Method for fracturing a section of an ultra-short radius sidetracked horizontal well and a production method

Abstract

The present invention discloses a method for fracturing a section of an ultra-short radius side-drilling horizontal well and a production method. The fracturing method may include: based on the current remaining reservoir distribution and the current reservoir pressure state of the target area, performing reservoir numerical simulation to determine the fractures and fracture parameters required to produce the remaining reservoir; based on the current state of the geostress field of the target area, determining the fracture expansion morphology under the current geostress field state; and hydraulically jetting the positions of the required fractures to form a mechanical weak surface, thereby guiding the hydraulic fractures to initiate at the injection position. The initiation and expansion of the required fractures are guided by jetting on the rock surface of the ultra-short radius side-drilling horizontal well section to form a mechanical weak surface, thereby guiding the hydraulic fractures to initiate at the injection position. During the construction process, a temporary plugging agent is used to increase the net pressure of the fractures, thereby promoting the uniform expansion of multiple fractures and increasing the complexity of the fractures, thereby achieving the expected fracturing effect.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas development, and in particular to a method for fracturing a well section of an ultra-short radius side-drilling horizontal well and a production method. Background Art

[0002] In recent years, the proportion of newly added low-grade oil and gas resources in my country has increased year by year, among which newly added low-grade oil proven reserves account for more than 70% of the total oil proven reserves, and newly added low-grade natural gas proven reserves account for more than 90% of the total natural gas proven reserves. Therefore, increasing the effective utilization of low-grade resources has become an important responsibility for the development of my country's oil and gas fields.

[0003] As an important component of low-grade resources, low-permeability old oil reservoirs have become an important pillar for the current and future use of crude oil reserves in my country. With the steady growth of low-permeability oil reservoir production, the situation of "many wells with low production" in my country has become increasingly serious. Taking PetroChina as an example, as of the end of 2020, low-permeability and unconventional oil production accounted for 62.64% of the company, with 241,000 oil wells, 185,000 wells in operation, and an average daily oil production of 1.42 tons per well, and the single well production continued to decline. Summary of the invention

[0004] The inventors found in the process of production and exploration that the development of old wells in low permeability reservoirs is currently generally faced with problems such as ineffective water injection development, low production, and large decline rate. As a result, the use of conventional repeated fracturing faces the problem of poor re-fracturing effect after multiple rounds. How to further improve the single well production, reserve utilization and ultimate recovery rate of low permeability old oil fields has become an urgent problem to be solved.

[0005] At present, the ultra-short radius small borehole sidetracking technology can drill the sidetracking horizontal section to the remaining oil-rich area according to the current remaining oil distribution in the low permeability reservoir. Due to the small curvature radius and wellbore size, the sidetracking horizontal section adopts the open hole completion method. How to efficiently transform the sidetracking horizontal section and increase the single well production has become a problem that needs to be solved urgently.

[0006] In view of the above problems, the present invention is proposed to provide a method for fracturing a section of an ultra-short radius sidetracked horizontal well and a production method that overcomes the above problems or at least partially solves the above problems.

[0007] In a first aspect, an embodiment of the present invention provides a method for fracturing a section of an ultra-short radius sidetracked horizontal well, which may include:

[0008] Based on the current remaining reservoir distribution and current reservoir pressure state in the target area, perform reservoir numerical simulation to determine the fractures and fracture parameters required to exploit the remaining reservoir;

[0009] Based on the state of the current geostress field in the target area, determining the crack extension morphology of the crack under the current geostress field state;

[0010] Hydraulic injection is performed at the desired crack location to form a mechanical weak surface, thereby guiding the hydraulic fracture to initiate at the injection location.

[0011] Optionally, the determining, based on the current state of the geostress field in the target area, the crack extension morphology under the current geostress field state includes:

[0012] Based on the current state of the geostress field in the target area and the results of the numerical simulation of the reservoir, a fully coupled three-dimensional fracturing fracture propagation simulation is performed under different fracturing processes to determine the fracture propagation morphology of the fracture under the current geostress field state and the required fracturing process.

[0013] Optionally, the crack extension morphology may include: crack spacing and crack extension direction.

[0014] Optionally, the method for determining the current remaining reservoir distribution and the current reservoir pressure state of the target area may include:

[0015] The production and extraction data and the parameters of the initial fracture stimulation are input into the pre-constructed geological model of the target area to determine the current remaining reservoir distribution and the current reservoir pressure status.

