Variable-sequence fracturing method and device for improving complexity of fractures between horizontal well sections

Abstract

The invention relates to the technical field of low-permeability compact oil and gas field development, in particular to a variable-sequence fracturing method and device for improving the complexity of fractures between horizontal well sections. The method comprises the steps that a block variable-sequence fracturing model is constructed based on target horizontal well drilling cuttings logging response characteristics, target block coring rock mechanical parameters, target block ground stress parameters and target block construction data; based on the block variable-sequence fracturing model, determining a variable-sequence fracturing depth section of a reservoir along the path of a target horizontal well shaft; a target horizontal well variable-sequence fracturing scheme is determined by combining the target horizontal well construction process conditions and the target horizontal well shaft along-way reservoir variable-sequence fracturing section depth; and on the basis of the target horizontal well variable-sequence fracturing scheme, variable-sequence fracturing is conducted on the target horizontal well. The method is suitable for field requirements of staged fracturing transformation of various oil and gas reservoir horizontal wells, the adaptability to various lithologic reservoirs such as sandstone, carbonate rock and limestone is high, and the technical application range is wide.

Description

Technical Field

[0001] This invention relates to the field of low-permeability tight oil and gas field development technology, and in particular to a variable-sequence fracturing method and apparatus for increasing the complexity of fractures between horizontal well sections. Background Technology

[0002] With the development of unconventional energy sources such as tight gas and shale oil and gas, hydraulic fracturing technology has made significant progress. In particular, breakthroughs in horizontal well segmented multi-cluster fracturing technology over the past decade have provided strong support for the exploration and development of unconventional oil and gas reservoirs. Horizontal well segmented multi-cluster fracturing technology, as a highly efficient production enhancement measure, is currently the main form of tight oil and gas extraction. Its main principle is to inject fracturing fluid into the formation, causing one or more fractures to open, creating channels for oil and gas to flow from the formation to the wellbore.

[0003] For the production enhancement and stimulation of low-permeability tight sandstone oil and gas reservoirs, the main approach adopted both domestically and internationally is horizontal well + volumetric fracturing technology. This approach is highly effective due to its significant production advantages and mature technology, and its specific application to low-permeability tight oil and gas reservoirs. On the one hand, through integrated horizontal well drilling and completion technology, the length of the horizontal section and the level of cementing and completion processes are continuously improved, enhancing wellbore completion quality and expanding the contact area between the wellbore and the reservoir matrix sandstone. On the other hand, segmented and clustered volumetric fracturing technology is fully utilized to "break up" the reservoir matrix, forming a volumetric fracture network. This maximizes the contact area between the fracture walls and the reservoir matrix, minimizing the seepage distance of oil and gas from the matrix to the fractures and minimizing the resistance to seepage of matrix fluids into the fractures. This greatly improves the overall seepage capacity of the reservoir, achieving "three-dimensional transformation" of the reservoir in length, width, and height, and continuously improving the initial and stable production capabilities of oil and gas wells.

[0004] According to the research on the monitoring and evaluation of artificial fracture network after horizontal well + volumetric fracturing technology, the existing horizontal well volumetric fracturing technology has a good effect on reservoir stimulation with lacustrine and marine sedimentary systems, weak planar heterogeneity, small biaxial stress difference, and well-developed natural fractures, and can achieve three-dimensional fracture network volumetric stimulation. However, for tight sandstone reservoirs dominated by braided river sedimentary systems, characterized by strong planar heterogeneity, rapid lateral variations in sand body properties and gas content, small effective sand body size, and well-developed flow-blocking zones, the use of a close-cutting fracturing sequence in horizontal wells results in numerous fracturing sections along the wellbore. These sections have relatively short intervals, and the stress conditions between different clusters vary, making uniform fracturing initiation difficult. Consequently, each section's artificial fracture morphology is dominated by a single main fracture, with local stress field interference between adjacent sections. This leads to a limited number of extended branch fractures and intersecting fractures, restricting the multidimensional extension scale of fractures and resulting in a small single-fracture fracturing volume. This fails to meet the volumetric fracturing requirements of tight, low-permeability oil and gas reservoirs. Therefore, it is urgent to optimize the technology through technical means to fully utilize the role of main fracture extension and communication between branch fractures and intersecting fractures within each section, thereby increasing the complexity of fractures and reservoir fracturing volume (SRV) between horizontal well sections and improving the overall efficiency of single oil and gas wells.

