Method for grading reconstruction and construction of artificial reservoir in deep sandstone reservoir and evaluation method

Abstract

The application discloses a method for grading reconstruction and construction of an artificial reservoir in a deep sandstone reservoir and an evaluation method, and comprises the following steps: dividing the sandstone reservoir into three types of reservoirs, i.e., a low porosity reservoir, a medium porosity reservoir and a high porosity reservoir, by using the obtained initial porosity, then formulating differentiated CO2-water-sandstone geochemical reaction regulation strategies respectively, so as to realize pore expansion in a near-well area and pore plugging in a far-well area of the target reservoir, and ensure that the porosity and permeability of the target reservoir after reconstruction meet the requirements; finally, performing integrity evaluation and injection-production trial operation on the target reservoir after reconstruction, and completing the construction of the artificial reservoir when the injection-production trial operation meets the requirements. Through the grading reconstruction strategy, the application completely gets rid of the dependence of underground energy storage on natural high-quality reservoirs with moderate porosity, realizes the optimization of reservoir construction cost and permanent mineralization and storage of CO2, and is suitable for various scenes such as oil and gas storage, hydrogen storage, compressed air energy storage and geothermal heat storage.

Description

Technical Field

[0001] This invention belongs to the field of underground energy storage and utilization technology, and specifically relates to a method and evaluation method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification. Background Technology

[0002] Deep sandstone reservoirs are widely distributed and represent excellent natural underground energy storage spaces. However, the site selection and construction of existing sandstone energy storage facilities generally adopt a "passive adaptation" strategy, relying solely on natural geological conditions to select sandstone reservoirs with suitable porosity for direct utilization. This strategy has resulted in a large number of sandstone reservoirs remaining unutilized. For example, high-porosity sandstone reservoirs with huge energy storage capacity have poor sealing properties, making them prone to severe leakage of the stored medium; while low-porosity sandstone reservoirs, although possessing good sealing properties and being less prone to leakage, have limited energy storage capacity, high injection resistance, and low energy storage efficiency, making them difficult to utilize efficiently. Furthermore, a large number of sandstone reservoirs deviating from the optimal porosity range are excluded from the usable scope, resulting in an extremely narrow range of energy storage facility sites, severely restricting the large-scale promotion and industrial application of sandstone underground energy storage technology.

[0003] Therefore, how to provide a method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification, and how to actively modify non-ideal sandstone reservoirs according to the initial porosity, while simultaneously improving energy storage capacity and achieving boundary self-sealing, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a method and evaluation method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification, addressing problems such as passive site selection limitations, insufficient sealing of high-porosity reservoirs, and insufficient capacity of low-porosity reservoirs. By implementing graded measures based on initial porosity and combining them with controllable carbon dioxide mineralization reactions, the method achieves active regulation of reservoir porosity and permeability, thereby constructing an integrated energy storage reservoir with "large-capacity energy storage space + external self-sealing barrier," and synergistically realizing carbon dioxide mineralization and carbon sequestration.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for constructing an artificial reservoir through graded modification in deep sandstone reservoirs. The method includes the following steps: obtaining the initial porosity, permeability, mineral composition, and formation water chemical properties of the target deep sandstone reservoir; classifying the sandstone reservoir into low-porosity, medium-porosity, and high-porosity reservoirs based on the initial porosity; formulating differentiated CO2-water-sandstone geochemical reaction control strategies for each reservoir; injecting CO2 and control fluids into the target reservoir in stages according to the control strategies to achieve porosity expansion in the near-wellbore area and porosity sealing in the far-wellbore area, with the near-wellbore expansion rate and far-wellbore sealing permeability reaching preset thresholds, thus completing the modification of the target reservoir; conducting an integrity evaluation and injection-production trial operation on the modified target reservoir; and completing the artificial reservoir construction once the injection-production trial operation meets the requirements.

[0006] In the first aspect, the initial porosity φ of low-porosity reservoirs is <10%; the initial porosity of medium-porosity reservoirs is 10% ≤ φ ≤ 15%; and the initial porosity of high-porosity reservoirs is >15%.

