Method and device for exploiting unconventional oil and gas reservoirs by high-energy gas pressurization

Abstract

The present application relates to oilfield development technical field, it is a kind of high-energy gas pressurized integration unconventional oil and gas reservoir exploitation method and device;The method includes subsection design, bridge plug setting, seal checking and preflush injection, high-energy gas energy-gathering pressurized, pressurized monitoring and parameter adjustment, sand carrying support, displacement cleanup, pressure stabilization stew and flowback control;The present application forms target reservoir pressurized operation section by bridge plug, combines preflush resistance reduction and anti-swelling, sand-carrying liquid fracture support, displacement cleanup liquid promotes flowback and high-energy gas pressurized fracture, realizes the integration operation of reservoir subsection pressurized, fracture connection, gas desorption, rock debris guide and residual liquid flowback, suitable for low-permeability, low-pressure, strong heterogeneity shale reservoir permeability improvement and unconventional oil and gas resource exploitation process pressurized cleanup operation, significantly improve the long-term conductivity of fracture, cleat system and oil and gas exploitation efficiency, provide reliable technical means for efficient development of unconventional oil and gas resources.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and is a high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method and apparatus. Background Technology

[0002] With the continuous advancement of shale oil and gas development and deep oil and gas resource exploitation, permeability enhancement and efficient drainage technologies for organic-rich shale and mudstone reservoirs have gradually attracted widespread attention. The development of internal cleavage, bedding, and natural fractures in these reservoirs directly affects the formation of seepage channels and the extraction efficiency of oil and gas. Simultaneously, gas is mostly adsorbed on the reservoir matrix surface and must undergo desorption, diffusion, and seepage processes before entering the wellbore. Therefore, research on fracturing permeability enhancement, gas displacement, and post-fracturing drainage technologies applicable to organic-rich shale and mudstone reservoirs is of great significance for improving reservoir fracture conductivity, promoting the desorption of adsorbed natural gas, and enhancing extraction efficiency.

[0003] Current methods for enhancing the permeability of unconventional oil and gas reservoirs primarily employ hydraulic fracturing. This involves injecting high-pressure fracturing fluid into the target rock section, causing fracture initiation and propagation under liquid pressure. Propane is then transported into the fractures using a proppant-carrying fluid to maintain fracture openness. During the process, the pre-fracturing fluid primarily transfers hydraulic energy and forms initial fractures, while the proppant-carrying fluid carries the proppant to create flow channels. Post-fracturing flowback removes residual fracturing fluid and cuttings. This method improves reservoir permeability to a certain extent, providing pathways for the release of reservoir oil and gas. In the oil and gas development field, hydraulic fracturing, staged isolation, proppant-carrying, post-fracturing flowback, and gas-assisted displacement technologies have been widely applied in low-permeability sandstone reservoirs, tight oil and gas reservoirs, shale oil and gas reservoirs, and the enhancement of production in old oilfields. Using bridge plugs or packers to segment the wellbore, creating fractures with pre-fracturing fluid, supporting fractures with proppant-carrying fluid, and restoring flowability with flowback fluid have become important technical pathways for improving single-well productivity in unconventional oil and gas reservoirs. Meanwhile, media such as nitrogen, carbon dioxide, foam fluids and high-energy gases are also commonly used in the near-wellbore zone of oil and gas wells for unblocking, fracture propagation, energy replenishment and residual fluid drainage, so as to improve reservoir seepage conditions and enhance recovery efficiency.

[0004] However, unconventional oil and gas reservoirs rich in organic matter, particularly shale and mudstone, differ significantly from conventional sandstone and carbonate reservoirs. During fracturing operations in shale and mudstone reservoirs, fracturing fluid preferentially leaks along low-resistivity channels, making it difficult for fluid pressure and hydraulic energy to form a uniform and controllable complex fracture network within the target section. The clay minerals in shale and mudstone reservoirs are prone to hydration and swelling upon contact with external fluids, leading to water-locking damage and reduced matrix permeability. Simultaneously, the low mechanical strength of these reservoir rocks makes them susceptible to generating large amounts of rock cuttings under high-pressure fluid. These cuttings, after migrating with the fracturing or flowback fluid, tend to deposit in pore throats, cleavage junctions, or proppant-filled channels, further reducing fracture conductivity.

[0005] In recent years, technologies such as high-energy gas fracturing, high-energy gas hydraulic displacement, nitrogen displacement, carbon dioxide displacement, and gas-liquid composite hydraulic displacement have been increasingly applied to the development of unconventional oil and gas resources. Compared with pure liquid fracturing, gaseous media have advantages such as less residue, lower flowback resistance, and the ability to promote the desorption of adsorbed gases to a certain extent. High-energy gas hydraulic displacement can also induce reservoir fracture propagation and cleavage connectivity through instantaneous or staged high-pressure combustion and explosion. However, existing gas hydraulic displacement methods mostly focus on the fracturing or displacement process itself, lacking measures for establishing effective low-resistivity channels in the early stages, controlling cuttings dispersion, preventing swelling and aiding flowback, and providing long-term fracture support. This results in gas easily dissipating rapidly along existing cleavages or local fracture channels, leading to a non-concentrated range of action and uneven fracture propagation. At the same time, fractures formed by high-energy gas are prone to re-closure under geostress, making it difficult to maintain long-term conductivity.

[0006] While bridge plug isolation segmentation technology has been widely applied in staged fracturing of oil and gas wells, enabling the wellbore to be divided into different working sections through mechanical isolation and improving the targeting of media action, in organic-rich shale reservoirs, it mainly addresses the problem of concentrated media action on specific sections. It struggles to simultaneously address complex challenges such as fluid damage, cuttings transport, insufficient desorption of adsorbed gas, and post-fracturing conductivity degradation. Furthermore, existing fracturing processes such as fracture creation, gas displacement, fluid-assisted drainage, and post-fracturing flowback are typically relatively independent, lacking synergistic design tailored to the strong heterogeneity, high cuttings production, and dominant adsorbed gas characteristics of this type of reservoir. This results in insufficient coordination between pre-fracturing fluid, proppant-carrying fluid, displacement and drainage media, and high-energy gas, making it difficult to fully leverage the overall synergistic effect of fracturing-displacement-assisted drainage-production.

[0007] Patent document CN120211721A discloses a shale oil extraction method based on multi-stage pulsed gas fracturing and nanocatalysis synergy, belonging to the field of oilfield development technology. The method includes the following steps: S1, determining the optimal drilling location of the target shale layer and conducting drilling operations; S2, using a high-frequency solenoid valve to control and generate an adjustable pulsed pressure wave of 0.1–10 Hz, injecting fracturing media mixed with functionalized nanoparticles into the formation through a fracturing pump, adjusting the pulse frequency of the high-frequency solenoid valve to perform staged pulsed fracturing operations, forming a fracture network; S3, after each stage of fracturing, injecting a mixture of proppant and fracturing fluid into the formation fractures; S4, after the fracturing operation is completed, applying a microwave field to the formation to maintain the formation temperature within a set range. This invention significantly reduces the environmental impact by using a mixture of gas fracturing media and functionalized nanoparticles for fracturing, and significantly improves the recovery rate of shale oil by employing multi-stage pulsed fracturing, composite proppant, and microwave field synergy.

[0008] Patent document CN112727427A discloses a controllable shock wave and gas fracturing combined fracturing production enhancement device and method. The device includes an injection pipe, an air compressor, a fracturing chamber, a shock wave generator, and a packer. The injection pipe is equipped with a pressure sensor, a flow sensor, and several valves. A fracturing hole is provided on the side wall of the fracturing chamber. The shock wave generator is located inside the fracturing chamber at the location of the fracturing hole. The packer is located in the circumferential space between the fracturing chamber and the borehole wall on the upper and lower sides of the fracturing hole. The method is as follows: Hole layout; drilling; inserting a fracturing chamber equipped with a shock wave generator and a packer into the borehole; inflating the circumferential packer bladder of the packer, which then completes the sealing; applying pulsed high voltage and high current to the shock wave generator to generate a controllable shock wave, which repeatedly acts on the ore body or reservoir rock mass; loading high-pressure gas into the circumferential packer section to further fracture the ore body or reservoir rock mass to expand the fractures; recovering and depressurizing the waste gas; and finally, releasing the gas from the circumferential packer bladder to complete the unsealing.

[0009] Patent document CN121630335A discloses a gas fracturing production enhancement device. This invention relates to the field of fracturing production enhancement equipment technology, and particularly to a gas fracturing production enhancement device aimed at alleviating the technical problem of difficulty in controlling the discharge rate of mixed-phase liquid materials between the low-pressure inlet and high-pressure outlet in related technologies. The gas fracturing production enhancement device includes a flow tank, which comprises a shell, an extension tube, a plug plate, and a drive component. The shell has a receiving cavity with an inlet and an outlet on its two opposite side walls. The extension tube is fixed within the receiving cavity and has multiple flow holes on its side walls, one end of which is open and connected to the inlet, while the other end is closed and extends towards the outlet. The plug plate is fitted onto the extension tube, and the drive component is drively connected to the plug plate. By incorporating the flow tank, this gas fracturing production enhancement device can control the flow rate of the mixed-phase liquid material, allowing the mixed-phase liquid material to carry a standard amount of sand to fill the formation.

