Dilution-resistant jelly composition and dilution-resistant jelly plugging agent, preparation method and application thereof

Abstract

The present invention belongs to the technical field of oilfield chemical profile control and water plugging, and discloses a dilution-resistant jelly composition and a dilution-resistant jelly plugging agent, as well as a preparation method and application thereof. The dilution-resistant jelly composition comprises polyacrylamide, a phenolic resin crosslinker and a dilution-resistant auxiliary agent which are independently preserved, wherein the dilution-resistant auxiliary agent is sodium alginate, and the sodium alginate is a polymer obtained by polymerizing the G segment shown in formula (1) and / or the M segment shown in formula (2): the polymerization degree of the sodium alginate is 80-750; the dilution-resistant auxiliary agent in the dilution-resistant jelly composition of the present invention can form a dense viscoelastic protective film with calcium ions in the formation water, isolate the water body, and prevent the formation water from diluting the gelling liquid, so that the dilution-resistant jelly plugging agent of the present invention has good gelling performance, high strength after gelling, and strong long-term thermal stability; #imgabs0#

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemical profile control and water plugging, and in particular to a dilution-resistant jelly composition and a dilution-resistant jelly plugging agent, and a preparation method and application thereof. Background Art

[0002] With the development of unconventional oil and gas resources in my country, the exploitation technology of high-temperature and high-salt fracture-cave oil and gas reservoirs has become more and more perfect. Fracture-cave carbonate reservoirs (fracture-cave reservoirs) are mainly distributed in the Tarim Basin. Among them, the total proven geological reserves of petroleum in Tahe Oilfield, Lungu Oilfield, Halahatang Oilfield, Fuman Oilfield, Shunbei Oil and Gas Field, etc. have exceeded 20.0×10 8 t, with an annual output of 700×10 4 t, is an important strategic successor resource. Among the current development technologies of high-temperature and high-salt fracture-cavity oil and gas reservoirs, water injection / gas production is relatively mature, while the natural energy development, water injection development, and gas injection development technologies of high-temperature and high-salt fracture-cavity oil and gas reservoirs are the main ones. However, bottom water cone intrusion and water channeling caused by reservoir heterogeneity have become important factors affecting the development of high-temperature and high-salt fracture-cavity oil and gas reservoirs. Unlike traditional porous oil reservoirs, many wells in fracture-cavity oil reservoirs will be shut down due to violent flooding after water injection (accounting for about 50%). Reservoir heterogeneity regulation has become an effective way to assist the development of high-temperature and high-salt fracture-cavity oil and gas reservoirs, and its core is the research and development of regulators. Gel-type regulators have stable gelling effect, controllable gelling performance, and simple preparation, making them widely used regulators. However, a large amount of formation water in high-temperature and high-salt fracture-cavity oil and gas reservoirs will dilute the injected gelling liquid, resulting in the poor gelling effect of traditional gelling due to the reduction of chemical agent concentration, or even failure to gel.

[0003] CN114427378A discloses a method for designing a selective water plugging segment in a fault-solution reservoir, discloses a dilution-resistant gel composition, the dilution-resistant gel composition comprises a polymer SDCA-8, a polymer SDCA-70 and a cross-linking agent, and the front segment plug thixotropic gel composition is resistant to high temperature of 130°C and salt resistance of 20×10 4 mg / L, dynamic thickening time>8h, static fast thickening, density 1.07~1.1mg / L, viscosity 30~50mPa·s, compressive strength>1MPa. After the composition is injected into the formation, it can rely on its own thixotropic characteristics to statically thicken and reduce subsequent plugging agent loss, but the composition cannot completely isolate the formation water, and its own slow flow and dynamic interference of the formation water will have a certain impact on the dilution resistance effect.

[0004] CN109280542A discloses a high temperature resistant gel plugging agent and its preparation method and application. The raw material components of the high temperature resistant gel plugging agent include: 2-5% sulfonated modified polysaccharide, 0.01-0.025% peroxide initiator, 20-25% acrylamide small molecule monomer, 1.2-1.5% aldehyde crosslinking agent A, 1.3-1.7% amine crosslinking agent B, 0.04-0.1% ammonium salt curing agent, 0.03-0.3% alkaline pH regulator, and the balance is water. It has strong thermal stability, good viscoelasticity, high gel strength, and can be used at a temperature of 100-150°C. However, the gel salt tolerance is not evaluated, and it does not have dilution tolerance.

[0005] CN113897189A discloses a gel composition suitable for high-temperature and high-salt fracture-cavity oil reservoir profile control and its application, the composition is composed of non-ionic polyacrylamide, hexamethylenetetramine, hydroquinone and residual water, can gel at about 130°C, tolerates mineralization of 220,000 mg / L, calcium ion concentration of 11273 mg / L, and magnesium ion concentration of 1519 mg / L. However, the invention does not study its ability to withstand dilution with formation water.

