Automatic gas generation foam channeling sealing agent as well as preparation method and application thereof

Abstract

The invention discloses an automatic gas generation foam channeling sealing agent as well as a preparation method and application thereof, and relates to the technical field of oil and gas recovery. The self-gas-generating foam channeling sealing agent comprises an agent A and an agent B. The agent A comprises 0-5% of an accelerant, the agent B comprises 5-20% of a gas generating agent, 0.1-1.0% of a foaming agent, 0.05-1.0% of a foam stabilizer and the balance of saline water according to the total mass percentage of the self-gas-generating foam channeling sealing agent, the gas generating agent is an azo organic compound, and the agent A and the agent B independently exist. According to the self-gas-generating foam channeling sealing agent, the azo organic matter serves as the gas generating agent and is nitrogen which is good in stability, high in gas generation rate and difficult to compress at the normal temperature, the thermal decomposition reaction serves as the exothermic reaction, energy increasing and heat increasing of a system are facilitated, the oil displacement efficiency is improved, the decomposition temperature and the gas generation rate of the gas generating agent are adjusted through the variety and the dosage of the accelerant, and the self-gas-generating foam channeling sealing agent is obtained. The method can be widely applied to thermal oil recovery such as steam drive, steam huff and puff and in-situ combustion in thickened oil recovery.

Description

Technical Field

[0001] This invention relates to the field of oil and gas recovery technology, and more specifically, to a self-generating foam sealant, its preparation method, and its application. Background Technology

[0002] Heavy oil reservoirs typically contain crude oil with high viscosity and poor fluidity, resulting in limited enhancement of oil recovery through conventional waterflooding or chemical flooding. Injecting high-temperature steam into heavy oil reservoirs can reduce viscosity, promote thermal expansion, and induce miscibility through steam extraction, thus significantly improving oil recovery. The most critical factor affecting steam flooding effectiveness is steam channeling. Due to the strong heterogeneity of oil reservoirs and significant differences in density, viscosity, and fluidity between oil and steam, steam channeling is common in heavy oil reservoirs treated with steam injection, leading to low steam sweep efficiency.

[0003] Currently, the main method for controlling steam channeling and improving steam sweep efficiency is to inject chemical agents capable of sealing steam channeling pathways. Since the injection temperature is generally above 200℃, conventional high-temperature resistant gel plugging agents have poor sealing ability and short effective period. Nitrogen foam plugging agents, however, can simultaneously exert selective foam plugging and gas-driven effects, making them the primary sealing technology. For example, the study "Research on Factors Affecting the Stability of Nitrogen Foam Systems" (Zhao Renbao et al., Acta Petrolei Sinica, 2009.01) discloses a foam plugging agent composition mainly composed of high-temperature resistant foaming agents, nitrogen, and foam stabilizers, which has good foaming and sealing capabilities. However, because the foam system is injected simultaneously with steam from the surface, on the one hand, the high-temperature steam easily causes the foaming agent and foam stabilizer to undergo thermal degradation and lose their foaming effect; on the other hand, the foam is mainly generated in the wellbore and near-wellbore area, increasing the steam injection pressure and making it impossible to achieve deep sealing of steam channeling pathways. The complex liquid nitrogen co-injection process also leads to higher construction costs and risks. The self-generating foam sealing system developed on this basis replaces nitrogen with a gas-generating agent that can decompose underground to produce nitrogen, thereby achieving the goals of good injectability, in-layer gas generation and foaming, convenient construction, and effective sealing of the gas channeling front, and therefore has been widely used. The gas-generating agent required for self-generating foam sealing agent should have the following characteristics: (1) stable at room temperature and controllable decomposition at high temperature; (2) the gas produced is mainly incompressible nitrogen; (3) large gas production and low cost.

