A method and system for closely spaced parabolic differential fracturing

Abstract

The application provides a close-to-cut parabolic differential fracturing distribution method and system, which collects geological and engineering data of target horizontal wells and adjacent wells, analyzes overall engineering geological characteristics and engineering geological characteristics of each well section; takes a homogeneous model as a hypothesis premise, formulates a basic close-to-cut parabolic fracturing distribution strategy based on the overall engineering geological characteristics; then distinguishes normal sweet spot sections and local special sections, respectively optimizes the difference based on the formulated basic fracturing distribution strategy according to the corresponding engineering geological characteristics of the well section and the fracturing distribution optimization principle; further improves the fracturing distribution parameters of each well section after the differential optimization according to the production capacity prediction result, and forms the current target close-to-cut parabolic fracturing distribution parameter with the optimal heterogeneous production capacity. The method can maximize the fracturing reconstruction efficiency, fully liberate the production capacity of the heterogeneous unconventional reservoir, and greatly improve the recovery rate and economic benefit of the unconventional oil and gas field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas field development geological modification technology, and particularly relates to a close-to-cut parabolic differential fracturing seam distribution method and system. BACKGROUND

[0002] In recent years, oil and gas exploration and development is facing the situation that oilfield reservoir types are more and more complex, and potential tapping is more and more difficult, and a considerable part of the newly added oil and gas reserves comes from low permeability reserves. In order to realize effective utilization of reserves, based on this, improving single well production is the goal of oil and gas regional development, and maximizing oil reservoir recovery becomes the core research topic. Horizontal well becomes one of the important technologies for improving recovery. The actual application of engineering implementation results shows that horizontal well is superior to vertical well in various scenes, can greatly improve the contact area of underground oil and gas, and optimize the extraction efficiency of fluid. As one of the effective means for developing reservoirs, horizontal well can increase the drainage area of the reservoir, change the percolation mechanism and mode of fluid in the reservoir, and significantly improve the single well production. The key problem of applying horizontal well to develop low permeability reservoirs is reservoir modification. Through fracturing construction, a fracture network composed of artificial fractures, natural fractures and secondary fractures can be formed in the reservoir. Compared with conventional original fractures, the fracture network has better reservoir connectivity. However, if the reservoir modification design is unreasonable and the process implementation effect is poor, the economic benefit of the oilfield developed by applying horizontal well will be greatly restricted. In the process of developing segmented fracturing modification for horizontal well, fracturing seam distribution design greatly affects the fracturing modification effect.

[0003] In the prior art, CN201810665624.3 provides a method for optimizing the fracture distribution of a horizontal well in a strongly heterogeneous and dense reservoir. The method determines the fracture spacing by simulating the propagation of pressure waves in a continuous sand body with different hydraulic fracture spacings, and optimizes the economic and effective fracture distribution scheme. The method analyzes the fracture effect by simulating the implementation of different fracturing schemes, and the optimization design has large limitations and poor practicability. Moreover, the method does not provide a differentiated fracturing optimization design scheme for heterogeneous reservoirs. CN201710599514.7 provides a method for optimizing the cluster spacing of volume fracturing in a horizontal well. The method establishes a minimum cluster spacing optimization model and a maximum cluster spacing optimization model for the stress shadow effect from two aspects of reducing the adverse effects and utilizing the beneficial effects, and determines the optimal cluster spacing. The method essentially belongs to the simulation evaluation of fracturing parameters based on the stress shadow effect, and cannot provide clear guidance for the design of oil and gas well fracturing distribution for technical personnel in the field, especially for the scene of horizontal wells in unconventional well areas. In the document “Research on differentiated fracturing technology for multi-layer heterogeneous reservoirs”, the stress profile of 18 wells is calculated by using logging data calculation method. The differences in the number of oil layers, span and stress distribution of the target sand body are analyzed by using the numerical simulation method with productivity as the evaluation index, and the dominant fracturing process is optimized. The method considers only a single factor in the process of deciding the fracturing modification scheme, and the optimization effect has insufficient reliability, which cannot provide high-quality fracturing modification guidance for users in heterogeneous geology.

[0004] The information disclosed in the background section of this document is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0005] To solve the above problems, the present application provides a closely cut parabolic differential fracturing distribution method. The purpose of the present application is to solve the problem that the oilfield site cannot achieve efficient and sufficient modification of unconventional reservoirs, to provide a closely cut parabolic differential fracturing distribution method, to form a complete fracturing optimization design scheme, to achieve full modification of horizontal wells and differential efficient modification of each fracturing section, to reduce the cost of fracturing modification while improving the modification effect, and to maximize the improvement of oil and gas field recovery and economic benefits. In one embodiment, the method comprises:

[0006] The geological feature analysis step collects the geological and engineering data of the target horizontal well and adjacent wells, and analyzes the engineering geological features of each horizontal section of the target horizontal well.

[0007] The basic fracture distribution design step establishes a hypothetical homogeneous model of the current horizontal well based on the overall engineering geological features of the target horizontal well, and formulates a closely cut parabolic basic fracturing distribution strategy corresponding to the hypothetical homogeneous model in combination with the productivity prediction result.

[0008] The segment division step, the local special segment and the normal sweet spot segment are divided based on the engineering geological features and the productivity prediction results of each well segment.

[0009] The differential fracturing optimization step, for each normal sweet spot segment and local special segment, based on the established basic fracturing distribution strategy, further segmental fracturing distribution optimization is carried out according to the engineering geological features and the fracturing distribution optimization principles corresponding to the current horizontal well segment.

[0010] The productivity comprehensive adjustment step, based on the productivity prediction results, the differential optimized fracturing distribution parameters of each horizontal well segment are optimized to form the target differential fracturing distribution parameters of the current heterogeneous horizontal well different segments.

[0011] As an improvement of the present application, in one embodiment, in the geological feature analysis step, the collected geological and engineering data includes: well logging data, porosity and permeability data, structural surface data and seismic interpretation data of the target horizontal well and adjacent wells.