[0006] Therefore, there is an urgent need to develop gels that are resistant to dilution by formation water to meet the needs of regulating reservoir heterogeneity in high-temperature and high-salt fracture-cavity oil and gas reservoirs. Summary of the invention

[0007] The purpose of the present invention is to overcome the problem in the prior art that the existing high-temperature and high-salt (≥110°C, mineralization ≥200,000 mg / L, calcium and magnesium ions ≥5000 mg / L) fracture-cavity oil and gas reservoir gel-type regulating agents cannot gel or have poor gel strength after dilution with formation water, and to provide a dilution-resistant gel composition and a dilution-resistant gel plugging agent and a preparation method and application thereof. The dilution-resistant auxiliary agent in the dilution-resistant gel composition of the present invention can form a dense viscoelastic protective film with calcium ions in formation water, can isolate water bodies, and prevent formation water from diluting the gelling liquid. Therefore, the dilution-resistant gel plugging agent of the present invention has good gelling performance, high strength after gelling, and strong long-term thermal stability.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a dilution-resistant jelly composition, wherein the dilution-resistant jelly composition comprises polyacrylamide, a phenolic resin cross-linking agent and a dilution-resistant auxiliary agent which are stored independently, wherein the dilution-resistant auxiliary agent is sodium alginate, and the sodium alginate is a polymer obtained by polymerizing the G segment represented by formula (1) and / or the M segment represented by formula (2):

[0009]

[0010] Wherein, the polymerization degree of the sodium alginate is 80-750.

[0011] The second aspect of the present invention provides a method for preparing a dilution-resistant jelly plugging agent using the aforementioned composition, wherein the preparation method comprises:

[0012] (1) contacting the liquid preparation water with the polyacrylamide under stirring conditions for a first mixing to obtain a polymer solution;

[0013] (2) contacting the polymer solution with a phenolic resin cross-linking agent for a second mixing to obtain a gelling solution;

[0014] (3) The gelling liquid is contacted with a dilution-resistant auxiliary agent for a third mixing and then subjected to a gelling treatment to obtain a dilution-resistant frozen gel plugging agent.

[0015] The third aspect of the present invention provides a dilution-resistant jelly plugging agent prepared by the aforementioned preparation method.

[0016] A fourth aspect of the present invention provides a use of the aforementioned dilution-resistant jelly plugging agent in high-temperature and high-salt fracture-cavern oil and gas reservoirs.

[0017] Through the above technical solution, the present invention has the following beneficial effects:

[0018] (1) The dilution-resistant gel plugging agent of the present invention has good gelling performance, high strength after gelling, and strong long-term thermal stability.

[0019] (2) The components of the dilution-resistant gel composition of the present invention have good compatibility with each other, and the gel solution is simple to prepare. The presence of the dilution-resistant additive will not affect the gel formation. The solution can be prepared with either clean water or highly mineralized oilfield injection water, thereby alleviating the problem of fresh water resource shortage during complex and harsh construction processes in deserts, Gobi, oceans, etc.

[0020] (3) The raw materials of the various components of the dilution-resistant jelly composition of the present invention are widely available and suitable for industrial production and large-scale preparation on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a macroscopic schematic diagram of the isolation of the dilution-resistant jelly-forming liquid prepared in Example 1 of the present invention from formation water;

[0022] Figure 2 This is a macroscopic schematic diagram of the high-temperature isolation formation water gel of the dilution-resistant jelly plugging agent prepared in Example 1 of the present invention;

[0023] Figure 3 This is a macroscopic schematic diagram of the gel formed by the dilution-resistant gel plugging agent prepared in Example 1 of the present invention;

[0024] Figure 4 This is a SEM photograph of the microscopic network structure of the dilution-resistant jelly plugging agent after gelling prepared in Example 3 of the present invention;

[0025] Figure 5 This is a macroscopic schematic diagram of the common jelly prepared in comparative example 1 after being diluted by formation water;

[0026] Figure 6 This is a SEM photo of the microscopic network structure of the common jelly prepared in Comparative Example 2;

[0027] Figure 7 It is a curve chart comparing the elastic modulus and viscoelastic modulus of the dilution-resistant gel diluted with formation water (Example 4), the undiluted ordinary gel (Comparative Example 1) and the ordinary gel diluted with formation water. DETAILED DESCRIPTION

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] As mentioned above, the first aspect of the present invention provides a dilution-resistant jelly composition, wherein the dilution-resistant jelly composition comprises polyacrylamide, a phenolic resin cross-linking agent and a dilution-resistant auxiliary agent which are stored independently, wherein the dilution-resistant auxiliary agent is sodium alginate, and the sodium alginate is a polymer obtained by polymerizing the G segment represented by formula (1) and / or the M segment represented by formula (2):

[0030]

[0031] Wherein, the polymerization degree of the sodium alginate is 80-750.

[0032] According to the present invention, the polymerization degree of the sodium alginate is 100-750.

[0033] According to the present invention, M is sodium β-D-mannuronic acid (β-D-mannuronic acid), and G is sodium α-L-guluronic acid (α-L-guluronic acid).

[0034] According to the present invention, in the sodium alginate, the connection mode between G and M can be one or more of GG shown in formula (a), MM shown in formula (b) and GM shown in formula (c).

