A composition suitable for degradation of non-conventional polymer thickening systems

Abstract

The application discloses a composition suitable for degradation of an unconventional polymer thickening system, relates to the technical field of new materials for chemical aids for oil exploitation, and comprises any one of the following 1) to 4): 1) a compound containing an N-hydroxyl-substituted amino functional group; 2) a compound containing an N-hydroxyl-substituted amino functional group and a compound containing an amine oxide functional group; 3) a compound containing an N-hydroxyl-substituted amino functional group and a compound containing a carboxyl functional group; and 4) a compound containing an N-hydroxyl-substituted amino functional group, a compound containing an amine oxide functional group and a compound containing a carboxyl functional group. The application adopts the combination of an N-hydroxyl-substituted amino group or an N-hydroxyl-substituted amino group and an amine oxide and a carboxylic acid group, and solves the problem of complete degradation of the unconventional polymer thickening system, and the technical scheme is more extensive than traditional hazardous oxidants such as ammonium persulfate, and is more friendly to production safety, an ecological environment and employee health.

Description

Technical Field

[0001] This invention relates to the field of new materials technology for chemical additives in petroleum extraction, and specifically to a composition suitable for the degradation of unconventional polymer thickening systems. Background Technology

[0002] Unconventional polymer thickener systems in oil extraction refer to thickening systems containing polymers with special functions, acid fracturing fluids, weighted fracturing fluids, and functional compounds containing triazine, etc. Conventional polymer thickener systems are primarily degraded by oxidants such as ammonium persulfate, as well as other non-oxidizing breaker agents. Invention patent CN201811497003.5, "Non-oxidizing Polymer Chemical De-clogging Breaker and its Preparation Method" (hereinafter referred to as "non-oxidizing breaker"), mentions that the antioxidant is N-hydroxy-2-methyl-2-propane, a compound containing an N-hydroxy-substituted amino functional group. This was also a novel approach proposed in China in 2018, demonstrating that compounds containing N-hydroxy-substituted amino functional groups have the function of degrading polymers. Its non-oxidizing breaker product has already been applied in the 25℃ ultra-low temperature reservoir of Yanchang Oilfield, the 40℃ high-salinity block of Qinghai Oilfield, and the 45℃ reservoir of Daqing Oilfield. Industrial application and promotion; This patent has already mentioned the shortcomings and deficiencies of oxidants and bio-enzymes as polymer degraders. At the same time, the invention patents CN121136695A, CN121449520A, CN121652091A, CN121699594A, etc., involve compounds containing N-hydroxy-substituted amino functional groups, which are used as reducing systems in combination with oxidants or to synthesize surfactants to solve the degradation of conventional liquid preparation polymer thickening systems. They do not mention the degradation problem of unconventional liquid preparation polymer thickening systems.

[0003] With advancements in oil extraction technology, the performance requirements for thickeners used in fracturing and drilling fluids are becoming increasingly stringent, leading to more complex fluid preparation conditions. Alcohol-based polymer thickeners, while widely used due to their numerous advantages, suffer from poor degradation performance by oxidants such as ammonium persulfate. This is because the oxidizing free radicals react first with the more reactive reducing alcohol groups, preventing them from reaching the polymer backbone and causing degradation. Furthermore, ammonium persulfate oxidants, when used in high-mineralized wastewater and seawater-based fluid preparations, produce large amounts of calcium sulfate and magnesium scale, resulting in high levels of broken-up residue that clogs formation flow channels and impacts oil recovery. Additionally, when removing filter cake from bottom-hole drilling fluids operating at temperatures above 100°C, the oxidant ammonium persulfate tends to become ineffective within 20-30 minutes, leading to incomplete cake removal. Currently, oxidants are not ideal for breaking up the gel in acidic solutions and polymer thickening systems containing triazine.

[0004] The aforementioned unconventional operating conditions pose a severe challenge to both oxidant-based and non-oxidant-based breaker agents, whose performance can no longer meet the needs of fracturing and drilling operations in unconventional conditions, thus affecting the extraction of oil and gas under these conditions. Therefore, there is an urgent need to develop a new degradation agent system composition to solve the problem of degradation of polymer thickeners under existing special operating conditions. Summary of the Invention

[0005] To address the aforementioned problems, the present invention provides a composition suitable for the degradation of unconventional polymer thickening systems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A composition suitable for degradation of unconventional polymer thickening systems, comprising at least one of the following 1) to 4):

[0008] 1) Compounds containing N-hydroxyl-substituted amino functional groups;

[0009] 2) Compounds containing N-hydroxyl-substituted amino functional groups and compounds containing amine oxide functional groups;

[0010] 3) Compounds containing N-hydroxyl-substituted amino functional groups and compounds containing carboxyl functional groups;

[0011] 4) Compounds containing N-hydroxy-substituted amino functional groups, compounds containing amine oxide functional groups, and compounds containing carboxyl functional groups.