[0004] Existing technology discloses a high-temperature, high-pressure expandable sealing agent. The expandable sealing agent, by weight percentage, comprises: 12-35% gas-generating material, 55-80% porous aluminosilicate microspheres, and 3-7% high-temperature resin. The gas-generating material is one or a combination of azodicarbonamide, azobisisobutyronitrile, barium azodicarboxylate, and azoaminebenzene. The porous aluminosilicate microspheres have a particle size of 10-250 μm and a pore volume of 0.20-0.60 cm³. 3 / g of waste microsphere silica-alumina catalyst, waste rare earth Y-type zeolite catalyst, waste bleaching clay Y-type zeolite catalyst or waste hydrocatalytic cracking catalyst or one or a combination thereof; wherein the high-temperature resin is one or a combination of high-temperature phenolic resin, high-temperature epoxy resin, high-temperature vinyl ester resin; the preparation method of the high-temperature and high-pressure expandable plugging agent mainly includes three steps: (1) mix the gas-generating material, organic solvent and porous aluminosilicate microspheres at a weight ratio of 100:20-80:150-300 at room temperature, and after sufficient adsorption for 3-5 hours, after saturation, vacuum dry at a temperature of 25-40℃ to obtain the core material, and the separated organic solvent is reused; (2) mix the high-temperature resin and butyl glycidyl ether at a weight ratio of 100:10-30 Mix evenly, then heat to 60-80℃, add water and emulsifier OP-10 under high-speed stirring, wherein the weight ratio of high-temperature resin, water and emulsifier OP-10 is 100:150-300:1.2-3.5, to obtain a stable water-in-oil shell material emulsion; (3) Under high-speed stirring, add core material and curing agent to shell material emulsion, wherein the weight ratio of shell material emulsion, core material and curing agent is 100:180-350:15-38, continue stirring and reacting at a constant temperature of 60-80℃ for 4-7 hours, the high-temperature resin is cured into a shell on the surface of porous aluminosilicate microspheres, thereby effectively encapsulating and wrapping the porous aluminosilicate microspheres adsorbed with gas-generating materials, filtering and drying, to obtain a high-temperature and high-pressure expandable agent. However, this high-temperature and high-pressure expandable sealant mainly uses the expansion of the resin material after the azo compound decomposes and produces gas to seal the leak. It mainly seals leaks and does not have a vapor sealing effect. Furthermore, it does not solve the problem of insufficient gas production of existing nitrogen foam sealants, which cannot achieve controllable decomposition temperature and speed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing nitrogen foam sealing agents, such as insufficient gas production and inability to control the decomposition temperature and gas production rate, and to provide a self-generating foam sealing agent.

[0006] Another object of the present invention is to provide a method for preparing a self-generating foam sealant.

[0007] Another object of the present invention is to provide an application of a self-generating foam sealant in oil and gas recovery.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] A self-generating foam sealant, characterized in that it comprises agent A and agent B, wherein agent A comprises 0-5% accelerator, and agent B comprises: 5-20% gas-generating agent, 0.1-1.0% foaming agent, 0.05-1.0% foam stabilizer, and the balance being brine.

[0010] The gas-generating agent is an azo organic compound.

[0011] The foaming agent is a high-temperature resistant, water-soluble surfactant.

[0012] The promoter is a catalyst that promotes the decomposition of azo organic compounds.

[0013] The foam stabilizer is a water-soluble polymer.

[0014] Agent A and Agent B exist independently.

[0015] It should be noted that:

[0016] The self-generating foam blocking agent B of this invention includes azo organic compounds as gas-generating agents. These compounds are stable at room temperature and do not readily decompose; their decomposition reaction is mainly affected by temperature, which is adjustable from 50℃ to 200℃. The decomposition gas is primarily nitrogen, and the gas production is substantial, meeting the requirements for gas-generating agents in blocking vapor channeling. Its thermal decomposition reaction formula is as follows:

[0017]

[0018] The azo organic compound gas-generating agent of this invention has good stability at room temperature and is not prone to premature decomposition or the generation of toxic nitrogen oxides. It is safe and environmentally friendly to use. Moreover, the decomposition rate of azo organic compounds is mainly controlled by temperature, and no additional oxidant is required. It is simple and convenient to apply. It produces high gas volume and is incompressible nitrogen gas. The thermal decomposition reaction is exothermic, which helps to enhance the energy and heat of the system and improve the oil displacement efficiency.

[0019] The self-generating foam sealing agent of this invention comprises agent A and agent B. The decomposition temperature and gas production rate of the gas-producing agent in agent B can be adjusted by the type and amount of the promoter in agent A, facilitating deep sealing. Furthermore, the system exhibits good foam stability, contains no acidic or alkaline substances, and will not damage the reservoir. It can be widely applied in thermal oil recovery measures such as steam drive, steam injection, and reservoir combustion in heavy oil extraction. It can also be used in self-generating foam drainage gas production, self-generating foam flooding, self-generating foam water shut-off, and self-generating foam fracturing, replacing nitrogen injection at the surface in various applications.