[0010] In summary, existing unconventional oil and gas reservoir fracturing and permeability enhancement technologies still suffer from the following major drawbacks: insufficient adaptability of hydraulic fracturing to reservoirs; gas pressure drive is prone to leakage along dominant channels and has poor long-term conductivity; weak synergy between bridge plug isolation and multi-media pressure drive drainage processes; and insufficient control over cuttings drainage and residual fluid return. Therefore, there is an urgent need for a high-energy gas pressure drive integrated unconventional oil and gas reservoir development method and apparatus that can adapt to the characteristics of low permeability, strong heterogeneity, easy cuttings production, and high adsorbed gas content in organic-rich shale reservoirs. This would achieve integrated operations including segmented precise pressure drive, effective fracture connectivity, adsorbed gas desorption promotion, residual fluid-assisted drainage and return, and maintenance of fracture conductivity, meeting the demands for efficient permeability enhancement and increased production in unconventional oil and gas reservoirs. Summary of the Invention

[0011] This invention provides a high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method and apparatus, which overcomes the shortcomings of the prior art. It can effectively solve the problems of insufficient adaptability of existing hydraulic fracturing to reservoirs, easy leakage of gas pressure drive along the dominant channel and poor long-term flow capacity, weak synergy between bridge plug isolation and multi-media pressure drive drainage process, and insufficient control of cuttings drainage and residual fluid return.

[0012] One of the technical solutions of this invention is achieved through the following measures: a high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method, which is carried out according to the following steps: The first step is segmented design, which determines the location and segment length of the target pressure drive operation section based on the bedding, cleavage development, rock mass integrity, oil and gas content, and wellbore stability of organic-rich mudstone and shale. The second step is bridge plug setting. The bridge plug is sent into the preset position inside the casing for sealing, thereby completing the bridge plug setting and forming a relatively independent target pressure drive operation section. The third step is to test the seal and inject pre-flush fluid. Pre-flush fluid is injected into the target pressure drive section at a low rate to test the seal. After confirming that the pressure remains stable, pre-flush fluid is injected to reduce flow resistance, inhibit clay expansion, disperse rock cuttings and establish an initial seepage channel. The fourth step is high-energy gas focusing pressure drive. The high-energy gas focusing pressure drive module is started, so that the high-energy gas is focused and released to act on the target pressure drive operation section. Under the action of transient or staged pressure pulses, crack initiation and expansion are induced, and multi-scale small cracks are connected with the original cleavage, bedding and natural fractures. The fifth step is pressure drive monitoring and parameter adjustment. The monitoring and control module collects the pressure drive pressure, pulse peak value, pressure decay characteristics and injection volume in real time, and adjusts the high-energy gas release intensity, release interval and subsequent pumping parameters according to the pressure response. Step 6: Propionage and proppant. After the high-energy gas pressure drive is completed, the propioning fluid is injected into the formed fractures to allow the proppant to enter the fractures and maintain the fracture opening state after compression. Step 7: Displacement and drainage assistance. Displacement and drainage assistance fluid, nitrogen, carbon dioxide or gas-liquid composite medium are injected into the target pressure drive section to allow it to diffuse evenly along the fractures, promoting the desorption of adsorbed natural gas, the return of residual liquid and the drainage of rock cuttings. Step 8: Pressure stabilization and backflow control. Close or slightly open the backflow control valve group to allow the target reservoir section to enter the pressure stabilization and backflow stage. After the backflow is completed, the residual liquid, rock cuttings and free gas are gradually discharged through step-by-step pressure reduction, intermittent backflow or pump stop and start circulation. Step 9: Repeat the operation in segments. After the target pressure drive operation segment is completed, remove or dissolve the bridge plug, and repeat the above steps in the next target pressure drive operation segment until the pressure drive mining operation of all designed target pressure drive operation segments is completed.

[0013] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: The aforementioned pretreatment solution uses clean water as the base solution, and adds drag-reducing agent, clay stabilizer, rock fragment dispersant and surfactant to the base solution to obtain the solution. The mass ratio of drag-reducing agent, clay stabilizer, rock fragment dispersant and surfactant is 1:10:2:1 to 3; or / and the apparent viscosity of the pretreatment solution is 3 mPa·s to 10 mPa·s, and the pH value of the pretreatment solution is 6.5 to 8.0; or / and in the third step, the low discharge rate is 0.2 cubic meters / minute to 5.0 cubic meters / minute.

[0014] The drag-reducing agent is polyacrylamide, hydrolyzed polyacrylamide, or polyacrylamide emulsion, and the amount of drag-reducing agent added is 0.05% to 0.15% of the mass of the pre-flue; or / and, the clay stabilizer is potassium chloride, ammonium chloride, or organic quaternary ammonium salt, and the amount of clay stabilizer added is 0.5% to 2.0% of the mass of the pre-flue; or / and, the rock cuttings dispersant in the pre-flue is sodium lignosulfonate, polycarboxylate, or sodium polyacrylate, and the amount of rock cuttings dispersant added is 0.1% to 0.3% of the mass of the pre-flue; or / and, the surfactant in the pre-flue is sodium dodecylbenzenesulfonate, alkyl glycoside, or betaine, and the amount of surfactant added is 0.05% to 0.15% of the mass of the pre-flue.

[0015] The aforementioned sand-carrying fluid is a low-damage guar gum-based sand-carrying fluid, with water as the base liquid and hydroxypropyl guar gum added as a thickener. The amount of hydroxypropyl guar gum added is 0.15% to 0.35% of the base liquid mass; or / and, the apparent viscosity of the sand-carrying fluid is 20 mPa·s to 60 mPa·s, and the sand ratio is 8% to 18%; or / and, the proppant is composed of sand of multiple particle sizes, wherein 100-mesh to 70-mesh fine sand accounts for 10% to 20% of the proppant mass, 70-mesh to 40-mesh fine sand accounts for 30% to 40% of the proppant mass, and 40-mesh to 20-mesh medium sand accounts for 30% to 40% of the proppant mass; or / and, the proppant is preferably quartz sand or low-density coated sand.

[0016] The above-mentioned displacement and drainage aid fluid is prepared by adding surfactant, cosolvent, drainage aid, rock fragment dispersant and demulsifier to the base fluid. The mass ratio of surfactant, cosolvent, drainage aid, rock fragment dispersant and demulsifier is 5:8:3:2:2; or / and. The apparent viscosity of the displacement and drainage aid fluid is 2 mPa·s to 8 mPa·s, and the pH value is 6.5 to 8.0.

[0017] The surfactant in the aforementioned displacement and drainage aid is sodium dodecylbenzenesulfonate, alkyl glycoside, or betaine, and the amount of surfactant added is 0.1% to 0.4% of the mass of the displacement and drainage aid; or / and, the mutual solvent is ethanol, isopropanol, or ethylene glycol butyl ether, and the amount of mutual solvent added is 0.2% to 0.6% of the mass of the displacement and drainage aid; or / and, the drainage aid is a fluorocarbon surfactant or anionic / nonionic compound surfactant, and the amount of drainage aid added is 0.05% to 0.2% of the mass of the displacement and drainage aid; or / and, the rock fragment dispersant in the displacement and drainage aid is sodium lignosulfonate or polycarboxylate, and the amount of rock fragment dispersant added is 0.05% to 0.15% of the mass of the displacement and drainage aid; or / and, the demulsifier is polyoxyethylene polyoxypropylene ether or organosilicon demulsifier, and the amount of demulsifier added is 0.05% to 0.15% of the mass of the displacement and drainage aid.

[0018] The second technical solution of the present invention is achieved through the following measures: an apparatus for unconventional oil and gas reservoir development using a high-energy gas pressure drive integrated method, comprising a bridge plug isolation segment module, a high-energy gas pressure drive module, a high-energy gas supply component, and a wellhead control component. The upper end of the wellhead control component and the high-energy gas supply component are connected together by a pipeline. A casing is connected to the lower end of the wellhead control component. The casing is located within the rock formation. The bridge plug isolation segment module and the high-energy gas pressure drive module are installed sequentially from top to bottom inside the casing.

[0019] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: The above also includes a pre-flush fluid storage tank, a sand-carrying fluid storage tank, and a displacement-assisted drainage fluid storage tank arranged from left to right. Each of the pre-flush fluid storage tank, sand-carrying fluid storage tank, and displacement-assisted drainage fluid storage tank has a discharge end at its lower part and an inlet end at the upper part of the wellhead control assembly. The discharge end of the pre-flush fluid storage tank and the inlet end of the wellhead control assembly are connected together by an inlet pipe. A connecting pipe is connected between the discharge end of the sand-carrying fluid storage tank and the inlet pipe. A connecting pipe is also connected between the discharge end of the displacement-assisted drainage fluid storage tank and the inlet pipe. A high-pressure pump assembly is installed on the inlet pipe between the displacement-assisted drainage fluid storage tank and the wellhead control assembly. Control valves are installed on the connecting pipe and the inlet pipe near the discharge end of the pre-flush fluid storage tank.

