Compressed air energy storage system and method for waste oil and gas well through electric detonation segmented fracturing dilatation

Abstract

The invention provides a compressed air energy storage system and method for an electric detonation segmented fracturing dilatation abandoned oil and gas well. The energy storage system comprises an energy storage unit, a segmented control unit, an electric detonation fracturing unit and a crack monitoring unit which are arranged in the abandoned oil and gas well. The energy storage unit comprises a plurality of original rock stratum fracturing sections which are mutually sealed and isolated; the segmented control unit comprises a sleeve which is inserted into the energy storage unit and is provided with a perforation on the side wall of the vehicle; and a discharge electrode of the electric detonation fracturing unit generates pulse discharge at the perforation position to impact the rock mass to form a fracture network so as to expand the gas storage space of the target layer section, and compressed air is injected into the fracture network of the target layer section to be stored. The energy storage unit is divided into a plurality of independent sealing rock stratum sections in the vertical direction, a sectional type structure of a plurality of gas storage capacity units, a shaft and a plurality of reservoirs is constructed, the overall energy storage scale of a single well is greatly increased, the energy storage capacity and flexibility of a system are improved, and different power grid dispatching requirements can be met.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of compressed air energy storage, and particularly relates to an electric detonation segmented fracturing expansion compressed air energy storage system and method for abandoned oil and gas wells. BACKGROUND

[0002] Compressed air energy storage technology is an important large-scale energy storage method, which converts electrical energy into the internal energy of compressed air for storage, and releases compressed air to drive a generator set to generate electricity when needed, thereby achieving peak shaving and stability support for the power grid. One of the core components of this technology is the gas storage chamber, which directly affects the energy storage efficiency, safety and economy of the system.

[0003] Currently, the commonly used types of gas storage chambers mainly include natural salt caves, artificial caverns, steel high-pressure containers, and idle oil and gas well shafts. Natural salt caves and artificial caverns have the advantages of large volume and strong pressure-bearing capacity, but have the problems of limited geographical location, long construction period, and high initial investment. Although steel high-pressure containers are flexible in layout, they have high manufacturing costs and limited storage capacity for a single container, making it difficult to meet the needs of large-scale energy storage. In contrast, idle oil and gas well shafts, as a ready-made underground space resource, have significant advantages such as high pressure resistance, low cost, and small land occupation, and are particularly suitable for the application of compressed air energy storage systems.

[0004] For example, CN202210352737.4 discloses a compressed air energy storage system for abandoned underground space, which includes acidification pipe column, air compression system, power generation equipment, and turbine generator components. The compressed air energy storage system pumps acid into the wellbore to erode and dissolve the original oil and gas reservoir rock, thereby expanding the pore volume and forming acid-etched fractures to increase the energy storage space. However, this scheme only uses a single production layer for gas storage, and the actual expansion effect is limited, and the gas storage capacity is still constrained by the formation conditions, making it difficult to achieve large-scale and high-efficiency energy storage. SUMMARY

[0005] To solve the technical problems existing in the prior art, the first aspect of the present application is to provide an electric detonation segmented fracturing expansion compressed air energy storage system for abandoned oil and gas wells. The second aspect, based on the same inventive concept, the present application also provides an energy storage method based on the aforementioned electric detonation segmented fracturing expansion compressed air energy storage system for abandoned oil and gas wells.

[0006] In the embodiment of the present application, the electric detonation segmented fracturing and expansion compressed air energy storage system and method for abandoned oil and gas wells comprises an energy storage unit, a segmented control unit, an electric detonation fracturing unit and a fracture monitoring unit arranged in the abandoned oil and gas well. The energy storage unit comprises a target layer segment constructed in the abandoned oil and gas well, and the target layer segment comprises a plurality of original rock layer fracturing segments sealed and isolated from each other and arranged along the height direction of the abandoned oil and gas well, and the original rock layer fracturing segment is a compact rock layer not yet exploited. The segmented control unit comprises a casing inserted into the vertical hole of the energy storage unit and arranged through the height direction of the energy storage unit, and the lateral wall of the casing is provided with a perforation corresponding to each segment of the target layer segment. The electric detonation fracturing unit comprises a high-voltage pulse power supply and a discharge electrode connected to the high-voltage pulse power supply through a high-voltage cable. The discharge electrode is lowered to the perforation position of the target layer segment through the casing via the high-voltage cable. The discharge electrode generates pulse discharge to impact the rock mass of the target layer segment to form a fracture network, so as to expand the gas storage space of the target layer segment, and the compressed air is injected into the fracture network of the target layer segment for storage. The fracture monitoring unit is used for monitoring the fracture development of each target layer segment.