[0020] In practical applications, different azo organic compound gas-generating agents have different thermal decomposition temperatures. For gas-generating agents with lower thermal decomposition temperatures, such as AIBN, the reaction can be completed without an accelerator. For gas-generating agents with higher thermal decomposition temperatures, the gas production rate and amount can be effectively controlled by adding an accelerator to accelerate the reaction.

[0021] The self-generating foam sealing agent of the present invention has the characteristics of being safe and environmentally friendly, having good injectability, convenient construction, high gas production, and good sealing effect.

[0022] In a specific embodiment, preferably, agent B includes 5-18% gas-generating agent, for example, it can be 5%, 10%, 15%, 18%, etc., preferably 10-18%.

[0023] In a specific embodiment, preferably, agent A includes 0.2 to 1.0% of an accelerator, for example, 0.2%, 0.5%, 0.7% or 1.0%, more preferably 0.2 to 0.7%.

[0024] In a specific embodiment, preferably, the mass ratio of the promoter and the gas-generating agent is 1:7 to 50.

[0025] In specific embodiments, the azo organic compounds of the present invention include any one or more of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ABVN), dimethyl azobisisobutyrate (AIBME), azodicarbonamide (ADC), azobisisobutyramidine hydrochloride (AIBA), azobisisobutyramidine imidazoline hydrochloride (AIBI), and azobiscyanopentanoic acid (ACVA).

[0026] The molecular formulas of the various azo organic compounds are as follows:

[0027]

[0028] Preferably, the azo organic compounds of the present invention are AIBN, ADC, and AIBA.

[0029] In specific embodiments, the foaming agent of the present invention includes any one or more of sodium alkylbenzene sulfonate, petroleum sulfonate, sulfobetaine, fluorocarbon surfactant, organosilicon surfactant, and sodium fatty alcohol polyvinyl ether sulfate.

[0030] In specific embodiments, the foam stabilizer of the present invention is one or more of polyacrylamide and its modified products, sodium carboxymethyl cellulose, guar gum and its modified products.

[0031] In a specific embodiment, the accelerator of the present invention is manganese dioxide and / or zinc chloride.

[0032] In a specific embodiment, the brine of the present invention can be reinjection water from an oil field that has undergone oil-water separation and removal of suspended solids, without the need for special preparation.

[0033] This invention also specifically protects a method for preparing a self-generating foam sealant, comprising the following steps:

[0034] The foaming agent and foam stabilizer are dissolved fully in brine, and then the gas-generating agent is slowly added and mixed evenly to obtain agent B.

[0035] Add agent A before use and mix thoroughly to obtain a self-generating foam sealant.

[0036] This invention also specifically protects the application of a self-generating foam sealant in oil and gas recovery.

[0037] The self-generating foam sealing agent of the present invention uses azo organic compounds alone or in combination with accelerators to meet the needs of in-situ underground nitrogen generation in oil and gas reservoirs with temperatures ranging from 50 to 190°C. When combined with other existing gas injection technologies, it can be applied to fields such as heavy oil thermal recovery, foam drainage gas production, foam water shut-off, and foam fracturing, and can be used to replace surface nitrogen injection in various occasions.

[0038] In specific applications, the invention is used in thermal oil recovery for heavy oil extraction, self-generated foam drainage for gas production, self-generated foam flooding, self-generated foam water shut-off, and self-generated foam fracturing.

[0039] The following application methods can be referenced in specific applications:

[0040] The construction method for the on-site operation of the self-generating foam sealing agent described in the invention is as follows: prepare the sealing agent system without adding accelerator in advance and transfer it to the tanker truck; disassemble the wellhead valve of the injection well and connect the pump truck and the tanker truck manifold; add a quantitative accelerator to the tanker truck before injection into the wellbore and circulate and mix it evenly; open the wellhead valve and inject the sealing agent solution into the wellbore at a fixed discharge rate; pump in brine to clean the pipeline and wellbore, and push the sealing agent into the formation; restore the wellhead equipment, disassemble the manifold and switch to normal steam injection.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] This invention relates to a self-generating foam sealing agent that uses azo-based organic compounds as the gas-generating agent. It exhibits good stability at room temperature, is less prone to premature decomposition and the generation of toxic nitrogen oxides, and is safe and environmentally friendly. Furthermore, the azo-based organic compounds produce high-yield, incompressible nitrogen gas, and the thermal decomposition reaction is exothermic, contributing to increased system energy and heat generation, thus improving oil displacement efficiency. The decomposition temperature and gas production rate of the gas-generating agent can be adjusted by the type and amount of accelerator, facilitating deep sealing. The system exhibits good foam stability, contains no acidic or alkaline substances, and will not damage the reservoir. It can be widely applied in thermal oil recovery measures such as steam flooding, steam injection, and reservoir combustion in heavy oil extraction. It can also be used in self-generating foam drainage gas production, self-generating foam flooding, self-generating foam water shut-off, and self-generating foam fracturing, replacing surface-injected nitrogen in various applications. Attached Figure Description