[0012] N-hydroxy-substituted amino functional groups are strong nucleophiles with reducing properties. They readily attack the positively charged C atoms on the polyacrylamide backbone, altering the electron cloud density of the C-C bonds and reducing their chemical bond energy, thus causing degradation. Amine oxide functional groups possess weak nucleophilicity and mild oxidizing properties. They also exhibit cationic characteristics, surface activity, and temperature resistance, providing emulsification, dispersion, foam stabilization, and synergistic activation functions, but they themselves do not possess de-gelling properties. Carboxylic acid functional groups, while possessing weak nucleophilic effects, do not inherently possess de-gelling properties. Compounds containing carboxyl groups (RCOOR1) can acquire more properties through changes in the R or R1 structure, such as chelated calcium and magnesium compounds. These compounds protect the N-hydroxy-substituted amino functional groups from attack and provide lone pair electrons for nucleophilic activity. Combining two or three of these functional groups can regulate activity and achieve complementary modification, addressing the issues of poor stability and limited applicability of single functional groups.

[0013] Meanwhile, in unconventional high-temperature systems, the N-hydroxy-substituted amino functional groups are interfered with by hydroxyl groups, high-calcium and magnesium ions, and electrophilic reagents, resulting in insufficient activity of nucleophilic attack on the positively charged C atom. In this case, the amine oxide functional group and the N-hydroxy-substituted amino functional group undergo a mild redox reaction to synergistically promote the complete decomposition and degradation of the polymer thickener. For example, in alcohol-based polymer thickening systems, oxidant free radicals cannot act on the polymer backbone and instead undergo a redox reaction with the alcohol group, leading to poorer degradation, which is more pronounced in high-mineralized water solutions, resulting in the formation of large amounts of calcium sulfate. In this invention, both the amine oxide functional group and the N-hydroxy-substituted amino functional group possess nucleophilic properties. When the N-hydroxy-substituted amino functional group nucleophilically attacks the C and C backbone, it can also undergo a mild redox reaction with the amine oxide, exhibiting a synergistic degradation effect, thus promoting the complete decomposition and degradation of the alcohol-based polymer thickener. Complete degradation and avoidance of calcium sulfate and magnesium scale formation from persulfate application; the polymer thickening system containing high-concentration mineralized water has a dual function of the carboxylic acid functional group. First, in the RCOOR1 compound, R, representing an amino group, acts as a nucleophile to attack the main chain, while the carboxyl functional group has a chelating effect, chelating calcium and magnesium in the mineralized water and protecting the N-hydroxy-substituted amino group to reduce ion interference and enhance its attack activity. It can also reduce the formation of calcium sulfate and magnesium scale caused by oxidative free radical degradation, mitigating reservoir damage. One agent achieves a dual effect; when cleaning high-temperature bottom-hole filter cake in drilling fluids above 100℃ or breaking the gel in acid fracturing industrial fluids, the oxidant ammonium persulfate has a short oxidizing activity time at the bottom of the well, and the filter cake becomes sulfate and becomes ineffective before it is completely removed; similarly, acid fracturing working fluids, whether hydrochloric acid or hydrofluoric acid systems, contain a large amount of H2O. + Both ions and triazine are strong electrophilic groups. Their interaction with N-hydroxy-substituted amino groups prevents them from attacking the C-C backbone, resulting in a significant decrease in their ability to degrade polymers. However, this invention utilizes the principles and functional group combinations mentioned above. The N-hydroxy-substituted amino functional group is the core functional group with polymer degradation function, while the amine oxide functional group and carboxyl functional group play a synergistic role, resulting in a good depolymerization effect on unconventional polymer thickening systems.

[0014] Preferably, the general structural formula of the N-hydroxy-substituted amino functional group compound is R1N(R2)-OH, wherein R1 and R2 are any one of hydrogen atom, alkyl, aryl, and acyl groups.

[0015] Preferably, the N-hydroxy-substituted amino functional group compound includes at least one of N-hydroxy-2-propanediamine, N,N-diethyl-N-hydroxyamine, N-hydroxy-2-methyl-2-propanediamine, 3-(N-hydroxyamino)-1-propanol, and hydroxyamine hydrochloride.