[0005] Currently, the main methods used in the industry and market to increase the complexity of inter-section fractures are increasing the number of clusters within a section and staggered fracture distribution in adjacent horizontal wells. However, their effectiveness in improving fracture complexity is unsatisfactory. On the one hand, gas production profile testing has revealed that the success rate of fluid injection in multi-cluster perforated sections within a section is low. Most sections only have high-intensity fluid injection in 1-2 clusters, while other clusters have almost no fluid injection, indicating very low effectiveness of intra-section clustering. On the other hand, staggered fracture distribution in adjacent horizontal wells requires high well spacing, and monitoring of adjacent well productivity has revealed technical defects such as inter-well fracture interference and low utilization between staggered fractures. The market application prospects of the above two similar technologies are limited. Therefore, continuously upgrading and optimizing the horizontal well + volumetric pressure fracture network stimulation technology is of great significance for the efficient development of low-permeability tight oil and gas reservoirs.

[0006] Monitoring of gas production contribution during on-site horizontal well volumetric fracturing technology tests revealed that the post-fracturing effect of horizontal wells was lower than expected. The main reasons for this are: firstly, the "failure" of the main fracture and branch fracture network extension is due to the large horizontal stress difference, strong reservoir heterogeneity, stress resistance between fracturing sections, and a relatively simple main fracture extension pattern; secondly, considering the influence of wellbore friction, even if each section maintains the same vertical depth and is part of the same pressure system, the wellbore friction increases over a long distance from the root to the toe, resulting in uneven distribution of net pressure provided during construction. This leads to fewer branch fractures and intersecting fractures in some sections, limiting the multidimensional extension scale of fractures and resulting in a smaller single-fracture volume. Summary of the Invention

[0007] The purpose of this invention is to provide a variable-sequence fracturing method and apparatus to improve the complexity of fractures between horizontal well sections. Addressing the shortcomings of existing techniques such as increasing the number of clusters within sections and staggered fracture distribution between adjacent horizontal wells, this invention, specifically for low-permeability tight oil and gas reservoirs, employs a reciprocating variable-sequence method to enhance the complexity of fractures between horizontal well sections. This method fully utilizes the artificially intervened stress field formed between sections during reciprocating fracturing to achieve dense fracture distribution, increasing branch fractures and staggered oblique fractures along the main fracture extension direction, thereby increasing the complexity of fractures between sections. This method is applicable to the field requirements of horizontal well section fracturing in various oil and gas reservoirs, exhibiting high adaptability to various lithological reservoirs such as sandstone, carbonate rocks, and limestone, and has a wide range of technical applications. To achieve the above objectives, this invention provides the following technical solution:

[0008] In a first aspect of the invention, a variable-sequence fracturing method is provided to improve the complexity of fractures between horizontal well sections, the method comprising,

[0009] Based on the drilling cuttings logging response characteristics of the target horizontal well, the rock mechanical parameters of the core sample of the target block, the geostress parameters of the target block, and the construction data of the target block, a block variable sequence fracturing model is constructed.

[0010] Based on the block variable-sequence fracturing model, the variable-sequence fracturing depth range of the reservoir along the wellbore of the target horizontal well is determined;

[0011] Based on the construction process conditions of the target horizontal well and the depth of the variable-sequence fracturing section of the reservoir along the wellbore of the target horizontal well, the variable-sequence fracturing scheme of the target horizontal well is determined.

[0012] Based on the target horizontal well variable-sequence fracturing scheme, the target horizontal well is subjected to variable-sequence fracturing.

[0013] Furthermore, the method also includes,

[0014] Based on the understanding of the geological structure and sand body distribution of the target block, the reservoir heterogeneity characteristics along the wellbore direction are evaluated. The reservoir heterogeneity characteristics along the wellbore direction include local micro-scale structures along the wellbore direction, planar heterogeneity characteristics, natural fracture development, lateral variation of sand body physical properties and gas content, effective sand body size and flow barrier development characteristics, and reservoir regularity.