[0035]

[0036]

[0037] According to the present invention, the molar ratio of the content of M to G is 0.6-2.22; preferably, the molar ratio of the content of M to G is 1.88-2.1.

[0038] The inventors of the present invention have found that the dilution-resistant additive of the present invention can form a dense viscoelastic protective film with calcium ions in formation water, which can isolate the water body and prevent the formation water from diluting the gelling liquid, thereby preventing the gelling liquid from being unable to gel or having poor gelling performance.

[0039] Specifically, for example, by using one of the connection modes of G and M, the dilution-resistant adjuvant of the present invention can react with calcium ions in the formation water by cross-linking, as shown below:

[0040]

[0041] When the gelling liquid comes into contact with formation water, the dilution-resistant additive and calcium ions on the contact surface quickly undergo a cross-linking reaction, and a water-proof layer is quickly formed on the contact surface to prevent the formation water from being diluted into the gelling liquid.

[0042] Furthermore, the phenolic resin cross-linking agent used in the present invention can form a primary network structure, and the dilution-resistant auxiliary agent participates in forming a secondary network structure, which can increase the network density of the gel and make the gel strength stronger.

[0043] According to the present invention, the polyacrylamide is an AM / AMPS copolymer, wherein AM (water-soluble acrylamide (AM) and AMPS (sodium 2-acrylamido-2-methylpropane sulfonate); and based on the total weight of the AM / AMPS copolymer, the content of AM is 60-70% by weight and the content of AMPS is 30-40% by weight.

[0044] According to the present invention, the relative molecular weight of the AM / AMPS copolymer is 5 million to 10 million.

[0045] According to the present invention, the hydrolysis degree of the AM / AMPS copolymer is 3-10%.

[0046] According to the present invention, the phenolic resin crosslinking agent is selected from one or more of phenolic phenolic resin, hydroquinone phenolic resin, catechol phenolic resin and resorcinol phenolic resin.

[0047] According to the present invention, based on the total weight of the dilution-resistant jelly composition, the content of the polyacrylamide is 0.5-1% by weight; the content of the phenolic resin cross-linking agent is 0.3-1.5% by weight, the content of the dilution-resistant auxiliary agent is 0.2-0.8% by weight, and the balance is liquid preparation water; preferably, based on the total weight of the dilution-resistant jelly composition, the content of the polyacrylamide is 0.5-1% by weight; the content of the phenolic resin cross-linking agent is 0.3-1.2% by weight, the content of the dilution-resistant auxiliary agent is 0.2-0.8% by weight, and the balance is liquid preparation water; more preferably, based on the total weight of the dilution-resistant jelly composition, the content of the polyacrylamide is 0.6-0.8% by weight; the content of the phenolic resin cross-linking agent is 0.6-0.8% by weight, the content of the dilution-resistant auxiliary agent is 0.4-0.6% by weight, and the balance is liquid preparation water.

[0048] The second aspect of the present invention provides a method for preparing a dilution-resistant jelly plugging agent using the aforementioned composition, wherein the preparation method comprises:

[0049] (1) contacting the liquid preparation water with the polyacrylamide under stirring conditions for a first mixing to obtain a polymer solution;

[0050] (2) contacting the polymer solution with a phenolic resin cross-linking agent for a second mixing to obtain a gelling solution;

[0051] (3) The gelling liquid is contacted with a dilution-resistant auxiliary agent for a third mixing and then subjected to a gelling treatment to obtain a dilution-resistant frozen gel plugging agent.

[0052] According to the present invention, in the present invention, the preparation water can be clean water and / or decalcified high-mineralization oilfield injection water, which alleviates the problem of shortage of fresh water resources during complex and harsh construction processes in deserts, Gobi, oceans, etc.; preferably, it can be preparation water with a mineralization of 200,000 mg / L.

[0053] According to the present invention, the stirring conditions include: stirring at a stirring rate of 400-600 rpm.

[0054] According to the present invention, the first mixing conditions include: temperature of 20±5° C., time of 60-90 min, preferably 60-70 min.

[0055] According to the present invention, the second mixing conditions include: temperature of 20±5° C., time of 10-20 min, preferably 10-15 min.

[0056] According to the present invention, the conditions for the third mixing include: a temperature of 20±5° C., and a time of 10-30 min, preferably 10-20 min.

[0057] According to the present invention, in step (3), the gelling treatment conditions include: gelling in a pressure bottle at a temperature of 110-150° C. for 2-48 hours; preferably, gelling at a temperature of 130-150° C. for 2-12 hours.

[0058] The third aspect of the present invention provides a dilution-resistant jelly plugging agent prepared by the aforementioned preparation method.

[0059] A fourth aspect of the present invention provides a use of the aforementioned dilution-resistant jelly plugging agent in high-temperature and high-salt fracture-cavern oil and gas reservoirs.

