CN112881588A - Method for measuring hydrolysis degree of partially hydrolyzed polyacrylamide for oil displacement - Google Patents
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- 230000007062 hydrolysis Effects 0.000 title claims abstract description 41
- 238000006460 hydrolysis reaction Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 41
- 229920002401 polyacrylamide Polymers 0.000 title claims abstract description 18
- 238000006073 displacement reaction Methods 0.000 title claims abstract description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 78
- 239000000243 solution Substances 0.000 claims abstract description 46
- 238000004448 titration Methods 0.000 claims abstract description 30
- 229920000642 polymer Polymers 0.000 claims abstract description 24
- 239000012086 standard solution Substances 0.000 claims abstract description 20
- 238000000954 titration curve Methods 0.000 claims abstract description 15
- 239000007787 solid Substances 0.000 claims abstract description 10
- 239000000523 sample Substances 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 239000012488 sample solution Substances 0.000 claims description 10
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 8
- PQUXFUBNSYCQAL-UHFFFAOYSA-N 1-(2,3-difluorophenyl)ethanone Chemical compound CC(=O)C1=CC=CC(F)=C1F PQUXFUBNSYCQAL-UHFFFAOYSA-N 0.000 claims description 4
- 239000008367 deionised water Substances 0.000 claims description 4
- 229910021641 deionized water Inorganic materials 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 4
- 229940047670 sodium acrylate Drugs 0.000 claims description 4
- 239000002131 composite material Substances 0.000 claims description 2
- 238000001514 detection method Methods 0.000 abstract description 11
- 230000035772 mutation Effects 0.000 abstract description 3
- 238000005259 measurement Methods 0.000 description 7
- 239000012153 distilled water Substances 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- 239000002696 acid base indicator Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000002479 acid--base titration Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- -1 sodium carboxylate Chemical class 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
- G01N31/162—Determining the equivalent point by means of a discontinuity
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Abstract
The invention relates to a method for measuring the hydrolysis degree of partially hydrolyzed polyacrylamide for oil displacement. The method mainly solves the problem that the color of the titration end point is difficult to identify and the artificial subjective judgment error is large because the indicator in the polymer solution in the existing determination method has no obvious color mutation point in the titration process. The method is characterized in that: the method comprises the following steps: (1) measuring the solid content of a polymer sample, and preparing a solution to be measured according to the solid content; (2) dropwise adding a hydrochloric acid standard solution into the prepared solution to be detected, measuring the pH value of the solution, and stopping titration when the pH value reaches 3.5; (3) drawing a pH-V titration curve; (4) the first derivative and the second derivative are calculated for the pH-V titration curve, and the maximum point and the second derivative d of the obtained first derivative curve2pH/dV2And (3) calculating the corresponding hydrochloric acid consumption amount as a titration end point when the value is not less than 0 to obtain the hydrolysis degree of the sample. The method can basically eliminate human errors caused by unobvious solution color change, and improve the accuracy and precision of detection.
Description
Technical Field
The invention relates to the technical field of oil extraction in oil fields, in particular to a method for measuring the hydrolysis degree of partially hydrolyzed polyacrylamide for oil displacement.
Background
The polymer mainly used in the oil displacement technology of the oil field polymer is partially hydrolyzed polyacrylamide, the degree of hydrolysis is an important physicochemical property index reflecting the quality of a polymer product and the performance of a solution, and is an important parameter influencing the aggregation structure, rheological property, tackifying property, adsorption property and stability of a polymer solution. At present, the partial hydrolysis degree of the polyacrylamide is characterized in China oil and gas industry standard SY/T5862-2008 and China oil and gas group enterprise standard Q/SY 119 + 2014, mainly by using an acid-base titration principle, titrating sodium carboxylate in a polymer solution by using 0.1mol/L hydrochloric acid standard solution, judging a titration end point according to the color change of an indicator, and calculating the hydrolysis degree of a sample according to the hydrochloric acid consumption of the titration end point. However, in the actual operation of the method, the color of the indicator in the polymer solution is gradually changed in the titration process, and no obvious color mutation point exists, so that the color of the titration end point is difficult to identify, and the artificial subjective error is large.