[0012] The analyzed engineering geological features include: porosity, permeability, oil saturation, gas saturation, water saturation, shale content, reservoir thickness, barrier thickness, natural fracture development density and bedding fracture density geological feature data; and Young's modulus, Poisson's ratio, brittleness index, horizontal stress difference coefficient and reservoir-barrier stress engineering feature parameters.

[0013] Preferably, in one embodiment, in the basic fracturing design step, a corresponding homogeneous hypothetical geological model is established based on the overall engineering geological features of the horizontal well, and a corresponding productivity prediction calculation model is constructed, different subdivided differential fracturing distribution parameters are substituted, and the matching fracturing distribution parameters are determined combined with the engineering geological features and the productivity prediction results, as the basic fracturing distribution strategy of the horizontal well.

[0014] As a further improvement of the present application, in one embodiment, in the segment division step, the influence weight of each factor in the geological engineering feature parameters on the productivity is determined by applying the analytic hierarchy process and the grey correlation analysis method, a comprehensive sweet spot calculation model of the well segment is constructed based thereon, and then the comprehensive sweet degree value of each segment along the horizontal well segment is calculated by using the calculation model.

[0015] Specifically, in one embodiment, in the segment division step, the well segment meeting the following situations is set as a local special segment in combination with the geological engineering data and the well logging data:

[0016] The segment with the comprehensive sweet degree value meeting the set condition and the distance from the wellbore exceeding the set value;

[0017] The section with the comprehensive sweetness value meeting the set condition and scattered and discontinuous distribution;

[0018] The section with the fracture pressure exceeding the set value.

[0019] In a preferred embodiment, in the differential fracture distribution optimization step, if the optimization target section is a normal sweet spot section, the differential optimization is realized according to the following steps:

[0020] The optimization principle is to improve the fracture reconstruction degree and fracture network complexity of the normal sweet spot section, and based on the specified basic fracture distribution strategy and the engineering geological characteristics of the current section, a plurality of groups of feasible fracture distribution parameters are set, which are substituted into the productivity prediction calculation model, and the fracture distribution parameter that optimizes the productivity calculation result of the current section is selected as the differential optimized fracture distribution strategy.

[0021] Further, in an embodiment, in the differential fracture distribution optimization step, if the optimization target section is a local special section, the differential optimization is realized according to the following steps:

[0022] It is judged whether the length of the local special section meets the set condition, and if so, a corresponding virtual homogeneous independent geological model is constructed based on the engineering address characteristics of the section, a corresponding section productivity prediction calculation model is constructed, different finely cut parabolic fracture distribution parameters are substituted into the section productivity prediction calculation, and the matching fracture distribution parameter of the section is determined based on the engineering geological characteristics and the productivity prediction result, which is used as the basic fracture distribution strategy of the current local special section.

[0023] If the length of the local special section does not reach the set condition, a plurality of groups of feasible fracture distribution parameters are set based on the specified basic fracture distribution strategy and the engineering geological characteristics of the current section, which are substituted into the productivity prediction calculation model, and the fracture distribution parameter that optimizes the productivity calculation result of the current section is selected as the differential optimized fracture distribution strategy.

[0024] As a further improvement of the present application, in an embodiment, in the productivity comprehensive adjustment step, it comprises:

[0025] Based on the finely cut parabolic basic fracture distribution strategy and the differential optimized fracture distribution parameters of the normal sweet spot section and the local special section, the overall fracture distribution scheme of the horizontal well is formed, which is substituted into the corresponding productivity prediction calculation model, and based on the productivity calculation result, the fracture distribution parameter is optimized in combination with the numerical calculation result of the fracture propagation morphology model.

[0026] Further, in an embodiment, in the productivity comprehensive adjustment step, the process of optimizing the fracture distribution parameter in combination with the numerical calculation result of the fracture propagation morphology model comprises:

[0027] Respectively simulate historical stitching design parameters, increase the stitching interval according to different setting adjustment coefficients and / or adjust the stitching interval and the stitching length according to different setting adjustment coefficients, form the capacity of the stitching network morphology scheme after construction, and re-determine the optimal scheme according to the capacity prediction.

[0028] Based on the method described in any one or more of the above embodiments, the application also provides a storage medium having program codes stored thereon, which can implement the method described in one or more of the above embodiments.

[0029] Based on the application aspect of the method described in any one or more of the above embodiments, the application also provides a close-cut parabolic differential fracturing stitching system, which comprises:

[0030] A geological feature analysis module configured to collect geological and engineering data of the target horizontal well and adjacent wells, and analyze the engineering geological features of each horizontal section of the target horizontal well;

[0031] A basic stitching design module configured to establish a hypothetical homogeneous model of the current horizontal well based on the overall engineering geological features of the target horizontal well, and develop a subdivided close-cut parabolic basic fracturing stitching strategy corresponding to the hypothetical homogeneous model in combination with the capacity prediction results;

[0032] A section division module configured to divide the local special sections and normal sweet spot sections based on the engineering geological features and capacity prediction results of each well section;

[0033] A differential stitching optimization module configured to, for each normal sweet spot section and local special section, further conduct targeted in-section fracturing stitching optimization according to the engineering geological features corresponding to the current horizontal section and the fracturing stitching optimization principles based on the developed basic fracturing stitching strategy;

[0034] A capacity comprehensive adjustment module configured to optimize the differential optimized fracturing stitching parameters of each horizontal section based on the capacity prediction results, and form the target close-cut parabolic differential fracturing stitching parameters with optimal capacity for different sections of the current heterogeneous horizontal well.

[0035] Compared with the closest prior art, the application has the following beneficial effects:

[0036] The application provides a close-cut parabolic differential fracturing stitching method and system, which collects geological and engineering data of the target horizontal well and adjacent wells, analyzes the overall engineering geological features and the engineering geological features of each well section; the application analyzes the geological features based on the current geological and engineering data of the horizontal well and adjacent wells, guarantees the comprehensiveness and accuracy of the feature analysis results, and provides reliable data support for the establishment and differential optimization of the subsequent basic stitching scheme.