[0043] Figure 1 The graph shows the change in gas generation rate of the self-generating foam sealant in Example 1 at the same temperature.

[0044] Figure 2 The graph shows the change in the sealing performance of the self-generating foam sealing agent of Example 1 as a function of the number of injected PVs.

[0045] Figure 3 This is a graph showing the change in gas generation rate of the self-generating foam sealant in Example 2 at the same temperature.

[0046] Figure 4 The graph shows the change in sealing performance of the self-generating foam sealant in Example 2 as a function of the number of injected PVs.

[0047] Figure 5 The graph shows the change in gas generation rate of the self-generating foam sealant in Example 3 at the same temperature.

[0048] Figure 6 The graph shows the change in sealing performance of the self-generating foam sealant in Example 3 as a function of the number of injected PVs.

[0049] Figure 7 This is a graph showing the change in gas generation rate of the self-generating foam sealant in Example 4 at the same temperature.

[0050] Figure 8 The graph shows the change in sealing performance of the self-generating foam sealant in Example 4 as a function of the number of injected PVs. Detailed Implementation

[0051] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0052] Azodicarbonamide: ADC-DN3, Guangzhou Jiangyan Chemical Co., Ltd.;

[0053] High-temperature resistant foaming agent: W-101, Dongying Shengdu Petroleum Technology Co., Ltd.;

[0054] Polyacrylamide: AP-P4, Sichuan Guangya Polymer Co., Ltd.;

[0055] Sodium carboxymethyl cellulose: FVH9, Henan Jiqian Biotechnology Co., Ltd.;

[0056] Hydroxypropyl guanidine gum: KLGJ-9, Renqiu Dayuan Chemical Co., Ltd.

[0057] Example 1

[0058] A self-generating foam sealant, totaling 200g, by weight percentage,

[0059] It includes: 10% gas-generating agent AIBN (thermal decomposition temperature 70℃), 0.4% high-temperature resistant foaming agent sulfobetaine, 0.1% foam stabilizer polyacrylamide, and the remainder is a 5% sodium chloride solution.

[0060] The preparation method of the self-generating foam sealant in Example 1 includes the following steps:

[0061] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine and fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0062] Methods for measuring gas production performance:

[0063] The prepared sealing agent solution was added to a high-temperature and high-pressure reactor with a reactor volume of 200 mL and a sealing agent solution of 50 mL. The heating rate was set to 3℃ / min, and the maximum temperature was 200℃. The temperature and pressure changes inside the reactor were recorded. After the experiment, the reactor was cooled to room temperature, and the gas production was calculated based on the PVT relationship.

[0064] Steam channeling performance evaluation method:

[0065] Quartz sand was packed into a sand-filled pipe and displaced with a 5% sodium chloride solution. The permeability and porosity of the sand-filled pipe were measured. The back pressure at the outlet end was 1 MPa. A horizontal flow pump was used to continuously inject 1 PV of sealing agent solution at a rate of 1 mL / min, followed by the injection of high-temperature steam at 200°C. The heating temperature of the sand-filled pipe was 200°C during steam injection. The pressure difference changes at both ends of the sand-filled pipe were recorded.

[0066] The system does not contain any accelerators, and there is no obvious decomposition and gas production reaction at 60℃. It produces gas stably in the range of 60-90℃.

[0067] Its drag coefficient and residual drag coefficient are 15.0 and 9.8, respectively, and the blocking rate is 93.3%.

[0068] Wherein, the drag coefficient is: RF = K2 / K1

[0069] Residual drag coefficient: RRF = K3 / K1

[0070] Blocking rate: η=(K1-K3) / K1*100%

[0071] In the formula

[0072] K1—Permeability when pressure is stable before plugging, D;

[0073] K2—Minimum permeability during the injection of the blocking agent; D;

[0074] K3 – Permeability when pressure is stable after plugging, D.