[0015] Based on the aforementioned reservoir heterogeneity characteristics along the wellbore direction, the target horizontal well is determined.

[0016] Furthermore,

[0017] The construction data for the target block includes: the results of the formation pressure test of adjacent wells in the early stage, the monitoring data of downhole pressure gauges, the fracture extension pressure during fracturing and / or the wellhead pump shutdown pressure.

[0018] Furthermore, the block variable-sequence fracturing model is a numerical model that couples geological parameters with the geostress field, based on the geological parameters of the block's framework wells, well logging and logging data of horizontal wells, rock mechanics parameters, and / or geostress test data.

[0019] Furthermore, based on the block-specific fracturing model, the fracturing depth range along the wellbore of the standard horizontal well is determined, including:

[0020] Based on the block-specific fracturing model, the artificial intervention stress field requirements in the wellbore direction of the target horizontal well are determined.

[0021] Based on the stress field requirements for artificial intervention along the wellbore direction of the horizontal well, the depth range of the reservoir along the target horizontal wellbore for variable-sequence fracturing is determined.

[0022] Furthermore, the target horizontal wellbore's wellbore-path fracturing depth segment along the reservoir is a reservoir segment with poor reservoir properties, tight lithology, underdeveloped natural fractures, or a difference between the maximum and minimum principal stresses exceeding a threshold. Furthermore, determining the artificial intervention stress field requirements along the target horizontal wellbore direction includes:

[0023] The distribution of geostress and fracture development at different locations along the wellbore direction were evaluated, and reservoir sections with large biaxial stress differences and poor natural fracture development were identified as reservoir sections requiring artificial intervention in the stress field.

[0024] For reservoir sections requiring artificial intervention in the stress field, variable-sequence fracturing is carried out. The left and right end sections of three adjacent sections are modified first, and a local stress field intervention change zone is constructed in the middle section to reduce the biaxial stress difference in the region, increase the number of branch fractures, turning fractures, and staggered oblique fractures, and improve the complexity of artificial fractures.

[0025] Based on the increased complexity of the artificial fractures, the required artificial intervention stress field in the direction of the target horizontal wellbore is determined.

[0026] Furthermore, the target horizontal well construction process conditions include the use of switchable sliding sleeve fracturing technology, a horizontal section length of more than 500m, and more than 5 fracturing and stimulation sections.

[0027] Furthermore, the target horizontal well variable-sequence fracturing scheme includes:

[0028] The location of the segment corresponding to the variable sequence fracturing depth segment, the modification sequence of the variable sequence fracturing depth segment, and the construction parameters of the corresponding variable sequence modification depth segment.

[0029] Furthermore, the target horizontal well variable-sequence fracturing scheme also includes:

[0030] The fracturing is carried out sequentially based on the varying fracturing depth. When a certain section is being modified, the fluid inlet channels of other sections are temporarily closed.

[0031] Furthermore, the target horizontal well variable-sequence fracturing scheme also includes:

[0032] After the target horizontal well is fractured in sequence, the wellhead is closed. Once all fractures are closed, the well is opened to release fluid.

[0033] In a second aspect of the invention, a variable-sequence fracturing device is provided to increase the complexity of fractures between horizontal well sections, characterized in that the device comprises,

[0034] The module is used to construct a block variable-sequence fracturing model based on the target horizontal well cuttings logging response characteristics, core rock mechanical parameters of the target block, geostress parameters of the target block, and construction data of the target block.

[0035] The first determining module is used to determine the depth range of the reservoir along the wellbore of the target horizontal well based on the block variable sequence fracturing model.

[0036] The second determination module is used to determine the variable-sequence fracturing scheme for the target horizontal well by combining the construction process conditions of the target horizontal well with the depth of the variable-sequence fracturing section of the reservoir along the wellbore of the target horizontal well.

[0037] The fracturing module is used to perform variable-sequence fracturing on the target horizontal well based on the variable-sequence fracturing scheme of the target horizontal well.

[0038] In a third aspect of the invention, an electronic device is provided, the electronic device comprising at least one processor and at least one memory, the memory being data-connected to the processor, wherein...

[0039] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method as described above.