[0037] Further, the present application firstly assumes a homogeneous model as a premise, formulates the base close-to-cut parabolic fracturing distribution strategy based on overall engineering geological characteristics, then identifies the local special section and normal sweet spot section of the whole horizontal well, and based on the formulated base fracturing distribution strategy, the corresponding engineering geological characteristics and fracturing distribution optimization principles of the well section are optimized respectively, the present application divides different fracturing well sections in the whole horizontal well section, at least divides the normal sweet spot section and the local special section (for example, the section with higher well section sweetness value), adopts different optimization principles to realize differentiated fracturing distribution parameter adjustment, controls the improvement cost, and the detailed fracturing distribution strategy of the corresponding well section design can contribute to the fracturing distribution strategy of the productivity;

[0038] Finally, further based on the productivity prediction result, the fracturing distribution parameters of each well section after differential optimization are improved, the target close-to-cut parabolic fracturing distribution parameters of the current non-homogeneous productivity optimum are formed, the scientific fracturing distribution decision is guaranteed, the maximum productivity is obtained, meanwhile, the fracturing distribution parameters of the individual well section are avoided to interfere with the fracturing operation of the whole well, a smooth and stable parabolic fracturing distribution scheme is formed, and the stability and economic benefit of the unconventional reservoir reconstruction project are further improved.

[0039] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate embodiments of the present application and explain the present application together with the written description, and do not limit the present application. In the drawings:

[0041] Figure 1 is a flowchart of the close-to-cut parabolic differential fracturing distribution method provided by an embodiment of the present application;

[0042] Figure 2 is an example diagram of the base close-to-cut parabolic differential fracturing distribution provided by the close-to-cut parabolic differential fracturing distribution method provided by the embodiment of the present application;

[0043] Figure 3 is an example diagram of the fracturing fracture set by the local encryption method in the close-to-cut parabolic differential fracturing distribution method provided by the embodiment of the present application;

[0044] Figure 4 is an example diagram of the change of the comprehensive sweetness value of each well section in the close-to-cut parabolic differential fracturing distribution method provided by the embodiment of the present application;

[0045] Figure 5 is a normal dessert section differential optimization fracturing and proppant placement diagram of differential fracturing and proppant placement of a close-cuts parabolic shape provided by another embodiment of the present application;

[0046] Figure 6 is a local special section differential optimization fracturing and proppant placement diagram of differential fracturing and proppant placement of a close-cuts parabolic shape provided by an embodiment of the present application;

[0047] Figure 7 is a structural schematic diagram of a differential fracturing and proppant placement system of a close-cuts parabolic shape provided by another embodiment of the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application will be described in detail hereinafter with reference to the drawings and embodiments, by which the person skilled in the art can fully understand how the present application applies technical means to solve technical problems and achieve the implementation process of technical effects and implement the present application according to the above implementation process. It should be noted that, as long as there is no conflict, each embodiment in the present application and each feature of each embodiment can be combined with each other, and the technical solutions formed thereby are all within the protection scope of the present application.

[0049] Although the flowchart describes the operations as sequential processing, many of the operations can be implemented in parallel, concurrently or simultaneously. The order of the operations can be rearranged. The processing can be terminated when its operations are completed, but can also have additional steps not included in the figure. The processing can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0050] The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. When a unit is referred to as being "connected" or "coupled" to another unit, it can be directly connected or coupled to the other unit, or there can be intervening units.

[0051] The terms used herein are merely used to describe specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, as used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well. It will be further understood that the terms "comprises" and / or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, units, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, units, components, and / or groups thereof.

[0052] In recent years, with the decrease of the recoverable reserves in the whole block and the maturation of the layered fracturing technology, the development of multi-thin layer reservoirs has been paid more and more attention. This kind of reservoir has the characteristics of multiple layer series, thin oil layer and strong heterogeneity, which makes the development process face serious interlayer interference and difficult to produce non-main layer.

[0053] In order to realize the effective utilization of reserves, based on this, improving single well production is the goal of oil and gas regional development, and maximizing the recovery of oil reservoirs becomes the core research topic. Horizontal well is one of the important technologies to improve recovery. The practical engineering implementation results show that horizontal well is superior to vertical well in various scenes, which can greatly improve the contact area of underground oil and gas, optimize the extraction efficiency of fluid, and increase the drainage area of oil reservoir, change the percolation mechanism and mode of fluid in the oil reservoir, and significantly improve the single well production. The key problem of applying horizontal well to develop low permeability oil reservoir is reservoir reconstruction. Through fracturing construction, a fracture network composed of artificial fractures, natural fractures and secondary fractures can be formed in the reservoir, which has better reservoir connectivity than conventional original fractures. However, if the reservoir reconstruction design is unreasonable and the process implementation effect is poor, the economic benefit of the oilfield developed by applying horizontal well will be greatly restricted. In the process of developing staged fracturing reconstruction for horizontal well, the fracturing fracture design greatly affects the fracturing reconstruction effect.