[0016] Optionally, the step of inputting the production and mining data and the parameters of the first fracture transformation into a pre-built geological model of the target area may include:

[0017] The production well data and the extraction well data are input into the geological model to perform production history matching.

[0018] Optionally, the method for determining the state of the current geostress field in the target area may include:

[0019] The production data and initial geostress field parameters are input into a pre-built multi-well group large-scale geostress field calculation model to determine the current state of the geostress field.

[0020] Optionally, inputting the production and mining data and the initial geostress field parameters into a pre-built multi-well group large-scale geostress field calculation model to determine the state of the current geostress field may include:

[0021] The production and mining data and initial geostress field parameters are input into a pre-built multi-well group large-scale geostress field calculation model;

[0022] The change of the geostress field under injection-production conditions in the multi-well group large-scale geostress field calculation model is calculated based on production and mining data to determine the current state of the geostress field.

[0023] Optionally, after the hydraulic jetting is performed on the desired crack positions, the method may further include: using a temporary plugging agent in the cracks to plug the hydraulic cracks so as to allow the hydraulic cracks to expand evenly.

[0024] Optionally, after the hydraulic jetting is performed on the desired crack position, the following steps may also be performed:

[0025] The jet string is dragged to jet at multiple locations to form multiple clusters of hydraulic fractures.

[0026] Optionally, the fracture parameters may include at least one of the following: fracture position, fracture spacing, fracture length and fracture conductivity.

[0027] In a second aspect, an embodiment of the present invention provides a method for fracturing a section of an ultra-short radius side-drilling horizontal well as described in the first aspect to exploit a low permeability reservoir area.

[0028] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0029] In an embodiment of the present invention, a method and a production method for fracturing based on an ultra-short radius side-drilling horizontal well are provided, wherein the fracturing method comprises: based on the current remaining reservoir distribution and the current reservoir pressure state of the target area, numerical simulation of the reservoir is performed to determine the fractures and fracture parameters required to exploit the remaining reservoir; based on the current state of the geostress field in the target area, the fracture extension morphology under the current geostress field state is determined; hydraulic injection is performed on the position of the required fracture to form a mechanical weak surface, thereby guiding the hydraulic fracture to initiate at the injection position. The initiation and expansion of the required fracture are guided by hydraulic injection, and the rock surface of the ultra-short radius side-drilling horizontal well section is injected to form a mechanical weak surface, thereby guiding the hydraulic fracture to initiate at the injection position, thereby changing the original fracture initiation position affected by the geostress field. During the construction process, a temporary plugging agent is used to increase the net pressure of the fracture, promote the uniform expansion of multiple fractures, and increase the complexity of the fractures, thereby achieving the expected fracturing effect.

[0030] Furthermore, the method is applied to low-permeability strip-shaped residual oil, thick oil layer top, fault edge, independent sand body and other reservoirs, and is suitable for tapping the potential of old wells with low production and low efficiency, poor injection-production relationship, blockage in the near-well area, casing damage, shutdown, etc., to improve the single well production and recovery rate. Furthermore, the present invention can be promoted and applied to tapping the potential of other low-permeability old oil fields, and has broad application prospects.

[0031] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 A schematic flow chart of a method for fracturing a section of an ultra-short radius sidetracked horizontal well provided in an embodiment of the present invention;

[0035] Figure 2 This is one of the schematic flow diagrams of a specific fracturing method provided in an embodiment of the present invention;

[0036] Figure 3 The second schematic diagram of a specific fracturing method provided in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of a specific process for implementing the above step S33 in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0039] This patent provides a process for carrying out fracturing transformation in the side-drilling horizontal well section of ultra-short radius (small borehole), which has guiding significance for improving single well production and recovery rate of low-permeability old oil reservoirs and achieving high-quality, efficient and sustainable development of low-permeability old oil fields.

[0040] Terminology explanation:

[0041] Ultra-short radius sidetracking horizontal well: refers to a horizontal well with a shorter radius of curvature than a conventional short radius horizontal well. Currently, it is defined as a horizontal wellbore with a radius of curvature between 2m and 4m drilled in the radial direction of the vertical wellbore. This type of drilling is to solve the problem that conventional fracturing tools cannot be implemented and can only be fractured using general fracturing processes, but cannot achieve staged fracturing, that is, it is impossible to achieve precise fracturing, and thus it is impossible to obtain the desired fractures or fracture groups to exploit the remaining oil reservoir.

