A polymer gel anti-channeling agent for heavy oil steam huff and puff and its preparation method

Abstract

The present invention provides a polymer gel channeling sealant for heavy oil steam stimulation. The polymer gel channeling sealant system employs nano-zirconium hydroxide particles as a strengthening agent, a phenolic crosslinker or a urotropine / hydroquinone mixed crosslinker as a crosslinker, and a nonionic polyacrylamide as a gelling agent. The polymer gel channeling sealant is stable for over 180 days at a high temperature of 170°C, achieving high sealing strength and a sealing rate exceeding 85%.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum development, and in particular relates to a polymer gel anti-channeling agent for heavy oil steam stimulation and a preparation method thereof. Background Art

[0002] my country is relatively rich in heavy oil resources. Heavy oil reservoirs are characterized by high oil density and viscosity. Development methods primarily rely on thermal recovery, including steam stimulation, steam flooding, and reservoir combustion. Steam stimulation is the most common development method. However, with the increasing number of stimulation cycles and the increasing density of well patterns, steam channeling is becoming increasingly serious. This can lead to a series of problems, including increased heat loss, sand production in oil wells, and pipeline damage, severely impacting production. Therefore, the development of high-temperature steam channeling-resistant agents, specifically designed for the high-temperature production conditions of heavy oil reservoirs, is crucial.

[0003] Currently, high-temperature channeling plugging agents used in oil development primarily include solid particle plugging agents, foam plugging agents, resin plugging agents, and polymer gel plugging agents. Solid particle plugging agents are generally large in size, making injection difficult and lacking selective plugging capabilities. Foam plugging agents require supporting facilities, have weak structural strength, and exhibit low plugging strength. Resin plugging agents are expensive and difficult to control their curing time at high temperatures, making them inadequate for channeling plugging. In contrast, polymer gel plugging agents offer advantages such as good injectability, controllable gelling time, and high plugging strength, making them promising for application in heavy oil reservoirs. Common polymer gel plugging agents, based on polyacrylamide, experience reduced strength and poor plugging performance at temperatures above 150°C, with a plugging life of typically less than three months. To improve the gel's suitability under high-temperature conditions, gel systems enhanced with nanoparticle additives have emerged.

[0004] Patent CN107011879A discloses a high-temperature-resistant, high-strength composite cross-linked gel. Its components, by weight, are: 0.5-0.9% polymer; 0.05-0.2% cross-linker; 0.25-1% retarder; 0.25-0.5% pH adjuster; and 0.2-1% hectorite. This system, with hectorite as an additive, is stable for over 15 days at 120-150°C. However, this system's stability is relatively short, making it difficult to meet channeling sealing requirements. Furthermore, hectorite particles are lamellar, with only one dimension at the nanoscale. Therefore, injectability in low-permeability reservoirs is difficult to guarantee.

[0005] Patent CN106590559B discloses a nanocomposite gel. The composition ratios are as follows: 0.4-0.5 parts of a main agent, 0.1-0.3 parts of an organic chromium crosslinker, 0.1-0.5 parts of an inorganic chromium crosslinker, 1-1.5 parts of a strengthening agent (silica sol), 0.2-0.4 parts of a stabilizer (thiourea), 0.1-0.5 parts of a dehydration inhibitor (organic phosphonate), and the balance water. The amounts are expressed in parts by weight, with the total weight of the components being 100. This system gels within 12-60 hours at temperatures between 50°C and 180°C, exhibits high strength and viscoelasticity, and exhibits no dehydration after aging at 180°C for three months. However, the system is complex, with additives such as thiourea and organic phosphonates in addition to the nanoparticle strengthening agent, resulting in high system costs.

[0006] In summary, it is an urgent problem to develop a polymer gel plugging agent for heavy oil steam stimulation with a simple formula system, enhanced stability and plugging performance under high temperature conditions. Summary of the Invention

[0007] To address the shortcomings of existing technologies, particularly the poor stability and sealing performance of existing polymer jelly channeling sealants under high-temperature conditions, the complex channeling sealant system, and the high cost, the present invention provides a polymer jelly channeling sealant for heavy oil steam stimulation. The polymer jelly channeling sealant system employs nano-zirconium hydroxide particles as a reinforcing agent, a phenolic crosslinker or a urotropine / hydroquinone mixed crosslinker as a crosslinker, and a nonionic polyacrylamide as a gelling agent. The polymer jelly channeling sealant is stable for over 180 days at temperatures of 170°C, achieving high sealing strength and a sealing rate exceeding 85%.