Disclosure of Invention
The invention aims to solve the technical problem that the color of a titration end point is difficult to identify due to no obvious color mutation point in the titration process of an indicator in a polymer solution in the existing determination method in the background technology, and the artificial subjective judgment error is large, and provides a method for determining the hydrolysis degree of partially hydrolyzed polyacrylamide for oil displacement. The method can intuitively judge the pH jump point so as to determine the titration end point; human errors caused by unobvious solution color change are basically eliminated, and the accuracy and precision of detection are improved.
The invention can solve the problems by the following technical scheme: the method for determining the hydrolysis degree of the partially hydrolyzed polyacrylamide for oil displacement comprises the following steps:
the method comprises the following steps:
(1) measuring the solid content of a polymer sample, and preparing a solution to be measured according to the measured solid content;
(2) dropwise adding a hydrochloric acid standard solution into the solution to be detected prepared in the step (1), measuring the pH value of the solution, and stopping titration when the pH value of the solution reaches 3.5;
(3) according to the experimental data measured in the step (2), taking hydrochloric acid consumption V (mL) as a horizontal coordinate, and taking the pH value of the solution as a vertical coordinate to draw a pH-V titration curve;
(4) the first derivative and the second derivative are calculated for the pH-V titration curve, and the maximum point and the second derivative d of the obtained first derivative curve2pH/dV2And (3) calculating to obtain the hydrolysis degree of the sample, wherein the corresponding hydrochloric acid consumption is the titration end point when the hydrochloric acid consumption is 0.
The polymer in the step (1) is partially hydrolyzed polyacrylamide, the preparation water is deionized water, and the concentration of the solution to be detected is about 100 ppm.
The concentration of the hydrochloric acid standard solution in the step (2) is 0.1mol/L, and a burette for titration is a 1mL micro burette; the pH meter used for measuring the pH value is a thunder magnetic PHS-25 type pH meter, and the used electrode is an E-201F type pH composite electrode.
The formula of the hydrolysis degree of the sample in the step (4) is shown as a formula (I):
in the formula: HD-degree of hydrolysis,%;
c, concentration of hydrochloric acid standard solution, mol/L;
v is the milliliter number, mL, of the hydrochloric acid standard solution consumed by the sample solution;
m-mass of 0.1% sample solution, g;
23-difference in mass of sodium acrylate and acrylamide linkages;
71-mass of acrylamide mer corresponding to 1.00mL of hydrochloric acid standard solution [ c (HCl) ═ 1.000mol/L ].
According to the invention, the titration endpoint is determined by the fact that the pH value of the solution changes sharply near the titration endpoint according to the principle of titration jump. However, as can be seen from the reaction equation (II), the titration of the partially hydrolyzed polyacrylamide converts weakly basic-COONa in the solution to-COOH, and the titration end point solution is acidic and in the polymer solution
A pH jump point is difficult to be observed on a pH-V titration curve of the pH value and the hydrochloric acid consumption V to judge the titration end point. Therefore, the pH-V curve is subjected to a derivative method to find the point with the highest change rate of the pH value of the solution to determine the titration end point, so as to calculate the hydrolysis degree of the polymer.
Compared with the background technology, the invention has the following beneficial effects: according to the invention, the pH jump point is intuitively judged according to the change condition of the derivative function by solving the first derivative and the second derivative of the pH-V titration curve of the pH value of the polymer solution and the hydrochloric acid consumption V, so that the titration end point is determined. Compared with the indicator method in the existing standard, the method can basically eliminate human errors caused by unobvious solution color change, and improve the accuracy and precision of detection. Is beneficial to controlling the quality of polymer products, thereby improving the economic effect of the polymer flooding technology.
Drawings
FIG. 1 is a graph of the titration curve pH-V and first derivative of the A001 sample in example 1;
FIG. 2 is a graph of the second derivative of the titration curve of the A001 sample in example 1;
FIG. 3 is a graph of the titration curve pH-V and the first derivative of the A002 sample in example 2;
FIG. 4 is a graph of the second derivative of the titration curve of the A002 sample in example 2.
