups of mixed liquor;

(4) taking a plurality of pieces of quantitative filter paper, drying to constant weight, recording the mass G1 of each piece of filter paper, filtering each mixed solution in the quantitative filter paper, placing the mixed solution in a 105-degree oven to dry to constant weight, recording the mass G2, calculating the mass G of precipitates in each mixed solution, wherein G is G2-G1, selecting one group with the largest mass of precipitates from 9 groups of mixed solutions, and determining the mixed ratio of the solution A and the solution B.

The mass of the capsule scale inhibition particles C added in the step 4) is determined by adding the effective concentration C of the capsule scale inhibition particles₁To determine that the user has taken a particular task,

c₁＝ν×c×1，

in the formula, c₁For adding the capsule scale inhibition particlesEffective concentration, mg/L; v is the average release rate of the capsule scale inhibiting particles C, mg/L ∙ d; c is the effective wrapping rate of the capsule scale inhibition particles C,%; 1 means reaction time 1 day, d.

And step 6) the special conical bottle comprises a conical bottle, a rubber plug and two glass tubes, wherein the rubber plug is plugged at the opening of the conical bottle, the two glass tubes penetrate through the rubber plug and then go deep into the conical bottle, one glass tube is on the liquid level, and the other glass tube is under the liquid level.

The effective concentration of the capsule scale inhibition particles is c₁The calculation formula of the calcium ion concentration is as follows:

in the formula, M is the molar concentration of an EDTA standard solution, mol/L; v is the volume of EDTA standard solution consumed in titration, ml; v₁Is the volume of the solution to be measured, ml; c is calcium ion concentration, mg/L.

The calcium carbonate scale inhibition rate calculation formula is as follows:

in the formula, c_{Sample application}The calcium ion concentration in the solution after the capsule scale inhibition particles are added is mg/L; c. C_{Without sample application}The concentration of calcium ions in the solution is mg/L after the capsule scale inhibition particles are not added; c. C_{Blank space}The concentration of calcium ions in the blank solution is mg/L; x is the number of₃The scale inhibition rate of the calcium carbonate scale is percent.

And 7), filtering the supernatant in the step 7) by using a 0.45um acetate fiber filter membrane.

The distance between the glass tube on the liquid surface and the liquid surface is 3-4 cm.

The two glass tubes are 10mm in diameter and 300mm in length.

The invention has the beneficial effects that:

the evaluation method of the scale inhibition performance of the oil well shaft capsule scale inhibition particles on the calcium carbonate scale provided by the invention accords with the actual production of an oil field, can scientifically guide the filling process of the oil well shaft capsule scale inhibition particles, and has the advantages of simple operation, low requirement on detection personnel, low detection cost, strong operability of oil production units and contribution to popularization.

The mixing proportion of the solution A and the solution B is determined by a precipitation method or scale scaling prediction software so as to meet the actual situation of oilfield production, and the scale inhibitor can be used in the whole shaft or different development periods of gathering and transportation sites according to the proportion evaluation.

In order to make the aforementioned and other aspects of the present invention more comprehensible, preferred embodiments are described in detail below.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art. The terminology used in the description of the exemplary embodiments is not intended to be limiting of the invention.

Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.