[0007] The energy storage method of the embodiment of the present application is realized based on the above-mentioned electric detonation segmented fracturing and expansion compressed air energy storage system for abandoned oil and gas wells, and comprises the following steps: S1, abandoned oil and gas well evaluation: the casing of the abandoned oil and gas well is checked, and the defect easy-to-fracture segment of the abandoned oil and gas well is located, and the defect easy-to-fracture segment is the target layer segment; S2, layered perforation: directional perforation is performed on the target layer segment; S3, electric detonation fracturing from bottom to top: the discharge electrode is lowered to the perforation position of the bottommost fracturing and expansion segment, the high-voltage pulse power supply is started, the discharge electrode performs pulse discharge, and the fracturing and expansion segment is fractured; after the fracturing is completed, inert gas is injected from the perforation for pressure maintaining test, and the integrity of the sealing and isolation of the fracturing and expansion segment is verified; the discharge electrode is sequentially moved upward to process each original rock layer fracturing segment, and sealing verification is performed after each original rock layer fracturing segment is fractured; S4, gas storage space expansion: a network-shaped fracture is formed in the target layer segment by electric detonation, and the fracture density is greater than or equal to 3 / m 3 ; S5, compressed air injection: the compressed air is injected from the perforation into the multi-layer fracture network composed of a plurality of target layer segments through the gas injection pipe inserted into the casing for storage.

[0008] Compared with the prior art, the beneficial effects of the preferred technical scheme of the present application include:

[0009] 1. The present application makes full use of the existing abandoned oil and gas well shaft, geological data and part of the infrastructure, avoids the huge cost and long construction period of drilling a new well, converts the abandoned assets into valuable energy storage facilities, and realizes the cyclic and efficient use of resources.

[0010] 2. By separating the energy storage unit into multiple independent sealed rock sections in the vertical direction, multiple gas storage reservoir units are constructed. This segmented structure of "one wellbore, multiple reservoirs" greatly increases the overall energy storage capacity of a single well, enhancing the system's energy storage capacity and flexibility, and can adapt to different power grid scheduling needs.

[0011] 3. The electric detonation fracturing technology is used to generate a powerful shock wave in the target layer through high-voltage pulse discharge, which can effectively fracture the rock mass to form a complex and uniform fracture network. Compared with traditional hydraulic fracturing, this method is more targeted, controllable, and energy-efficient, and avoids environmental risks caused by water and chemical additives, achieving safe, green, and efficient expansion of the gas storage space.

[0012] 4. The segmented control unit (perforated casing) is combined with the segmented fracturing to allow compressed air to be independently injected or extracted from different layers, effectively managing pressure and stress changes in different depth rock layers, reducing interlayer interference, optimizing gas injection and production processes, and improving the system's cycle efficiency and long-term operation stability.

[0013] 5. The fracture monitoring unit can monitor the development pattern and spatial distribution of the fracture network in each target layer in real time or periodically, ensuring that the operator can master the integrity, sealing, and stability of each reservoir, enabling independent and fine management and safety warning of each reservoir, greatly improving the reliability and safety of the entire system operation.

[0014] 6. The use of deep underground dense rock layers to store compressed air has good sealing, high energy storage density, is far from the surface biosphere, and has extremely low environmental risks. The entire transformation and operation process does not require a large amount of new land occupation, making it an environmentally friendly large-scale energy storage solution.

[0015] 7. The invention combines abandoned oil and gas wells, segmented fracturing expansion technology, and compressed air energy storage, forming an innovative system that integrates resource reuse, large-scale energy storage, precise control, intelligent monitoring, and environmental friendliness, providing a highly potential new path for the commercialization of large-scale compressed air energy storage. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of the electric detonation segmented fracturing and expansion of the abandoned oil and gas well compressed air energy storage system of the embodiment.

[0017] Figure 2 is a structural schematic diagram of the electric detonation fracturing unit in the embodiment.

[0018] The reference signs in the drawings of the specification include: a sealing cap layer section 11, an original rock layer fracturing section 12, a stable sealing section 13, a fracturing and capacity expansion section 14, a sealing ring 15, a perforation 16, a casing 17, a sealing plug 18, a high-voltage pulse power supply 21, a high-voltage cable 22, a discharge electrode 23, and an electrode positioning sensor 24. DETAILED DESCRIPTION

[0019] Embodiments of the present application are described in detail below with reference to examples of embodiments shown in the accompanying drawings, in which the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application.