[0060] According to the present invention, the conditions of the high-temperature and high-salt fracture-cave oil and gas reservoir include: temperature of 110-150°C, mineralization of 200,000 mg / L-300,000 mg / L, and calcium and magnesium ion content of 5,000 mg / L-15,000 mg / L.

[0061] According to a particularly preferred embodiment of the present invention, a method for preparing a dilution-resistant jelly plugging agent comprises:

[0062] At room temperature (20±5°C), first add 0.6-0.8% of AM / AMPS copolymer in total components to the prepared liquid water, stir for 60-90 minutes at a stirring rate of 500-600 rpm to obtain a polymer solution; add 0.6-0.8% by weight of phenolic resin crosslinking agent while stirring, stir for 10-20 minutes to dissolve it, and form a high-temperature resistant gel solution; finally, add 0.4-0.6% by weight of dilution-resistant auxiliary agent while stirring, stir for 20-30 minutes to obtain a gel solution resistant to formation water dilution, and then gel at 130-150°C to obtain a frozen gel plugging agent resistant to formation water dilution for high-temperature and high-salt fracture-cavity oil and gas reservoirs.

[0063] The present invention will be described in detail below through examples.

[0064] In the following examples and comparative examples:

[0065] The gel strength parameters were measured by the GSC strength code method;

[0066] The strength retention parameter was measured by the rheometer elasticity test method;

[0067] The core plugging rate parameter is measured by high temperature and high salt core flooding experimental method;

[0068] SEM was purchased from Hitachi, model: Hitachi S-4800;

[0069] The rheometer was purchased from Haake, model Haake Rheostree RS75;

[0070] AM / AMPS copolymer raw materials were commercially available from Noel Biotechnology Co., Ltd.;

[0071] The raw materials of phenol-type, hydroquinone-type, catechol-type, and resorcinol-type phenolic resin crosslinking agents are commercially available products of Lifeng Chemical New Materials Co., Ltd.;

[0072] The dilution aid sodium alginate was purchased from Qingdao Mingyue Seaweed Co., Ltd.

[0073] Example 1

[0074] The dilution-resistant gel composition comprises: an AM / AMPS copolymer with a relative molecular mass of 10 million and a hydrolysis degree of 10%, with a mass fraction of 0.8%; a hydroquinone-type phenolic resin crosslinking agent, with a mass fraction of 0.6%; a dilution-resistant auxiliary agent sodium alginate, with a mass fraction of 0.6%; the balance is liquid preparation water, with a mass fraction of 98.0%, and the sum of the mass fractions of each component is 100%.

[0075] Among them, in the dilution aid sodium alginate, the connection mode between G and M can be one or more of GG shown in formula (a), MM shown in formula (b) and GM shown in formula (b), and the molar ratio M / G of the content of M to G is 1.88, and the degree of polymerization (n) of the sodium alginate is 600-750.

[0076] At room temperature (20±5°C), 0.8g AM / AMPS copolymer was added to clean water at a stirring rate of 600 rpm, and stirred for 60 minutes to obtain a polymer solution; 0.6g hydroquinone phenolic resin crosslinking agent was added while stirring, and stirred for 10 minutes to obtain a gelling solution; and 0.6g sodium alginate, a dilution-resistant auxiliary agent, was slowly added while stirring, and stirred for 30 minutes until it was fully dissolved to obtain a gelling solution resistant to dilution by formation water, which was then mixed with simulated formation water with a mineralization of 200,000mg / L (including sodium ions 73282mg / L, calcium ions 6000mg / L, magnesium ions 1000mg / L) in a volume ratio of 1:1 were placed in a pressure-resistant bottle. Once the gelling liquid containing the dilution-resistant additive came into contact with calcium ions, a viscoelastic protective film would be formed. Moreover, the gelling liquid was gelled in an oven at 130°C for 8 hours to obtain the frozen gel plugging agent A1 for high-temperature and high-salt fracture-cavity oil and gas reservoirs resistant to formation water dilution. The system was always clearly stratified and insoluble with the simulated formation water before and after gelling. The stable period after gelling could reach 90 days, the strength retention rate was 95%, and the core plugging rate was 97%.

[0077] Figure 1 Schematic diagram of the macroscopic view of the dilution-resistant jelly plugging agent prepared in Example 1 of the present invention before and after gelation. Figure 1 It can be seen that the gelling liquid is obviously separated from the formation water, and a water-isolating membrane is formed in the middle to prevent the formation water from diluting the gelling liquid. That is, the formation water cannot dilute the gelling liquid under the action of the dilution-resistant additive. Figure 2is a macroscopic schematic diagram of the dilution-resistant jelly plugging agent prepared in Example 1 of the present invention after high-temperature aging. Figure 2 It can be seen that after high-temperature aging, the water-isolating film protects the gelling liquid to stabilize the gelling, that is, the high-temperature aging effect will not destroy the water-isolating effect of the dilution-resistant additive; Figure 3 This is a macroscopic schematic diagram of the gelling of the dilution-resistant jelly plugging agent prepared in Example 1 of the present invention. Figure 3 It can be seen that the dilution-resistant additive protects the gel inside the film, indicating that the dilution-resistant additive can obviously separate the formation water from the gelling liquid. Without the dilution effect of the formation water, the gel can be effectively gelled.