[0054] In existing research, the patent document "A method for optimizing fracture spacing of horizontal well staged fracturing in strong heterogeneous tight reservoirs (CN201810665624.3)" determines the fracture spacing by simulating the pressure wave propagation in continuous sand bodies with different hydraulic fracture spacing, and optimizes the economic and effective fracture spacing scheme, but does not give a differentiated fracturing optimization design scheme for heterogeneous reservoirs. The patent application "A method for optimizing cluster spacing of horizontal well volume fracturing (CN201710599514.7)" uses finite element numerical simulation method to establish minimum cluster spacing optimization model and maximum cluster spacing optimization model for reducing the adverse effects of stress shadow effect and taking advantage of the beneficial effects of stress shadow effect, respectively, to determine the optimal cluster spacing, but does not develop a differentiated fracture spacing scheme, and does not evaluate and research the effect of differentiated fracture spacing scheme. The patent application "Method and device for selecting fracture spacing pattern of horizontal well staged fracturing (CN201611265845.9)" determines the location information of the possibility value of forming complex fracture network and the demand value of complex fracture network in the target area on the pattern selection chart by obtaining the possibility value of forming complex fracture network and the demand value of complex fracture network, and selects the fracture spacing pattern of horizontal well staged fracturing, but does not give a detailed differentiated fracture spacing scheme for dense and shale reservoirs. The literature "Research on differential fracturing technology for multi-layer heterogeneous reservoirs" calculates the stress profile of 18 wells by using logging data calculation method, optimizes the dominant fracturing technology according to the number of target sand body oil layers, span and stress distribution difference, and designs and conducts fracturing for the wells to be fractured in the work area, but does not give a differentiated fracturing spacing scheme for specific target horizontal wells. The literature "Application of dense fracture staged fracturing technology in deep shale gas Zi2 well" carries out field test of dense fracture staged fracturing technology, and the complexity of fractures and the improvement of single well reservoir volume are obvious, which proves the applicability of dense fracture staged fracturing technology in deep shale gas wells, but does not give a differentiated fracturing spacing scheme for fluid flow characteristics and reservoir heterogeneity.

[0055] The inventors of the present application consider that in order to reasonably and efficiently formulate a staged fracturing reconstruction scheme for a horizontal well, it is necessary to fully understand the reservoir heterogeneity characteristics and the post-fracturing reservoir fluid flow rule. By studying the influence of different fracturing distribution schemes for a horizontal well on the productivity of the horizontal well, the optimal fracturing distribution and design scheme are evaluated and formulated, so that the fracturing reconstruction effect can be maximized. According to the previous fracturing simulation and field test and production experience, it is considered that for a relatively homogeneous horizontal well, the contribution rate of the root and toe fracturing segments to the productivity is usually higher than that of the middle segment. The numerical simulation results show that the parabolic distribution scheme is superior to the traditional equal-length distribution scheme. And due to the reservoir heterogeneity along the horizontal wellbore direction, the corresponding construction scheme is designed according to the reservoir characteristics of each fracturing segment, so that the fracturing reconstruction effect can be improved. Therefore, it is very necessary to invent a fine subdivision close-cuts parabolic differential fracturing distribution method. In summary, although the research on fracturing distribution schemes is increasingly valued, the research on fine subdivision close-cuts parabolic differential fracturing distribution schemes and the matching fracturing optimization design method is still in the blank, and it is urgently needed to be developed.

[0056] Therefore, in view of the field development and reservoir reconstruction needs, the present application designs a fine subdivision close-cuts parabolic differential fracturing distribution method to maximize the fracturing reconstruction effect and improve the recovery ratio and economic benefits of unconventional oil and gas fields.

[0057] Next, the detailed flow of the method of the embodiment of the present application is described in detail based on the accompanying drawings. The steps shown in the flowchart of the accompanying drawings can be executed in a computer system including, for example, a set of computer executable instructions. Although the logical order of the steps is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0058] Embodiment one

[0059] Figure 1 A flowchart of the fine subdivision close-cuts parabolic differential fracturing distribution method provided by the first embodiment of the present application is shown, referring to Figure 1 It can be seen that the method comprises the following steps.

[0060] The geological feature analysis step collects the geological and engineering data of the target horizontal well and adjacent wells, and analyzes the engineering geological features of each horizontal well segment of the target horizontal well;

[0061] The basic distribution design step establishes a hypothetical homogeneous model of the current horizontal well based on the overall engineering geological features of the target horizontal well, and formulates a fine subdivision close-cuts parabolic basic fracturing distribution strategy corresponding to the hypothetical homogeneous model in combination with the productivity prediction results;

[0062] The segment division step divides the local special segment and the normal sweet spot segment of the fracturing reconstruction based on the engineering geological features and the productivity prediction results of each well segment;

[0063] The differential stitching optimization step is based on the established basic fracturing stitching strategy, and further based on the engineering geological characteristics and fracturing stitching optimization principles of the current horizontal well section to perform targeted in-section fracturing stitching optimization for each normal sweet spot section and local special section.

[0064] The productivity comprehensive adjustment step is based on the productivity prediction result to optimize the fracturing stitching parameters of each horizontal well section after differential optimization, and forms the target differential fracturing stitching parameters of the parabolic line of the current heterogeneous horizontal well different sections.

[0065] Based on the logic in the above embodiments, through the associated reservoir horizontal well reservoir geological engineering characteristic analysis operation, the overall basic stitching scheme design operation, the sweet spot section stitching optimization operation, the local special section stitching optimization operation, and the overall productivity comprehensive optimization adjustment operation, a matching subdivided differential fracturing stitching scheme of the parabolic line can be designed for different fracturing sections of the horizontal well. Based on sufficient evaluation of the reservoir geological engineering characteristics of the horizontal well section, the subdivided differential fracturing stitching scheme design can improve the transformation effect while reducing the fracturing transformation cost, and can maximize the improvement of oil and gas field recovery and economic benefit.

[0066] Further, in an embodiment, in the geological characteristic analysis step, the collected geological and engineering data includes well logging data, porosity and permeability data, structural surface data, and seismic interpretation data of the target horizontal well and adjacent wells.

[0067] In actual application, the wells with similar geological engineering data in the same block and satisfying the set conditions are selected as the adjacent wells of the target well, which can be one or more.

[0068] Specifically, in an embodiment, the analyzed engineering geological characteristics include geological characteristics and engineering parameter characteristics; the geological characteristics include porosity, permeability, oil saturation, gas saturation, water saturation, shale content, reservoir thickness, barrier thickness, natural fracture development density, and bedding fracture density; and the engineering parameter characteristics include Young's modulus, Poisson's ratio, brittleness index, horizontal stress difference coefficient, and reservoir-barrier stress.

[0069] In the geological characteristic analysis step, the geological and engineering data of the target horizontal well and adjacent wells are collected, and after the analysis of the engineering geological characteristics of each horizontal well section, the normal sweet spot section and the local special section of the fracturing transformation are also divided.