[0007] In the first aspect, the differentiated CO2-water-sandstone geochemical reaction control strategy formulated for each reservoir specifically includes: for low-porosity reservoirs, injecting saturated CO2 aqueous solution into the target reservoir to complete near-wellbore pore expansion and far-wellbore mineral precipitation sealing; for medium-porosity reservoirs, selecting whether to inject CO2 aqueous solution for modification or not based on the initial porosity and permeability detection and energy storage requirements; for high-porosity reservoirs, first injecting CO2 aqueous solution into the target reservoir to carry out mineralization reaction, and then injecting nano-cement mortar or chemical sealing reagent into the reservoir edge and far-wellbore sealing area to form a composite sealing layer.

[0008] In the first aspect, the preset threshold includes: the permeability after sealing the far-well area is less than 0.001 times the permeability after dissolution and expansion in the near-well area.

[0009] In the first aspect, the method includes: using core drilling technology to perform multi-point core sampling of the target deep sandstone reservoir, and using the lithological distribution of the core to determine the strata distribution of the deep formation.

[0010] In a first aspect, the method includes: drilling, casing and cementing operations at a target deep sandstone reservoir, and deploying temperature, pressure and flow sensors along the wellbore to monitor the injection temperature and injection rate of the fluid.

[0011] In a first aspect, the method includes: constructing a low-porosity reservoir into a geothermal energy storage facility; constructing a medium-porosity reservoir into a compressed air energy storage facility; and constructing a high-porosity reservoir into a natural gas storage facility.

[0012] In the first aspect, the CO2 aqueous solution is prepared by pumping formation water to the surface and mixing it with carbon dioxide gas in a mixing pumping station, and a portion of the original formation water is reserved in the mixing pumping station for later storage and sealing.

[0013] The second aspect of this invention provides an evaluation method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification. The reservoir is constructed using the method described in the first aspect. The evaluation method includes: during the construction phase, real-time monitoring of temperature and pH changes in the near-wellbore and far-wellbore areas to determine the reservoir's boundary range; after construction, measuring the expanded porosity of the near-wellbore area and the sealing performance of the far-wellbore area through water / gas / heat injection tests to detect the reservoir's connectivity and obtain curves showing the relationship between injection pressure and liquid level; and establishing a reservoir leakage early warning model based on these curves to ensure the normal operation of the reservoir.

[0014] In the second aspect, the evaluation method further includes: for low-porosity reservoirs, detecting whether the expanded reservoir meets the preset production capacity requirements; for high-porosity reservoirs, detecting the sealing performance of the composite sealing layer.

[0015] Beneficial effects: This invention provides a method for constructing an artificial reservoir in a deep sandstone reservoir through graded modification. First, the target deep sandstone reservoir is sampled and tested to obtain its initial porosity, permeability, mineral composition, and formation water chemistry, facilitating graded treatment. Next, based on the initial porosity, the sandstone reservoir is divided into low-porosity, medium-porosity, and high-porosity reservoirs. Differentiated CO2-water-sandstone geochemical reaction control strategies are developed for each type of reservoir to achieve full utilization of all reservoir types. Then, CO2 and control fluids are injected into the target reservoir in stages according to the control strategies to modify it, achieving porosity expansion in the near-wellbore area and porosity sealing in the far-wellbore area. When the near-wellbore expansion rate and far-wellbore sealing permeability reach preset thresholds, injection is stopped, completing the modification of the target reservoir. Finally, the integrity of the modified target reservoir is evaluated, and an injection-production test run is conducted. Once the injection-production test run meets the requirements, the construction of the artificial reservoir is complete. This invention achieves full-coverage utilization of different sandstone reservoirs by performing a three-level classification treatment on the porosity of the target deep sandstone reservoir, transforming passive site selection into active site selection and improving the utilization efficiency of sandstone reservoirs. At the same time, different stimulation schemes are implemented according to reservoirs with different porosities, optimizing construction costs while actively controlling reservoir porosity and permeability, and converting carbon dioxide into stable minerals for permanent storage, improving environmental and economic benefits. The artificial reservoir structure constructed by the graded approach is stable and has excellent sealing performance, and can be widely used in various scenarios such as geothermal energy storage, oil and gas storage, compressed air energy storage, and hydrogen storage, and can be used for large-scale storage.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification, as described in this invention. Detailed Implementation

[0019] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0020] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or by existing methods.