[0020] The aforementioned chemical metering and dosing assembly is installed on the feed pipe between the high-pressure pumping assembly and the displacement fluid storage tank; or / and, a bypass pipe is connected in parallel to the feed pipe between the high-pressure pumping assembly and the wellhead control assembly, and at least one multi-channel switching valve assembly is installed on the bypass pipe and the corresponding feed pipe; or / and, a gas-liquid separation assembly and a cuttings collection assembly are located outside the wellhead control assembly, with a discharge end at the top of the wellhead control assembly, feed ends at the middle of the gas-liquid separation assembly and the cuttings collection assembly, and a discharge end at the bottom of the gas-liquid separation assembly, and the discharge end of the wellhead control assembly and The feed end of the gas-liquid separation component is connected to the discharge end through the discharge pipe. The discharge end of the gas-liquid separation component and the feed end of the cuttings collection component are connected to each other through pipelines. A control valve is installed on the discharge pipe. Or / and, a monitoring and control module is located outside the wellhead control component. A pressure transmitter and a flow meter are installed on the feed pipe and the discharge pipe, respectively. The signal output terminals of the pressure transmitter and the flow meter are electrically connected to the signal input terminal of the monitoring and control module through wires. The signal output terminal of the monitoring and control module is electrically connected to the signal input terminals of the high-pressure pump injection component and the multi-channel switching valve group through wires.

[0021] The aforementioned high-pressure pumping assembly is a high-pressure pump; and / or the chemical metering and adding assembly is a chemical metering and adding tank or a chemical metering tank; and / or the multi-channel switching valve group includes at least one control valve; and / or the gas-liquid separation assembly is a gas-liquid separator; and / or the cuttings collection assembly is a cuttings collection tank; and / or the monitoring and control module is a PLC controller; and / or the bridge plug isolation segment module is a soluble bridge plug; and / or the high-energy gas pressure drive module is a high-energy gas generator; and / or the wellhead control assembly is a Christmas tree or production tubing.

[0022] This invention primarily targets organic-rich mudstone and shale in unconventional oil and gas reservoirs. It establishes a pressure-driven operation section within the target reservoir through bridging plugs, combining pre-positioned fluid to reduce drag and prevent swelling, proppant-carrying fluid fracture support, displacement fluid to promote flowback, and high-energy gas pressure-driven fracture expansion. This achieves integrated operations of segmented pressure-driven reservoir operation, fracture connectivity, gas desorption, cuttings removal, and residual fluid flowback. It is suitable for permeability enhancement of low-permeability, low-pressure, and highly heterogeneous mudstone and shale reservoirs, shale gas and coalbed methane extraction, and pressure-driven production in unconventional oil and gas resource development. It significantly improves the long-term conductivity of fracture and cleavage systems and oil and gas extraction efficiency, providing a reliable technical means for the efficient development of unconventional oil and gas resources. Attached Figure Description

[0023] Appendix Figure 1 This is a process flow diagram of the present invention.

[0024] The codes in the attached diagram are as follows: 1 is the bridge plug isolation segment module, 2 is the high-energy gas pressure drive module, 3 is the high-energy gas supply component, 4 is the wellhead control component, 5 is the casing, 6 is the pre-flush fluid tank, 7 is the sand-carrying fluid tank, 8 is the displacement and drainage fluid tank, 9 is the feed pipe, 10 is the connecting pipe, 11 is the high-pressure pump injection component, 12 is the control valve, 13 is the chemical agent metering and addition component, 14 is the bypass pipe, 15 is the gas-liquid separation component, 16 is the cuttings collection component, 17 is the discharge pipe, and 18 is the monitoring and control module. Detailed Implementation

[0025] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid.

[0026] In this invention, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0027] The present invention will be further described below with reference to embodiments and accompanying drawings: Example 1: This high-energy gas pressure drive integrated unconventional oil and gas reservoir development method is carried out according to the following steps: The first step is segmented design, which determines the location and segment length of the target pressure drive operation section based on the bedding, cleavage development, rock mass integrity, oil and gas content, and wellbore stability of organic-rich mudstone and shale. The second step is bridge plug setting. The bridge plug is sent into the preset position inside the casing 5 for sealing, thereby completing the bridge plug setting and forming a relatively independent target pressure drive operation section. The third step is to test the seal and inject pre-flush fluid. Pre-flush fluid is injected into the target pressure drive section at a low rate to test the seal. After confirming that the pressure remains stable, pre-flush fluid is injected to reduce flow resistance, inhibit clay expansion, disperse rock cuttings and establish an initial seepage channel. The fourth step is high-energy gas focusing pressure drive. The high-energy gas pressure drive module 2 is started, so that the high-energy gas is released through focusing and acts on the target pressure drive operation section. Under the action of transient or staged pressure pulses, crack initiation and expansion are induced, and multi-scale small cracks are connected with the original cleavage, bedding and natural fractures. The fifth step is pressure drive monitoring and parameter adjustment. The monitoring and control module 18 collects the pressure drive pressure, pulse peak value, pressure decay characteristics and injection volume in real time, and adjusts the high-energy gas release intensity, release interval and subsequent pumping parameters according to the pressure response. Step 6: Propionage and proppant. After the high-energy gas pressure drive is completed, the propioning fluid is injected into the formed fractures to allow the proppant to enter the fractures and maintain the fracture opening state after compression. Step 7: Displacement and drainage assistance. Displacement and drainage assistance fluid, nitrogen, carbon dioxide or gas-liquid composite medium are injected into the target pressure drive section to allow it to diffuse evenly along the fractures, promoting the desorption of adsorbed natural gas, the return of residual liquid and the drainage of rock cuttings. Step 8: Pressure stabilization and backflow control. Close or slightly open the backflow control valve group to allow the target reservoir section to enter the pressure stabilization and backflow stage. After the backflow is completed, the residual liquid, rock cuttings and free gas are gradually discharged through step-by-step pressure reduction, intermittent backflow or pump stop and start circulation. Step 9: Repeat the operation in segments. After the target pressure drive operation segment is completed, remove or dissolve the bridge plug, and repeat the above steps in the next target pressure drive operation segment until the pressure drive mining operation of all designed target pressure drive operation segments is completed.

[0028] In the seventh step, displacement fluid, nitrogen, carbon dioxide, or a gas-liquid composite medium can be injected into the target pressure-driven section as needed, with the proportions depending on the reservoir. Generally, the displacement fluid accounts for 20% to 40% of the volume, nitrogen accounts for 20% to 35%, and carbon dioxide accounts for 30% to 60% of the volume; or, the volume ratio of displacement fluid, nitrogen, and carbon dioxide is 3:3:4. The gas-liquid composite medium is a known and commonly used medium, which can be a mixture of carbon dioxide and liquid; or it can be a mixture of liquid nitrogen (LN2) in the gas phase, which is completely vaporized by heating upon entry into the ground, and liquid phases such as slickwater, guar gum pretreatment liquid, active water, and drainage aid base liquid.

[0029] The above embodiment 1 can be further optimized and / or improved according to actual needs: As needed, the pretreatment fluid is prepared by adding drag-reducing agent, clay stabilizer, rock fragment dispersant and surfactant to the base fluid, with the mass ratio of drag-reducing agent, clay stabilizer, rock fragment dispersant and surfactant being 1:10:2:1 to 3; or / and, the apparent viscosity of the pretreatment fluid is 3 mPa·s to 10 mPa·s, and the pH value of the pretreatment fluid is 6.5 to 8.0; or / and, in the third step, the low discharge rate is 0.2 cubic meters / minute to 5.0 cubic meters / minute.

[0030] As needed, the drag-reducing agent is polyacrylamide, hydrolyzed polyacrylamide, or polyacrylamide emulsion, and the amount of drag-reducing agent added is 0.05% to 0.15% of the mass of the pre-flue; or / and, the clay stabilizer is potassium chloride, ammonium chloride, or organic quaternary ammonium salt, and the amount of clay stabilizer added is 0.5% to 2.0% of the mass of the pre-flue; or / and, the rock cuttings dispersant in the pre-flue is sodium lignosulfonate, polycarboxylate, or sodium polyacrylate, and the amount of rock cuttings dispersant added is 0.1% to 0.3% of the mass of the pre-flue; or / and, the surfactant in the pre-flue is sodium dodecylbenzenesulfonate, alkyl glycoside, or betaine, and the amount of surfactant added is 0.05% to 0.15% of the mass of the pre-flue.

[0031] As required, the sand-carrying fluid adopts a low-damage guar gum-based sand-carrying fluid, with water as the base liquid and hydroxypropyl guar gum added as a thickener, the amount of hydroxypropyl guar gum added being 0.15% to 0.35% of the base liquid mass; or / and, the apparent viscosity of the sand-carrying fluid is 20 mPa·s to 60 mPa·s, and the sand ratio is 8% to 18%; or / and, the proppant is composed of sand of multiple particle sizes, wherein 100 mesh to 70 mesh fine sand accounts for 10% to 20% of the proppant mass, 70 mesh to 40 mesh fine sand accounts for 30% to 40% of the proppant mass, and 40 mesh to 20 mesh medium sand accounts for 30% to 40% of the proppant mass; or / and, the proppant is preferably quartz sand or low-density coated sand.