The specific implementation mode is as follows:
the present invention will be further described with reference to the following drawings and examples, but the present invention is not limited to the following examples. The experimental methods are all conventional methods unless otherwise specified. The starting materials are commercially available from the public unless otherwise specified.
Example 1 determination of the degree of hydrolysis of a high-molecular salt-resistant Polymer A001 produced by Aisen, France
The specific determination steps are as follows:
1. determination of the solid content of a sample
Method for determining solid content S of polymer sample: according to SY/T5862-.
2. Preparation of sample solution
(1) Weighing (200-1/S) g of distilled water (accurate to 0.01g) in a 500mL beaker;
(2) accurately weighing (1/S) g of sample to 0.0001g, adjusting the rotating speed of a vertical stirrer to (400 +/-20) r/min to enable distilled water to form a vortex, slowly and uniformly withdrawing the sample into a vortex wall within 1min, and continuously stirring for 2h to prepare a solution with the concentration of 0.5%;
(3) adding 40.00g of 0.5% solution and 160.00g of distilled water into a 500mL beaker, and stirring with a magnetic stirrer for about 15min until uniform to prepare 0.1% solution;
(4) in three 250mL conical flasks, about 10g of 0.1% solution was added, diluted to 100mL with deionized water and shaken well.
3. Step of measuring degree of hydrolysis of sample
(1) Placing the conical flask on a magnetic stirrer, and inserting a pH meter electrode into the solution and fixing;
(2) dropwise adding 0.1mol/L hydrochloric acid standard solution while stirring, recording the pH value of the solution and the hydrochloric acid consumption V after the reading of the pH meter is stable, and stopping titration when the pH value of the solution reaches 3.5;
(3) using hydrochloric acid consumption V (mL) as abscissa and solution pH value as ordinate to draw pH-V titration curve, and calculating first derivative and second derivative of the curve to obtain maximum point and second derivative d of the first derivative curve2pH/dV2When the hydrochloric acid consumption is 0, the corresponding hydrochloric acid consumption is the titration end point (as shown in fig. 1 and fig. 2);
(4) the degree of hydrolysis is calculated according to formula (I):
in the formula: HD-degree of hydrolysis,%;
c, concentration of hydrochloric acid standard solution, mol/L;
v is the milliliter number, mL, of the hydrochloric acid standard solution consumed by the sample solution;
m-mass of 0.1% sample solution, g;
23-difference in mass of sodium acrylate and acrylamide linkages;
71-mass of acrylamide mer corresponding to 1.00mL of hydrochloric acid standard solution [ c (HCl) ═ 1.000mol/L ].
TABLE 1
TABLE 2
(5) The samples were subjected to at least 3 replicates according to the above procedure, and the maximum deviation of the individual measurements from the mean was within. + -. 0.5%, and the measurements were re-sampled if the maximum deviation was exceeded. The results of the measurement of the degree of hydrolysis of A001 are shown in Table 1, and samples were obtained by calculationThe average value of the hydrolysis degree of the product is 29.2 percent, and the variance is 1.67 multiplied by 10-6。
(6) The hydrolysis degree of the sample A001 is measured according to an acid-base indicator method in the China oil and gas industry standard SY/T5862-2008, the detection results are shown in Table 2, the average value of the hydrolysis degree of the sample is 29.8%, and the variance is 7.33 multiplied by 10-6。
Example 2 detection of degree of hydrolysis of A002A polymer produced by Daqing refining company
The specific determination steps are as follows:
1. determination of the solid content of a sample
Method for determining solid content S of polymer sample: according to SY/T5862-.