[0020] Embodiment One

[0021] The present embodiment provides an electric detonation segmented fracturing and capacity expansion abandoned oil and gas well compressed air energy storage system (referred to as energy storage system), as shown in Figure 1 and Figure 2 In a preferred embodiment, the energy storage system includes an energy storage unit, a segmented control unit, an electric detonation fracturing unit, and a fracture monitoring unit arranged in the abandoned oil and gas well.

[0022] The energy storage unit includes a target layer section constructed in the abandoned oil and gas well, and the target layer section includes a plurality of original rock layer fracturing sections 12 (30-50 m in length) arranged in the height direction of the abandoned oil and gas well and sealed and isolated from each other, and the original rock layer fracturing section 12 is an unexplored dense rock layer. Preferably, the target layer section further includes a fracturing and capacity expansion section 14 (5-10 m in length) arranged below and isolated from the plurality of original rock layer fracturing sections 12, and the fracturing and capacity expansion section 14 is a crude oil and gas production layer section. The fracturing and capacity expansion section 14 and the original rock layer fracturing section 12, and the adjacent two original rock layer fracturing sections 12 are sealed and isolated by a stable sealing section 13 (30-50 m in length), and the stable sealing section 13 is a non-perforation 16 sealing structure. The top of the uppermost original rock layer fracturing section 12 is sealed by a sealing cap layer section 11 (a dense cap rock layer, about 300 m in length). That is, the fracturing and capacity expansion section 14 is arranged at the lowermost layer, the sealing cap layer section 11 is arranged at the uppermost layer, and the plurality of stable sealing sections 13 and the plurality of original rock layer fracturing sections 12 are alternately arranged between the fracturing and capacity expansion section 14 and the sealing cap layer section 11, and the stable sealing section 13 is arranged close to the fracturing and capacity expansion section 14. The fracturing and capacity expansion section 14 and the plurality of original rock layer fracturing sections 12 are both target layer sections.

[0023] The segment control unit comprises a sleeve 17 inserted into the vertical hole of the energy storage unit and arranged through the height direction of the energy storage unit, the sleeve 17 is inserted into the energy storage unit through the sealing cap layer segment 11, and the upper end opening of the sleeve 17 is closed by a sealing plug 18 (such as a cement plug). The sleeve 17 is provided with a perforation 16 corresponding to each target layer segment on the side wall of the sleeve 17, and the perforation 16 is preferably distributed along the circumferential direction and the height direction of the sleeve 17. Preferably, a sealing ring 15 (such as a cement ring) for sealing the inner wall of the vertical hole is arranged between the sleeve 17 and the vertical hole, and the perforation 16 extends to the side wall of the sealing ring 15.

[0024] The electric detonation fracturing unit comprises a high-voltage pulse power supply 21 (located outside the abandoned oil and gas well) and a discharge electrode 23 connected to the high-voltage pulse power supply 21 through a high-voltage cable 22. The discharge electrode 23 is lowered to the position of the perforation 16 of the target layer segment through the sleeve 17 by the high-voltage cable 22, and the discharge electrode 23 generates a pulse discharge to impact the rock mass of the target layer segment to form a fracture network, thereby expanding the gas storage space of the target layer segment, and compressed air is injected into the fracture network of the target layer segment for storage. The discharge electrode 23 is integrated with an inflatable packer (which can be a gas bladder or a water bladder), which is used to close the perforation 16 to form a closed chamber in the target layer segment. Preferably, the discharge electrode 23 is provided with an electrode positioning sensor 24 for positioning the position of the discharge electrode 23.

[0025] The fracture monitoring unit is used for monitoring the development of the fractures of each target layer segment, and the fracture monitoring unit comprises a microseismic monitoring array arranged around the wellhead of the abandoned oil and gas well, which is used for monitoring the development form and spatial distribution of the fracture network of each target layer segment.

[0026] It should be noted that the original rock layer fracturing segment 12 is a tight rock layer that has not been mined, the fracturing and expansion segment 14 is a crude oil and gas production layer segment, and the sealing cap layer segment 11 is a tight cap rock layer, all of which are originally present in the abandoned oil and gas well. The original rock layer fracturing segment 12 has a stable sealing segment 13 of tens of meters in the middle without fracturing. The sleeve 17 and the sealing ring 15 (cement ring) are also originally present in the abandoned oil and gas well, and the sleeve 17 and the sealing ring 15 do not need to be reinstalled.