[0070] After the engineering geological characteristics of the horizontal well are determined, further according to the overall engineering geological characteristics of the horizontal well, a fracturing scheme is formulated based on the assumption of a homogeneous model, a subdivided dense cutting parabolic fracturing distribution scheme is formed, and the optimization design of the subdivided dense cutting parabolic distribution scheme under the assumption of homogeneity is completed. Here, the homogeneous model is an assumption, and the actual model is basically a heterogeneous model.

[0071] Specifically, in an optional embodiment, a corresponding homogeneous assumed geological model is established based on the overall engineering geological characteristics of the horizontal well, and a corresponding productivity prediction calculation model is constructed, different subdivided dense cutting parabolic fracturing distribution parameters are substituted, and the matching fracturing distribution parameters are determined by combining the engineering geological characteristics and the productivity prediction results, serving as the basic fracturing distribution strategy of the horizontal well.

[0072] In actual application, based on the overall geological engineering characteristic analysis results of the horizontal well section, a plurality of fracturing schemes are formulated based on the assumption of a homogeneous model, a subdivided dense cutting parabolic differential distribution overall scheme is designed in each scheme, parameters such as section spacing, cluster spacing, fracturing fracture half-length (proportional parabolic optimization), and fracture conductivity are optimized, the optimal dense cutting parabolic fracturing distribution parameters are selected or adjusted through productivity simulation calculation to select or adjust the design of the best dense cutting parabolic fracturing distribution parameters as the current optimal overall basic distribution scheme, as shown in Figure 2 .

[0073] Specifically, in an optional embodiment, the process of formulating a fracturing scheme based on the assumption of a homogeneous model includes:

[0074] A numerical model of the target block is established by applying CMG and / or Eclipse reservoir numerical simulation software, and fracturing fracture parameters are set by using a local encryption method, as shown in Figure 3 . Under the assumption of a homogeneous model, a dense cutting parabolic fracturing distribution design is performed, and the fracturing fracture length and fracture spacing are optimized according to the productivity prediction results. During the optimization process, the fracturing fracture length and fracture spacing are increased or decreased in the same amplitude in proportion, and the overall maintains the parabolic equidistant fracture network phase of long at both ends and short in the middle.

[0075] In subsequent steps, the local special section and the normal sweet spot section are adjusted respectively, and the fracture parameters are further optimized according to the productivity prediction. The logical step-by-step adjustment method of the present application can avoid repeated and chaotic adjustment, reduce unnecessary productivity prediction times, and quickly find the optimal scheme.

[0076] In order to improve the fracturing reconstruction effect of unconventional reservoirs and ensure the efficient and sufficient reconstruction of heterogeneous horizontal well reservoirs, it is necessary to carry out subdivided dense cutting parabolic differential fracturing distribution scheme design based on sufficient evaluation of the reservoir geological engineering characteristics of the horizontal well section.

[0077] The local special section is mainly obtained based on geological engineering data and logging data. The section satisfying the following conditions is set as the local special section: the oil and gas is distributed at the far end of the horizontal well, and a long fracture needs to be formed to communicate; the oil and gas is scattered (discontinuous) in a low sweet spot area, and only the area with oil and gas distribution is selected to form a fracture, avoiding the area without oil and gas distribution; and the section needs to avoid a high fracture pressure and cannot be fractured.

[0078] Therefore, in one embodiment, the section division step divides the local special section and the normal sweet spot section of the fracturing reconstruction based on the engineering geological characteristics and the productivity prediction results of each section.

[0079] Specifically, in the section division step, the analytic hierarchy process and the grey correlation analysis method are used to determine the influence weight of each factor in the geological engineering characteristic parameter on the productivity, a comprehensive sweet spot calculation model of the section is constructed based on the influence weight, and then the comprehensive sweet degree value of each section along the horizontal section is calculated by using the calculation model.

[0080] In specific application, the step of dividing and determining the sweet spot section of the horizontal well includes:

[0081] The geological engineering parameters of each section of the target block are collected, the influence weight of each factor in the geological engineering characteristic parameter on the productivity is determined by using the analytic hierarchy process and the grey correlation analysis method, a comprehensive sweet spot calculation model is established, and then the comprehensive sweet degree value of each section along the horizontal section is calculated by using the calculation model, as shown in formula (1). Figure 4 In actual application, the section with the comprehensive sweet degree value greater than 0.5 can be set as the target high sweet spot section.

[0082] Further, in one embodiment, the section satisfying the following conditions is set as the local special section in combination with the geological engineering data and the logging data:

[0083] The section with the comprehensive sweet degree value satisfying the set condition and the distance from the wellbore exceeding the set value;

[0084] The section with the comprehensive sweet degree value satisfying the set condition and the scattered and discontinuous distribution;

[0085] The section with the fracture pressure exceeding the set value.

[0086] Further, in one embodiment, in the differential fracture distribution optimization step, if the optimization target section is the normal sweet spot section, the differential optimization is realized according to the following steps:

[0087] The optimization principle is to improve the fracturing reconstruction degree and fracture network complexity of the dessert section. Based on the specified basic fracturing distribution strategy and the engineering geological characteristics of the current well section, a plurality of groups of fracturing distribution parameters are set. The fracturing distribution parameters are substituted into the productivity prediction calculation model. The fracturing distribution parameter that optimizes the productivity calculation result of the current well section is selected as the differential optimization fracturing distribution strategy. The interval between the distribution sections and the cluster interval are shortened. The normal dessert section is adjusted to create a high conductivity fracturing system for the normal dessert section. The differential optimization fracturing distribution scheme of the normal dessert section is shown in FIG. 8. The fracturing distribution parameters of the normal dessert section are adjusted according to the productivity prediction result to maximize the yield. Figure 5

[0088] In a preferred embodiment, in the differential distribution optimization step, if the optimization target well section is a local special section, the differential optimization is realized according to the following steps:

[0089] It is judged whether the length of the local special section meets the set condition. If yes, a corresponding virtual homogeneous independent geological model is constructed based on the engineering address characteristics of the section. A corresponding section productivity prediction calculation model is constructed. Different finely cut parabolic fracturing distribution parameters are substituted into the section productivity prediction calculation. The fracturing distribution parameters matched with the section are determined according to the engineering geological characteristics and the productivity prediction result, which are used as the basic fracturing distribution strategy of the current local special section.