[0032] As needed, the displacement and drainage aid fluid is prepared by adding surfactant, co-solvent, drainage aid, rock fragment dispersant and demulsifier to the base fluid as a base fluid. The mass ratio of surfactant, co-solvent, drainage aid, rock fragment dispersant and demulsifier is 5:8:3:2:2; or / and. The apparent viscosity of the displacement and drainage aid fluid is 2 mPa·s to 8 mPa·s, and the pH value is 6.5 to 8.0.

[0033] As needed, the surfactant in the displacement and drainage aid is sodium dodecylbenzenesulfonate, alkyl glycoside, or betaine, and the amount of surfactant added is 0.1% to 0.4% of the mass of the displacement and drainage aid; or / and, the mutual solvent is ethanol, isopropanol, or ethylene glycol butyl ether, and the amount of mutual solvent added is 0.2% to 0.6% of the mass of the displacement and drainage aid; or / and, the drainage aid is a fluorocarbon surfactant or anionic / nonionic compound surfactant, and the amount of drainage aid added is 0.05% to 0.2% of the mass of the displacement and drainage aid; or / and, the rock fragment dispersant in the displacement and drainage aid is sodium lignosulfonate or polycarboxylate, and the amount of rock fragment dispersant added is 0.05% to 0.15% of the mass of the displacement and drainage aid; or / and, the demulsifier is polyoxyethylene polyoxypropylene ether or organosilicon demulsifier, and the amount of demulsifier added is 0.05% to 0.15% of the mass of the displacement and drainage aid.

[0034] Example 2, as shown in the attached document Figure 1As shown, the device for unconventional oil and gas reservoir development using an integrated high-energy gas pressure drive method includes a bridge plug isolation module 1, a high-energy gas pressure drive module 2, a high-energy gas supply component 3, and a wellhead control component 4. The upper end of the wellhead control component 4 is connected to the high-energy gas supply component via a pipeline. A casing 5 is connected to the lower end of the wellhead control component 4. The casing 5 is located within the rock formation, and the bridge plug isolation module 1 and the high-energy gas pressure drive module 2 are installed sequentially from top to bottom inside the casing 5. The high-energy gas supply component 3 is a known and commonly used component and can be a high-pressure gas tank or a high-pressure gas cylinder.

[0035] The above embodiment 2 can be further optimized and / or improved according to actual needs: As attached Figure 1 As shown, it also includes a pre-flush fluid storage tank 6, a sand-carrying fluid storage tank 7, and a displacement-assisted drainage fluid storage tank 8 arranged from left to right. The lower parts of the pre-flush fluid storage tank 6, the sand-carrying fluid storage tank 7, and the displacement-assisted drainage fluid storage tank 8 are respectively provided with discharge ends, and the upper part of the wellhead control component 4 is provided with a feed end. The discharge end of the pre-flush fluid storage tank 6 and the feed end of the wellhead control component 4 are connected together by a feed pipe 9. A connecting pipe 10 is connected between the discharge end of the sand-carrying fluid storage tank 7 and the feed pipe 9. A connecting pipe 10 is connected between the discharge end of the displacement-assisted drainage fluid storage tank 8 and the feed pipe 9. A high-pressure pump injection component 11 is installed on the feed pipe 9 between the displacement-assisted drainage fluid storage tank 8 and the wellhead control component 4. Control valves 12 are installed on the connecting pipe 10 and the feed pipe 9 near the discharge end of the pre-flush fluid storage tank 6, respectively.

[0036] As attached Figure 1As shown, a chemical metering and adding component 13 is installed on the feed pipe 9 between the high-pressure pumping assembly 11 and the displacement fluid storage tank 8; or / and, a bypass pipe 14 is connected in parallel on the feed pipe 9 between the high-pressure pumping assembly 11 and the wellhead control assembly 4, and at least one multi-channel switching valve group is installed on the bypass pipe 14 and the corresponding feed pipe 9; or / and, a gas-liquid separation assembly 15 and a cuttings collection assembly 16 are located outside the wellhead control assembly 4, the upper part of the wellhead control assembly 4 is provided with a discharge end, the middle parts of the gas-liquid separation assembly 15 and the cuttings collection assembly 16 are respectively provided with feed ends, and the lower part of the gas-liquid separation assembly 15 is provided with a discharge end. The feed end and the feed end of the gas-liquid separation component 15 are connected together via the discharge pipe 17. The discharge end of the gas-liquid separation component 15 and the feed end of the cuttings collection component 16 are connected together via pipelines. A control valve 12 is installed on the discharge pipe 17; and / or, a monitoring and control module 18 is located outside the wellhead control component 4. A pressure transmitter and a flow meter are installed on the feed pipe 9 and the discharge pipe 17, respectively. The signal output terminals of the pressure transmitter and the flow meter are electrically connected to the signal input terminals of the monitoring and control module 18 via wires. The signal output terminals of the monitoring and control module 18 are electrically connected to the signal input terminals of the high-pressure pump injection component 11 and the multi-channel switching valve group via wires. The high-pressure pump injection component 11 is a known and commonly used component and can be a variable frequency high-pressure pump.

[0037] As needed, the high-pressure injection assembly 11 is a high-pressure pump; and / or the chemical metering and addition assembly 13 is a chemical metering and addition tank or a chemical metering tank; and / or the multi-channel switching valve group includes at least one control valve 12; and / or the gas-liquid separation assembly 15 is a gas-liquid separator; and / or the cuttings collection assembly 16 is a cuttings collection tank; and / or the monitoring and control module 18 is a PLC controller; and / or the bridge plug isolation segment module 1 is a soluble bridge plug; and / or the high-energy gas pressure drive module 2 is a high-energy gas generator; and / or the wellhead control assembly 4 is a Christmas tree or production tubing. The high-energy gas generator is a known and commonly used through-tubing high-energy gas fracturing gas generator; the high-energy gas generator can also be a shaped charge fracturing tool with application number 2025101059123.

[0038] Example 3: This high-energy gas pressure drive integrated unconventional oil and gas reservoir development method is carried out according to the following steps: (1) Target rock segment selection and segment design Low-permeability, organic-rich shale reservoirs were selected as the target for stimulation. The location of the target hydraulic displacement section was determined based on the degree of bedding and cleavage development, rock mass integrity, hydrocarbon content, and wellbore stability. Strongly fractured zones, severely flaking sections, and sections with unstable wellbore walls were preferably avoided. In this embodiment, the target hydraulic displacement section was 10m long, and the hydraulic displacement was carried out in stages, either from deep to shallow or from far to near.

[0039] (2) Bridge plug setting and pressure drive section formation The bridge plug sealing segment module 1 is inserted into a preset position within the casing 5. After setting, the flexible sealing component expands radially and fits against the inner wall of the casing 5, while the anchoring component simultaneously forms an axial fixation. In this embodiment, the axial length of the bridge plug body is 650 mm, and the initial outer diameter is 0.85 times the inner diameter of the casing 5; the axial length of the flexible sealing component is 180 mm, and the radial expansion is 12 mm; the anchoring component adopts a multi-point distributed wide-tooth structure with a tooth height of 1.2 mm and an axial contact length of 80 mm; the setting pressure is 8 MPa, and the pressure difference is 25 MPa. After the bridge plug is set, a relatively independent pressure-driven operating space is formed within the target section.

[0040] (3) Seal verification and pre-filling fluid injection After the bridge plug is set, a pre-filled fluid is injected at a rate of 0.3 m³ / min for sealing verification. The verification pressure is 6 MPa. If the pressure remains stable after 15 minutes, the seal is considered reliable. Subsequently, a low-damage pre-filled fluid is injected. This pre-filled fluid uses water as a base liquid and contains drag-reducing agent, clay stabilizer, rock cuttings dispersant, and surfactant in a mass ratio of 1:10:2:3. Specifically, the drag-reducing agent is partially hydrolyzed polyacrylamide at 0.08%; the clay stabilizer is potassium chloride at 1.0%; the rock cuttings dispersant is sodium lignosulfonate at 0.16%; and the surfactant is betaine at 0.08%. The pre-filled fluid has an apparent viscosity of 6 mPa·s and a pH of 7.2, and is used to reduce flow resistance, inhibit clay swelling, disperse rock cuttings, and establish initial seepage channels.

[0041] (4) High-energy gas focusing pressure drive After the pre-fluid injection is completed, the high-energy gas pressure drive module 2 is activated, causing the high-energy gas to be concentrated and applied to the target section borehole wall and surrounding rock mass along a preset direction via the energy-concentrating release component. The high-energy gas generating component has an axial length of 900 mm and an outer diameter that is 0.72 times the inner diameter of the pressure drive string; the target pressure drive pressure is 20 MPa; the heat-resistant lining thickness is 6 mm, and the buffer cavity volume is 0.8 times the volume of the energy-concentrating cavity; the unidirectional anti-backflow component has a filter pore size of 1.0 mm. During the pressure drive process, multiple low-damage pulse release methods are used to induce cracking and expansion of the shale under transient pressure disturbance, and to promote the connection between small cracks and primary cleavage, bedding, and natural fractures.