[0042] Fracturing: In the oil field, fracturing refers to a method of using hydraulic force to form cracks in oil and gas layers during oil or gas production, also known as hydraulic fracturing. Fracturing is to artificially create cracks in the formation to improve the flow environment of oil underground and increase the production of oil wells. It plays an important role in improving the flow conditions at the bottom of the oil well, slowing down the interlayer and improving the utilization of the oil layer. Fracturing is an important way to transform low-permeability oil and gas reservoirs and achieve efficient development. Temporary plugging and diversion fracturing technology can plug the original cracks, realize crack diversion, form new cracks, thereby forming a complex fracture network system, increasing the leakage area of ​​oil and gas wells, and achieving the purpose of increasing oil and gas well production.

[0043] Effective utilization: It is a technical term related to reserves. For example, if the distance between adjacent wells of a well is a (meter), the row distance is b (meter), and the reservoir thickness is h (meter), then the control area (ab) of the well multiplied by the reservoir thickness (h) is the control volume. Then the control volume is multiplied by the formation porosity, permeability, oil saturation, etc. to calculate the reserves of the target well. However, in actual production, some areas within the above control volume cannot be used, that is, they cannot be produced. The oil production that can be effectively produced is the effective utilization of the well control reserves.

[0044] Open hole well: It is a special term related to oil and gas exploration drilling. In order to keep the strata in certain special strata sections in their original state during the drilling process, casing is placed in certain special strata during the drilling. Open hole well means a well without casing.

[0045] Numerical simulation of oil reservoirs: refers to the use of computers to solve the mathematical model of oil reservoirs, simulate the flow of underground oil and water, and give the oil and water distribution at a certain moment in order to predict the dynamics of oil reservoirs.

[0046] Fracture conductivity: The ability of a fracture filled with proppant to pass fluid under the influence of reservoir in-situ stress. It is usually measured by the permeability of the fracture support zone (K f ) and the support gap width (w f ). In the fracturing optimization design, the concept of dimensionless conductivity is also used, expressed as (K f ·w f ) / (K·L f ) is used to represent the f represents the fracture length, and K represents the reservoir permeability.

[0047] In an embodiment of the present invention, a method for fracturing a horizontal well section of an ultra-short radius sidetracking is provided, referring to Figure 1 and Figure 2 As shown, the fracturing method may include the following steps:

[0048] Step S11: Based on the current remaining oil reservoir distribution and the current oil reservoir pressure state in the target area, perform oil reservoir numerical simulation to determine the fractures and fracture parameters required to exploit the remaining oil reservoir.

[0049] In this step, the target area of ​​the oil reservoir that has been exploited is first analyzed by computer to analyze the current distribution of the remaining oil reservoir and the current oil reservoir pressure status, and then the location, pressure, reserves and other information of the remaining oil reservoir are obtained. Then, the computer is used to carry out oil reservoir numerical model analysis, so as to determine what kind of fractures are needed to exploit the above-mentioned remaining oil reservoir.

[0050] The above-mentioned fracture parameters in this step include at least one of the following: fracture position, fracture spacing, fracture length and fracture conductivity.

[0051] Step S12: based on the current state of the in-situ stress field in the target area, determine the crack extension morphology under the current state of the in-situ stress field.

[0052] During the exploitation of oil reservoirs, the geostress field in the strata will change due to the influence of production factors such as water injection and oil production, as well as environmental factors such as cracks generated by the initial fracturing. Therefore, during the fracturing process, the cracks will expand and extend under the influence of the current geostress field.

[0053] The purpose of this step is to carry out fracturing simulation under different fracturing processes under the current state of the in-situ stress field in the target area, so as to determine the corresponding fracture extension morphology under different fracturing processes, and to select the fracture morphology that is closest to the remaining oil reservoir to be exploited in the above steps and the fracturing process that matches the fracture morphology.

[0054] It should be noted here that in the actual production process, after the fracturing process is implemented, the cracks in the formation can only expand in the direction of crack expansion and extension. However, this step is to simulate the different forms of crack expansion under different fracturing processes through a computer, that is, different fracturing processes match different crack expansion forms, which is convenient for screening of fracturing processes.