[0022] The overall concept of this invention is as follows: To address the limitations of passive site selection, insufficient sealing of high-porosity reservoirs, and insufficient capacity of low-porosity reservoirs in traditional sandstone reservoirs, this invention utilizes CO2 dissolved in water to form a weakly acidic solution, which undergoes a directional dissolution-precipitation geochemical reaction with sandstone. Sandstone reservoirs are then categorized into high-porosity, medium-porosity, and low-porosity reservoirs based on their initial porosity, allowing for different stimulation schemes for each category. During the stimulation process, the CO2 aqueous solution near the injection well has a high concentration and strong acidity, which can rapidly dissolve soluble substances in the sandstone reservoir and release Ca. 2+ Mg 2+ K + Na + Si 4+Plasma increases the pore volume and connectivity of sandstone, forming a high-capacity energy storage space. As the CO2 aqueous solution carries the dissolved ions to distant locations, the concentration of the CO2 aqueous solution decreases, the acidity weakens, the pH value increases, and the solution reaches a supersaturated state. Mineral precipitation occurs in the distant well section, and the resulting mineral precipitation fills the pores and microfractures in the sandstone reservoir, causing the reservoir permeability to drop sharply and forming a self-sealing layer. This transforms the sandstone reservoir into an integrated underground energy storage reservoir consisting of a "high-capacity energy storage space near the well + a high-sealing composite layer far from the well".

[0023] Please see Figure 1 This invention provides a method for constructing an artificial reservoir through graded modification in deep sandstone reservoirs. The method includes the following steps: obtaining the initial porosity, permeability, mineral composition, and formation water chemical properties of the target deep sandstone reservoir; classifying the sandstone reservoir into low-porosity, medium-porosity, and high-porosity reservoirs based on the initial porosity; formulating differentiated CO2-water-sandstone geochemical reaction control strategies for each reservoir; injecting CO2 and control fluids into the target reservoir in stages according to the control strategies to achieve porosity expansion in the near-wellbore area and porosity sealing in the far-wellbore area, with the near-wellbore expansion rate and far-wellbore sealing permeability reaching preset thresholds, thus completing the modification of the target reservoir; conducting an integrity evaluation and injection-production trial operation on the modified target reservoir; and completing the artificial reservoir construction once the injection-production trial operation meets the requirements.

[0024] Specifically, this invention provides a method for constructing an artificial reservoir in a deep sandstone reservoir through graded modification. First, the target deep sandstone reservoir is sampled and tested to obtain its initial porosity, permeability, mineral composition, and formation water chemistry, facilitating graded treatment. Next, based on the initial porosity, the sandstone reservoir is divided into low-porosity, medium-porosity, and high-porosity reservoirs. Differentiated CO2-water-sandstone geochemical reaction control strategies are formulated for each type of reservoir to achieve full coverage utilization. Then, CO2 and control fluids are injected into the target reservoir in stages according to the control strategies to modify it, achieving porosity expansion in the near-wellbore area and porosity sealing in the far-wellbore area. When the near-wellbore expansion rate and far-wellbore sealing permeability reach preset thresholds, injection is stopped, thus completing the modification of the target reservoir. Finally, the integrity of the modified target reservoir is evaluated, and an injection-production test run is conducted. Once the injection-production test run meets the requirements, the construction of the artificial reservoir is complete. This invention achieves full-coverage utilization of different sandstone reservoirs by performing a three-level classification treatment on the porosity of the target deep sandstone reservoir, transforming passive site selection into active site selection and improving the utilization efficiency of sandstone reservoirs. At the same time, different stimulation schemes are implemented according to reservoirs with different porosities, optimizing construction costs while actively controlling reservoir porosity and permeability, and converting carbon dioxide into stable minerals for permanent storage, improving environmental and economic benefits. The artificial reservoir structure constructed by the graded approach is stable and has excellent sealing performance, and can be widely used in various scenarios such as geothermal energy storage, oil and gas storage, compressed air energy storage, and hydrogen storage, and can be used for large-scale storage.