[0078] Example 2

[0079] The dilution-resistant gel composition comprises: an AM / AMPS copolymer with a relative molecular mass of 15 million and a hydrolysis degree of 12%, with a mass fraction of 0.6%; a hydroquinone-type phenolic resin crosslinking agent, with a mass fraction of 0.8%; a dilution-resistant auxiliary agent sodium alginate, with a mass fraction of 0.5%; the balance is liquid preparation water, with a mass fraction of 98.1%, and the sum of the mass fractions of each component is 100%.

[0080] Among them, in the dilution aid sodium alginate, the connection mode between G and M can be one or more of GG shown in formula (a), MM shown in formula (b) and GM shown in formula (b), and the molar ratio M / G of the content of M to G is 1.88, and the degree of polymerization (n) of the sodium alginate is 600-750.

[0081] At room temperature (20±5°C), 0.6g AM / AMPS copolymer was added to clean water at a stirring rate of 600 rpm, and stirred for 60 minutes to obtain a polymer solution; 0.8g hydroquinone phenolic resin crosslinking agent was added while stirring, and stirred for 10 minutes to obtain a gelling solution; and 0.5g sodium alginate, a dilution-resistant auxiliary agent, was slowly added while stirring, and stirred for 30 minutes until it was fully dissolved to obtain a gelling solution resistant to dilution by formation water, which was then mixed with simulated formation water with a mineralization of 200,000mg / L (wherein sodium ions 73282mg / L, calcium ions 6000mg / L, magnesium ions 1000mg / L) in a volume ratio of 1:4 were placed in a pressure-resistant bottle. Once the gelling liquid containing the dilution-resistant additive came into contact with calcium ions, a viscoelastic protective film would be formed. Moreover, the gelling liquid was gelled in an oven at 130°C for 6 hours to obtain a frozen gel plugging agent A2 for high-temperature and high-salt fracture-cavity oil and gas reservoirs resistant to formation water dilution. The system was always clearly stratified and insoluble with simulated formation water before and after gelling. The stable period after gelling could reach 90 days, with a strength retention rate of 93% and a core plugging rate of 92%.

[0082] Example 3

[0083] The dilution-resistant gel composition comprises: an AM / AMPS copolymer with a relative molecular mass of 8 million and a hydrolysis degree of 8%, with a mass fraction of 0.8%; a catechol-type phenolic resin crosslinking agent, with a mass fraction of 0.8%; a dilution-resistant auxiliary agent sodium alginate, with a mass fraction of 0.5%; the balance is liquid preparation water, with a mass fraction of 97.9%, and the sum of the mass fractions of each component is 100%.

[0084] Among them, in the dilution aid sodium alginate, the connection mode between G and M can be one or more of GG shown in formula (a), MM shown in formula (b) and GM shown in formula (b), and the molar ratio of the content of M to G M / G is 2.10, and the degree of polymerization (n) of the sodium alginate is 400-600.

[0085] At room temperature (20±5°C), 0.8g AM / AMPS copolymer was added to clean water at a stirring rate of 600 rpm, and stirred for 60 minutes to obtain a polymer solution; 0.8g catechol-type phenolic resin crosslinking agent was added while stirring, and stirred for 10 minutes to obtain a gelling solution; and 0.5g sodium alginate, a dilution-resistant auxiliary agent, was slowly added while stirring, and stirred for 30 minutes until it was fully dissolved to obtain a gelling solution resistant to dilution by formation water, and then mixed with simulated formation water with a mineralization of 200,000mg / L (wherein sodium ions 73282mg / L, calcium ions 6000mg / L, magnesium ions 1000mg / L) in a volume ratio of 2:3 were placed in a pressure-resistant bottle. Once the gelling liquid containing the dilution-resistant additive came into contact with calcium ions, a viscoelastic protective film would be formed. Moreover, the gelling liquid was gelled in an oven at 150°C for 4 hours to obtain the frozen gel plugging agent A3 for high-temperature and high-salt fracture-cavity oil and gas reservoirs resistant to formation water dilution. The system was always clearly stratified and insoluble with the simulated formation water before and after gelling. The stable period after gelling could reach 90 days, the strength retention rate was 91%, and the core plugging rate was 91%.

[0086] Figure 4 This is a SEM photo of the microscopic network structure of the dilution-resistant jelly plugging agent prepared in Example 3 of the present invention after gelation. Figure 4 It can be seen that the microscopic morphology of the gel containing the dilution-resistant additive has a dense three-dimensional network structure, which indicates that the dilution-resistant additive can significantly increase the density of the three-dimensional network structure, which is more conducive to the stability of the gel.

[0087] Example 4

[0088] The dilution-resistant gel composition comprises: an AM / AMPS copolymer with a relative molecular mass of 8 million and a hydrolysis degree of 8%, with a mass fraction of 0.8%; a hydroquinone phenolic resin and a catechol-type phenolic resin crosslinking agent, with a mass fraction of 0.4% each; a dilution-resistant auxiliary agent sodium alginate, with a mass fraction of 0.4%; the balance is liquid preparation water, with a mass fraction of 98.0%, and the sum of the mass fractions of each component is 100%.

