CN-118671038-B - Method for measuring content of residual guanidine gum in guanidine gum breaking liquid

CN118671038BCN 118671038 BCN118671038 BCN 118671038BCN-118671038-B

Abstract

The invention provides a method for measuring the content of residual guanidine gum in guanidine gum breaking liquid. The method comprises the steps of sample pretreatment, preparation of guanidine gum breaking liquid series samples with different guanidine gum contents, regression analysis by taking the content of guanidine gum standard substances in the guanidine gum breaking liquid series samples with different guanidine gum contents as a response value and taking the characteristic fluorescence peak intensity and viscosity of the guanidine gum breaking liquid series samples with different guanidine gum contents after subtraction of blank as variables, obtaining a standard curve equation of residual guanidine gum, and substituting the characteristic fluorescence peak intensity and viscosity of the guanidine gum breaking liquid samples with the pretreatment after subtraction of blank into the standard curve equation of the residual guanidine gum, so as to obtain the content of the residual guanidine gum in the guanidine gum breaking liquid samples to be measured. The determination method is scientific and reasonable, has high repeatability and accuracy, realizes qualitative and quantitative analysis of residual guanidine gum in the guanidine gum breaking liquid, and can support efficient recycling treatment of the fracturing flowback fluid of the oil and gas field.

Inventors

ZHANG HUA
WANG ZHANSHENG
ZHANG XIAOFEI
XIE JIACAI
LI TING

Assignees

中国石油天然气集团有限公司
中国石油集团安全环保技术研究院有限公司

Dates

Publication Date: 20260508
Application Date: 20230314

Claims (15)