[0025] In some possible embodiments, the initial porosity φ of a low-porosity reservoir is <10%; the initial porosity of a medium-porosity reservoir is 10% ≤ φ ≤ 15%; and the initial porosity of a high-porosity reservoir is >15%.

[0026] In this application, the preferred sandstone reservoirs are feldspathic sandstone, lithic sandstone, and deep underground reservoirs containing carbonate cement, feldspar, and clay minerals. The initial porosity of these reservoirs is obtained to classify the target reservoirs into three levels, and different stimulation schemes are implemented accordingly. This avoids the situation where only reservoirs with specific porosities can be selected for reservoir construction, and greatly improves the utilization efficiency of underground reservoirs.

[0027] In some possible embodiments, the differentiated CO2-water-sandstone geochemical reaction control strategy formulated for each reservoir specifically includes: for low-porosity reservoirs, injecting saturated CO2 aqueous solution into the target reservoir to complete near-wellbore pore expansion and far-wellbore mineral precipitation sealing; for medium-porosity reservoirs, selecting whether to inject CO2 aqueous solution for modification or not based on the initial porosity and permeability detection and energy storage requirements; for high-porosity reservoirs, first injecting CO2 aqueous solution into the target reservoir to carry out mineralization reaction, and then injecting nano-cement mortar or chemical sealing reagent into the reservoir edge and far-wellbore sealing area to form a composite sealing layer.

[0028] In this application, the primary porosity of low-porosity reservoirs is small, and mineral precipitation is sufficient for sealing. Therefore, a saturated CO2 aqueous solution is injected into the low-porosity reservoir, and the reaction between the CO2 aqueous solution and the mineral components is used to expand the near-wellbore porosity and seal the far-wellbore porosity, thus completing the reservoir construction. The initial porosity of medium-porosity reservoirs is more suitable, and their capacity and sealing performance are relatively balanced. They can be used directly for energy storage, or, depending on the actual energy storage requirements, a lower concentration of CO2 aqueous solution can be injected to modify the reservoir and improve its energy storage efficiency. The primary porosity and dissolution voids of high-porosity reservoirs are both large, and mineral precipitation alone is insufficient to seal the far-wellbore area. Therefore, after the CO2 aqueous solution is injected, nano-cement mortar and chemical sealing agents are injected at the edge of the far-wellbore area to strengthen the sealing, forming a composite sealing layer and improving the reservoir's sealing performance.

[0029] In some possible embodiments, the preset threshold includes: the permeability after sealing the far-well area is less than 0.001 times the permeability after dissolution and expansion in the near-well area.

[0030] In this application, the mineral components in the near-wellbore region are dissolved by the CO2 aqueous solution, resulting in enlarged pores, increased permeability, and the formation of high-permeability channels. As the solution diffuses and permeates towards the far-wellbore, the CO2 concentration decreases, the acidity decreases, and the solution gradually becomes saturated. Secondary mineral precipitation occurs with the dissolved ions or mineral components, causing a sharp increase in permeability and forming a seal to prevent leakage of the energy storage medium. In some specific embodiments, the mineral components in the near-wellbore region include carbonate cements (calcite or dolomite), feldspar minerals (potassium feldspar, sodium feldspar, or calcium feldspar), clay cements (chlorite, illite, or montmorillonite), or soluble silicate rock fragments and fillers. The mineral precipitation formed in the far-wellbore region mainly includes carbonate minerals (calcite or dolomite, etc.), clay minerals (kaolinite or montmorillonite, etc.), silicate minerals (opal or quartz microcrystals, etc.), and zeolite-type secondary silicate minerals.