[0027] Embodiment two

[0028] The embodiment provides a compressed air energy storage method for electric detonation segment fracturing and expansion of an abandoned oil and gas well, which is realized based on the electric detonation segment fracturing and expansion compressed air energy storage system of embodiment one, and comprises the following steps:

[0029] S1, abandoned oil and gas well evaluation: a complete inspection of the abandoned oil and gas well casing 17, locating the defect prone section of the abandoned oil and gas well, and the defect prone section is the target section. Specifically, the defect prone section can be located by using acoustic logging instruments, and the ultrasonic transducer is inserted into the abandoned oil and gas well to collect full wave train waveforms, combined with other logging data to finally calculate the rock mechanics parameters (such as elastic modulus, or uniaxial compressive strength, or porosity, etc.) of the evaluated formation, determine which sections of the abandoned oil and gas well are defect prone sections, and determine the target section to determine the location of the perforation 16 on the casing.

[0030] S2, layered perforation 16: directional perforation 16 is performed in the target section (including the fracturing and expansion section 14 located at the bottom and several alternating original rock layer fracturing sections 12). Specifically, the perforating gun can be lowered to a specific position in the casing 17, and the perforation 16 can be increased on the casing 17 and the sealing ring 15.

[0031] S3, self-bottom-up electric explosion fracturing: the discharge electrode 23 is lowered to the perforation 16 position of the bottommost fracturing and expansion section 14, the high-voltage pulse power supply 21 is started, and the discharge electrode 23 performs pulse discharge to control the fracturing of the fracturing and expansion section 14. The discharge electrode 23 generates a microsecond high-voltage pulse (>100kV) at the perforation 16, and the shock wave expands along the natural weak plane to form a network of cracks, avoiding disturbance to the stable sealing section 13; after fracturing, the inert gas delivery pipe is inserted into the casing, and inert gas (such as nitrogen) is injected into the interior through the perforation 16 for pressure test, verifying the integrity of the fracturing and expansion section 14 (i.e. verifying the integrity of the stable sealing section 13 above the fracturing and expansion section 14 and the sealing ring 15 inside). The discharge electrode 23 is moved up in sequence to process each original rock layer fracturing section 12, and sealing verification is performed after each original rock layer fracturing section 12 is fractured (i.e. verifying the integrity of the stable sealing section 13 above and below the original rock layer fracturing section 12 and the sealing ring 15 inside).

[0032] S4, gas storage space expansion: a network of cracks (new cracks) is formed in the target section by electric explosion. During fracturing, the development of cracks in each target section is monitored by a microseismic monitoring array to ensure that the crack density is ≥3 / m 3 .

[0033] S5, compressed air injection: compressed air is injected into the multi-layer fracture network composed of several target sections through the gas injection pipe inserted into the casing from the perforation 16.

[0034] S6, dynamic monitoring: the pressure and temperature of each target section after compressed air injection are dynamically monitored by the distributed optical fiber sensor arranged in the target section.

[0035] In step S3 of the present application, the electric explosion parameters are dynamically adjusted: the discharge parameters are adjusted in real time according to the lithology of the target section rock mass:

[0036] E=k*sigma t ·V 2 / 3

[0037] Wherein, E is the single discharge energy (kJ) of the discharge electrode, sigma t is the tensile strength of the rock mass (MPa), V is the volume (m 3 ) of the target section, and k is the lithology coefficient of the rock mass (sandstone k=0.8, limestone k=1.2).

[0038] The application forms an alternating multi-layer structure of "fracturing expansion section-stable sealing section-original rock layer fracturing section" from bottom to top by reforming the structure of the abandoned oil and gas well shaft; sets perforation in the fracturing expansion section and the original rock layer fracturing section, uses the high-pressure pulse shock wave generated by the electric detonation cracking unit to perform controllable cracking on the target section, forms a network crack system to expand the gas storage space; adopts the bottom-up layered construction sequence, combines with the nitrogen pressure test to verify the interlayer sealing property; and finally injects compressed air into the multi-layer fracture network after expansion for storage. The application realizes the resource utilization of the abandoned oil and gas well shaft, solves the problem of geological structure dependence of the traditional compressed air energy storage (CAES), and improves the single-well energy storage capacity by more than 30%.

[0039] Although the embodiments of the application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the application, and the scope of the application is defined by the claims and their equivalents.