[0008] The technical solutions of the present invention are as follows:

[0009] The invention provides a polymer gel anti-channeling agent for heavy oil steam stimulation. The polymer gel anti-channeling agent comprises a gelling agent, a cross-linking agent, a strengthening agent and water, wherein the strengthening agent is a zirconium hydroxide nanoparticle sol.

[0010] According to the present invention, preferably, based on the total weight of the polymer jelly anti-channeling agent, the polymer jelly anti-channeling agent comprises: 0.5-1.2 wt% of a gelling agent, 0.1-1.0 wt% of a cross-linking agent, 1.0-3.0 wt% of a strengthening agent and the balance water.

[0011] According to the present invention, preferably, based on the total weight of the polymer jelly anti-channeling agent, the polymer jelly anti-channeling agent comprises: 0.6-1.0 wt% of a gelling agent, 0.2-0.8 wt% of a cross-linking agent, 1.2-2.0 wt% of a strengthening agent and the balance water.

[0012] According to the present invention, preferably, the particle size of the zirconium hydroxide nanoparticle sol is 20 to 40 nm.

[0013] According to the present invention, preferably, the solid content of the zirconium hydroxide nanoparticle sol is 25-35 wt%, preferably 30 wt%.

[0014] According to the present invention, preferably, the nano zirconium hydroxide particle sol is purchased from Dongying Liuhe Industry and Trade Co., Ltd., model G-24, with a particle size of 20-40 nm and a solid content of 25-35 wt%, most preferably 30 wt%.

[0015] According to the present invention, preferably, the gelling agent is nonionic polyacrylamide.

[0016] According to the present invention, preferably, the cross-linking agent is selected from hexamethylenetetramine / hydroquinone, or water-soluble phenolic resin.

[0017] According to the present invention, further preferably, the cross-linking agent is hexamethylenetetramine / hydroquinone, wherein the mass ratio of hexamethylenetetramine to hydroquinone is 1:1.

[0018] According to the present invention, preferably, based on the total weight of the polymer jelly sealing agent, the polymer jelly sealing agent comprises: 0.6-1.0 wt% of nonionic polyacrylamide, 0.2-0.8 wt% of water-soluble phenolic resin or hexamethylenetetramine / hydroquinone mixed crosslinking agent, 1.2-2.0 wt% of nano zirconium hydroxide particles and the balance water.

[0019] According to the present invention, preferably, the molecular weight of the nonionic polyacrylamide is 8×10 6 ~10×10 6 The molecular weight of the nonionic polyacrylamide includes but is not limited to the above range, and limiting it within the above range is beneficial to improving the strength of the gel formed by the gelling agent and the cross-linking agent while ensuring the injection of the gelling solution, thereby further improving its sealing strength and high temperature resistance.

[0020] According to the present invention, preferably, the gelling time of the polymer gel sealing agent is 8 to 25 hours.

[0021] According to the present invention, preferably, the dehydration rate of the polymer jelly sealant at 170° C. over 180 days is less than 15%.

[0022] According to the present invention, preferably, the blocking rate of the polymer jelly channel sealing agent is greater than 85%, specifically 86.3-97.1%.

[0023] According to the present invention, preferably, the elastic modulus of the polymer jelly sealant reaches 46-80 Pa when aged in an oven at 170° C. for 30 days.

[0024] The composition of the polymer jelly channel sealing agent of the present invention includes but is not limited to the above composition, and limiting it to the above range is beneficial to further improve the blocking performance and high temperature resistance of the polymer jelly channel sealing agent.

[0025] The present invention also provides a method for preparing the polymer gel anti-channeling agent for heavy oil steam stimulation, comprising the following steps:

[0026] Under normal temperature conditions, the cross-linking agent and water are mixed and fully dissolved, the gelling agent is added and stirred to completely dissolve, and finally the strengthening agent is added and stirred evenly to obtain the polymer gel sealing agent.

[0027] The polymer gel channeling blocking agent for heavy oil steam huff and puff of the present invention is used for blocking gas channeling during the steam huff and puff process in the field of petroleum extraction.