[0075] Among them, the change in gas generation rate of the self-generating foam sealant in Example 1 at the same temperature is as follows: Figure 1 As shown. From Figure 1 It can be seen that: there is basically no gas production before 60℃, gas production is faster between 60-80℃, and then gas production is slow and steady.

[0076] Among them, the sealing performance of the self-generated foam sealing agent in Example 1 varies with the number of injected PVs as follows: Figure 2 As shown, from Figure 2 As can be seen, after the sealing agent is injected, the pressure rises slowly, indicating that gas production and foaming begin slowly, gradually forming a higher sealing pressure. In the subsequent steam drive, gas production continues, maintaining a good sealing capability.

[0077] Example 2

[0078] A self-generating foam sealant, totaling 200g, by weight percentage,

[0079] It includes: 10% gas-generating agent AIBI (thermal decomposition temperature of 50℃), 0.4% high-temperature resistant foaming agent sulfobetaine, 0.1% foam stabilizer polyacrylamide, and the remainder is a 5% sodium chloride solution.

[0080] The preparation method of the self-generating foam sealant in Example 2 includes the following steps:

[0081] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine and fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0082] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0083] This system exhibits no significant decomposition and gas production reaction at 40℃, and produces gas stably within the range of 50–70℃.

[0084] Its drag coefficient and residual drag coefficient are 10.7 and 5.3 respectively, and the blocking rate is 90.7%.

[0085] Among them, the change in gas generation rate of the self-generating foam sealant in Example 2 at the same temperature is as follows: Figure 3 As shown. From Figure 3 It can be seen that: no gas is produced before 40℃, gas production is faster between 40-60℃, and then gas production is slow and steady.

[0086] Among them, the sealing performance of the self-generated foam sealing agent in Example 2 varies with the number of injected PVs as follows: Figure 4 As shown, from Figure 4 As can be seen, after the sealing agent is injected, the pressure rises slowly, indicating that gas production and foaming begin slowly, gradually forming a higher sealing pressure. In the subsequent steam drive, gas production continues, maintaining a good sealing capability.

[0087] Example 3

[0088] A self-generating foam sealant, totaling 200g, comprises agent A and agent B, by mass percentage.

[0089] Agent A includes 0.2% manganese dioxide as an accelerator;

[0090] Agent B includes: 10% gas-generating agent ADC, 0.1% high-temperature resistant foaming agent sodium alkylbenzene sulfonate, 0.5% foam stabilizer hydroxypropyl guar gum, and the remainder is a 5% sodium chloride solution.

[0091] The preparation method of the self-generating foam sealant in Example 3 includes the following steps:

[0092] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine, followed by the accelerator, which was then fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0093] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0094] No significant decomposition and gas production reaction was observed at 90℃, and stable gas production was observed within the 150-190℃ range. Its drag coefficient and residual drag coefficient were 34.6 and 13.1, respectively, with a plugging rate of 97.1%.

[0095] Among them, the change in gas generation rate of the self-generating foam sealant in Example 3 at the same temperature is as follows: Figure 5 As shown. From Figure 5 It can be seen that: before 150℃, there is basically no gas production, and the pressure rise is due to the increase in water saturated vapor pressure; after 150℃, gas production is stable.

[0096] Among them, the sealing performance of the self-generated foam sealing agent in Example 3 varies with the number of injected PVs as follows: Figure 6 As shown, from Figure 6 As can be seen, after the sealing agent is injected, the pressure rises slowly, indicating that gas production and foaming begin slowly, gradually forming a higher sealing pressure. In the subsequent steam drive, gas production continues, maintaining a good sealing capability.

[0097] Example 4

[0098] A self-generating foam sealant, totaling 200g, comprises agent A and agent B, by mass percentage.

[0099] Agent A includes 0.7% zinc chloride accelerator;

[0100] Agent B includes: 18% gas-generating agent ADC, 0.5% high-temperature resistant foaming agent fluorocarbon surfactant, 0.2% foam stabilizer hydrophobically modified polyacrylamide, and the remainder is a 10% sodium chloride solution.

[0101] The preparation method of the self-generating foam sealant in Example 4 includes the following steps:

[0102] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine, followed by the accelerator, which was then fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0103] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0104] No significant decomposition and gas production reaction was observed at 90℃, and stable gas production was observed in the range of 110–160℃. Its drag coefficient and residual drag coefficient were 33.2 and 11.3, respectively, with a plugging rate of 97.0%.