[0090] If the length of the local special section does not meet the set condition, a plurality of groups of fracturing distribution parameters are set based on the specified basic fracturing distribution strategy and the engineering geological characteristics of the current well section. The fracturing distribution parameters are substituted into the productivity prediction calculation model. The fracturing distribution parameter that optimizes the productivity calculation result of the current well section is selected as the differential optimization fracturing distribution strategy.

[0091] In the horizontal well of the unconventional reservoir, for the complex reservoir conditions, in addition to the normal dessert section and the local special section, there is a continuous low dessert section. It is different from the normal dessert section and the discontinuous scattered local special low dessert section. Based on the homogeneous assumption parabolic overall distribution design, the fracture parameters are optimized according to the productivity prediction.

[0092] On the other hand, due to the high operation cost of horizontal well fracturing, in addition to the reservoir conditions and technical problems, the operation cost factor also needs to be considered. In an embodiment, in the differential distribution optimization step, if the optimization target well section is a local special section, the differential optimization is realized according to the following steps:

[0093] ​In principle, the cost of control is transformed, combined with the current well section engineering geological characteristics based on the development of the basic fracturing strategy design optimization adjustment measures. In practical application, for the local special section of the individual section, such as the discontinuous low dessert in the ordinary dessert section, the fracture length, interval, cluster spacing and other parameters are optimized according to the actual situation during the optimization of fracture distribution, so as to realize low-cost and efficient reconstruction; the optimization of local special section is shown in the heterogeneous difference fracture distribution scheme example of Figure 6

[0094] Further, the researchers consider that the fracturing technology of horizontal well section needs to be considered for specific geological and engineering conditions, and economic benefits and productivity contribution, so that the productivity prediction after fracturing of horizontal well has important significance. On the one hand, it can further improve the scientificity of fracturing decision of horizontal well, and obtain the optimal economic benefit, on the other hand, it can also provide reliable optimization basis for determination of fracturing process parameters of horizontal well, and ensure the success rate and reliability of fracturing operation.

[0095] Therefore, in a preferred embodiment, in the productivity comprehensive adjustment step, it includes:

[0096] Based on the fine subdivision close-to-cut parabolic basic fracturing distribution strategy and the optimized fracturing distribution parameters of normal dessert section and local special section, the overall fracturing distribution scheme of horizontal well is formed, which is substituted into the corresponding productivity prediction operation model. According to the productivity calculation result, the fracturing distribution parameters are optimized combined with the numerical calculation result of fracture propagation morphology model.

[0097] Specifically, in an embodiment, in the productivity comprehensive adjustment step, the process of optimizing fracturing distribution parameters combined with the numerical calculation result of fracture propagation morphology model includes:

[0098] The productivity of the fracture network morphology scheme formed after increasing the fracture interval according to different set adjustment coefficients and / or adjusting the fracture interval and fracture length at the same time according to different set adjustment coefficients is simulated respectively, and the optimal scheme is determined again according to the productivity prediction.

[0099] In practical application, based on the overall fracturing design, dessert section and local section fracturing optimization scheme in the early stage, the target is to realize the maximum productivity, and the overall differential local parabolic and semi-parabolic fracturing scheme optimization design is completed, and the optimal fracturing scheme is formed.

[0100] Specifically, in an embodiment, the process of realizing productivity prediction includes: applying CMG and / or Eclipse reservoir numerical simulation software to establish numerical model of target block, substituting current and different group fracturing fracture parameters with prediction value into operation, determining optimal scheme according to productivity prediction result, and in specific application, field technicians can adopt other existing productivity prediction calculation model or method according to demand.​

[0101] In actual operation, the operation in the above-mentioned embodiment is repeated based on the engineering geological features corresponding to each target horizontal well and the fracturing seam optimization design concept of the present application, and the overall fracturing scheme optimization design of each horizontal well in the target block is gradually promoted.

[0102] In addition, the present inventors have found that for a reservoir with a small stress difference between the reservoir and the barrier and a thin barrier thickness, there may be a need to avoid crossing the barrier during construction, and in this case, the fracturing parameters can be set according to a set proportion to reduce the fracturing discharge and the fracturing fluid viscosity, so that the fracture reaches the designed length with the same average fracture height as the high stress difference and high barrier thickness area. For the case of crossing the barrier, the discharge can be increased, and the fracturing fluid volume can be appropriately increased to achieve the designed length, which is beneficial to improving the production.

[0103] Further, in a preferred embodiment, considering the crack deformation caused by inter-crack stress interference, if the stress interference is serious, the middle crack is difficult to reach the designed length, the comprehensive productivity of multiple schemes of the existing design scheme construction forming a crack network morphology, the construction forming a crack network morphology after appropriately increasing the crack spacing, and the construction forming a crack network morphology after increasing the crack spacing and adjusting the crack length can be simulated and predicted according to the actual engineering address parameters, and the optimal scheme is determined again according to the productivity prediction results.

[0104] The present application designs a method for subdividing closely cut parabolic differential fracturing seam distribution, including overall fracturing seam distribution scheme design, sweet spot area fracturing seam optimization, local section fracturing seam optimization, and overall scheme optimization design. According to the overall engineering geological features of the horizontal section, the overall scheme of subdividing closely cut parabolic differential fracturing seam distribution is optimized and designed; the sweet spot area is densely distributed, the cluster spacing and the section spacing are shortened, the sweet spot area reconstruction degree is improved, and a high conductivity fracturing system is created; targeted fracturing design is carried out for local special sections; finally, the fracturing scheme is further optimized to achieve the maximum productivity, and the overall fracturing scheme optimization design is completed. The fracturing seam distribution design method provided by the present application can maximize the fracturing reconstruction efficiency, fully liberate the productivity of heterogeneous unconventional reservoirs, and maximize the recovery rate and economic benefit of unconventional oil and gas fields.