[0028] The polymer gel sealant for heavy oil steam huff-and-puff provided by the present invention is preferably a phenolic crosslinker or a urotropine / hydroquinone mixed crosslinker, the gelling agent is preferably nonionic polyacrylamide, and the strengthening agent is nano zirconium hydroxide particles. Nano zirconium hydroxide can play different roles at different stages of gel aging. In the early stages of gel aging, the degree of hydrolysis of the amide groups in the polyacrylamide molecules is low, and the carboxyl content in the molecules is low. The polyacrylamide molecules first undergo a cross-linking reaction with the phenolic crosslinker to form a gel network structure, while the nano zirconium hydroxide mainly binds to the polyacrylamide molecules through hydrogen bonds, thereby improving the viscoelasticity and water holding capacity of the gel and enhancing the gel strength and stability. As the gel aging time increases, the amide groups in the molecules begin to hydrolyze and the carboxyl content in the molecules increases. The nano zirconium hydroxide then undergoes a secondary cross-linking reaction with the gel mainly through coordination and complexation, thereby further enhancing the gel strength and gel stability.

[0029] The technical solution of the present invention has the following beneficial effects:

[0030] 1. The nano zirconium hydroxide particles of the present invention not only play the role of ordinary particles in improving the strength of the jelly, but also play the role of a cross-linking agent to a certain extent. After multiple cross-linking, the final jelly has extremely strong thermal stability.

[0031] 2. The polymer gel sealant of the present invention has simple ingredients and adopts a synergistic composition of non-ionic polyacrylamide, phenolic crosslinking agent or hexamethylenetetramine / hydroquinone mixed crosslinking agent, and nano zirconium hydroxide particles to obtain high temperature stability and good sealing performance and mechanical strength.

[0032] 3. The polymer gel sealant of the present invention has good thermal stability and is stable under the action of high-temperature steam. It can be stable for more than 180 days at 170°C, and the dehydration rate within 180 days is less than 15%.

[0033] 4. The polymer gel sealing agent of the present invention has a gelling time of 8 to 25 hours, which is flexible and controllable.

[0034] 5. The polymer gel anti-channeling agent of the present invention has excellent gas channeling blocking performance, with a blocking rate exceeding 85%, and under optimal conditions, a blocking rate exceeding 97%. Its high blocking strength can effectively solve the gas channeling problem during heavy oil steam huff-and-puff processes.

[0035] 6. The polymer gel sealing agent of the present invention also has the advantages of low cost and simple preparation process. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the examples.

[0037] Example

[0038] Example 1

[0039] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 0.5% non-ionic polyacrylamide, 0.1% hexamethylenetetramine and 0.1% hydroquinone, 1.0% nano zirconium hydroxide sol and 98.3% water, based on the total mass of the polymer gel anti-channeling agent.

[0040] The preparation method is as follows:

[0041] Add 0.1g of methenamine, 0.1g of hydroquinone, and 98.3g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 0.5g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. Once the polymer is completely dissolved, add 1.0g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the gel-forming solution of the present invention.

[0042] The properties of the polymer jelly sealant of Example 1 are as follows:

[0043] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0044] The polymer gel sealant has a gelling time of 25 hours at 170°C, an elastic modulus of 46 Pa after aging in an oven at 170°C for 30 days, and a dehydration rate of 15% after aging for 180 days.

[0045] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealing ability of the sealant against steam was studied through physical simulation experiments. The permeability of the sand-filled tube used in this experiment was 2275 md and the porosity was 38.2%. The experimental steps were as follows: (1) 170°C water vapor was injected into the sand-filled tube at a flow rate of 1 mL / min in the positive direction, and its equilibrium pressure was measured. The permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the gel solution of this embodiment was injected in the positive direction at a flow rate of 1 mL / min. The valves at both ends of the sand-filled tube were closed and the sand-filled tube was placed in a 170°C oven for aging for 25 hours; (3) 170°C water vapor was injected into the sand-filled tube at a flow rate of 1 mL / min in the positive direction, and its equilibrium pressure was measured. The permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated as 86.3% according to the formula E = (k1-k2) / k1×100%.

[0046] Example 2

[0047] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 0.6% non-ionic polyacrylamide, 0.4% water-soluble phenolic resin, 1.0% nano zirconium hydroxide sol and 98.0% water, based on the total mass of the polymer gel anti-channeling agent.

[0048] The preparation method is as follows:

[0049] Add 0.4g of water-soluble phenolic resin and 98.0g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 0.6g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 1.0g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the jelly-forming solution of the present invention.