[0105] Among them, the change in gas generation rate of the self-generating foam sealant in Example 4 at the same temperature is as follows: Figure 7 As shown. From Figure 7 It can be seen that no gas is produced before 110℃, and gas production is stable after 110℃.

[0106] Among them, the sealing performance of the self-generated foam sealing agent in Example 4 varies with the number of injected PVs as follows: Figure 8 As shown, from Figure 8 As can be seen, after the sealing agent is injected, the pressure rises slowly, indicating that gas production and foaming begin to occur slowly, gradually forming a higher sealing pressure. In the subsequent steam drive, gas production continues, maintaining a high sealing pressure in the early stage, and maintaining a good sealing ability as the foam is driven out.

[0107] Example 5

[0108] A self-generating foam sealant, totaling 200g, comprises agent A and agent B, by mass percentage.

[0109] Agent A includes 0.5% zinc chloride accelerator;

[0110] Agent B includes: 5% gas-generating agent ADC, 0.3% high-temperature resistant foaming agent silicone surfactant, 0.2% foam stabilizer sodium carboxymethyl cellulose, and the remainder is a 10% sodium chloride solution.

[0111] The preparation method of the self-generating foam sealant in Example 5 includes the following steps:

[0112] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine, followed by the accelerator, which was then fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0113] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0114] No significant decomposition and gas production reaction was observed at 90℃, and stable gas production was observed within the 130-180℃ range. Its drag coefficient and residual drag coefficient were 18.3 and 6.5, respectively, with a plugging rate of 94.5%.

[0115] Example 6

[0116] A self-generating foam sealant, totaling 200g, comprises agent A and agent B, by mass percentage.

[0117] Agent A includes 0.2% zinc chloride accelerator;

[0118] Agent B includes: 5% gas-generating agent ADC, 0.1% high-temperature resistant foaming agent alkyl betaine, 0.5% foam stabilizer sodium carboxymethyl cellulose, and the remainder is a 20% sodium chloride solution.

[0119] The preparation method of the self-generating foam sealant in Example 6 includes the following steps:

[0120] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine, followed by the accelerator, which was then fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0121] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0122] No significant decomposition and gas production reaction was observed at 90℃, and stable gas production was observed within the 170-190℃ range. Its drag coefficient and residual drag coefficient were 17.7 and 6.8, respectively, with a plugging rate of 94.3%.

[0123] Example 7

[0124] A self-generating foam sealant, totaling 200g, comprises agent A and agent B, by mass percentage.

[0125] Agent A includes 0.7% zinc chloride accelerator;

[0126] Agent B includes: 5% gas-generating agent ADC, 0.1% high-temperature resistant foaming agent fluorocarbon surfactant, 0.5% foam stabilizer hydroxypropyl guar gum, and the remainder is a salt solution containing 10% sodium chloride and 0.5% calcium chloride by mass.

[0127] The preparation method of the self-generating foam sealant in Example 7 includes the following steps:

[0128] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine, followed by the accelerator, which was then fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0129] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0130] No significant decomposition and gas production reaction was observed at 90℃, and stable gas production was observed within the range of 105-135℃. Its drag coefficient and residual drag coefficient were 10.8 and 7.1, respectively, with a plugging rate of 90.7%.

[0131] Example 8

[0132] A certain heavy oil well group has a reservoir depth of 450m, a porosity of 31%, an average permeability of 5520mD, a reservoir temperature of 44℃, and a crude oil underground viscosity of 35000mPa.s. In the early stage, four rounds of steam huff and puff were used. Displacement ended when the water cut reached 98%, and the total recovery rate was 56%. Steam channeling occurred with two adjacent production wells. Analysis shows that due to the heterogeneity of the formation, severe large-channel steam channeling has occurred.

[0133] A self-generating foam sealant was used as the pre-fluid, composed of: 12% gas-producing agent ADC + 0.5% high-temperature resistant foaming agent dodecyl betaine + 0.2% foam stabilizer sodium carboxymethyl cellulose + 0.5% accelerator zinc chloride. The self-generating foam sealant was injected into the wellbore according to the aforementioned field operation method. After injecting 0.2 PV of sealant, steam injection was initiated. A total of 5 steam injection cycles were completed, injecting 2208 tons of steam. No steam channeling occurred in the original steam-channeling well, the water cut decreased to 78%, and a cumulative oil production of 350 tons was achieved, increasing the recovery rate by 11.5%, demonstrating significant effectiveness.