[0042] (5) Sand-carrying fluid injection and fracture support After high-energy gas-driven pressure displacement is completed, the proppant-carrying stage begins, in which proppant-carrying fluid is injected into the target rock section. The proppant-carrying fluid uses water as the base liquid, with 0.25% hydroxypropyl guar gum added as a thickener, and supplemented with drag-reducing agents, rock fragment dispersants, and surfactants. The apparent viscosity of the proppant-carrying fluid is 40 mPa·s, the sand ratio is 12%, and ammonium persulfate is used as the breaker. The proppant adopts a multi-particle size combination system, with 15% 100–70 mesh silt, 35% 70–40 mesh fine sand, and 35% 40–20 mesh medium sand. Low-density coated sand is preferred as the proppant. After the proppant-carrying fluid enters the fracture, it distributes the proppant throughout the fracture area, maintaining the post-compression fracture open state.

[0043] (6) Displacement and drainage fluid injection After the sand-carrying support is completed, a displacement and drainage aid fluid is injected into the target section. This displacement and drainage aid fluid uses water as the base liquid and consists of a surfactant, a mutual solvent, a drainage aid, a cuttings dispersant, and a demulsifier in a mass ratio of 5:8:3:2:2. Specifically, the surfactant is an alkyl glycoside, used at 0.2%; the mutual solvent is ethylene glycol butyl ether, used at 0.4%; the drainage aid is an anionic / nonionic compound surfactant, used at 0.1%; the cuttings dispersant is a polycarboxylate, used at 0.1%; and the demulsifier is polyoxyethylene polyoxypropylene ether, used at 0.08%. The apparent viscosity of the displacement and drainage aid fluid is 5 mPa·s, and the pH value is 7.0. It is used to reduce the interfacial tension of the residual liquid, mitigate the water-locking effect, promote the desorption of adsorbed natural gas, and improve the conditions for cuttings return.

[0044] (7) Pressure stabilization and intermittent backflow After completing pressure driving, sand-carrying support, and displacement-assisted drainage, the return valve group is closed or kept at a small opening to allow the target section to enter the pressure stabilization and settling stage, which lasts for 12 hours. After settling, a combination of stepped pressure reduction and intermittent return drainage is used for return drainage control, with each pressure difference variation being 0.8 MPa and the intermittent return drainage cycle being 30 minutes. When the return cuttings concentration increases or the return drainage pressure fluctuates significantly, the return drainage pressure difference is reduced and the stop time is extended; when the cuttings concentration decreases and the return drainage volume steadily increases, the return drainage intensity is gradually increased.

[0045] (8) Monitoring results and effect analysis During construction, the monitoring and control module 18 collected real-time data on pressure, pulse peak value, pressure decay characteristics, backflow volume, backflow liquid volume, gas composition, and rock cuttings concentration. Results showed that the pressure remained stable during the bridge plug sealing stage; the pressure curve showed a peak and rapid decay during the high-energy gas pressure drive stage, indicating that the shale fracturing had occurred; during the backflow stage, the backflow volume gradually increased, and the rock cuttings concentration first increased and then decreased, indicating that residual liquid, rock cuttings, and free gas were gradually discharged. Through the above implementation process, segmented isolation of the target section, pre-treatment with pre-filled liquid, high-energy gas focused pressure drive, fracture support, displacement-assisted backflow, and post-pressure backflow control can be achieved, improving fracture connectivity and long-term conductivity.

[0046] The purpose of this invention is to address existing problems in the fracturing and permeation enhancement and pressure drive production of organic-rich shale in unconventional oil and gas reservoirs. These problems include insufficient adaptability of hydraulic fracturing to such reservoirs, rapid dispersion of gas-driven media along dominant cleavage or natural fractures, poor synergy between bridge plug sealing and pressure drive production processes, inadequate control of cuttings drainage and residual fluid return, and difficulty in maintaining post-fracturing fracture conductivity. This invention uses bridge plug sealing to precisely control the target rock section in segments, concentrating the pressure drive medium on the area to be modified and reducing ineffective dispersion of the medium along non-target sections or existing low-resistivity channels. Combined with the drag reduction, swelling prevention, and cuttings dispersion effects of pre-flush fluid, it establishes an initial seepage channel for subsequent high-energy gas pressure drive. Finally, it utilizes high-energy gas condensation combustion to induce reservoir fracturing and homogenize the flow. The expansion and connection of fracture and cleavage systems increase the complexity of the fracture network. Propionate is transported into the fractures through proppant-carrying fluid to maintain the open state of the fractures after compression. This is combined with displacement fluid or gas-liquid composite media to promote the desorption of adsorbed gas, efficient return of residual liquid, and rock cuttings. After compression, pressure control methods such as pressure stabilization, step-by-step pressure reduction, intermittent return, or pump stop-start cycle are used to gradually remove residual liquid, rock cuttings, and free gas. This achieves integrated and coordinated operation of reservoir segmented compression, fracture connectivity, gas desorption, rock cuttings, and residual liquid return within the same unit and process flow, significantly improving the long-term conductivity of the fracture-cleavage system and the efficiency of oil and gas extraction, and providing a reliable technical means for the efficient development of unconventional oil and gas resources.

[0047] The technical solution of this invention can also be composed of the following modules from the prior art, including a bridge plug isolation segment module 1, a high-energy gas pressure drive module 2, a pump injection and fluid preparation module, a monitoring and control module 18, and a post-pressure stabilization and runoff control module. The bridge plug isolation segment module 1 is used to mechanically isolate the target rock section within the casing 5, concentrating the pressure drive medium on the area to be modified; the high-energy gas pressure drive module 2 is used to inject high-energy gas into the target reservoir section; the pump injection and fluid preparation module is used to prepare and inject pre-flush fluid, proppant-carrying fluid, and displacement and runoff aid fluid sequentially according to the construction stages; the monitoring and control module 18 is used to monitor pressure, discharge rate, and cuttings concentration in real time during bridge plug isolation, pump injection and fluid preparation, high-energy gas pressure drive, and post-pressure runoff, and adjust pump injection parameters, high-energy gas release intensity, and runoff regime based on the monitoring results to improve the safety and controllability of the pressure drive operation. The post-pressure stabilization and runoff control module is used to implement pressure stabilization, step-wise pressure reduction, intermittent runoff, or pump stop-start cycle control after pressure driving, so that residual liquid, rock cuttings, and free gas are gradually discharged. This invention achieves integrated operation of organic-rich shale oil and gas reservoir development within the same device and process flow through the synergistic effects of bridge plug isolation, high-energy gas pressure driving, pump injection and fluid preparation, monitoring and control, and post-pressure stabilization and runoff control, thereby improving oil and gas extraction efficiency.

[0048] (1) Bridge plug isolation segment module The bridge plug packer segmented module may include a bridge plug body, a setting assembly, a flexible sealing assembly, an anchoring assembly, a segmented positioning assembly, and a release or drilling assembly. The bridge plug body forms a mechanical packer within the casing 5, creating an independent pressure-driven operating section. It employs a drillable, soluble, or recyclable structure, with an axial length of 500–800 mm and an initial outer diameter 0.80–0.90 times the inner diameter of the casing 5, ensuring smooth insertion of the bridge plug and effective setting after setting. The setting assembly delivers the bridge plug to a preset position and completes the setting. The flexible sealing assembly is located on the outer periphery of the bridge plug body, used for radial expansion and tight contact with the inner wall of the casing 5 to form an effective sealing boundary. It adopts a low-setting-pressure expansion rubber sleeve structure, with an axial length of 120–… The sealing element has a diameter of 220mm and a radial expansion of 8–18mm. Its outer surface is equipped with micro-textured or circumferential sealing teeth to adapt to the irregular pore wall characteristics of shale reservoirs. The anchoring assembly improves the axial stability of the bridge plug during pressure drive, employing a multi-point distributed wide-tooth structure with a tooth height of 0.8–1.8mm and an axial contact length of 50–100mm to reduce localized reservoir damage and improve anti-slip capability. The segmented positioning assembly determines the setting position based on bedding, cleavage development, rock mass integrity, and hydrocarbon content. The unsealing or drilling assembly releases the seal after operation. When applied to a 5-tube casing wellbore, the setting pressure is 8–20MPa, and the designed pressure differential is 10–30MPa. This structure achieves reliable sealing, providing precise segmented control for integrated high-energy gas pressure drive operations.