[0055] It should also be noted that the execution order of the above-mentioned step S11 and step S12 is not specific, that is, there is no specific order for first determining the cracks and crack parameters required for exploiting the remaining oil reservoir and first determining the crack extension morphology under the current ground stress field state. Step S11 can be executed first and then step S12, or step S12 can be executed first and then step S11, or step S11 or step S12 can be executed at the same time. The embodiment of the present invention does not specifically limit the terms.

[0056] Step S13: hydraulically spray the desired crack positions to form mechanical weak surfaces, thereby guiding the hydraulic fractures to initiate at the spraying positions.

[0057] In the above step S11, it has been determined what kind of cracks are needed to exploit the remaining oil reservoir, and in step S12, it is determined what kind of cracks can be produced under the current state of the geostress field and how the cracks expand during the fracturing process. In order to avoid the situation in which the cracks produced by the current state of the geostress field are not the cracks required to exploit the remaining oil reservoir during the production process, the inventor needs to guide the generation of the required cracks in this step S13, by means of hydraulic jetting, to form a mechanical weak surface on the rock surface of the ultra-short radius side-drilling horizontal well section, and then guide the hydraulic fractures to start at the jetting position.

[0058] The inventor uses a hydraulic jetting method to guide the injection of a mechanically weak surface to guide the initiation and expansion of the desired cracks. In this way, during fracturing construction, the rock formation will crack and expand at the mechanically weak surface, changing the original cracking position under the action of the ground stress field and achieving the expected fracturing effect.

[0059] In an optional embodiment, the above-mentioned step S12 is specifically as follows: based on the current state of the geostress field in the target area, combined with the results of numerical simulation of the reservoir, a fully coupled three-dimensional fracturing crack extension simulation is performed under different fracturing processes to determine the fracture extension morphology under the current geostress field state and determine the required fracturing process.

[0060] It should be noted here that the fracturing process in the embodiment of the present invention can be classified according to the process principle into: general fracturing, packer layered fracturing, flow limiting fracturing, ball throwing fracturing, yarn stripping fracturing, protective barrier fracturing, repeated fracturing, composite fracturing, foam fracturing, void high pressure fracturing, sand control fracturing, etc.

[0061] The above-mentioned crack extension morphology in the embodiment of the present invention mainly includes: crack spacing and crack extension direction.

[0062] In another specific embodiment, the present invention also provides a specific method for fracturing a section of an ultra-short radius sidetracking horizontal well, referring to Figure 2 and Figure 3 As shown, the method may include the following steps:

[0063] Step S31: input the production and exploitation data and the parameters of the initial fracture stimulation into the pre-constructed geological model of the target area to determine the current remaining reservoir distribution and the current reservoir pressure state.

[0064] This step is to study the distribution of remaining oil after selecting wells and layers. The geological model in the embodiment of the present invention can refer to the modeling methods of the prior art. This embodiment only uses the already constructed geological model for analysis. By inputting the production and exploitation data and the parameters of the previous initial fracture transformation into the geological model, the historical production dynamics from the initial production to the current can be simulated, and the current remaining oil distribution and reservoir pressure status can be obtained.

[0065] Specifically, this step is achieved by inputting the data of production wells and mining wells (oil production wells) into the geological model for production history fitting to obtain the current remaining oil distribution and reservoir pressure, that is, how much oil reservoir is left in which block in the target area, the specific location of the reservoir, the pressure of the reservoir, the reserves of the reservoir, etc., to provide a basis for fracture parameter optimization.

[0066] Step S32: Based on the current remaining oil reservoir distribution and the current oil reservoir pressure state in the target area, perform oil reservoir numerical simulation to determine the fractures and fracture parameters required to exploit the remaining oil reservoir.

[0067] This step is a reservoir engineering study, and its specific implementation refers to the implementation method of the above step S11, and the embodiment of the present invention will not be repeated here. The specific fracture parameter optimization is what kind of fracture is needed to produce the above remaining oil reservoir, that is, the position of the fracture in the horizontal well section, the spacing of the fracture, the length of the fracture, and the fracture conductivity and other parameters.

[0068] Step S33: input the production and mining data and the initial geostress field parameters into a pre-built multi-well group large-scale geostress field calculation model to determine the current state of the geostress field.