[0050] The performance test of the polymer jelly sealing agent of Example 2 is as follows:

[0051] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0052] The polymer gel sealant has a gelling time of 20 hours at 170°C, an elastic modulus of 50 Pa after aging in an oven at 170°C for 30 days, and a dehydration rate of 8% after aging for 180 days.

[0053] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 2112 md and the porosity was 37.8%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min in the positive direction, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe in the positive direction at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 20 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min in the positive direction, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 88.1% according to the formula E = (k1-k2) / k1×100%.

[0054] Example 3

[0055] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 0.8% non-ionic polyacrylamide, 0.2% hexamethylenetetramine and 0.2% hydroquinone, 1.2% nano zirconium hydroxide sol and 97.6% water, based on the total mass of the polymer gel anti-channeling agent.

[0056] The preparation method is as follows:

[0057] Add 0.2g of methenamine, 0.2g of hydroquinone, and 97.6g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 0.8g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 1.2g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the jelly-forming solution of the present invention.

[0058] The performance test of the polymer jelly sealing agent of Example 3 is as follows:

[0059] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0060] The polymer gel sealant has a gelling time of 17 hours at 170°C, an elastic modulus of 52 Pa after aging in an oven at 170°C for 30 days, and a dehydration rate of 10% after aging for 180 days.

[0061] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 1584 md and the porosity was 35.9%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 17 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 89.9% according to the formula E = (k1-k2) / k1×100%.

[0062] Example 4

[0063] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 0.8% non-ionic polyacrylamide, 0.4% hexamethylenetetramine and 0.4% hydroquinone, 1.5% nano zirconium hydroxide sol and 96.90% water, based on the total mass of the polymer gel anti-channeling agent.

[0064] The preparation method is as follows:

[0065] Add 0.4g of methenamine, 0.4g of hydroquinone, and 96.90g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 0.8g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 1.5g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the jelly-forming solution of the present invention.

[0066] The performance test of the polymer jelly sealing agent of Example 4 is as follows:

[0067] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0068] The polymer gel sealant has a gelling time of 12 hours at 170°C, an elastic modulus of 62 Pa after aging in an oven at 170°C for 30 days, and a dehydration rate of 8% after aging for 180 days.

[0069] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 2073 md and the porosity was 37.2%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min in the positive direction, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe in the positive direction at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 12 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min in the positive direction, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 91.5% according to the formula E = (k1-k2) / k1×100%.

[0070] Example 5

[0071] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 0.8% non-ionic polyacrylamide, 0.5% hexamethylenetetramine and 0.5% hydroquinone, 2.0% nano zirconium hydroxide sol and 96.2% water, based on the total mass of the polymer gel anti-channeling agent.

[0072] The preparation method is as follows:

[0073] Add 0.5g of methenamine, 0.5g of hydroquinone, and 96.2g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 0.8g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 2.0g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the jelly-forming solution of the present invention.

[0074] The performance test of the polymer jelly sealant of Example 5 is as follows:

[0075] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0076] The polymer gel sealant has a gelling time of 9 hours at 170°C, an elastic modulus of 68 Pa after aging in an oven at 170°C for 30 days, and a dehydration rate of 5% after aging for 180 days.

[0077] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 2126 md and the porosity was 37.5%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 9 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 93.8% according to the formula E = (k1-k2) / k1×100%.

[0078] Example 6

[0079] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 0.8% non-ionic polyacrylamide, 0.5% hexamethylenetetramine and 0.5% hydroquinone, 2.5% nano zirconium hydroxide sol and 95.7% water, based on the total mass of the polymer gel anti-channeling agent.

[0080] The preparation method is as follows:

[0081] Add 0.5g of methenamine, 0.5g of hydroquinone, and 95.7g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 0.8g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 2.5g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the jelly-forming solution of the present invention.

[0082] The performance test of the polymer jelly sealant of Example 6 is as follows:

[0083] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0084] The polymer gel sealant has a gelling time of 8 hours at 170°C, an elastic modulus of 72 Pa after aging in an oven at 170°C for 30 days, and a dehydration rate of 2% after aging for 180 days.

[0085] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 1653 md and the porosity was 36.8%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 8 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 95.3% according to the formula E = (k1-k2) / k1×100%.

[0086] Example 7

[0087] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 1.0% non-ionic polyacrylamide, 0.5% water-soluble phenolic resin, 2.0% nano zirconium hydroxide sol and 96.5% water, based on the total mass of the polymer gel anti-channeling agent.