[0016] Preferably, the general structural formula of the compound containing the carboxyl functional group is: R3COOR4, wherein R3 is any one of amino or alkyl; R4 is sodium, hydrogen, cobalt, or NH4+. 4+ and Fe 2+ Any one of them.

[0017] Preferably, the compound containing a carboxyl functional group includes at least one of ammonium acetate, sodium diethyltriaminepentaacetate, EDTA4Na, and citric acid.

[0018] Preferably, the general structural formula of the compound containing the amine oxide functional group is: (R5)3N + O - R5 is any one of C8-C18 alkyl or amamidopropyl.

[0019] Preferably, the compound containing the amine oxide functional group includes at least one of: cocoyl dimethylamine oxide, lauramide propylamine oxide, and tetradecyl dimethylamine oxide.

[0020] Preferably, the molar ratio of the compound containing N-hydroxy-substituted amino functional groups to the compound containing amine oxide functional groups is 1.5 to 3:1;

[0021] The molar ratio of the compound containing an N-hydroxy-substituted amino functional group to the compound containing a carboxyl functional group is 1:1 to 3.

[0022] Preferably, the composition is used for the degradation of unconventional polymer thickening systems such as alcohol-based polymers, acid fracturing fluids, weighted fracturing fluids, triazine-containing working fluids, and high-temperature well drilling fluid filter cake removal.

[0023] Preferably, the composition can be added separately or prepared on demand, and the operating temperature of the composition is greater than 60°C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] With the advancement of petroleum extraction technology, the research and application of chemical additives that are safer for production, more environmentally friendly, and better for the physical and mental health of employees is an inevitable trend. This invention uses a combination of amine oxide, N-hydroxy-substituted amino groups, and carboxylic acid functional groups to solve the problem of complete degradation of unconventional polymer thickening systems. This technical solution has a wider range of applications, is safer, and is more environmentally friendly than traditional hazardous oxidants such as ammonium persulfate. Its widespread use will be of great significance to the iterative upgrading of chemical breaker additives for fracturing and drilling in petroleum extraction, and will provide strong technical support for improving oil and gas recovery rates under unconventional working conditions. Detailed Implementation

[0026] The following describes embodiments of the present invention. These embodiments are exemplary and intended to explain the present invention, and are not to be construed as limiting the present invention.

[0027] Example 1

[0028] This invention provides a composition suitable for the degradation of unconventional polymer thickening systems, specifically comprising the following raw materials:

[0029] (1) The compound containing the amine oxide functional group is cocoyl dimethylamine oxide;

[0030] (2) The compound containing an N-hydroxy-substituted amino functional group is 3-(N-hydroxyamino)-1-propanol;

[0031] (3) The compound containing the carboxylic acid functional group is sodium diethyltriaminepentaacetate;

[0032] The compounds (1)-(3) were prepared into 10wt% aqueous solutions for later use;

[0033] The degradation effects of polymer thickening systems on compounds with different functional groups under conventional solution preparation conditions were compared. The water used for solution preparation was oilfield wastewater with a salinity of 10000 mg / L. According to the technical requirements of the petroleum industry standard SY / T7627-2021, the breaking viscosity was ≤5 mPa.s and the residue content of the polymer system was ≤100 mg / L.

[0034] The specific application was as follows: 0.5 wt% dry powder polymer thickener, initial viscosity of 100.5 mPa·s, breaking temperature of 60℃, breaking time of 12 h. The relevant results are shown in Table 1.

[0035] Example 2

[0036] This invention provides a composition suitable for the degradation of unconventional polymer thickening systems, specifically comprising the following raw materials:

[0037] The compound containing the amine oxide functional group is cocoyl dimethylamine oxide; the compound containing the N-hydroxy-substituted amino functional group is N-hydroxy-2-propane; and the compound containing the carboxylic acid functional group is citric acid, wherein the molar ratio of the amine oxide functional group, the N-hydroxy-substituted amino functional group, and the carboxylic acid functional group is 1:1.5:3.

[0038] Using the composition of Example 2, ammonium persulfate oxidant, and non-oxidizing breaker (patent number CN201811497003.5, the product of Example 1), the degradation effect of the polymer thickening system under unconventional liquid preparation conditions was compared. According to the technical indicators required in the petroleum industry standard SY / T7627-2021, the breaker viscosity was ≤5mPa.s, and the residue content of the polymer system was ≤100mg / L.

[0039] Specifically, 0.5 wt% dry powder alcohol-based polymer thickener was prepared using high-mineralization oilfield wastewater with a mineralization of 50,000 mg / L. The gel breaking temperature was 70℃ and the gel breaking time was 12 h. The relevant results are shown in Table 2.