[0134] Comparative Example 1

[0135] A self-generating foam sealant, totaling 200g, by weight percentage,

[0136] 5% gas-generating agent ADC, 0.1% high-temperature resistant foaming agent fluorocarbon surfactant, 0.5% foam stabilizer hydroxypropyl guar gum, and the remainder is a salt solution containing 10% sodium chloride and 0.5% calcium chloride by mass.

[0137] The preparation method of the self-generating foam sealant of Comparative Example 1 includes the following steps:

[0138] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0139] Comparative Example 2

[0140] A self-generating foam sealant, totaling 200g, by weight percentage,

[0141] 5% gas-generating agent urea, 0.1% high-temperature resistant foaming agent fluorocarbon surfactant, 0.5% foam stabilizer hydroxypropyl guar gum, and the remainder is a salt solution containing 10% sodium chloride and 0.5% calcium chloride by mass.

[0142] The preparation method of the self-generating foam sealant of Comparative Example 2 includes the following steps:

[0143] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0144] Comparative Example 3

[0145] A self-generating foam sealant, totaling 200g, comprises agent A and agent B, by mass percentage.

[0146] Agent A includes 0.7% zinc chloride accelerator;

[0147] Agent B includes: 25% gas-generating agent ADC, 0.1% high-temperature resistant foaming agent fluorocarbon surfactant, 0.5% foam stabilizer hydroxypropyl guar gum, and the remainder is a salt solution containing 10% sodium chloride and 0.5% calcium chloride by mass.

[0148] The preparation method of the self-generating foam sealant of Comparative Example 3 includes the following steps:

[0149] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine, followed by the accelerator, which was then fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0150] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0151] Comparative Example 4

[0152] A self-generating foam sealant, totaling 200g, comprises agent A and agent B, by mass percentage.

[0153] Agent A includes 6.0% zinc chloride accelerator;

[0154] Agent B includes: 5% gas-generating agent ADC, 0.1% high-temperature resistant foaming agent fluorocarbon surfactant, 0.5% foam stabilizer hydroxypropyl guar gum, and the remainder is a salt solution containing 10% sodium chloride and 0.5% calcium chloride by mass.

[0155] The preparation method of the self-generating foam sealant of Comparative Example 4 includes the following steps:

[0156] In a 500mL beaker, sodium chloride solution was added and magnetically stirred. The foaming agent and foam stabilizer solid powders were then added to the brine and stirred until fully dissolved. The gas-generating agent solid powder was then slowly added to the brine, followed by the accelerator, which was then fully dissolved. The prepared self-generating foam sealant mixture was transferred to a testing instrument for performance evaluation.

[0157] The methods for measuring gas production performance and evaluating steam channeling performance are the same as in Example 1.

[0158] Compared with Example 7, this comparative example has a higher accelerator concentration. Experimental results show that as the accelerator concentration increases, the thermal decomposition temperature decreases, the gas production rate increases, and the gas production volume and drag coefficient remain essentially unchanged, but the residual drag coefficient decreases significantly. This is mainly because the high concentration of gas-producing agent generates a large amount of heat during decomposition, further accelerating the gas production reaction. Simultaneously, the excessively high gas-liquid ratio in the foam system affects foam stability.

[0159] Result detection

[0160] Methods for measuring gas production performance:

[0161] The prepared sealing agent solution was added to a high-temperature and high-pressure reactor with a reactor volume of 200 mL and a sealing agent solution of 50 mL. The heating rate was set to 3℃ / min, and the maximum temperature was 200℃. The temperature and pressure changes inside the reactor were recorded. After the experiment, the reactor was cooled to room temperature, and the gas production was calculated based on the PVT relationship.

[0162] Steam channeling performance evaluation method:

[0163] Quartz sand was packed into a sand-filled pipe and displaced with a 5% sodium chloride solution. The permeability and porosity of the sand-filled pipe were measured. The back pressure at the outlet end was 1 MPa. A horizontal flow pump was used to continuously inject 1 PV of sealing agent solution at a rate of 1 mL / min, followed by the injection of high-temperature steam at 200°C. The heating temperature of the sand-filled pipe was 200°C during steam injection. The pressure difference changes at both ends of the sand-filled pipe were recorded.