Claims

1. The electric detonation segmented fracturing and expanding compressed air energy storage system for abandoned oil and gas well, characterized in that, The system comprises a storage unit, a segmented control unit, an electric detonation fracturing unit and a fracture monitoring unit in the abandoned oil and gas well. The storage unit comprises a target layer section constructed in the abandoned oil and gas well, the target layer section comprises a plurality of original rock layer fracturing sections sealed and isolated from each other along the height direction of the abandoned oil and gas well, and the original rock layer fracturing section is an unexplored dense rock layer. The segmented control unit comprises a casing inserted into the vertical hole of the storage unit and arranged along the height direction of the storage unit, and the side wall of the casing is provided with a perforation corresponding to each section of the target layer section. The electric detonation fracturing unit comprises a high-voltage pulse power supply and a discharge electrode connected to the high-voltage pulse power supply through a high-voltage cable, the discharge electrode is lowered to the perforation position of the target layer section through the casing, and the discharge electrode generates pulse discharge to impact the rock mass of the target layer section to form a fracture network to expand the gas storage space of the target layer section, and compressed air is injected into the fracture network of the target layer section for storage. The fracture monitoring unit is used for monitoring the fracture development of each target layer section.

2. The electrical detonation segmental fracturing and expanding abandoned oil and gas well compressed air energy storage system according to claim 1, characterized in that, The target layer section further comprises a fracturing expansion section arranged below and isolated from the original rock layer fracturing sections, and the fracturing expansion section is a crude oil and gas production layer section.

3. The electrical detonation segmental fracturing and expanding abandoned oil and gas well compressed air energy storage system according to claim 2, characterized in that, The fracturing expansion section and the original rock layer fracturing section, and the adjacent two original rock layer fracturing sections are sealed and isolated by a stable sealing section, and the top of the uppermost original rock layer fracturing section is sealed by a sealing cap section.

4. The electrical detonation segmental fracturing and expanding abandoned oil and gas well compressed air energy storage system according to claim 3, characterized in that, The casing is inserted into the storage unit through the sealing cap section, and the upper end opening of the casing is closed by a sealing plug.

5. The electrical detonation segmental fracturing and expanding abandoned oil and gas well compressed air energy storage system according to claim 1, characterized in that, A sealing ring is arranged between the casing and the vertical hole for sealing the inner wall of the vertical hole, and the perforation extends to the side wall of the sealing ring.

6. The electrical detonation segmental fracturing and expanding abandoned oil and gas well compressed air energy storage system according to claim 1, characterized in that, The discharge electrode is integrated with an inflatable packer for closing the perforation to form a closed chamber in the target layer section.

7. The electrical detonation segmental-fracturing expanded waste oil and gas well compressed air energy storage system according to any one of claims 1-6, characterized in that, The discharge electrode is provided with an electrode positioning sensor.

8. The electrical detonation segmental-fracturing expanded waste oil and gas well compressed air energy storage system according to any one of claims 1-6, characterized in that, The fracture monitoring unit comprises a microseismic monitoring array arranged around the wellhead of the abandoned oil and gas well.

9. A method for expanding the compressed air energy storage of a multi-zone waste oil and gas well by electrically induced seismic fracturing, characterized in that, The system is realized based on the electric detonation segmented fracturing and expansion compressed air storage system of the abandoned oil and gas well according to any one of claims 1-8, comprising the following steps: S1, abandoned oil and gas well evaluation: the casing of the abandoned oil and gas well is checked, and the defect easy fracturing section of the abandoned oil and gas well is located, and the defect easy fracturing section is the target layer section; S2, layered perforation: directional perforation is performed in the target layer section; S3, electric detonation fracturing from bottom to top: the discharge electrode is lowered to the perforation position of the bottommost fracturing expansion section, the high-voltage pulse power supply is started, the discharge electrode performs pulse discharge, and the fracturing expansion section is fractured; after the fracturing is completed, inert gas is injected from the perforation for pressure test to verify the integrity of the sealing isolation of the fracturing expansion section; the discharge electrode is moved upward to process each original rock layer fracturing section, and sealing verification is performed after each original rock layer fracturing section is fractured; S4, gas storage space expansion: form a network of cracks in the target section through electric detonation, crack density ≥ 3 / m 3 ; S5, compressed air injection: compressed air is injected from the perforation into the multi-layer fracture network composed of a plurality of target layer sections through the gas injection pipe inserted into the casing for storage.

10. The electrical detonation segmental fracturing and expanding waste oil and gas well with compressed air energy storage method according to claim 9, characterized in that, In step S3, the electric detonation parameters are dynamically adjusted according to the lithology of the rock mass of the target layer section in real time. E = k • σ t • V 2 / 3 Wherein, E is the single discharge energy of the discharge electrode, sigma t is the tensile strength of the rock mass, V is the volume of the target interval, and k is the lithology coefficient of the rock mass.

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