[0040] The technical effects and advantages of this invention are as follows:

[0041] (1) By artificially adjusting and changing the fracturing construction sequence of each section of the horizontal well, the geostress field between two adjacent sections of the reservoir is intervened, and the magnitude and direction of the geostress are induced to change locally by utilizing the artificial main fracture extension process.

[0042] (2) In the stress-induced change zone, reciprocating fracture fracturing is carried out to fully tap the remaining oil and gas reserves between sections and form a dense network of fractures in the horizontal well segmentation of the oil and gas reservoir.

[0043] (3) By using the reciprocating seam modification of the induced stress zone, branch seams and intersecting oblique seams are added in the direction of the main crack extension, the complexity of inter-segment cracks is increased, and the effective seam control modification volume is increased.

[0044] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0045] Figure 1 This is a flowchart of a variable-sequence fracturing method for improving the complexity of fractures between horizontal well sections according to the present invention;

[0046] Figure 2 This is a fracture feature diagram of a reservoir section that does not require sequential fracturing (artificial intervention in stress field modification) in a specific embodiment of the present invention;

[0047] Figure 3 This is a fracture feature diagram of a reservoir section that requires variable-sequence fracturing (artificial intervention in stress field modification) in a specific embodiment of the present invention;

[0048] Figure 4 This is a schematic diagram of the stimulation sequence of a reservoir segment with underdeveloped fractures during variable-sequence fracturing in a specific embodiment of the present invention.

[0049] Figure 5 This is a schematic diagram of the fractures after the modification of a reservoir segment with undeveloped fractures in a specific embodiment of the present invention.

[0050] Figure 6 This is a block diagram of the electronic device structure in a specific embodiment of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] To address the shortcomings of existing technologies, this invention discloses a variable-sequence fracturing method that increases the complexity of fractures between horizontal well sections, such as... Figure 1 As shown, the method includes,

[0053] Step 1: Construct a block variable-sequence fracturing model based on the target horizontal well cuttings logging response characteristics, core rock mechanical parameters of the target block, geostress parameters of the target block, and construction data of the target block;

[0054] Step 2: Based on the block variable-sequence fracturing model, determine the variable-sequence fracturing depth range of the reservoir along the wellbore of the target horizontal well;

[0055] Step 3: Based on the construction process conditions of the target horizontal well and the depth of the variable-sequence fracturing section along the wellbore of the target horizontal well, determine the variable-sequence fracturing scheme for the target horizontal well; among which, the construction process conditions of the target horizontal well are: adopting the switchable sliding sleeve fracturing process, with a horizontal section length of more than 500m and more than 5 fracturing stimulation sections.

[0056] Step 4: Based on the target horizontal well variable sequence fracturing scheme, perform variable sequence fracturing on the target horizontal well.

[0057] In one specific embodiment of the present invention, the method further includes determining a target horizontal well, comprising the following steps:

[0058] Based on the understanding of the geological structure and sand body distribution of the target block, the reservoir heterogeneity characteristics along the wellbore direction are assessed. The reservoir heterogeneity characteristics along the wellbore direction include local micro-scale structures along the wellbore direction, planar heterogeneity characteristics, development of natural fractures, lateral variation of sand body physical properties and gas content, effective sand body size and the development characteristics of flow-blocking zones, etc.

[0059] Based on the aforementioned reservoir heterogeneity characteristics along the wellbore direction, the target horizontal well is determined.

[0060] like Figure 2 and Figure 3 As shown in the diagram illustrating the reservoir heterogeneity characteristics along the wellbore direction of a horizontal well, it can be seen that... Figure 2 The middle reservoir section is characterized by well-developed natural fractures, small biaxial stress differences, and a high proportion of fractures parallel to the wellbore direction. When the reservoir section has well-developed natural fractures, small biaxial stress differences, and a high proportion of fractures parallel to the wellbore direction ( Figure 2 The proposed modification scheme is not suitable for this application. Figure 3 The middle reservoir section is characterized by underdeveloped natural fractures, a large biaxial stress difference, and a high proportion of fractures perpendicular to the wellbore direction. When the reservoir section has the characteristics of underdeveloped natural fractures, a large biaxial stress difference, and a high proportion of fractures perpendicular to the wellbore direction ( Figure 3 This application's modification scheme is suitable for use.