2. Preparation of sample solution
(1) Weighing (200-1/S) g of distilled water (accurate to 0.01g) in a 500mL beaker;
(2) accurately weighing (1/S) g of sample to 0.0001g, adjusting the rotating speed of a vertical stirrer to (400 +/-20) r/min to enable distilled water to form a vortex, slowly and uniformly withdrawing the sample into a vortex wall within 1min, and continuously stirring for 2h to prepare a solution with the concentration of 0.5%;
(3) adding 40.00g of 0.5% solution and 160.00g of distilled water into a 500mL beaker, and stirring with a magnetic stirrer for about 15min until uniform to prepare 0.1% solution;
(4) in three 250mL conical flasks, about 10g of 0.1% solution was added, diluted to 100mL with deionized water and shaken well.
3. Step of measuring degree of hydrolysis of sample
(1) Placing the conical flask on a magnetic stirrer, and inserting a pH meter electrode into the solution and fixing;
(2) dropwise adding 0.1mol/L hydrochloric acid standard solution while stirring, recording the pH value of the solution and the hydrochloric acid consumption V after the reading of the pH meter is stable, and stopping titration when the pH value of the solution reaches 3.5;
(3) using hydrochloric acid consumption V (mL) as abscissa and solution pH value as ordinate to draw pH-V titration curve, and calculating first derivative and second derivative of the curve to obtain maximum of first derivative curvePoint and second derivative d2pH/dV2The corresponding hydrochloric acid consumption at 0 is the titration end point (as shown in fig. 3 and 4);
(4) the degree of hydrolysis is calculated according to formula (I):
in the formula: HD-degree of hydrolysis,%;
c, concentration of hydrochloric acid standard solution, mol/L;
v is the milliliter number, mL, of the hydrochloric acid standard solution consumed by the sample solution;
m-mass of 0.1% sample solution, g;
23-difference in mass of sodium acrylate and acrylamide linkages;
71-mass of acrylamide mer corresponding to 1.00mL of hydrochloric acid standard solution [ c (HCl) ═ 1.000mol/L ].
TABLE 3
TABLE 4
(5) The samples were subjected to at least 3 replicates according to the above procedure, and the maximum deviation of the individual measurements from the mean was within. + -. 0.5%, and the measurements were re-sampled if the maximum deviation was exceeded. The results of the measurement of the degree of hydrolysis of A002 are shown in Table 3, and the average value of the degree of hydrolysis of the sample was calculated to be 21.1% and the variance was calculated to be 2X 10-6。
(6) The hydrolysis degree of the sample A002 is measured according to an acid-base indicator method in the China oil and gas industry standard SY/T5862-2008, the detection results are shown in Table 4, the average value of the hydrolysis degree of the sample is 21.2%, and the variance is 9.67 multiplied by 10-6。
In conclusion, the invention initiatively determines the endpoint of the titration reaction by means of derivation of the polymer titration curve, compared with the indicator method in the existing standard, the sample measurement result is more accurate, the variance of the experimental result is smaller, the influence of artificial subjective errors in the detection process of the polymer hydrolysis degree is effectively reduced, and the accuracy and precision of the detection of the hydrolysis degree of the partially hydrolyzed polyacrylamide for oil displacement are greatly improved. And the detection equipment depended by the whole detection method is simple to operate and low in cost, and the popularization and application of the detection method are facilitated.
The above description is only a preferred embodiment of the present invention, and any modifications and variations made by those skilled in the art based on the main technical idea of the present invention are within the technical scope of the present invention.
Claims (6)
1. A method for measuring the hydrolysis degree of partially hydrolyzed polyacrylamide for oil displacement is characterized by comprising the following steps: the method comprises the following steps:
(1) measuring the solid content of a polymer sample, and preparing a solution to be measured according to the measured solid content;
(2) dropwise adding a hydrochloric acid standard solution into the solution to be detected prepared in the step (1), measuring the pH value of the solution, and stopping titration when the pH value of the solution reaches 3.5-4.5;
(3) according to the experimental data measured in the step (2), taking hydrochloric acid consumption V (mL) as a horizontal coordinate, and taking the pH value of the solution as a vertical coordinate to draw a pH-V titration curve;
(4) the first derivative and the second derivative are calculated for the pH-V titration curve, and the maximum point and the second derivative d of the obtained first derivative curve2pH/dV2And (3) calculating to obtain the hydrolysis degree of the sample, wherein the corresponding hydrochloric acid consumption is the titration end point when the hydrochloric acid consumption is 0.