[0049] (2) High-energy gas pressure drive module The high-energy gas pressure drive module may include a high-energy gas generating component, a focused release component, a pulse control component, a thermal insulation buffer component, a one-way backflow prevention component, a pressure monitoring component, and a safety pressure relief component. The high-energy gas generating component is located within the pressure drive tubing or connected to it via a surface high-pressure manifold. It provides transient or phased high-pressure gas to the target rock segment, with an axial length of 600–1200 mm and an outer diameter 0.65–0.80 times the inner diameter of the pressure drive tubing. The generated or output pressure range is 10–30 MPa. The focused release component is located in the target release section of the pressure drive tubing and includes a focused cavity, a directional release orifice, and a guide nozzle. It concentrates and releases high-energy gas along a preset direction to the pore wall of the rock formation and the surrounding rock mass, inducing multi-scale small fractures in the reservoir and promoting the interaction of these small fractures with primary cleavage, bedding, and other features. The system incorporates natural fracture connectivity. The pulse control component controls the number of high-energy gas releases, the release interval, and the release intensity, employing multiple low-damage pulse pressure drives to reduce excessive rock fragmentation and the generation of large amounts of rock debris. A heat-insulating buffer component reduces localized thermal and mechanical shocks from high-temperature, high-pressure gas to the pressure drive string, bridge plug seals, and borehole walls. This component includes a heat-resistant lining, a buffer chamber, and an impact diffuser. The heat-resistant lining thickness is 4–10 mm. The buffer chamber volume is 0.5–1.2 times the volume of the energy-concentrating chamber. A one-way anti-backflow component prevents rock debris, residual liquid, and backflow gas from re-entering the high-energy gas generating component. The filter aperture is 0.5–1.5 mm. A pressure monitoring component collects real-time pressure changes within the pressure drive string and the target pressure drive operating section. A safety pressure relief component provides pressure relief protection when the pressure drive pressure exceeds a preset threshold. The high-energy gas pressure drive module 2 described above can induce the formation of a multi-scale, relatively uniform network of small fractures in the reservoir, and promote the effective connection between small fractures and primary cleavage, bedding and natural fissures, providing a good channel for subsequent sand-carrying support, displacement and drainage and gas desorption.

[0050] (3) Pump injection and liquid preparation module The pump-injection and preparation module may include a storage and preparation unit, a chemical metering and addition unit 13, a mixing and homogenizing unit, a pre-fluid injection unit, a sand-carrying support unit, a displacement and drainage unit, a gas-liquid mixing and foam generation unit, a high-pressure pumping unit 11, a multi-channel switching valve group, and a monitoring and control unit. The storage and preparation unit is used to store the pre-fluid base liquid, sand-carrying base liquid, displacement and drainage base liquid, chemical agents, proppant, and displacement liquid, respectively.

[0051] The chemical metering and adding component 13 is used to quantitatively add drag-reducing agents, clay stabilizers, rock chip dispersants, surfactants, drainage aids, degumming agents, demulsifiers, and mutual solvents according to the construction stage. The mixing and homogenizing component is used to fully mix the base liquid, chemical agents, and proppant to form a working fluid with stable concentration and uniform sand ratio.

[0052] The pre-fluid injection unit is used to inject a low-damage pre-fluid into the target reservoir section before high-energy gas pressure driving to achieve drag reduction, swelling prevention, cuttings dispersion, and the establishment of initial seepage channels. Taking organic-rich shale oil and gas reservoirs as an example, the pre-fluid uses water as the base fluid and is composed of drag-reducing agents, clay stabilizers, cuttings dispersants, and surfactants in a mass ratio of 1:10:2:1~3. Among them, the drag-reducing agent is polyacrylamide, partially hydrolyzed polyacrylamide, or polyacrylamide emulsion, with a dosage of 0.05%~0.15%; the clay stabilizer is potassium chloride, ammonium chloride, or organic quaternary ammonium salt, with a dosage of 0.5%~2.0%; the cuttings dispersant is sodium lignosulfonate, polycarboxylate, or sodium polyacrylate, with a dosage of 0.1%~0.3%; and the surfactant is sodium dodecylbenzenesulfonate, alkyl glycosides, or betaine, with a dosage of 0.05%~0.15%. The apparent viscosity of the pre-fluid is 3–10 mPa·s, and the pH value is 6.5–8.0, in order to adapt to the characteristics of this type of oil and gas reservoir, which is highly water-sensitive, has well-developed cleavage, and is prone to producing rock cuttings.

[0053] The proppant-carrying unit is used to prepare and inject proppant-carrying fluid, allowing the proppant to enter the mudstone fractures formed by high-energy gas pressure driving, thereby maintaining the open state of the fractures after pressure. The proppant-carrying fluid adopts a low-damage guar gum-based proppant-carrying fluid system, with water as the base liquid, and 0.15%–0.35% hydroxypropyl guar gum added as a thickener, along with drag-reducing agents, cuttings dispersants, and surfactants. The apparent viscosity of the proppant-carrying fluid is 20–60 mPa·s, the sand ratio is 8%–18%, and the breaker is ammonium persulfate or an enzyme-based breaker. The proppant adopts a multi-particle-size combination system, in which 100–70 mesh silt accounts for 10%–20%, 70–40 mesh fine sand accounts for 30%–40%, and 40–20 mesh medium sand accounts for 30%–40%. The proppant is preferably quartz sand or low-density coated sand to adapt to the characteristics of this type of reservoir, such as large differences in fracture size, easy fracture closure, and easy blockage by cuttings.

[0054] The displacement and drainage unit is used to inject displacement and drainage fluid into fracture and cleavage systems to promote the desorption of adsorbed gases, the return of residual liquids, and the drainage of cuttings. Taking organic-rich shale oil and gas reservoirs as an example, the displacement and drainage fluid uses water as the base fluid and is composed of surfactants, mutual solvents, drainage aids, cuttings dispersants, and demulsifiers in a mass ratio of 5:8:3:2:2. Among them, the surfactant is sodium dodecylbenzenesulfonate, alkyl glycosides, or betaine, with a dosage of 0.1% to 0.4%; the mutual solvent is ethanol, isopropanol, or ethylene glycol butyl ether, with a dosage of 0.2% to 0.6%; the drainage aid is a fluorocarbon surfactant or anionic / nonionic compound surfactant, with a dosage of 0.05% to 0.2%; the cuttings dispersant is sodium lignosulfonate or polycarboxylate, with a dosage of 0.05% to 0.15%; and the demulsifier is polyoxyethylene polyoxypropylene ether or organosilicon demulsifier, with a dosage of 0.05% to 0.15%. The apparent viscosity of the displacement fluid is 2–8 mPa·s, and the pH value is 6.5–8.0, in order to reduce the interfacial tension of the residual liquid, mitigate the water-locking effect, and reduce the adverse effects of rock debris agglomeration on fracture conductivity.

[0055] The gas-liquid mixing and foam generation unit is used to form a gas-liquid composite pressure drive medium or foam to replace the auxiliary discharge medium. The high-pressure pumping assembly 11 is used to pump different working fluids into the target pressure drive operation section according to preset pressure and discharge rate. The multi-channel switching valve group is used to realize rapid switching between different media. The monitoring and control assembly is used to monitor the pumping parameters in real time and make intelligent adjustments based on the pressure response.

[0056] (4) Monitoring and control module The monitoring and control module includes an injection monitoring component, a target pressure-driven section monitoring component, a backflow monitoring component, a safety pressure relief component, and a linkage control component. The injection monitoring component is installed on the pump injection and dispensing module, the high-energy gas pressure-driven module 2, and the high-pressure manifold. It is used to acquire in real time the injection pressure, flow rate, temperature, sand ratio, and gas-liquid ratio parameters of the pre-fluid, sand-carrying fluid, displacement-aiding fluid, gas-liquid composite medium, and high-energy gas. The target pressure-driven section monitoring component is used to monitor the pressure response, pulse pressure peak value, and pressure decay characteristics within the target section formed by the bridge plug seal, to determine the bridge plug seal status and fracture propagation. The pressure monitoring range is 0–80 MPa, preferably 0–50 MPa. The sampling frequency during the high-energy gas pulse phase is no less than 100Hz. The backflow monitoring component monitors the backflow volume, backflow liquid volume, gas composition, cuttings concentration, and backflow pressure during the backflow process. The cuttings concentration monitoring range is 0.01–20 g / L to identify risks of cuttings inrush, residual liquid retention, and fracture blockage. The safety pressure relief component includes a pressure relief valve, a buffer tank, and alarm interlocks, used for pressure relief protection when the manifold pressure or target section pressure exceeds 1.1–1.5 times the design working pressure. The linkage control component adjusts the pump injection rate, chemical agent dosage, sand-carrying liquid sand ratio, high-energy gas release intensity, and backflow pressure differential based on monitoring data. Through the above structure, bridge plug sealing verification, pressure drive response identification, cuttings backflow monitoring, and abnormal overpressure protection can be achieved, improving the safety and controllability of high-energy gas pressure drive operations.