[0061] In a specific embodiment of the present invention, for step 1: the construction data of the target block includes: the results of the formation pressure test of the adjacent well in the early stage, the monitoring data of the downhole pressure gauge, the fracture extension pressure during fracturing construction and / or the wellhead pump shutdown pressure, etc.

[0062] The block-specific variable-sequence fracturing model is a coupled model of the block's geological model and geostress field model. Specifically, it establishes a coupled numerical model of geological parameters and geostress field based on data such as geological parameters from the block's framework wells, horizontal well logging and well logging data, rock mechanics parameters, and geostress test data.

[0063] In a specific embodiment of the present invention, for step 2: determining the reservoir fracturing depth range along the standard horizontal wellbore based on the block variable-sequence fracturing model, the following is included:

[0064] Based on the block-specific variable-sequence fracturing model, the required artificial intervention stress field along the wellbore direction of the target horizontal well is determined; combined with the required artificial intervention stress field along the wellbore direction, the variable-sequence fracturing depth range along the reservoir along the target horizontal well is determined. Among these,

[0065] The requirement for artificial intervention in the stress field along the wellbore direction of a horizontal well refers to the evaluation of the stress distribution and fracture development at different locations along the wellbore direction. Reservoir sections with large biaxial stress differences and no natural fractures are the reservoir sections that require artificial intervention in the stress field.

[0066] In one specific embodiment of the present invention, the target horizontal wellbore's reservoir-specific fracturing depth section is a reservoir section with poor reservoir properties, tight lithology, underdeveloped natural fractures, and a maximum principal stress to minimum principal stress difference exceeding a threshold value. The threshold value is preferably 8 MPa.

[0067] The construction process conditions for the target horizontal well mainly include the use of sequential fracturing in each section. The left and right ends of the three adjacent sections are modified first to give full play to the disturbance and excitation effect of the modified fractures on the adjacent stress field. A local stress field intervention and change zone is constructed in the middle section to reduce the biaxial stress difference in the region, increase the number of branch fractures, turning fractures, and staggered oblique fractures, and improve the complexity of artificial fractures.

[0068] In a specific embodiment of the present invention, for step 3, the target horizontal well construction process conditions are as follows: a switchable sliding sleeve fracturing process is adopted, the horizontal section length is more than 500m, and the number of fracturing and stimulation sections is more than 5. Preferably, under normal circumstances, the horizontal well length does not exceed 1500m, and there are approximately 15-20 sections.

[0069] The target horizontal well variable sequence fracturing scheme implements horizontal well reciprocating variable sequence segmented fracturing stimulation, including: determining the segment positions corresponding to the variable sequence fracturing depth segments, the stimulation sequence of the variable sequence fracturing depth segments, and the construction parameters of the corresponding variable sequence stimulation depth segments.

[0070] The aforementioned implementation of horizontal well reciprocating variable sequence segmented fracturing stimulation refers to: according to the variable sequence fracturing stimulation plan, a construction operation is carried out in accordance with the designed number of segments. After each segment is completed, the next segment is carried out. When a segment is being constructed, the fluid inlet channels of other segments are temporarily closed to ensure that the fluid inlet stimulation is carried out in accordance with the design requirements.

[0071] The specific procedures for shutting in and draining fluid after fracturing a horizontal well following a change-sequence fracturing process are as follows: After the change-sequence fracturing section and other sections have been completed, the wellhead is shut in, the fracturing injection equipment is removed, the fracture closure time is calculated based on the formation pressure diffusion rate, and the well is opened to drain fluid after all fractures have closed. To ensure effective support for branch fractures and intersecting fractures during the change-sequence fracturing process, a controlled pressure draining system is initially adopted, and a conventional draining system is adopted later based on the fluid production situation.

[0072] This invention is a variable-sequence fracturing method for increasing the complexity of fractures between horizontal well sections in tight oil and gas reservoirs.

[0073] This invention provides a method for increasing the complexity of inter-stage fractures and improving fracturing effects, meeting the field requirements of horizontal well staged fracturing in major oil and gas fields. It is highly adaptable to various lithological reservoirs such as sandstone, carbonate rocks, and limestone, and has a wide range of technical applications. It enables reciprocating variable-sequence fracturing operations under existing technological conditions, with a simple process flow and low construction costs.