[0105] Implementation case:

[0106] A subdivided closely cut parabolic differential overall fracturing seam distribution scheme optimization design is carried out for a heterogeneous tight horizontal gas well in the Ordos block, and the specific steps are as follows:

[0107] (1) Collect the target well production geological data, well logging data and adjacent well data, according to the reservoir permeability, gas saturation, reservoir lithology, fracturing pressure and other engineering geological parameters, evaluate the overall engineering geological characteristics of the horizontal well section, and divide the fracturing reconstruction sweet spot area and local special section. The length of the horizontal section is 1200m, and the high sweet spot area is concentrated in the root end of the horizontal well, with a length of 120m. The toe end of the horizontal section is 120m, with low gas saturation, and the far well zone is 130m away.

[0108] (2) Based on the analysis results of the overall geological engineering characteristics of the horizontal section, design the overall scheme of fine cutting parabolic differential fracture distribution. According to the numerical simulation results, the overall basic fracturing fracture distribution scheme is preliminarily completed: 20 fracturing sections are designed, each section is divided into 2 clusters of fracturing, the section interval is 60m, the cluster interval is 30m, the fracturing fracture conductivity is 50D.cm, and the half length of each section and cluster fracturing fracture is shown in Table 1.

[0109] Table 1 Half length of each section and cluster preliminary design fracturing fracture

[0110]

[0111] (3) For the sweet spot section, the 19th and 20th sections are changed from 2 clusters to 3 clusters, the cluster interval is 20m, and the fracture conductivity is increased to 80D.cm.

[0112] (4) For the toe end special area, the 1st and 2nd sections are changed from 2 clusters to 1 cluster, and the fracture half length is 135m.

[0113] (5) Based on the production capacity prediction results, further optimize the fracturing fracture parameters of each section to form the optimal fracture distribution scheme. Based on the optimization scheme of (1)-(4), the length of the 3rd-8th section and the 15th-18th section is increased by 10m, and the final fracture length optimization design scheme is shown in Table 2:

[0114] Table 2 Final design of half length of each section and cluster fracturing fracture

[0115]

[0116] (6) Based on the target well fracturing optimization design results, repeat steps (1)-(5), and gradually promote the overall fracturing scheme optimization design of multiple horizontal wells in the target block.

[0117] The present application aims at the problem that the unconventional reservoir cannot be efficiently and fully transformed in oilfield site, and provides a fine close-cut parabolic differential fracturing distribution method, which forms a matching fracturing optimization design scheme, including overall distribution scheme design, sweet spot area distribution optimization, local section distribution optimization and overall scheme optimization design.

[0118] For the foregoing method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the action sequence described, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification all belong to preferred embodiments, and the actions and modules involved are not necessarily necessary for the present application.

[0119] It should be pointed out that in other embodiments of the present application, the method can also be obtained by combining one or several of the above embodiments to obtain a new close-cut parabolic differential fracturing distribution method, so as to realize the optimized transformation of the horizontal well reservoir.

[0120] It should be pointed out that based on the method in any one or more of the above embodiments of the present application, the present application also provides a storage medium, which stores a program code for realizing the method in any one or more of the above embodiments, and the code can realize the close-cut parabolic differential fracturing distribution method as described above when executed by an operating system.

[0121] Embodiment two

[0122] The above embodiments of the present application disclose the method in detail, and the method of the present application can be realized by various forms of devices or systems, so based on other aspects of the method in any one or more of the above embodiments, the present application also provides a close-cut parabolic differential fracturing distribution system, which is used to execute the close-cut parabolic differential fracturing distribution method in any one or more of the above embodiments. The following specific embodiments are given for detailed description.

[0123] Specifically, Figure 7A structure diagram of a close-cut parabolic differential fracturing distribution system provided in an embodiment of the present application is shown in FIG. 1, which comprises: Figure 7

[0124] a geological feature analysis module configured to collect geological and engineering data of a target horizontal well and adjacent wells, and analyze engineering geological features of each horizontal well section of the target horizontal well;

[0125] a basic distribution design module configured to establish a hypothetical homogeneous model of the current horizontal well based on the overall engineering geological features of the target horizontal well, and formulate a close-cut parabolic basic fracturing distribution strategy corresponding to the hypothetical homogeneous model in combination with the productivity prediction result;

[0126] a section division module configured to divide local special sections and normal sweet spot sections based on the engineering geological features and the productivity prediction result of each well section;

[0127] a differential distribution optimization module configured to, for each normal sweet spot section and local special section, further conduct targeted intra-section fracturing distribution optimization according to the engineering geological features and fracturing distribution optimization principles of the current horizontal well section based on the formulated basic fracturing distribution strategy;

[0128] a productivity comprehensive adjustment module configured to optimize the fracturing distribution parameters of each horizontal well section after differential optimization based on the productivity prediction result, and form target close-cut parabolic differential fracturing distribution parameters of different well sections of the current heterogeneous horizontal well with optimal productivity.

[0129] Further, in an embodiment, the geological feature analysis module is configured to collect the following geological and engineering data: well logging data, porosity and permeability data, structural surface data, and seismic interpretation data of the target horizontal well and adjacent wells;

[0130] and analyze the following engineering geological features: porosity, permeability, oil saturation, gas saturation, water saturation, shale content, reservoir thickness, barrier thickness, natural fracture development density, and bedding fracture density geological feature data; and Young's modulus, Poisson's ratio, brittleness index, horizontal stress difference coefficient, and reservoir-barrier stress engineering feature parameters.