[0040]

[0041] Example 3

[0042] This invention provides a composition suitable for the degradation of unconventional polymer thickening systems, specifically comprising the following raw materials:

[0043] The compound containing the amine oxide functional group is lauramidopropylamine oxide; the compound containing the N-hydroxy-substituted amino functional group is N-hydroxy-2-methyl-2-propane; the compound containing the carboxylic acid functional group is EDTA4Na, wherein the molar ratio of the amine oxide functional group, the N-hydroxy-substituted amino functional group and the carboxylic acid functional group is 1:2:4.

[0044] Using the composition of Example 3, ammonium persulfate oxidant, and non-oxidizing breaker (the product of Example 2, patent number CN201811497003.5), the degradation effect of the polymer thickening system under unconventional liquid preparation conditions was compared. According to the technical requirements of the petroleum industry standard SY / T7627-2021, the breaker viscosity was ≤5mPa.s, and the residue content of the polymer system was ≤100mg / L.

[0045] Specifically, the following components were used: 1.0 wt% salt-resistant suspension polymer thickener (provided by Jiangsu Fumiao Technology Co., Ltd.), 25 wt% calcium chloride for weighting, 1.0 wt% magnesium chloride, 3 wt% sodium chloride, and the balance being water; the breaking temperature was 90℃, and the breaking time was 12 h. The relevant results are shown in Table 3.

[0046] Example 4

[0047] This invention provides a composition suitable for the degradation of unconventional polymer thickening systems, specifically comprising the following raw materials:

[0048] The compound containing the amine oxide functional group is lauramidopropylamine oxide; the compound containing the N-hydroxy-substituted amino functional group is N,N-diethyl-N-hydroxyamine; wherein the molar ratio of the amine oxide functional group to the N-hydroxy-substituted amino functional group is 1:2.5;

[0049] Using the composition of Example 4, ammonium persulfate oxidant, and non-oxidizing breaker (the product of Example 3, patent number CN201811497003.5), the degradation effect of the polymer thickening system under unconventional liquid preparation conditions was compared. According to the technical requirements of the petroleum industry standard SY / T7627-2021, the breaker viscosity was ≤5mPa.s, and the residue content of the polymer system was ≤100mg / L.

[0050] Specifically: 1.0 wt% acid-resistant polymer thickener (provided by Jiangsu Fumiao Technology Co., Ltd.), hydrochloric acid (8 wt%), hydrofluoric acid (8 wt%), and water as the remainder; the breaking temperature was 90℃, and the breaking time was 24h. The relevant results are shown in Table 4.

[0051]

[0052] Example 5

[0053] This invention provides a composition suitable for the degradation of unconventional polymer thickening systems, specifically comprising the following raw materials:

[0054] The compound containing an N-hydroxy-substituted amino functional group is N,N-diethyl-N-hydroxyamine; the compound containing a carboxylic acid functional group is sodium diethyltriaminepentaacetate, wherein the molar ratio of the N-hydroxy-substituted amino functional group to the carboxylic acid functional group is 1:2.

[0055] Drilling fluid was prepared according to GB / T 16783.1-2025 standard, stirred at high speed for 20 min, and allowed to stand for aging for 16 h. An API filtration loss test was conducted at room temperature. After filtration loss for 30 min, the pressure was slowly released, and the filter cake was removed to conduct a drilling fluid mud cake erosion rate test. The erosion effect of the breaker on the mud cake was evaluated by the change in mud cake mass before and after soaking with the breaker. The experimental conditions were 120℃ and the erosion reaction was carried out for 2 h. The results are shown in Table 5, where the erosion rate η = (m1−m2) / (m1−m0)×100%.

[0056]

[0057] Example 6

[0058] This invention provides a composition suitable for the degradation of unconventional polymer thickening systems, specifically comprising the following raw materials:

[0059] The compound containing the amine oxide functional group is tetradecyl dimethylamine oxide; the mixture containing 3-(N-hydroxyamino)-1-propanol and hydroxyamine hydrochloride in a mass ratio of 1:1, and the compound containing the carboxylic acid functional group is ammonium acetate; wherein the molar ratio of the amine oxide functional group, the N-hydroxy substituted amino functional group and the carboxylic acid functional group is 1:2:4;

[0060] Using the composition of Example 6, ammonium persulfate oxidant, and non-oxidizing breaker (the product of Example 1, patent number CN201811497003.5), the degradation effect of the polymer thickening system under unconventional liquid preparation conditions was compared. According to the technical requirements of the petroleum industry standard SY / T7627-2021, the breaker viscosity was ≤5mPa.s, and the residue content of the polymer system was ≤100mg / L.