[0074] This invention and patent belong to the field of low-permeability tight oil and gas field development. The segmented fracturing technology for horizontal wells in low-permeability tight oil and gas reservoirs is increasingly widely used in oil and gas fields at home and abroad, and has become a core technical means for large-scale and efficient development of oil and gas fields. However, the volumetric effect of post-fracturing fracture network modification is poor. It is necessary to increase the complexity of fractures between horizontal well segments, increase the utilization of remaining oil and gas reserves between segments, and thus increase oil and gas production and improve the economic benefits of horizontal wells.

[0075] This invention provides a variable-sequence fracturing method for increasing the complexity of fractures between horizontal well sections in tight oil and gas reservoirs. It can solve the common and urgent problems in the industry, such as the single main fracture morphology and the difficulty in utilizing remaining reserves between sections. This innovative achievement has advanced theory and innovative process. Compared with similar technologies at home and abroad, its main technical indicators have reached the leading level. It can solve common problems faced in the industry, and has low operating costs and simple construction operation. It can generate significant economic and social benefits in terms of cost reduction and efficiency improvement, and has broad market application prospects.

[0076] The present invention also provides a variable-sequence fracturing device for increasing the complexity of fractures between horizontal well sections, the device comprising,

[0077] The module is used to construct a block variable-sequence fracturing model based on the target horizontal well cuttings logging response characteristics, core rock mechanical parameters of the target block, geostress parameters of the target block, and construction data of the target block.

[0078] The first determining module is used to determine the depth range of the reservoir along the wellbore of the target horizontal well based on the block variable sequence fracturing model.

[0079] The second determination module is used to determine the variable-sequence fracturing scheme for the target horizontal well by combining the construction process conditions of the target horizontal well with the depth of the variable-sequence fracturing section of the reservoir along the wellbore of the target horizontal well.

[0080] The fracturing module is used to perform variable-sequence fracturing on the target horizontal well based on the variable-sequence fracturing scheme of the target horizontal well.

[0081] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0082] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0083] The main implementation process includes:

[0084] ①Assess the reservoir heterogeneity characteristics along the wellbore direction in horizontal wells

[0085] Based on the geological structure and sand body distribution of the block where the horizontal well is located, the heterogeneity characteristics of the reservoir along the wellbore direction were analyzed and evaluated. It was found that within the range of sections 1-5, the reservoir has strong planar heterogeneity, poor development of natural fractures, small effective sand body size, and local obstruction zone development.

[0086] ② Determine the depth of sequence modification based on the stress field requirements of artificial intervention.

[0087] Based on the drilling cuttings logging response characteristics, core rock mechanics and geomechanical parameters of the horizontal well, as well as the formation pressure test results from adjacent wells and the fracture propagation pressure during fracturing operations, a block geological model and a geostress field model were established. The evaluation concluded that there is a need for artificial intervention in the stress field along sections 1-5 of the horizontal wellbore. Figure 3 The depth range of the reservoir along the wellbore was determined to be the 1st to 5th stages;

[0088] ③ Develop a process plan for reciprocating variable-sequence fracturing stimulation of horizontal wells.

[0089] Based on the horizontal well construction process conditions and the sequential fracturing sections (sections 1, 2, 3, 4, and 5) along the wellbore, the specific sequential fracturing depth sections corresponding to the section positions (sections 1-5) are determined. These sections are then numbered according to the expected number of fracturing sections, and the corresponding sequence of reciprocating sequential fracturing sections is determined as follows: Figure 4 The sequence is divided into three sections: Section 1-Section 3-Section 2-Section 5-Section 4. Construction parameters for the variable-sequence modification sections are optimized using in-situ stress field intervention parameters (discharge rate of 6-8 cubic meters / minute for Sections 1, 3, and 5; discharge rate of 10-12 cubic meters / minute for Sections 2 and 4).

[0090] like Figure 4As shown, the modification order is: ①→③→②→⑤→④. Specifically, modify paragraph 1 first, then paragraph 3, then back to modify paragraph 2, then paragraph 5, and then back to modify paragraph 4, to achieve the goal of fully modifying paragraphs 2 and 4.