[0164] The specific test results are shown in Table 1 below:

[0165] Table 1. Detection results of the examples and comparative examples

[0166]

[0167]

[0168] Compared with Example 7, Comparative Example 1 did not include a accelerator. During the experiment, the pressure curve of the autoclave was basically consistent with the pressure change curve when water was heated, indicating that the gas generation reaction basically did not occur without the accelerator, and a foam system could not be formed. Therefore, the resistance coefficient, residual resistance coefficient, and plugging rate were extremely low.

[0169] Compared with Example 7, the gas-generating agent in Comparative Example 2 was urea. During the experiment, the pressure rise was relatively small. This is mainly because the product gases of the urea hydrolysis reaction are CO2 and ammonia, which have high solubility and high compressibility, resulting in poor foaming properties and low drag coefficient, residual drag coefficient, and plugging rate.

[0170] Compared with Example 7, Comparative Example 3 had a gas-generating agent concentration of 25%. No significant decomposition and gas-generating reaction was observed at 90°C, and rapid gas generation occurred within the 105-135°C range. Its drag coefficient and residual drag coefficient were 4.5 and 2.2, respectively, with a blocking rate of 78%. Despite increasing the gas-generating agent concentration, there was no corresponding improvement in gas-generating performance or blocking effect. This is mainly because the high-concentration gas-generating agent generates a large amount of heat during decomposition, further accelerating the gas-generating reaction. Simultaneously, the excessively high gas-liquid ratio in the foam system affected foam stability.

[0171] Compared with Example 7, Comparative Example 4 had a higher accelerator concentration. Experimental results showed that as the accelerator concentration increased, the thermal decomposition temperature decreased, the gas production rate increased, and the gas production volume and drag coefficient remained essentially unchanged, but the residual drag coefficient decreased significantly. This is mainly because the high concentration of gas-producing agent generates a large amount of heat during decomposition, further accelerating the gas production reaction. Simultaneously, the excessively high gas-liquid ratio in the foam system affected foam stability.

[0172] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A self-generating foam sealant, characterized in that, It includes Agent A and Agent B. Based on the percentage of the total mass of the self-generating foam sealant, Agent A includes 0-5% accelerator, and Agent B includes: 5-20% gas-generating agent, 0.1-1.0% foaming agent, 0.05-1.0% foam stabilizer, with the balance being brine. The gas-generating agent is an azo organic compound. The foaming agent is a high-temperature resistant, water-soluble surfactant. The accelerator is one or more of zinc oxide or chloride and manganese oxide or chloride. The foam stabilizer is a water-soluble polymer. Agent A and Agent B exist independently.

2. The self-generating foam sealant as described in claim 1, characterized in that, Agent A includes 0.2% to 1.0% accelerator.

3. The self-generating foam sealant as described in claim 1, characterized in that, The mass ratio of the accelerator and the gas-generating agent is 1:7 to 50.

4. The self-generating foam sealant according to any one of claims 1 to 3, characterized in that, The azo organic compounds include any one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azodicarbonamide, azobisisobutyramidine hydrochloride, azobisisobutyramidine hydrochloride, and azobisisobutyramidal acid.

5. The self-generating foam sealant according to any one of claims 1 to 3, characterized in that, The foaming agent includes any one or more of sodium alkylbenzene sulfonate, petroleum sulfonate, sulfobetaine, fluorocarbon surfactant, organosilicon surfactant, and sodium fatty alcohol polyvinyl ether sulfate.

6. The self-generating foam sealant according to any one of claims 1 to 3, characterized in that, The foam stabilizer is one or more of polyacrylamide and its modified products, sodium carboxymethyl cellulose, guar gum and its modified products.

7. The self-generating foam sealant according to any one of claims 1 to 3, characterized in that, The accelerator is manganese dioxide and / or zinc chloride.

8. A method for preparing the self-generating foam sealant according to any one of claims 1 to 7, characterized in that, Includes the following steps: The foaming agent and foam stabilizer are dissolved fully in brine, and then the gas-generating agent is slowly added and mixed evenly to obtain agent B. Add agent A before use and mix thoroughly to obtain a self-generating foam sealant.

9. The application of the self-generating foam sealant according to any one of claims 1 to 7 in oil and gas recovery.

10. The application of the self-generating foam sealant as described in claim 9 in oil and gas recovery, characterized in that, The applications include thermal oil recovery for heavy oil extraction, self-generated foam drainage for gas production, self-generated foam flooding, self-generated foam water shut-off, and self-generated foam fracturing.

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