[0069] This step is to study the geostress field before the fracturing process is carried out. In the embodiment of the present invention, during the oil reservoir exploitation process, the pressure of the formation changes, that is, the geostress field changes during the production process due to water and oil exploitation. The initial geostress field is known, but after a certain period of production, the current geostress field is affected by the impact of exploitation and production and the cracks generated after the initial fracturing. Therefore, it is necessary to determine the current state of the geostress field. The current state of the geostress field determines the extension direction of the cracks during subsequent fracturing.

[0070] A large-scale geostress calculation model for multiple well groups is established. The geostress changes of the entire model under the dynamic production conditions of injection and production wells are calculated based on production data to obtain the current stress field distribution state, providing support for the optimization of repeated fracturing technology and fracture spacing.

[0071] Specifically, the implementation of this step S33 is as follows: Figure 4 As shown, the following steps may be included:

[0072] Step S331: input the production and mining data and the initial geostress field parameters into a pre-constructed multi-well group large-scale geostress field calculation model.

[0073] The above multi-well group large-scale geostress field calculation model in the embodiment of the present invention,

[0074] Step S332: Calculate the change of the geostress field under injection-production conditions in the large-scale geostress field calculation model of the multi-well group based on the production and exploitation data to determine the state of the current geostress field.

[0075] Step S34: Based on the current state of the in-situ stress field in the target area, determine the crack extension morphology under the current state of the in-situ stress field.

[0076] This step is to study the expansion law of multiple fractures under various fracturing process simulation scenarios. The specific implementation of this step refers to the implementation of the above step S12, and the embodiment of the present invention will not be repeated here.

[0077] Step S35, hydraulically spraying the desired crack positions to form mechanical weak surfaces, thereby guiding the hydraulic fractures to initiate at the spraying positions.

[0078] After the analysis of the above steps S31 to S34, this step determines the fracture optimization parameters, injection position and specific fracturing process. Specifically, this step uses tubing + flexible drilling tools + hydraulic jet gun barrel string to perform hydraulic jetting on the preferred perforation position, forming a mechanical weak surface at the injection position, and inducing hydraulic fractures to start and expand at the injection position. The specific implementation of this step refers to the implementation method of the above step S13, and the embodiment of the present invention will not be repeated here.

[0079] Before fracturing, it is necessary to optimize the construction parameters (displacement, sand volume, liquid volume, sand ratio, etc.), as well as the fracturing string, pumping procedure, construction material optimization, etc., and then determine the final fracturing scheme design, and then carry out hydraulic injection according to the fracturing process design. After the injection is completed, on-site fracturing construction is carried out, and finally the fracturing effect is evaluated. After the effect meets the requirements, return production is carried out.

[0080] Step S36: Use a temporary plugging agent in the crack to seal the hydraulic cracks so that the hydraulic cracks can expand evenly.

[0081] This step is to add temporary plugging agent into the cracks during the construction process to increase the net pressure in the cracks, which is conducive to the uniform expansion of multiple clusters of cracks, and also helps to open natural cracks and increase the complexity of cracks, thereby achieving the expected fracturing effect.

[0082] Step S37, dragging the injection string to inject at multiple locations to form multiple clusters of hydraulic fractures.

[0083] In the embodiment of the present invention, a horizontal side drilling is operated on a vertical well, which is equivalent to the horizontal open hole fracturing in the vertical direction. When spraying, it is not at one position, but the upper body pipe string is used to press open multiple cracks at one time. During the fracturing process, some cracks expand quickly, some cracks expand slowly, and even some cracks stop extending after extending to a certain position. However, we want to connect multiple cracks in the oil layer, and each crack expands evenly. Therefore, it is necessary to move the spraying position, that is, hydraulic spraying of multiple perforation positions can be achieved by lifting the pipe string in sequence.

[0084] The technical idea of ​​the present invention is to determine the repeated fracturing process and fracture parameters based on the research of remaining oil and geostress field, combined with reservoir numerical simulation and research on the expansion law of multiple clusters of fractures, and to match the hydraulic jet perforation and temporary plugging fracturing process in the fracture to form multiple hydraulic fractures in the side-drilling horizontal section, so as to realize the efficient transformation of the side-drilling of ultra-short radius small wellbore.

[0085] Since 2020, this technology has been applied on site in 6 wells in Wangyao and Ansai oilfields in Changqing. It has realized multi-cluster fracturing of ultra-short radius small borehole side drilling for the first time in China, successfully revived low-yield and low-efficiency old wells, with an average daily increase of 2.37 tons per well and a cumulative increase of more than 1,200 tons, with significant economic benefits. The present invention can be promoted and applied to other low-permeability old oilfields to tap their potential, and has broad application prospects.