1. A method for measuring the content of residual guar gum in a guar gum breaking solution comprises the following steps: (1) Sample pretreatment, namely filtering a guar gum gel solution sample to be measured by adopting a filter column filled with a calcium alginate based composite material filler to obtain a pretreated guar gum gel solution sample; (2) Preparing a guanidine gum breaking liquid series sample with different guanidine gum contents, namely preparing the guanidine gum breaking liquid with a breaker according to the formula of an actual guanidine gum fracturing liquid corresponding to the guanidine gum breaking liquid sample to be measured, adopting a guanidine gum standard substance, and reacting for a period of time at a proper temperature to obtain the guanidine gum breaking liquid; (3) Preparing a standard curve equation, namely respectively carrying out fluorescence spectrum detection and viscosity detection on the photoresist-breaking liquid of the residual photoresist and the photoresist-breaking liquid series samples with different photoresist contents to obtain the characteristic fluorescence peak intensity and viscosity of the photoresist-breaking liquid of the residual photoresist, taking the characteristic fluorescence peak intensity and viscosity of the photoresist-breaking liquid of the residual photoresist as a blank, subtracting the blank from the characteristic fluorescence peak intensity and viscosity of the photoresist-breaking liquid series samples with different photoresist contents to obtain the characteristic fluorescence peak intensity and viscosity of the photoresist-breaking liquid series samples with different photoresist contents after the blank is subtracted, taking the content of the photoresist standard substance in the photoresist-breaking liquid series samples with different photoresist contents as a response value, taking the characteristic fluorescence peak intensity and viscosity of the photoresist-breaking liquid series samples with different photoresist contents after the blank is subtracted as variables, and carrying out regression analysis to obtain the standard curve equation of the residual photoresist; (4) The method comprises the steps of sample detection, namely performing fluorescence spectrum detection and viscosity detection on a pretreated guar gum breaking liquid sample to obtain the characteristic fluorescence peak intensity and viscosity of the pretreated guar gum breaking liquid sample, performing fluorescence spectrum detection and viscosity detection on water adopted in an actual guar gum fracturing liquid corresponding to the pretreated guar gum breaking liquid sample to obtain the characteristic fluorescence peak intensity and viscosity of the water, taking the characteristic fluorescence peak intensity and viscosity of the pretreated guar gum breaking liquid sample as a blank, subtracting the blank from the characteristic fluorescence peak intensity and viscosity of the pretreated guar gum breaking liquid sample to obtain the characteristic fluorescence peak intensity and viscosity of the pretreated guar gum breaking liquid sample after subtracting the blank, substituting the characteristic fluorescence peak intensity and viscosity into a standard curve equation of residual guar gum, and obtaining the content of the residual guar gum in the guar gum breaking liquid sample to be measured; The standard curve equation of the residual guanidine gum is a polynomial equation based on the characteristic fluorescence peak intensity and the viscosity, and is C= -14.1+0.1xDeltaF+84.3xDeltaeta, wherein C is the content of the guanidine gum, deltaF is the characteristic fluorescence peak intensity of the sample after blank deduction, and Deltaeta is the viscosity of the sample after blank deduction.
2. The method for determining the residual guar gum content of a guar gum solution according to claim 1, wherein in the step (1), the calcium alginate-based composite filler comprises a calcium alginate-MgO composite and a calcium alginate-bentonite composite.
3. The method for measuring the content of residual guanidine gum in the guanidine gum rubber solution according to claim 2, wherein the calcium alginate-MgO composite material is prepared by mixing, by weight, 0.5-3% of sodium alginate, 0.2-2% of calcium chloride, 1-5% of magnesium oxide and the balance of water to obtain calcium alginate-MgO composite material gel, and drying the calcium alginate-MgO composite material gel to constant weight at 20-50 ℃ to obtain the calcium alginate-MgO composite material.
4. The method for determining the content of residual guar gum in a guar gum breaking solution according to claim 2 or 3, wherein the particle size of the calcium alginate-based-MgO composite material is 0.5-2 mm.
5. The method for measuring the content of residual guanidine gum in the guanidine gum rubber solution according to claim 2, wherein the calcium alginate-bentonite composite material is prepared by mixing, by weight, 0.5-3% of sodium alginate, 0.2-2% of calcium chloride, 1-5% of bentonite and the balance of water to obtain calcium alginate-bentonite composite material gel, and drying the calcium alginate-bentonite composite material gel to constant weight at 20-50 ℃ to obtain the calcium alginate-bentonite composite material.
6. The method for determining the content of residual guar gum in a guar gum breaking solution according to claim 2 or 5, wherein the particle size of the calcium alginate-bentonite composite material is 0.5-2 mm.
7. The method for determining the content of residual guar gum in a guar gum solution according to claim 2, wherein the weight ratio of the calcium alginate-MgO composite material to the calcium alginate-bentonite composite material is 1:5-4:1.
8. The method for determining the content of residual guar gum in a guar gum solution according to claim 1, wherein in the step (1), when the guar gum solution sample is filtered, the volume ratio of the filler to the guar gum solution sample is 1:2-1:20.
9. The method for measuring the residual guar gum content in a guar gum solution according to claim 1, wherein in the step (1), the petroleum content in the pretreated guar gum solution sample is 15 mg/L or less and the suspended matter content is 30 mg/L or less.
10. The method for determining the content of residual guar gum in a guar gum breaking solution according to claim 1, wherein in the step (2), the addition amount of the breaker is 0.005% -1% based on 100% of the total weight of the guar gum fracturing solution added with the breaker, the reaction temperature of the breaking is 80-100 ℃, and the reaction time is 0.5-12 hours.
11. The method for measuring the residual guar gum content of the guar gum solution according to claim 1, wherein in the step (2), the viscosity of the guar gum solution is not more than 12 mpa s.
12. The method for determining the content of residual guar gum in a guar gum breaking solution according to claim 1, wherein in the step (2), the content of the standard guar gum in the series of guar gum breaking solution samples with different guar gum contents is 100-4000 mg/L.
13. The method for determining the residual guar gum content of a guar gum solution according to claim 12, wherein in the step (2), the series of guar gum solution samples having different guar gum contents comprise a series of samples having a content of 100mg/L, 500mg/L, 1000mg/L, 1500mg/L, 2000mg/L, 2500mg/L, 3000mg/L, 3500mg/L, 4000mg/L of a guar gum standard.
14. The method for determining the content of residual guar gum in a guar gum breaking solution according to claim 1, wherein in the step (3) and the step (4), the characteristic fluorescence peak positions detected by the fluorescence spectrum are excitation wavelength Ex/emission wavelength em=260-280 nm/320-340 nm.
15. The method for determining the content of residual guar gum in a guar gum breaking solution according to claim 1, wherein in the step (3), a correction coefficient R 2 =0.99 of a standard curve equation of the residual guar gum.