[0089] Among them, in the dilution aid sodium alginate, the connection mode between G and M can be one or more of GG shown in formula (a), MM shown in formula (b) and GM shown in formula (b), and the molar ratio of the content of M to G M / G is 2.10, and the degree of polymerization (n) of the sodium alginate is 400-600.

[0090] At room temperature (20±5°C), 0.8g AM / AMPS copolymer was added to clean water at a stirring rate of 600 rpm, and stirred for 60 minutes to obtain a polymer solution; 0.4g hydroquinone phenolic resin and 0.4g catechol phenolic resin crosslinker were added while stirring, and stirred for 10 minutes to obtain a gelling solution; 0.4g sodium alginate, a dilution-resistant auxiliary agent, was slowly added while stirring, and stirred for 30 minutes until it was fully dissolved to obtain a gelling solution resistant to dilution by formation water, which was then mixed with a simulated sodium alginate with a mineralization degree of 200,000 mg / L. Formation water (including 73282 mg / L sodium ions, 6000 mg / L calcium ions, and 1000 mg / L magnesium ions) in a volume ratio of 3:7 was placed in a pressure-resistant bottle. Once the gelling liquid containing a dilution-resistant additive came into contact with calcium ions, a viscoelastic protective film would be formed. Furthermore, the gelling liquid was placed in an oven at 150°C for 3 hours to obtain a gel plugging agent A4 for high-temperature and high-salt fracture-cavity oil and gas reservoirs that was resistant to formation water dilution. The system was always clearly stratified and insoluble with simulated formation water before and after gelling. The stable period after gelling could reach 90 days, with a strength retention rate of 92% and a core plugging rate of 93%.

[0091] Example 5

[0092] The dilution-resistant gel composition comprises: an AM / AMPS copolymer with a relative molecular mass of 6 million and a hydrolysis degree of 5%, with a mass fraction of 1.2%; a resorcinol-type phenolic resin crosslinking agent, with a mass fraction of 0.6%; a dilution-resistant auxiliary agent sodium alginate, with a mass fraction of 0.4%; the balance is liquid preparation water, with a mass fraction of 97.9%, and the sum of the mass fractions of each component is 100%.

[0093] Among them, in the dilution aid sodium alginate, the connection mode between G and M can be one or more of GG shown in formula (a), MM shown in formula (b) and GM shown in formula (b), and the molar ratio of the content of M to G M / G is 1.95, and the degree of polymerization (n) of the sodium alginate is 100-400.

[0094] At room temperature (20±5°C), 1.2g AM / AMPS copolymer was added to clean water at a stirring rate of 600 rpm, and stirred for 60 minutes to obtain a polymer solution; 0.6g resorcinol phenolic resin crosslinking agent was added while stirring, and stirred for 10 minutes to obtain a gelling solution; 0.4g sodium alginate, a dilution-resistant auxiliary agent, was slowly added while stirring, and stirred for 30 minutes until it was fully dissolved to obtain a gelling solution resistant to dilution by formation water, and then mixed with simulated formation water with a mineralization degree of 200,000mg / L (including sodium ions 73282mg / L, calcium ions 6000mg / L, magnesium ions 1000mg / L) in a volume ratio of 1:4 were placed in a pressure-resistant bottle. Once the gelling liquid containing the dilution-resistant additive came into contact with calcium ions, a viscoelastic protective film would be formed. Moreover, it was gelled in an oven at 120°C for 2 hours to obtain the frozen gel plugging agent A5 for high-temperature and high-salt fracture-cavity oil and gas reservoirs resistant to formation water dilution. The system was always clearly stratified and insoluble with the simulated formation water before and after gelling. The stable period after gelling could reach 90 days, the strength retention rate was 89%, and the core plugging rate was 90%.

[0095] Example 6

[0096] The dilution-resistant gel composition comprises: an AM / AMPS copolymer with a relative molecular mass of 6 million and a hydrolysis degree of 5%, with a mass fraction of 1.2%; a phenol-type phenolic resin crosslinking agent, with a mass fraction of 1.5%; a dilution-resistant auxiliary agent sodium alginate, with a mass fraction of 0.8%; the balance is liquid preparation water, with a mass fraction of 96.5%, and the sum of the mass fractions of each component is 100%.

[0097] Among them, in the dilution aid sodium alginate, the connection mode between G and M can be one or more of GG shown in formula (a), MM shown in formula (b) and GM shown in formula (b), and the molar ratio of the content of M to G M / G is 1.95, and the degree of polymerization (n) of the sodium alginate is 100-400.