[0091] Phase 1, Sections 1-3: First, modify Sections 1 and 3 at the left and right ends, giving full play to the disturbance and excitation effect of the modified cracks in Sections 1 and 3 on the adjacent stress field. In the middle Section 2 area, construct a local stress field intervention and change zone to reduce the biaxial stress difference in the Section 2 area, increase the number of branch cracks, turning cracks, and staggered oblique cracks, and improve the complexity of artificial cracks.

[0092] The second phase, sections 3-5, involves first modifying sections 3 and 5 at the left and right ends, fully utilizing the disturbance and excitation effect of the modified cracks in sections 3 and 5 on the adjacent stress field, and then constructing a local stress field intervention and change zone in the middle section 4 area to reduce the biaxial stress difference in the section 4 area, increase the number of branch cracks, turning cracks, and staggered oblique cracks, and improve the complexity of artificial cracks.

[0093] ④ Implement reciprocating variable-sequence staged fracturing stimulation of horizontal wells

[0094] According to the variable-sequence fracturing modification scheme (Section 1-Section 3-Section 2-Section 5-Section 4), the specific implementation process is as follows: lower the perforation fracturing drill string and adjust the depth, perform coiled tubing hydraulic jet fracturing in Section 1 → trip the drill string, replace the sliding sleeve switch tool and hydraulic jet tool, set the packer → open the sliding sleeve fracturing in Section 3 → close the sliding sleeve in Section 3, unseal the packer → lower the tool string to Section 2 → open the sliding sleeve fracturing in Section 2 → raise the tool string, open the sliding sleeve in Section 3 → raise the tool string, set the packer, open the sliding sleeve fracturing in Section 5 → close the sliding sleeve in Section 5, unseal the packer → lower the tool string to Section 4 → open the sliding sleeve fracturing in Section 4 → trip the drill string.

[0095] ⑤ Well shut-in and fluid release after horizontal well fracturing

[0096] After the completion of the construction of all sections of the sequence modification project (sections 1-5), if Figure 5 As shown, the degree of fracture in sections 1-5 is significantly uniform. The controlled area of ​​artificial fractures in sections 2 and 4 has increased significantly. There are basically no untouched or unused reserve areas. The wellhead is closed, the fracturing injection equipment is removed, and the fracture closure time is calculated according to the formation pressure diffusion rate (40-60 min). After all fractures are closed, the well is opened and the fluid is released. In order to fully ensure the effective support of branch fractures, turning fractures and intersecting fractures in the sequence modification, a pressure-controlled release system is adopted in the early stage (the nozzles are 4mm-6mm-8mm-10mm...). In the later stage, a conventional release system is adopted based on the fluid production situation.

[0097] Based on the above disclosure, the present invention also provides an electronic device. For example... Figure 6 As shown, the electronic device of this disclosure includes at least one processor electrically connected to the present invention and at least one memory electrically connected to the processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the method steps as executed by the controller above.

[0098] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of increasing fracture complexity between horizontal intervals by varying the sequence of fracturing, comprising: The method comprises, Based on the target horizontal well drilling rock cuttings logging response characteristics, target block coring rock mechanics parameters, target block geostress parameters and target block construction data, a block variable sequence fracturing model is constructed; Based on the block variable sequence fracturing model, the reservoir variable sequence fracturing depth section along the target horizontal well bore is determined; Combined with the target horizontal well construction process conditions and the reservoir variable sequence fracturing section depth along the target horizontal well bore, the target horizontal well variable sequence fracturing scheme is determined; Based on the target horizontal well variable sequence fracturing scheme, the target horizontal well is subjected to variable sequence fracturing.

2. The method according to claim 1, wherein, The method further comprises, Based on the understanding of the geological structure and sand body distribution of the target block, the reservoir heterogeneity characteristics along the well bore direction are evaluated, including local micro-amplitude structure along the well bore direction, planar heterogeneity characteristics, natural fracture development, lateral variation of sand body physical properties and gas content, effective sand body size and development characteristics of flow resistance zone reservoir law; Based on the reservoir heterogeneity characteristics along the well bore direction, the target horizontal well is determined.