[0031] In some possible embodiments, the method includes: using core drilling technology to perform multi-point core sampling of the target deep sandstone reservoir, and using the lithological distribution of the core to determine the strata distribution of the deep formation.

[0032] In this application, before determining the construction of the reservoir, core samples are obtained from the target deep sandstone reservoir through drilling. Analysis of the core samples reveals the distribution of the deep strata, with particular attention paid to the burial depth, thickness, distribution range of the sandstone reservoir, and the sealing condition of the top and bottom plates, thereby planning the type of energy storage medium to be stored. In a specific embodiment, the target sandstone reservoir is required to be burial depth between 500-3000m, formation pressure not less than 2.5MPa, formation temperature not exceeding 250℃, and both the top and bottom plates to be dense rock layers without large fractures or breccia zones.

[0033] In some possible embodiments, the method includes drilling, casing, and cementing operations at the target deep sandstone reservoir, and deploying temperature, pressure, and flow sensors along the wellbore to monitor the injection temperature and injection rate of the fluid.

[0034] In this application, the casing is made of a high-strength alloy that is resistant to acid corrosion, can resist fatigue loads during injection and production cycles, and can resist ground stress. Furthermore, a high-sealing cementing material is used between the casing and the wellbore to prevent leakage of the stored medium.

[0035] In some possible embodiments, the method includes: constructing a low-porosity reservoir into a geothermal energy storage facility; constructing a medium-porosity reservoir into a compressed air energy storage facility; and constructing a high-porosity reservoir into a natural gas storage facility.

[0036] In this application, since the sandstone reservoir is divided into three levels according to its initial porosity, more types of media, such as crude oil, natural gas, compressed air, hydrogen, or geothermal working fluids, can be stored according to the level. After the reservoir is constructed, the injection pressure of the storage medium should not exceed the formation pressure to prevent the storage medium from leaking due to rock fracture.

[0037] In some possible embodiments, the CO2 aqueous solution is prepared by pumping formation water to the surface and mixing it with carbon dioxide gas in a mixing pumping station, and reserving a portion of the original formation water in the mixing pumping station for later storage and sealing.

[0038] In this application, a mixing pumping station can be pre-constructed on the ground. This station has at least two storage tanks. One tank is used to mix the extracted formation water with CO2 to form a CO2 aqueous solution, and the concentration of the CO2 aqueous solution can be adjusted as needed. The other tank is used to store the extracted original formation water for later sealing of the storage medium. The injection volume, injection rate, and injection time of the CO2 aqueous solution are related to the reservoir's design capacity, reservoir shape, and sealing, and need to be determined comprehensively.

[0039] Based on a general inventive concept, the second aspect of this invention provides an evaluation method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification. The reservoir is constructed using the method described in the first aspect for constructing artificial reservoirs in deep sandstone reservoirs through graded modification. The evaluation method includes: during the construction phase, real-time monitoring of temperature and pH changes in the near-wellbore and far-wellbore areas to determine the reservoir's boundary range; after construction, measuring the expanded porosity of the near-wellbore area and the sealing performance of the far-wellbore area through water injection / gas injection / heat injection tests to detect the reservoir's connectivity and obtain curves showing the relationship between injection pressure and liquid level changes; and establishing a reservoir leakage early warning model based on the curves to ensure the normal operation of the reservoir.

[0040] Specifically, this application provides an evaluation method for constructing artificial reservoirs in deep sandstone reservoirs through staged stimulation. During the construction phase, real-time monitoring of temperature and pH changes in the near-wellbore and far-wellbore areas allows for timely adjustment of the CO2 aqueous solution injection concentration and pressure, while also determining the reservoir's boundary range. After construction, water / gas / heat injection tests are conducted to assess the expanded porosity of the near-wellbore area and the sealing performance of the far-wellbore area. This facilitates the determination of the injection pressure and temperature of the storage medium, ensuring the reservoir's normal operation during storage. Furthermore, the reservoir's connectivity needs to be assessed, and curves showing the injection pressure and liquid level changes of the storage medium are obtained. Finally, a reservoir leakage early warning model can be established based on these curves. When an alarm is triggered, operation can be stopped promptly, the cause investigated, and maintenance performed, thereby extending the reservoir's service life.