[0057] (5) Post-pressurization stabilization and backflow control module The post-pressure stabilization and backflow control module may include a backflow valve assembly, a stepped pressure reduction component, an intermittent backflow component, a gas-liquid separation component 15, a cuttings collection component 16, and a backflow monitoring component. The backflow valve assembly is connected to the pressure drive string and is used to control the target section from a closed state to a backflow state after high-energy gas pressure drive, proppant support, and displacement-assisted backflow are completed. The stepped pressure reduction component includes a throttle valve, a back pressure valve, and a pressure regulator, used to gradually reduce the pressure of the target section according to a preset pressure difference, avoiding sudden cuttings surges and proppant backflow caused by large instantaneous pressure differences during backflow. The flow or fissure blockage; the intermittent backflow assembly is used to alternate between backflow and stopflow in the target section by periodically opening and closing the backflow valve or adjusting the opening of the throttle valve, so as to promote the gradual discharge of residual liquid, rock cuttings and free gas; the gas-liquid separation assembly 15 is used to separate the natural gas, carbon dioxide, nitrogen and residual liquid in the backflow; the rock cuttings collection assembly 16 is used to settle, filter or cyclone separate the rock cuttings in the backflow liquid or gas-liquid mixture; the backflow monitoring assembly is used to monitor the backflow pressure, backflow gas volume, backflow liquid volume, gas composition and rock cuttings concentration.

[0058] Unlike conventional oil and gas reservoirs that require rapid flowback after compression, the above-mentioned modules are adapted to the characteristics of organic-rich mudstone and shale in unconventional oil and gas reservoirs. After compression, the flowback valve group is first closed for pressure stabilization and holding. When it is necessary to control the pressure of the target section, the flowback valve group can be kept at a small opening for pressure limiting and holding, with a holding time of 6–24 hours. This allows high-energy gases, carbon dioxide, nitrogen, or displacement fluids to continue to diffuse in the fracture and cleavage system, promoting the desorption of adsorbed gases. Subsequently, step-down pressure flowback is carried out, with each pressure difference change ranging from 0.5 to 1.0 MPa; the intermittent flowback cycle is 10–60 minutes. When the flowback cuttings concentration increases or the pressure fluctuation is significant, the flowback pressure difference is reduced and the stop time is extended; when the cuttings concentration decreases and the flowback volume steadily increases, the flowback intensity is gradually increased. Through the above structure, the orderly discharge of residual liquids, cuttings, and natural gas can be achieved, reducing the risks of cuttings blockage, proppant backflow, and reduction of fracture conductivity.

[0059] (6) Working principle of the above integrated module In operation, the target pressure drive section is first determined based on the reservoir bedding, cleavage development, rock mass integrity, and hydrocarbon content. The bridge plug isolation section module 1 is then inserted into the preset position within the reservoir casing 5. The bridge plug body is set by the setting assembly, forming a relatively independent target pressure drive section. Subsequently, a low-flow-rate pre-flush fluid is injected for verification. Once the pressure in the target pressure drive section remains stable, low-damage pre-flush fluid is injected to allow it to enter the cleavage and initial fractures, thereby reducing flow resistance, inhibiting clay expansion, dispersing rock cuttings, and establishing initial seepage channels.

[0060] During the pressure drive process, the high-energy gas pressure drive module 2 is activated, allowing high-energy gas to be concentrated along a preset direction by the energy-concentrating release component and applied to the target section borehole wall and surrounding rock mass. Under transient or staged pressure pulses, this induces crack initiation and expansion, and promotes the connection between multi-scale small fractures and primary cleavages, bedding planes, and natural fissures. Simultaneously, the monitoring and control module 18 monitors the pressure drive pressure, pulse peak value, pressure decay characteristics, and injection rate in real time, and adjusts the high-energy gas release intensity and subsequent pumping parameters based on the pressure response. After the high-energy gas pressure drive is completed, the pumping and drainage module switches to the proppant-carrying support stage, injecting proppant-carrying fluid into the formed fractures to allow the proppant to enter the fractures and maintain the open state of the fractures after pressure drive. Subsequently, displacement aid fluid or gas-liquid composite medium is injected to uniformly diffuse along the fractures, promoting the desorption of adsorbed natural gas and improving the return conditions of residual liquid and rock cuttings.

[0061] After pressure drive, support, and displacement-assisted drainage are completed, the flowback valve group is closed or partially opened to allow the target reservoir section to enter a pressure stabilization and annealing stage, allowing high-energy gas and displacement-assisted drainage media to continue acting on the fracture network. After annealing, residual liquid, cuttings, and free gas are gradually discharged through stepped depressurization, intermittent flowback, or pump stop-start circulation. By jointly monitoring the pressure response, flowback gas volume, flowback liquid volume, and cuttings concentration, the operating regime can be adjusted and the pressure drive effect evaluated, achieving integrated and coordinated operation of segmented pressure drive, fracture connectivity, natural gas desorption, cuttings drainage, and residual liquid flowback.

[0062] Compared with existing fracturing and hydraulic displacement mining methods, the present invention has the following advantages: (1) By setting up a bridge plug isolation segment module 1, the present invention realizes reliable mechanical isolation and segment control of the target segment, which enables the pre-filled liquid, high-energy gas, sand-carrying liquid and displacement auxiliary liquid to act on the area to be modified, effectively reducing the risk of pressure driving medium ineffectively dissipating along non-target segments, dominant cleavage or existing low-resistance channels.

[0063] (2) This invention can address the characteristics of low strength, irregular borehole walls, and well-developed cleavage fractures in organic-rich mudstone and shale. By adapting the bridge plug (soluble bridge plug) structure to mudstone and shale, and by reducing tooth height, increasing contact length, and using flexible sealing and micro-textured sealing structures, the local damage to the borehole wall during the bridge plug setting process can be reduced, thereby improving the stability and applicability of the inner seal of the casing 5.

[0064] (3) By setting up a high-energy gas pressure drive module 2, the high-energy gas is concentrated and released to the target section along a preset direction. The invention also uses multiple low-damage pulse pressure drive methods to induce the initiation, expansion and connection of cleavage in mudstone and shale. This can form a multi-scale and relatively uniform small crack network in mudstone and shale, reduce the local crushing and large amount of rock debris caused by a single strong impact, and improve the uniformity of crack modification.

[0065] (4) The present invention uses a low-damage pre-fluid system to reduce drag, prevent swelling, disperse rock debris and establish initial seepage channels before high-energy gas pressure drive. This can reduce the impact of water-sensitive damage and clay swelling, improve the conditions for high-energy gas to enter the fracture, and thus improve the efficiency of subsequent pressure drive.

[0066] (5) By setting up a sand-carrying support unit, the present invention adopts a combination system of low-damage guar gum-based sand-carrying liquid and multi-particle-size proppant, which enables the proppant to enter the fracture formed by high-energy gas pressure drive and maintain the open state of the fracture after pressure, thereby reducing the risk of the fracture reclosing under the action of geostress and improving the long-term conductivity of the fracture.

[0067] (6) By setting up a displacement and drainage unit, the present invention combines surfactants, mutual solvents, drainage aids, rock fragment dispersants and demulsifiers to form a displacement and drainage liquid, which can reduce the interfacial tension of residual liquid, alleviate the water-locking effect, promote the desorption of adsorbed natural gas, and reduce the adverse effects of rock fragment deposition on the fracture conductivity.

[0068] (7) By setting up a monitoring and control module 18, the present invention can monitor the injection pressure, discharge rate, peak pulse pressure, pressure decay characteristics, return gas volume, return liquid volume and rock cuttings concentration in real time, and adjust the pumping parameters, high-energy gas release intensity and return system according to the monitoring results, thereby improving the safety, continuity and controllability of the pressure drive operation process.

[0069] (8) By setting up a pressure stabilization and backflow control module, the present invention adopts a pressure stabilization, step-by-step pressure reduction, intermittent backflow or pump stop-start cycle mode, so that high-energy gas and displacement aid medium continue to act on the fracture system after pressure, and gradually discharge residual liquid, rock cuttings and free gas, thereby reducing the risk of rock cuttings surge, proppant backflow and fracture blockage.

[0070] (9) Through the synergistic effect of the above modules, the present invention realizes the integrated operation of bridge plug segmental isolation, pre-fluid pretreatment, high-energy gas condensing pressure drive, fracture support, displacement and drainage assistance, real-time monitoring and post-pressure drainage control. It can improve the segmental pressure drive efficiency, natural gas desorption effect, cuttings drainage capacity and residual liquid drainage efficiency of shale reservoirs, and provide reliable technical means for the efficient development of organic-rich shale oil and gas resources.