Description

Method for measuring content of residual guanidine gum in guanidine gum breaking liquid Technical Field The invention relates to a method for measuring the content of residual guanidine gum in guanidine gum breaking liquid, and belongs to the technical field of oil gas exploitation. Background In the development process of oil and gas fields, guanidine gum fracturing fluid is often adopted for yield increasing operation. The pollution composition of the guanidine gum fracturing flowback fluid is complex, and the guanidine gum which is not completely broken remains in the flowback fluid, so that the treatment difficulty of the flowback fluid is increased, and the flowback fluid needs to be subjected to enhanced destabilization and resource utilization. Therefore, it is necessary to study the properties and concentration of the residual guanidine gum in the flowback fluid. The guanidine gum breaking liquid (namely, flowback liquid) is waste liquid which is discharged back to the ground after underground gum breaking in the development process of the oil-gas field, the viscosity of the guanidine gum breaking liquid is about 1.2-10 mpa.s, the guanidine gum breaking liquid is mainly caused by incomplete gum breaking, and particularly, the molecular weight of organic matters remained in the flowback liquid with the viscosity of more than 5 mpa.s is larger. At present, a method for measuring residual guanidine gum in gel breaking liquid is not available. Part of industry or enterprise standards list determination methods for residues in a gel breaking liquid, such as SY/T5107-2005 water-based fracturing liquid evaluation method and SY/T6376-2008 general technical Condition for fracturing liquid, which define determination flow of residues after gel breaking of the fracturing liquid, but are different from the residues, and the gel breaking liquid is an aqueous phase composition which is difficult to centrifugally separate. CN105156087a proposes to adjust the guanidine gum content in the guanidine gum fracturing flow-back fluid to 1.0-1.5% by mass, and then reinject the fluid back into the ground after a series of treatments to improve the recovery ratio of crude oil, but it does not describe the concentration of residual guanidine gum in the gel breaking fluid and how to adjust the total amount of guanidine gum. CN108435215A represents the concentration of residual guanidine gum in the gel breaking solution by COD concentration, and the content of residual guanidine gum cannot be determined. More researchers use viscosity, molecular weight and the like to represent the guar gum breaking solution (Huang Feifei and the like, and the high-efficiency breaking degradation agent system of the guar gum fracturing solution is researched, chemical industry is applied, 2021), and also have researchers use hydroxyl functional groups of the guar gum to conduct indirect quantitative analysis. Yin Zichen et al (study of adsorption properties of hydroxypropyl guar on kaolin, analytical chemistry, 2019) utilize the structural similarity of guar and cellulose to prepare an acidified guar solution, react with an anthrone-containing ethyl acetate solution in a 90 ℃ water bath, and then measure the absorbance of the reacted solution at a wavelength of 620 nm. The color reaction method uses guanidine gum as a standard sample to prepare a standard curve, the concentration range is 20-100 mg/L, but the structure, viscosity, molecular weight and the like of the guanidine gum after oxidative gel breaking are not considered, and the result only represents the amount of hydroxyl functional groups capable of reacting with a color reagent. Aiming at the structural and property changes in the process of breaking the guar gum, a method for determining the content of residual guar gum in the guar gum breaking liquid with strong adaptability is established, and the method becomes one of the problems to be solved in the field. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a method for measuring the content of residual guar gum in a guar gum breaking solution. The determination method is scientific and reasonable, and has high repeatability and accuracy. In order to achieve the above purpose, the invention provides a method for measuring the content of residual guar gum in a guar gum breaking solution, which comprises the following steps: (1) Sample pretreatment, namely filtering a guar gum gel solution sample to be measured by adopting a filter column filled with a calcium alginate based composite material filler to obtain a pretreated guar gum gel solution sample; (2) Preparing a guanidine gum breaking liquid series sample with different guanidine gum contents, namely preparing the guanidine gum breaking liquid with a breaker according to the formula of an actual guanidine gum fracturing liquid corresponding to the guanidine gum breaking liquid sample to be measured, adopting a guanidine gum stand