[0041] In conjunction with the second aspect of this application, the evaluation method further includes: for low-porosity reservoirs, detecting whether the expanded reservoir meets the preset production capacity requirements; for high-porosity reservoirs, detecting the sealing performance of the composite sealing layer.

[0042] In this application, medium-porosity reservoirs can be put into use after basic construction; while low-porosity and high-porosity reservoirs require modification. Therefore, when evaluating the reservoir, for low-porosity reservoirs, it is necessary to focus on testing whether the expanded reservoir can meet the preset production capacity requirements; for high-porosity reservoirs, it is necessary to focus on testing the sealing performance of the composite sealing layer.

[0043] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0044] Example 1: Constructing a geothermal storage reservoir from a low-porosity sandstone reservoir Drilling, casing, and cementing operations were conducted in a feldspathic sandstone reservoir at a depth of 800m and an initial porosity of φ=8%. Temperature, pressure, and flow sensors were installed along the wellbore. Simultaneously, extracted formation water was stored in a mixing pump station set up on the surface, and CO2 was introduced to prepare a saturated CO2 aqueous solution. Then, the saturated CO2 aqueous solution was injected into the feldspathic sandstone reservoir through the wellbore and reacted for 45 days. It was detected that the porosity in the near-wellbore area expanded to 15%, forming a thermal storage space. In the far-wellbore area, mineral precipitation naturally formed a sealing barrier, and its sealing performance was tested to meet the requirements, without the need for cement mortar sealing reinforcement. Finally, geothermal medium was injected into the thermal storage tank, and it operated in a sealed manner with no significant leakage or heat loss.

[0045] Example 2: Constructing a Compressed Air Energy Storage Cell in a Medium-Porosity Sandstone Reservoir Drilling, casing, and cementing operations were conducted at a lithic sandstone reservoir with a depth of 600m and an initial porosity of φ=14%. Temperature, pressure, and flow sensors were installed along the wellbore. Simultaneously, the extracted formation water was stored at a mixing pump station set up on the surface. After testing, the effective capacity and sealing performance of the lithic sandstone reservoir met the requirements and no modification was needed. It could be used directly as a gas storage facility. Compressed air was injected into the lithic sandstone reservoir through the wellbore. After testing, the gas storage capacity was stable and the leakage rate was low, meeting the normal operation requirements of compressed air energy storage.

[0046] Example 3: Constructing a natural gas storage facility from a high-porosity sandstone reservoir Drilling, casing, and cementing operations were conducted in a feldspathic sandstone reservoir at a depth of 1000m with an initial porosity of φ=22%. Temperature, pressure, and flow sensors were installed along the wellbore. Simultaneously, extracted formation water was stored in a surface-mounted mixing pump station, and CO2 was introduced to prepare a CO2 aqueous solution. Then, the CO2 aqueous solution was injected into the feldspathic sandstone reservoir through the wellbore to initiate a mineralization reaction, thereby expanding the near-wellbore area and establishing a basic seal in the far-wellbore area. Subsequently, cement mortar and gel sealing agent were injected into the far-wellbore sealing zone for enhanced sealing. Testing showed that the permeability of the far-wellbore area was 0.0005 times that of the near-wellbore area, and it possessed a large effective capacity, good sealing performance, and no leakage, meeting the reservoir requirements. Finally, natural gas was injected into the reservoir for sealed operation.