3. The variable sequence fracturing method for improving the complexity of interwell fractures of a horizontal well section according to claim 1, characterized in that, The target block construction data includes: previous adjacent well formation pressure test results, downhole pressure gauge monitoring data, fracturing construction fracture extension pressure and / or wellhead pump stop pressure.

4. The method of claim 1, wherein the method further comprises, The block variable sequence fracturing model is a numerical model of geological parameters and geostress field coupling established according to the geological parameters of the block skeleton well, well logging and logging data, rock mechanics parameters and / or geostress test data.

5. The method of claim 1, wherein the method further comprises, Based on the block variable sequence fracturing model, the reservoir variable sequence fracturing depth section along the target horizontal well bore is determined, including: Based on the block variable sequence fracturing model, the artificial intervention stress field demand of the target horizontal well bore direction is determined; Combined with the artificial intervention stress field demand of the horizontal well bore direction, the reservoir variable sequence fracturing depth section along the target horizontal well bore is determined.

6. The variable sequence fracturing method for improving the complexity of interwell fractures of a horizontal well section according to claim 5, characterized in that, The reservoir variable sequence fracturing depth section along the target horizontal well bore is a reservoir section with poor reservoir properties, dense lithology, undeveloped natural fractures or a difference between the maximum principal stress and the minimum principal stress higher than a threshold value.

7. The method of claim 6, wherein the method further comprises, Determining that the target horizontal well bore direction has an artificial intervention stress field demand includes: Evaluating the geostress distribution and fracture development at different positions along the well bore direction to determine that the reservoir section with a large two-way stress difference and undeveloped natural fractures is a reservoir section that needs artificial intervention stress field; Performing variable sequence fracturing reconstruction on the reservoir section that needs artificial intervention stress field, using the left and right end sections of the adjacent three sections for reconstruction first, constructing a local stress field intervention change area in the middle section area, reducing the two-way stress difference in the area, increasing the number of branch fractures, turning fractures and staggered oblique fractures, and improving the complexity of artificial fractures; Based on the requirement for improving the complexity of artificial fractures, the artificial intervention stress field demand of the target horizontal well bore direction is determined.

8. The variable sequence fracturing method for improving the complexity of interwell fractures of a horizontal well section according to claim 1, characterized in that, The target horizontal well construction process condition is that a switchable sliding sleeve fracturing process is used, the length of the horizontal section is more than 500 m, and the number of fracturing sections is more than 5.

9. The method of claim 1, wherein the method further comprises, The target horizontal well variable sequence fracturing scheme includes: The segment position corresponding to the variable sequence fracturing depth section, the reconstruction order of the variable sequence fracturing depth section, and the construction parameters of the corresponding variable sequence reconstruction depth section.

10. The method of claim 1, wherein the method is characterized by, The target horizontal well variable sequence fracturing scheme further includes: The reconstruction is sequentially performed based on the reconstruction order of the variable sequence fracturing depth section, wherein when a section is reconstructed, the liquid inlet channels of other sections are temporarily closed.

11. The method of claim 1-10, wherein the method is characterized by, The target horizontal well variable sequence fracturing scheme further includes: After the target horizontal well variable sequence fracturing is completed, the wellhead is closed, and after the fractures are closed, the well is opened to discharge liquid.

12. A variable sequence fracturing device for increasing fracture complexity between horizontal intervals, comprising: The device includes, The construction module is configured to construct a block variable sequence fracturing model based on a drilling cuttings logging response feature of a target horizontal well, coring rock mechanics parameters of a target block, geostress parameters of the target block, and construction data of the target block; The first determination module is configured to determine a variable sequence fracturing depth section of a reservoir along a wellbore of a target horizontal well based on the block variable sequence fracturing model; The second determination module is configured to determine a target horizontal well variable sequence fracturing scheme in combination with a construction process condition of the target horizontal well and the variable sequence fracturing section depth of the reservoir along the wellbore of the target horizontal well. The fracturing module is configured to perform variable sequence fracturing on the target horizontal well based on the target horizontal well variable sequence fracturing scheme. 13.An electronic device, comprising at least one processor and at least one memory data-connected with the processor, wherein, The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-11.

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