[0071] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A high-energy gas pressure-driven integrated unconventional oil and gas reservoir exploitation method, characterized in that... Follow these steps: The first step is segmented design, which determines the location and segment length of the target pressure drive operation section based on the bedding, cleavage development, rock mass integrity, oil and gas content, and wellbore stability of organic-rich mudstone and shale. The second step is bridge plug setting. The bridge plug is sent into the preset position inside the casing for sealing, thereby completing the bridge plug setting and forming a relatively independent target pressure drive operation section. The third step is to test the seal and inject pre-flush fluid. Pre-flush fluid is injected into the target pressure drive section at a low rate to test the seal. After confirming that the pressure remains stable, pre-flush fluid is injected to reduce flow resistance, inhibit clay expansion, disperse rock cuttings and establish an initial seepage channel. The fourth step is high-energy gas focusing pressure drive. The high-energy gas focusing pressure drive module is started, so that the high-energy gas is focused and released to act on the target pressure drive operation section. Under the action of transient or staged pressure pulses, crack initiation and expansion are induced, and multi-scale small cracks are connected with the original cleavage, bedding and natural fractures. The fifth step is pressure drive monitoring and parameter adjustment. The monitoring and control module collects the pressure drive pressure, pulse peak value, pressure decay characteristics and injection volume in real time, and adjusts the high-energy gas release intensity, release interval and subsequent pumping parameters according to the pressure response. Step 6: Propionage and proppant. After the high-energy gas pressure drive is completed, the propioning fluid is injected into the formed fractures to allow the proppant to enter the fractures and maintain the fracture opening state after compression. Step 7: Displacement and drainage assistance. Displacement and drainage assistance fluid, nitrogen, carbon dioxide or gas-liquid composite medium are injected into the target pressure drive section to allow it to diffuse evenly along the fractures, promoting the desorption of adsorbed natural gas, the return of residual liquid and the drainage of rock cuttings. Step 8: Pressure stabilization and backflow control. Close or slightly open the backflow control valve group to allow the target reservoir section to enter the pressure stabilization and backflow stage. After the backflow is completed, the residual liquid, rock cuttings and free gas are gradually discharged through step-by-step pressure reduction, intermittent backflow or pump stop and start circulation. Step 9: Repeat the operation in segments. After the target pressure drive operation segment is completed, remove or dissolve the bridge plug, and repeat the above steps in the next target pressure drive operation segment until the pressure drive mining operation of all designed target pressure drive operation segments is completed.

2. The high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method according to claim 1, characterized in that... The pretreatment solution is prepared by mixing drag-reducing agent, clay stabilizer, rock fragment dispersant and surfactant into the base solution, with the mass ratio of drag-reducing agent, clay stabilizer, rock fragment dispersant and surfactant being 1:10:2:1 to 3; or / and, the apparent viscosity of the pretreatment solution is 3 mPa·s to 10 mPa·s, and the pH value of the pretreatment solution is 6.5 to 8.0; or / and, in the third step, the low discharge rate is 0.2 cubic meters / minute to 5.0 cubic meters / minute.

3. The high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method according to claim 2, characterized in that... The drag-reducing agent is polyacrylamide, hydrolyzed polyacrylamide, or polyacrylamide emulsion, and the amount of drag-reducing agent added is 0.05% to 0.15% of the mass of the pre-flue; or / and, the clay stabilizer is potassium chloride, ammonium chloride, or organic quaternary ammonium salt, and the amount of clay stabilizer added is 0.5% to 2.0% of the mass of the pre-flue; or / and, the rock cuttings dispersant in the pre-flue is sodium lignosulfonate, polycarboxylate, or sodium polyacrylate, and the amount of rock cuttings dispersant added is 0.1% to 0.3% of the mass of the pre-flue; or / and, the surfactant in the pre-flue is sodium dodecylbenzenesulfonate, alkyl glycoside, or betaine, and the amount of surfactant added is 0.05% to 0.15% of the mass of the pre-flue.

4. The high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method according to claim 1, 2, or 3, characterized in that... The sand-carrying fluid is a low-damage guar gum-based sand-carrying fluid with water as the base liquid and hydroxypropyl guar gum added as a thickener. The amount of hydroxypropyl guar gum added is 0.15% to 0.35% of the base liquid mass; or / and, the apparent viscosity of the sand-carrying fluid is 20 mPa·s to 60 mPa·s, and the sand ratio is 8% to 18%; or / and, the proppant is composed of sand of multiple particle sizes, wherein 100-mesh to 70-mesh fine sand accounts for 10% to 20% of the proppant mass, 70-mesh to 40-mesh fine sand accounts for 30% to 40% of the proppant mass, and 40-mesh to 20-mesh medium sand accounts for 30% to 40% of the proppant mass; or / and, the proppant is preferably quartz sand or low-density coated sand.

5. The high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method according to claim 1, 2, or 3, characterized in that... The displacement and drainage aid fluid is prepared by mixing a surfactant, a co-solvent, a drainage aid, a rock fragment dispersant, and a demulsifier with water as the base fluid. The mass ratio of the surfactant, co-solvent, drainage aid, rock fragment dispersant, and demulsifier is 5:8:3:2:2; or / and. The apparent viscosity of the displacement and drainage aid fluid is 2 mPa·s to 8 mPa·s, and the pH value is 6.5 to 8.

0.

6. The high-energy gas pressure drive integrated unconventional oil and gas reservoir exploitation method according to claim 5, characterized in that... The surfactant in the displacement and drainage aid fluid is sodium dodecylbenzenesulfonate, alkyl glycoside, or betaine, and the amount of surfactant added is 0.1% to 0.4% of the mass of the displacement and drainage aid fluid; or / and, the mutual solvent is ethanol, isopropanol, or ethylene glycol butyl ether, and the amount of mutual solvent added is 0.2% to 0.6% of the mass of the displacement and drainage aid fluid; or / and, the drainage aid is a fluorocarbon surfactant or anionic / nonionic compound surfactant, and the amount of drainage aid added is 0.05% to 0.2% of the mass of the displacement and drainage aid fluid; or / and, the rock fragment dispersant in the displacement and drainage aid fluid is sodium lignosulfonate or polycarboxylate, and the amount of rock fragment dispersant added is 0.05% to 0.15% of the mass of the displacement and drainage aid fluid; or / and, the demulsifier is polyoxyethylene polyoxypropylene ether or organosilicon demulsifier, and the amount of demulsifier added is 0.05% to 0.15% of the mass of the displacement and drainage aid fluid.

7. An apparatus for the integrated high-energy gas pressure drive unconventional oil and gas reservoir exploitation method as described in claim 1, 2, 3, 4, 5, or 6, characterized in that... It includes a bridge plug isolation segment module, a high-energy gas pressure drive module, a high-energy gas supply component, and a wellhead control component. The upper end of the wellhead control component and the high-energy gas supply component are connected together by a pipeline. The lower end of the wellhead control component is connected to a casing located inside the rock formation. The bridge plug isolation segment module and the high-energy gas pressure drive module are installed sequentially from top to bottom inside the casing. The bridge plug isolation segment module is a soluble bridge plug, the high-energy gas pressure drive module is a high-energy gas generator, the wellhead control component is a Christmas tree or production tubing, and the high-energy gas supply component is a high-pressure gas tank or high-pressure gas cylinder.

8. The apparatus according to claim 7, characterized in that... It also includes a pre-flush fluid storage tank, a sand-carrying fluid storage tank, and a displacement-assisted drainage fluid storage tank arranged from left to right. Each of the pre-flush fluid storage tank, sand-carrying fluid storage tank, and displacement-assisted drainage fluid storage tank has a discharge end at its lower part and an inlet end at the upper part of the wellhead control assembly. The discharge end of the pre-flush fluid storage tank and the inlet end of the wellhead control assembly are connected together by an inlet pipe. A connecting pipe is connected between the discharge end of the sand-carrying fluid storage tank and the inlet pipe. A connecting pipe is also connected between the discharge end of the displacement-assisted drainage fluid storage tank and the inlet pipe. A high-pressure pump assembly is installed on the inlet pipe between the displacement-assisted drainage fluid storage tank and the wellhead control assembly. Control valves are installed on the connecting pipe and the inlet pipe near the discharge end of the pre-flush fluid storage tank.

9. The apparatus according to claim 8, characterized in that... A chemical metering and dosing assembly is installed on the feed pipe between the high-pressure pumping assembly and the displacement fluid storage tank; or / and a bypass pipe is connected in parallel to the feed pipe between the high-pressure pumping assembly and the wellhead control assembly, and at least one multi-channel switching valve assembly is installed on the bypass pipe and the corresponding feed pipe; or / and a gas-liquid separation assembly and a cuttings collection assembly are located outside the wellhead control assembly, with a discharge end at the top of the wellhead control assembly, feed ends at the middle of the gas-liquid separation assembly and the cuttings collection assembly, and a discharge end at the bottom of the gas-liquid separation assembly. The feed end of the liquid separation component is connected together through the discharge pipe, and the discharge end of the gas-liquid separation component and the feed end of the cuttings collection component are connected together through pipelines. A control valve is installed on the discharge pipe; and / or, a monitoring and control module is located outside the wellhead control component. A pressure transmitter and a flow meter are installed on the feed pipe and the discharge pipe, respectively. The signal output terminals of the pressure transmitter and the flow meter are electrically connected to the signal input terminal of the monitoring and control module through wires. The signal output terminal of the monitoring and control module is electrically connected to the signal input terminals of the high-pressure pump injection component and the multi-channel switching valve group through wires.

10. The apparatus according to claim 9, characterized in that... The high-pressure pumping assembly is a high-pressure pump; and / or the chemical metering and adding assembly is a chemical metering and adding tank or a chemical metering tank; and / or the multi-channel switching valve group includes at least one control valve; and / or the gas-liquid separation assembly is a gas-liquid separator; and / or the cuttings collection assembly is a cuttings collection tank; and / or the monitoring and control module is a PLC controller.

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