[0047] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0048] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0049] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for constructing artificial reservoirs through graded modification in deep sandstone reservoirs, characterized in that, The method includes the following steps: To obtain the initial porosity, permeability, mineral composition, and formation water chemistry of the target deep sandstone reservoir; Based on the initial porosity, sandstone reservoirs are classified into low-porosity reservoirs, medium-porosity reservoirs, and high-porosity reservoirs. Differentiated CO2-water-sandstone geochemical reaction control strategies were developed for each reservoir. According to the control strategy, CO2 and control fluid are injected into the target reservoir in stages to achieve pore expansion in the near-wellbore area and pore plugging in the far-wellbore area of ​​the target reservoir. The near-wellbore expansion rate and the far-wellbore plugging permeability reach the preset threshold, thus completing the transformation of the target reservoir. Integrity evaluation and injection-production trial operation are carried out on the target reservoir after the modification is completed. Once the injection-production trial operation meets the requirements, the artificial reservoir is constructed.

2. The method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification according to claim 1, characterized in that, The initial porosity of low-porosity reservoirs is φ < 10%; the initial porosity of medium-porosity reservoirs is 10% ≤ φ ≤ 15%; and the initial porosity of high-porosity reservoirs is φ > 15%.

3. The method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification according to claim 2, characterized in that, The specific strategies for regulating CO2-water-sandstone geochemical reactions based on each reservoir include: For low-porosity reservoirs, a saturated CO2 aqueous solution is injected into the target reservoir to complete near-wellbore pore expansion and far-wellbore mineral precipitation sealing; For medium-porosity reservoirs, the decision to inject CO2 aqueous solution for modification or not to modify the reservoir is made based on the initial porosity and permeability measurements and energy storage requirements. For high-porosity reservoirs, CO2 aqueous solution is first injected into the target reservoir to carry out mineralization reaction, and then nano-cement mortar or chemical sealing agent is injected into the reservoir edge and far-well sealing area to form a composite sealing layer.

4. The method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification according to claim 3, characterized in that, The preset thresholds include: the permeability of the far-well area after sealing is less than 0.001 times the permeability of the near-well area after dissolution and expansion.

5. The method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification according to claim 4, characterized in that, The method includes: using core drilling technology to perform multi-point core sampling of the target deep sandstone reservoir, and using the lithological distribution of the core to determine the strata distribution of the deep formation.

6. The method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification according to claim 5, characterized in that, The method includes drilling, casing, and cementing operations at the target deep sandstone reservoir, and deploying temperature, pressure, and flow sensors along the wellbore to monitor the injection temperature and injection rate of the fluid.

7. The method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification according to claim 6, characterized in that, The method includes: constructing a geothermal energy storage facility from a low-porosity reservoir; constructing a compressed air energy storage facility from a medium-porosity reservoir; and constructing a natural gas storage facility from a high-porosity reservoir.

8. The method for constructing artificial reservoirs in deep sandstone reservoirs through graded modification according to claim 7, characterized in that, The CO2 aqueous solution is prepared by pumping formation water to the surface and mixing it with carbon dioxide gas in a mixing pumping station, and reserving a portion of the original formation water in the mixing pumping station for later storage and sealing.

9. An evaluation method for constructing artificial reservoirs through graded stimulation in deep sandstone reservoirs, characterized in that, The reservoir is constructed using the method for constructing artificial reservoirs through graded stimulation in deep sandstone reservoirs as described in claim 8, wherein the evaluation method includes: During the construction phase, real-time monitoring of temperature and pH changes in the near-well and far-well areas is conducted to determine the boundary range of the reservoir. After construction is completed, water injection / gas injection / heat injection tests are conducted to determine the expanded porosity of the near-wellbore area and the sealing performance of the far-wellbore area in order to detect the connectivity of the reservoir and obtain curves of injection pressure and liquid level changes. A storage leakage early warning model is established based on the aforementioned curve to ensure the normal operation of the storage facility.

10. The evaluation method for constructing artificial reservoirs through graded modification in deep sandstone reservoirs according to claim 9, characterized in that, The evaluation method further includes: for low-porosity reservoirs, detecting whether the expanded reservoir meets the preset production capacity requirements; for high-porosity reservoirs, detecting the sealing performance of the composite sealing layer.

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