[0098] At room temperature (20±5°C), add 1.2g AM / AMPS copolymer to clean water at a stirring rate of 600 rpm, stir for 60 minutes to obtain a polymer solution; add 1.5g phenol-type phenolic resin crosslinking agent while stirring, stir for 10 minutes to obtain a gelling solution; then slowly add 0.8g dilution-resistant auxiliary agent sodium alginate while stirring, stir for 30 minutes until it is fully dissolved, and obtain a gelling solution resistant to dilution by formation water. Once the gelling solution containing the dilution-resistant auxiliary agent comes into contact with calcium ions, a viscoelastic protective film will be formed. And then, it was placed in a pressure-resistant bottle in a volume ratio of 1:1 with simulated formation water with a mineralization of 200,000 mg / L (including 73282 mg / L sodium ions, 6000 mg / L calcium ions, and 1000 mg / L magnesium ions), and gelled in an oven at 110°C for 10 hours to obtain the frozen gel plugging agent A6 for high-temperature and high-salt fracture-cavity oil and gas reservoirs that is resistant to dilution by formation water. The system is always clearly stratified and insoluble with the simulated formation water before and after gelation. The stable period after gelation can reach 90 days, the strength retention rate is 96%, and the core plugging rate is 94%.

[0099] Comparative Example 1

[0100] The dilution-resistant jelly plugging agent was prepared in the same manner as in Example 4, except that no dilution-resistant auxiliary agent was added. The obtained jelly plugging agent B1 gelled for 13 hours, had a stable period of only 6 days, a strength retention rate of 7%, and a core plugging rate of 29%.

[0101] Figure 5 This is a macroscopic diagram of the ordinary gel prepared in Example 1 after being diluted by formation water. Figure 5 It can be seen that: Figure 5 In the first picture, the gelling liquid is obviously unable to be separated from the formation water, and the gelling liquid is completely diluted by the formation water; Figure 5 The second one in the picture, after high temperature aging, cannot form gel due to dilution; Figure 5 The third picture shows that the gelling liquid cannot be gelled after dilution, which means that the gelling liquid is completely diluted by the formation water, resulting in the inability to gel.

[0102] in addition, Figure 7 : is a curve diagram comparing the elastic modulus and viscoelastic modulus of the dilution-resistant gel diluted by formation water (Example 4), the undiluted ordinary gel (Comparative Example 1) and the ordinary gel diluted by formation water, wherein G' is the elastic modulus and G" is the viscous modulus; Figure 7 It can be seen that the addition of the dilution-resistant additive sodium alginate can not only effectively isolate the water body and prevent the water body from diluting the gelling liquid, but also increase the strength of the gel; in addition, the gel containing the dilution-resistant additive has a higher viscoelastic modulus.

[0103] Comparative Example 2

[0104] The dilution-resistant jelly plugging agent was prepared in the same manner as in Example 5, except that no dilution-resistant auxiliary agent was added. The obtained jelly plugging agent B2 gelled for 10 hours, had a stable period of only 4 days, a strength retention rate of 11%, and a core plugging rate of 34%.

[0105] Figure 6 This is a SEM photo of the microscopic network structure of the ordinary jelly prepared in Comparative Example 2. Figure 6 It can be seen that the three-dimensional network structure of the jelly without the dilution-resistant additive is sparse and not stable enough, which means that the jelly without the dilution-resistant additive has a loose three-dimensional network structure, which is not conducive to locking water molecules and has insufficient stability.

[0106] Comparative Example 3

[0107] The dilution-resistant jelly plugging agent was prepared in the same manner as in Example 6, except that no dilution-resistant auxiliary agent was added. The obtained jelly plugging agent B3 gelled for 11 hours, had a stable period of only 14 days, a strength retention rate of 8%, and a core plugging rate of 31%.

[0108] Comparative Example 4

[0109] A dilution-resistant jelly plugging agent was prepared in the same manner as in Example 5, except that the "dilution-resistant auxiliary agent sodium alginate" was replaced with "auxiliary agent sodium silicate" to obtain jelly plugging agent B4. Although the jelly plugging agent B4 could effectively isolate simulated formation water, the obtained gelling liquid could not gel.

[0110] Comparative Example 5

[0111] A dilution-resistant jelly plugging agent was prepared in the same manner as in Example 6, except that the "dilution-resistant auxiliary agent sodium alginate" was replaced with "auxiliary agent sodium carbonate" to obtain jelly plugging agent B5. Although the jelly plugging agent B5 could effectively isolate simulated formation water, the obtained gelling liquid could not gel.

[0112] Comparative Example 6

[0113] The dilution-resistant jelly plugging agent was prepared in the same manner as in Example 4, except that the contents of the components in the dilution-resistant jelly composition were different, specifically:

[0114] The dilution-resistant gel composition comprises: an AM / AMPS copolymer with a relative molecular weight of 8 million and a hydrolysis degree of 8%, with a mass fraction of 0.5%; a hydroquinone phenolic resin and a catechol-type phenolic resin crosslinking agent, with a mass fraction of 0.3% each; a dilution-resistant auxiliary agent sodium alginate, with a mass fraction of 0.2%; the balance is liquid preparation water, with a mass fraction of 99.0%, and the sum of the mass fractions of each component is 100%.