[0086] Taking a well in Wangyao Ansai block of Changqing Oilfield Production Plant No. 1 as an example, before the well was operated, the daily liquid production was 0.10m 3 , with a daily oil production of 0.07t. In June 2020, flexible drilling tools were used for side drilling, and temporary plugging and fracturing in the fractures were carried out in July. After the operation, the daily oil production was 3.91t. From August 10 to now, the cumulative oil production has increased by 700t. The goal of low-cost potential tapping of old wells has been successfully achieved, with significant economic benefits.

[0087] Based on the same inventive concept, an embodiment of the present invention also provides a method for exploiting a low permeability reservoir area using the above-mentioned method for fracturing a well section of an ultra-short radius sidetracking horizontal well.

[0088] In the embodiments of the present invention, the method is mainly used for low permeability oil reservoir areas, that is, it is mainly used for low permeability strip-shaped residual oil, thick oil layer top, fault edge, independent sand body and other reservoirs. It is suitable for tapping the potential of old wells with low production and efficiency, poor injection-production relationship, blockage in the near-well area, casing damage, and shutdown, so as to improve the single well production and recovery rate.

[0089] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for fracturing a section of an ultra-short radius sidetracked horizontal well, characterized in that: include: Input production and extraction data and initial fracture stimulation parameters into the pre-built geological model of the target area to determine the current remaining reservoir distribution and current reservoir pressure status; Based on the current remaining reservoir distribution and current reservoir pressure state in the target area, perform reservoir numerical simulation to determine the fractures and fracture parameters required to exploit the remaining reservoir; Input the production and mining data and the initial geostress field parameters into a pre-built multi-well group large-scale geostress field calculation model to determine the current state of the geostress field; based on the current state of the geostress field in the target area, determine the crack extension morphology under the current geostress field state; Perform hydraulic jetting at the desired crack location to form a mechanical weak surface, thereby guiding the hydraulic fracture to start at the jetting location, changing the original cracking location affected by the ground stress field; Through the method of hydraulic jetting, a mechanical weak surface is guided to be sprayed out to guide the initiation and expansion of the required cracks. During the fracturing construction, the rock formation will crack and expand on the mechanical weak surface, changing the original cracking position under the action of the ground stress field and achieving the expected fracturing effect.

2. The method according to claim 1, characterized in that The determining, based on the current state of the in-situ stress field in the target area, the crack extension morphology under the current state of the in-situ stress field comprises: Based on the current state of the geostress field in the target area and combined with the results of the numerical simulation of the reservoir, a fully coupled three-dimensional fracturing fracture propagation simulation is performed under different fracturing processes to determine the fracture propagation morphology of the fracture under the current geostress field state and determine the required fracturing process.

3. The method according to claim 2, characterized in that The crack extension morphology includes: crack spacing and crack extension direction.

4. The method according to claim 1, characterized in that: The step of inputting the production and mining data and the parameters of the first fracture transformation into the geological model pre-built in the target area includes: The production well data and the extraction well data are input into the geological model to perform production history matching.

5. The method according to claim 1, characterized in that: The step of inputting the production and mining data and the initial geostress field parameters into a pre-built multi-well group large-scale geostress field calculation model to determine the current state of the geostress field comprises: inputting the production and mining data and the initial geostress field parameters into a pre-built multi-well group large-scale geostress field calculation model; The change of the geostress field under injection-production conditions in the multi-well group large-scale geostress field calculation model is calculated based on production and mining data to determine the current state of the geostress field.

6. The method according to any one of claims 1 to 5, characterized in that: After the hydraulic jetting is performed on the desired crack positions, the method further includes: using a temporary plugging agent in the cracks to plug the hydraulic cracks so that the hydraulic cracks can be evenly expanded.

7. The method according to any one of claims 1 to 5, characterized in that: After the desired crack position is subjected to hydraulic jetting, the method further comprises: The jet string is dragged to jet at multiple locations to form multiple clusters of hydraulic fractures.

8. The method according to any one of claims 1 to 5, characterized in that: The fracture parameters include at least one of the following: fracture location, fracture spacing, fracture length and fracture conductivity.

9. A method for producing a low permeability oil reservoir area by using the method for fracturing a section of an ultra-short radius sidetracking horizontal well as claimed in any one of claims 1 to 8.

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