[0088] The preparation method is as follows:

[0089] Add 0.5g of water-soluble phenolic resin and 96.5g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 1.0g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 2.0g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the gel-forming solution of the present invention.

[0090] The performance test of the polymer jelly sealant of Example 7 is as follows:

[0091] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0092] The polymer gel sealing agent has a gelling time of 18 hours at 170°C, an elastic modulus of 58 Pa after aging in an oven at 170°C for 30 days, and a dehydration rate of 2% after aging for 180 days.

[0093] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 2238 md and the porosity was 38.2%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min in the positive direction, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe in the positive direction at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 18 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min in the positive direction, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 92.1% according to the formula E = (k1-k2) / k1×100%.

[0094] Example 8

[0095] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 1.0% non-ionic polyacrylamide, 0.8% water-soluble phenolic resin, 2.5% nano zirconium hydroxide sol and 95.7% water, based on the total mass of the polymer gel anti-channeling agent.

[0096] The preparation method is as follows:

[0097] Add 0.8g of water-soluble phenolic resin and 95.7g of tap water to a beaker and stir until fully dissolved. Slowly pour 1.0g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. Once the polymer is completely dissolved, add 2.5g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the gel-forming solution of the present invention.

[0098] The performance test of the polymer jelly sealant of Example 8 is as follows:

[0099] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0100] The polymer gel sealant has a gelling time of 15 hours at 170°C, an elastic modulus of 78 Pa after aging in an oven at 170°C for 30 days, and no dehydration phenomenon after aging for 180 days.

[0101] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 2118 md and the porosity was 37.3%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 15 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 94.8% according to the formula E = (k1-k2) / k1×100%.

[0102] Example 9

[0103] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 1.0% non-ionic polyacrylamide, 1.0% water-soluble phenolic resin, 3.0% nano zirconium hydroxide sol and 95.0% water, based on the total mass of the polymer gel anti-channeling agent.

[0104] The preparation method is as follows:

[0105] Add 1.0 g of water-soluble phenolic resin and 95.0 g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 1.0 g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 3.0 g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the gel-forming solution of the present invention.

[0106] The performance test of the polymer jelly sealant of Example 9 is as follows:

[0107] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0108] The polymer gel sealant has a gelling time of 10 hours at 170°C, an elastic modulus of 80 Pa after aging in an oven at 170°C for 30 days, and no dehydration phenomenon after aging for 180 days.

[0109] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 2039 md and the porosity was 36.8%. The experimental steps were as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 10 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 97.1% according to the formula E = (k1-k2) / k1×100%.

[0110] Example 10

[0111] A polymer gel anti-channeling agent for heavy oil steam stimulation comprises: 1.2% non-ionic polyacrylamide, 0.8% water-soluble phenolic resin, 2.0% nano zirconium hydroxide sol and 96.0% water, based on the total mass of the polymer gel anti-channeling agent.

[0112] The preparation method is as follows:

[0113] Add 0.8g of water-soluble phenolic resin and 96.0g of tap water to a beaker and stir until fully dissolved. Then, slowly pour 1.2g of nonionic polyacrylamide into the beaker and stir for 4-6 hours. After the polymer is completely dissolved, add 2.0g of nano-zirconium hydroxide sol to the beaker and stir evenly to obtain the jelly gel solution of the present invention.

[0114] The performance test of the polymer jelly sealant of Example 10 is as follows:

[0115] (a) The gel-forming solution is injected into an ampoule and sealed with an alcohol burner. The sealed ampoule is then placed in an aging tank, which is then placed in an oven at 170°C for aging. The ampoule is then removed from the oven at regular intervals and the gel state is observed. The gel strength is measured according to the Sydansk code method, with the gel time defined as the time when the gel strength reaches Grade F. The dehydration rate is defined as the ratio of the mass of water removed during aging to the mass of the initial gel-forming solution in the ampoule.

[0116] The gelling time of the polymer gel sealant at 170°C is 13h, the elastic modulus is 71Pa after aging in an oven at 170°C for 30 days, and there is no dehydration phenomenon after aging for 180 days.