[0115] As a result, a stable waterproof membrane cannot be formed, the waterproof layer is easily destroyed, and the gelling liquid will still be diluted by the formation water, resulting in a very low gelling strength.

[0116] In addition, the properties of the dilution-resistant jelly plugging agents prepared in Examples 1-6 and Comparative Examples 1-6 are shown in Table 1.

[0117] Table 1

[0118]

[0119]

[0120] In summary, the dilution-resistant jelly plugging agent prepared by the present invention, wherein the dilution-resistant additive can quickly cross-link with calcium and magnesium ions in the formation water to form a dense viscoelastic protective film, prevents the jelly plugging agent from being diluted by the formation water and failing to gel or having a poor gelling effect. At the same time, the gelling time of the dilution-resistant jelly plugging agent is controllable, and after gelling, it has high strength and can control water discharge from cracks and holes.

[0121] In Comparative Examples 1-3, since no dilution-resistant additive was added, the gelling liquid was diluted by the formation water under the disturbance of formation water flow. At the same time, the calcium and magnesium ions in the formation water were mutually soluble and reacted with the cross-linking sites, which was not conducive to the stability of the gelling, so the gelling effect was not good.

[0122] In Comparative Examples 4-5, due to the addition of a dilution-resistant additive similar to sodium alginate, the gelling liquid reacts with calcium and magnesium ions to form a dense water-proof layer, so it can effectively isolate the water body. However, due to the influence of silicate / carbonate on the pH of the water body, the gelling liquid cannot gel in this environment, so the effect is not good.

[0123] In Comparative Example 6, since the added sodium alginate dilution resistance additive content is insufficient, the formed water-proof layer is insufficient in strength and is easily damaged, resulting in the gelling liquid being diluted by formation water, so the gelling effect is not good.

[0124] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A dilution-resistant jelly composition, characterized in that: The dilution-resistant jelly composition is composed of the following components which are stored independently: 0.6-1.2 wt % of polyacrylamide, 0.6-1.5 wt % of a phenolic resin crosslinking agent, and 0.4-0.8 wt % of a dilution-resistant auxiliary agent, with the remainder being water; wherein the polyacrylamide is an AM / AMPS copolymer, the dilution-resistant auxiliary agent is sodium alginate, and the sodium alginate is a polymer obtained by polymerizing the G segment represented by formula (1) and / or the M segment represented by formula (2): Formula (1); ; Formula (2); Wherein, the polymerization degree of the sodium alginate is 80-750.

2. The composition according to claim 1, wherein The molar ratio of M to G is 0.6-2.

22.

3. The composition according to claim 2, wherein The molar ratio of M to G is 1.88-2.

1.

4. The composition according to claim 1, wherein Based on the total weight of the AM / AMPS copolymer, the content of AM is 60-70% by weight, and the content of AMPS is 30-40% by weight; and / or, the relative molecular weight of the AM / AMPS copolymer is 5 million to 10 million; And / or, the degree of hydrolysis of the AM / AMPS copolymer is 3-10%.

5. The composition according to claim 1, wherein The phenolic resin crosslinking agent is selected from one or more of phenol-type phenolic resin, hydroquinone-type phenolic resin, catechol-type phenolic resin and resorcinol-type phenolic resin.

6. A method for preparing a dilution-resistant jelly plugging agent using the composition according to any one of claims 1 to 5, characterized in that: The preparation method comprises: (1) contacting clean water with polyacrylamide under stirring conditions for a first mixing to obtain a polymer solution; (2) contacting the polymer solution with a phenolic resin cross-linking agent for a second mixing to obtain a gelling solution; (3) The gelling liquid is contacted with a dilution-resistant auxiliary agent for a third mixing and then subjected to a gelling treatment to obtain a dilution-resistant frozen gel plugging agent.

7. The preparation method according to claim 6, wherein: The stirring conditions include: stirring at a stirring rate of 400-600 rpm; And / or, the first mixing conditions include: temperature of 20±5°C, time of 60-90min; And / or, the second mixing conditions include: temperature of 20±5°C, time of 10-20min; And / or, the third mixing conditions include: temperature of 20±5° C. and time of 10-30 min.

8. The preparation method according to claim 6, wherein: In step (3), the gelling treatment conditions include: gelling in a pressure-resistant bottle at a temperature of 110-150° C. for 2-48 hours.

9. The preparation method according to claim 8, wherein: In step (3), the gelling treatment conditions include: gelling in a pressure-resistant bottle at a temperature of 130-150° C. for 2-12 hours.

10. A dilution-resistant jelly plugging agent prepared by the preparation method according to any one of claims 6 to 9.

11. Use of the dilution-resistant jelly plugging agent according to claim 10 in high-temperature and high-salt fracture-cavity oil and gas reservoirs.

12. The use according to claim 11, wherein: The conditions of the high-temperature and high-salt fracture-cave oil and gas reservoir include: a temperature of 110-150°C, a mineralization of 200,000 mg / L-300,000 mg / L, and a calcium and magnesium ion content of 5,000 mg / L-15,000 mg / L.

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