[0061] Specifically, the dry powder polymer thickener was 0.8 wt%, the triazine content was 1 wt%, and the balance was water; the breaking temperature was 90℃, and the breaking time was 12 h. The relevant results are shown in Table 6.

[0062]

[0063] As shown in Table 1, compounds containing amine oxide functional groups and compounds containing carboxylic acid functional groups have no ability to degrade polymers, and their breaking viscosity is much greater than 5 mPa·s. Compounds containing N-hydroxy-substituted amino functional groups meet the polymer degradation standards. Tables 2-6 show that the oxidant ammonium persulfate and non-oxidizing breakers do not meet the degradation effect on unconventional polymer thickening systems, and the viscosity or residue content of the broken solution is higher than the industry standard technical indicators. The breaking effect of the composition of this invention meets the industry standard requirements, with a breaking solution viscosity below 5 mPa·s and a breaking solution residue below 100 mg / L. Table 5 shows that the composition of this invention achieves a 91.3% removal effect on drilling fluid filter cake, far exceeding the 64.9% removal rate of the oxidant ammonium persulfate. Therefore, the functional group composition mentioned in this invention can achieve complete degradation of unconventional polymer thickening systems.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composition suitable for degradation of unconventional polymer thickening systems, characterized in that, The composition includes at least one of the following 1) to 4): 1) Compounds containing N-hydroxyl-substituted amino functional groups; 2) Compounds containing N-hydroxyl-substituted amino functional groups and compounds containing amine oxide functional groups; 3) Compounds containing N-hydroxyl-substituted amino functional groups and compounds containing carboxyl functional groups; 4) Compounds containing N-hydroxy-substituted amino functional groups, compounds containing amine oxide functional groups, and compounds containing carboxyl functional groups.

2. The composition according to claim 1 suitable for the degradation of unconventional polymer thickening systems, characterized in that, The general structural formula of the N-hydroxy-substituted amino functional group compound is: R1N(R2)-OH, wherein R1 and R2 are any one of hydrogen atom, alkyl, aryl, and acyl groups.

3. The composition according to claim 2 suitable for the degradation of unconventional polymer thickening systems, characterized in that, The N-hydroxy-substituted amino functional group compounds include at least one of N-hydroxy-2-propane, N,N-diethyl-N-hydroxyamine, N-hydroxy-2-methyl-2-propane, 3-(N-hydroxyamino)-1-propanol, and hydroxyamine hydrochloride.

4. The composition according to claim 1 suitable for the degradation of unconventional polymer thickening systems, characterized in that, The general structural formula of the compound containing the carboxyl functional group is: R3COOR4, wherein R3 is any one of amino or alkyl; R4 is sodium, hydrogen, cobalt, or NH4+. 4+ and Fe 2+ Any one of them.

5. The composition according to claim 4 suitable for degradation of unconventional polymer thickening systems, characterized in that, The compounds containing carboxyl functional groups include at least one of: ammonium acetate, sodium diethyltriaminepentaacetate, EDTA4Na, and citric acid.

6. The composition according to claim 1 suitable for degradation of unconventional polymer thickening systems, characterized in that, The general structural formula of the compound containing the amine oxide functional group is: (R5)3N + O - R5 is any one of C8-C18 alkyl or amamidopropyl.

7. The composition according to claim 6 suitable for the degradation of unconventional polymer thickening systems, characterized in that, The compounds containing amine oxide functional groups include at least one of cocoyl dimethylamine oxide, lauramide propylamine oxide, and tetradecyl dimethylamine oxide.

8. The composition according to claim 1 suitable for the degradation of unconventional polymer thickening systems, characterized in that, The molar ratio of the compound containing N-hydroxy-substituted amino functional groups to the compound containing amine oxide functional groups is 1.5~3:1; The molar ratio of the compound containing an N-hydroxy-substituted amino functional group to the compound containing a carboxyl functional group is 1:1 to 3.

9. The composition according to claim 1 suitable for the degradation of unconventional polymer thickening systems, characterized in that, The composition is used for the degradation of unconventional polymer thickening systems in alcohol-based polymers, acid fracturing fluids, weighted fracturing fluids, triazine-containing working fluids, and high-temperature well drilling fluid filter cake removal systems.

10. The composition according to claim 1 suitable for degradation of unconventional polymer thickening systems, characterized in that, The composition can be added separately or prepared on demand. The unconventional polymer thickening system used in the composition has a temperature greater than 60°C.

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