[0117] (b) The above-mentioned polymer gel sealant was used as the research object, and the sealant's ability to block steam was studied through physical simulation experiments. The permeability of the sand-filled pipe used in this experiment was 2234 md and the porosity was 37.8%. The experimental steps are as follows: (1) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k1 was calculated according to the Darcy formula; (2) 0.5 PV of the sealant was injected into the sand-filled pipe at a flow rate of 1 mL / min, the valves at both ends of the sand-filled pipe were closed, and the sand-filled pipe was placed in a 170°C oven for aging for 13 hours; (3) 170°C steam was injected into the sand-filled pipe at a flow rate of 1 mL / min, the equilibrium pressure was measured, and the permeability k2 was calculated according to the Darcy formula. Finally, the steam blocking efficiency was calculated to be 96.5% according to the formula E = (k1-k2) / k1×100%.

[0118] Comparative Examples 1 and 2

[0119] The difference from Example 3 is the different composition, see Table 1 for details.

[0120] The proportions of the components in the steam sealing gels in Examples 1 to 10 and Comparative Examples 1 and 2 and their performance parameters are summarized in Table 1, where all components in Table 1 are in parts by weight.

[0121] Table 1

[0122]

[0123]

[0124] As shown in Table 1, the polymer jelly anti-channeling agent of the present invention has a flexible and controllable gelation time of 8 to 25 hours. Its dehydration rate after 180 days at 170°C is less than 15%, demonstrating excellent thermal stability. Furthermore, the anti-channeling agent exhibits excellent steam channeling blocking capability, with a blocking efficiency of 86.3 to 97.1%. Furthermore, the steam channeling blocking jelly of the present invention exhibits excellent strength stability, with a 30-day elastic modulus greater than 40 Pa, and preferably reaching 80 Pa.

[0125] By comparing the experimental results of Examples 1-10 and Comparative Examples 1-2, it can be seen that the thermal stability of the steam sealing jelly of the present invention is far superior to that of the jelly system using nano-silica sol as an additive.

[0126] In addition, the polymer jelly anti-channeling agent of the present invention also has the advantages of low cost and simple preparation process. In summary, the polymer jelly anti-channeling agent of the present invention has good thermal stability, and also has the advantages of low cost and simple preparation process.

[0127] The above description is merely a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent variation based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A polymer gel anti-channeling agent for heavy oil steam huff and puff, characterized in that: The polymer gel sealing agent comprises: a gelling agent, a cross-linking agent, a strengthening agent and water, wherein the gelling agent is nonionic polyacrylamide, the cross-linking agent is selected from hexamethylenetetramine / hydroquinone, or water-soluble phenolic resin, and the strengthening agent is zirconium hydroxide nanoparticle sol.

2. The polymer jelly sealing agent according to claim 1, characterized in that Based on the total weight of the polymer jelly anti-channeling agent, the polymer jelly anti-channeling agent includes: 0.5-1.2 wt% of a gelling agent, 0.1-1.0 wt% of a cross-linking agent, 1.0-3.0 wt% of a strengthening agent and the balance of water.

3. The polymer jelly sealing agent according to claim 2, characterized in that Based on the total weight of the polymer jelly anti-channeling agent, the polymer jelly anti-channeling agent includes: 0.6-1.0 wt% of a gelling agent, 0.2-0.8 wt% of a cross-linking agent, 1.2-2.0 wt% of a strengthening agent and the balance of water.

4. The polymer jelly sealing agent according to claim 1 or 2, characterized in that The particle size of the zirconium hydroxide nanoparticle sol is 20-40 nm.

5. The polymer jelly sealing agent according to claim 4, characterized in that The solid content of the zirconium hydroxide nanoparticle sol is 25-35 wt %.

6. The polymer jelly sealing agent according to claim 1 or 2, characterized in that The molecular weight of the nonionic polyacrylamide is 8×10 6 ~10×10 6 .

7. A method for preparing the polymer jelly anti-channeling agent for heavy oil steam stimulation according to any one of claims 1 to 6, characterized in that: The steps include: The cross-linking agent and water are mixed and fully dissolved at room temperature, the gelling agent is added and stirred to completely dissolve, and finally the strengthening agent is added and stirred evenly to obtain the polymer gel sealing agent.

8. A polymer gel channeling sealant according to any one of claims 1 to 6 for use in blocking gas channeling during steam stimulation in the field of oil production, characterized in that: The polymer gel sealing agent can be stable for more than 180 days at a high temperature of 170° C., and obtains a sealing strength with a 30d elastic modulus greater than 45 Pa and a sealing rate greater than 85%.

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