2. The method for determining the hydrolysis degree of the partially hydrolyzed polyacrylamide for flooding according to claim 1, wherein the method comprises the following steps: the polymer in the step (1) is partially hydrolyzed polyacrylamide, and the preparation water is deionized water.
3. The method for determining the hydrolysis degree of the partially hydrolyzed polyacrylamide for flooding according to claim 1, wherein the method comprises the following steps: the concentration of the solution to be detected in the step (1) is about 100 ppm.
4. The method for determining the hydrolysis degree of the partially hydrolyzed polyacrylamide for flooding according to claim 1, wherein the method comprises the following steps: the concentration of the hydrochloric acid standard solution in the step (2) is 0.1mol/L, and a burette for titration is a 1mL micro burette.
5. The method for determining the hydrolysis degree of the partially hydrolyzed polyacrylamide for flooding according to claim 1, wherein the method comprises the following steps: and (3) the pH meter used for measuring the pH value in the step (2) is a thunder-magnetic PHS-25 type pH meter, and the used electrode is an E-201F type pH composite electrode.
6. The method for determining the hydrolysis degree of the partially hydrolyzed polyacrylamide for flooding according to claim 1, wherein the method comprises the following steps: the formula (I) of the hydrolysis degree of the sample in the step (4) is as follows:
in the formula: HD-degree of hydrolysis,%;
c, concentration of hydrochloric acid standard solution, mol/L;
v is the milliliter number, mL, of the hydrochloric acid standard solution consumed by the sample solution;
m-mass of 0.1% sample solution, g;
23-difference in mass of sodium acrylate and acrylamide linkages;
71-mass of acrylamide mer corresponding to 1.00mL of hydrochloric acid standard solution [ c (HCl) ═ 1.000mol/L ].
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1415956A (en) * | 2002-12-05 | 2003-05-07 | 大庆油田有限责任公司 | Detection method of degree of hydrolysis in detection of polymer mass |
| CN1804617A (en) * | 2005-12-30 | 2006-07-19 | 中国原子能科学研究院 | Method for analyzing pH value |
| CN101339139A (en) * | 2007-07-04 | 2009-01-07 | 中国石油天然气股份有限公司 | Method for determining anion type polyacrylamide hydrolysis degree |
| CN101506243A (en) * | 2006-06-26 | 2009-08-12 | 沙伯基础创新塑料知识产权有限公司 | Compositions and methods for polymer composites |
| CN106770914A (en) * | 2016-12-02 | 2017-05-31 | 山东非金属材料研究所 | Boron contents assay method in a kind of boride |
| CN109668941A (en) * | 2018-12-06 | 2019-04-23 | 普瑞斯伊诺康有限公司 | A kind of method of sulfuric acid and manganese sulfate concentration in measurement electrolyte aqueous solution |
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2021
- 2021-01-18 CN CN202110060057.0A patent/CN112881588A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1415956A (en) * | 2002-12-05 | 2003-05-07 | 大庆油田有限责任公司 | Detection method of degree of hydrolysis in detection of polymer mass |
| CN1804617A (en) * | 2005-12-30 | 2006-07-19 | 中国原子能科学研究院 | Method for analyzing pH value |
| CN101506243A (en) * | 2006-06-26 | 2009-08-12 | 沙伯基础创新塑料知识产权有限公司 | Compositions and methods for polymer composites |
| CN101339139A (en) * | 2007-07-04 | 2009-01-07 | 中国石油天然气股份有限公司 | Method for determining anion type polyacrylamide hydrolysis degree |
| CN106770914A (en) * | 2016-12-02 | 2017-05-31 | 山东非金属材料研究所 | Boron contents assay method in a kind of boride |
| CN109668941A (en) * | 2018-12-06 | 2019-04-23 | 普瑞斯伊诺康有限公司 | A kind of method of sulfuric acid and manganese sulfate concentration in measurement electrolyte aqueous solution |
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