[0131] Preferably, in an embodiment, the basic distribution design module is specifically configured to establish a corresponding homogeneous hypothetical geological model based on the overall engineering geological features of the horizontal well, and then construct a corresponding productivity prediction calculation model, substitute different close-cut parabolic fracturing distribution parameters, determine the matching fracturing distribution parameters in combination with the engineering geological features and the productivity prediction result, and use the matching fracturing distribution parameters as the basic fracturing distribution strategy of the horizontal well.

[0132] ​In actual application, in an embodiment, the section division module is configured to determine the influence weight of each factor in the geological engineering characteristic parameter on the productivity by applying the analytic hierarchy process and the grey correlation analysis method, construct a comprehensive sweet spot calculation model of the well section based thereon, and then calculate the comprehensive sweet degree value of each section along the horizontal well section by using the calculation model.

[0133] Further, in an embodiment, the section division module is further configured to set, in combination with the geological engineering data and the logging data, a well section meeting the following conditions as a local special section:

[0134] a section with a comprehensive sweet degree value meeting a set condition and a distance from the wellbore exceeding a set value;

[0135] a section with a comprehensive sweet degree value meeting a set condition and a scattered and discontinuous distribution;

[0136] a section with a fracture pressure exceeding a set value.

[0137] As a further improvement of the present application, in an embodiment, if the optimization target well section is a normal sweet spot section, the differential fracture distribution optimization module is configured to realize differential optimization according to the following steps:

[0138] Taking the improvement of the fracture reconstruction degree and the complexity of the fracture network in the sweet spot section as the optimization principle, setting feasible multiple groups of fracture distribution parameters based on the specified basic fracture distribution strategy and the engineering geological characteristics of the current well section, substituting the parameters into the productivity prediction calculation model, and selecting the fracture distribution parameters making the productivity calculation result of the current well section optimal as the differential optimization fracture distribution strategy.

[0139] If the optimization target well section is a local special section, the differential fracture distribution optimization module is configured to realize differential optimization according to the following steps:

[0140] judging whether the duration of the local special section meets a set condition, if yes, constructing a corresponding virtual homogeneous independent geological model based on the engineering address characteristics of the section, constructing a corresponding section productivity prediction calculation model, substituting different groups of fine subdivision close-to-parabolic fracture distribution parameters into the model for section productivity prediction calculation, and determining the fracture distribution parameters matched with the section based on the engineering geological characteristics and the productivity prediction result, as the basic fracture distribution strategy of the current local special section;

[0141] if the duration of the local special section does not meet the set condition, setting feasible multiple groups of fracture distribution parameters based on the specified basic fracture distribution strategy and the engineering geological characteristics of the current well section, substituting the parameters into the productivity prediction calculation model, and selecting the fracture distribution parameters making the productivity calculation result of the current well section optimal as the differential optimization fracture distribution strategy.

[0142] Further, in an embodiment, the productivity comprehensive adjustment module is specifically configured to:

[0143] Based on the fine-cut parabolic base fracturing distribution strategy and the fracturing distribution parameters optimized according to the normal dessert section and the local special section, the overall fracturing distribution scheme of the horizontal well is formed, and the fracturing distribution parameters are optimized according to the capacity calculation results and the numerical calculation results of the fracture propagation model.

[0144] Specifically, in one embodiment, the capacity comprehensive adjustment module optimizes the fracturing distribution parameters according to the following logic and the numerical calculation results of the fracture propagation model:

[0145] The capacity of the fracture network morphology scheme formed after the fracture spacing is increased according to different set adjustment coefficients and / or the fracture spacing and the fracture length are adjusted according to different set adjustment coefficients is simulated respectively, and the optimal scheme is determined again according to the capacity prediction.

[0146] In the fine-cut parabolic differential fracturing distribution system provided by the embodiment of the application, each module or unit structure can be independently operated or combined to realize the corresponding technical effect according to the actual analysis and optimization requirements.

[0147] It should be understood that the disclosed embodiments of the application are not limited to the specific structure, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those skilled in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and are not meant to be limiting.

[0148] The phrase "one embodiment" appearing in the specification means that the specific feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Therefore, the phrase "one embodiment" appearing throughout the specification does not necessarily mean the same embodiment.

[0149] Although the disclosed embodiments of the application are as above, the content described is only for the purpose of facilitating understanding of the application and is not intended to limit the application. Any person skilled in the art of the application can make any modification and change in the implementation form and details without departing from the spirit and scope of the application. The patent protection scope of the application shall be subject to the scope defined by the appended claims.

Claims

1. A method of closely cutting parabolic differential fracturing strata, characterized in that, The method comprises: a geological feature analysis step, collecting geological and engineering data of the target horizontal well and adjacent wells, and analyzing engineering geological features of each horizontal well section of the target horizontal well; a base stitching design step, establishing a hypothetical homogeneous model of the current horizontal well based on the overall engineering geological features of the target horizontal well, and formulating a subdivided close-to-parabolic base fracturing stitching strategy corresponding to the hypothetical homogeneous model in combination with a productivity prediction result; a section division step, dividing local special sections and normal sweet spot sections based on the engineering geological features and the productivity prediction result of each well section; a differential stitching optimization step, for each normal sweet spot section and local special section, further performing targeted in-section fracturing stitching optimization according to the corresponding engineering geological features and fracturing stitching optimization principles of the current horizontal well section based on the formulated base fracturing stitching strategy; a productivity comprehensive adjustment step, optimizing the fracturing stitching parameters of each horizontal well section after differential optimization based on the productivity prediction result, and forming target close-to-parabolic differential fracturing stitching parameters of different well sections of the current heterogeneous horizontal well with optimal productivity; in the base stitching design step, a corresponding homogeneous hypothetical geological model is established based on the overall engineering geological features of the horizontal well, and a corresponding productivity prediction calculation model is constructed, different subdivided close-to-parabolic fracturing stitching parameters are substituted, and the matching fracturing stitching parameters are determined in combination with the engineering geological features and the productivity prediction result, serving as the base fracturing stitching strategy of the horizontal well; in the productivity comprehensive adjustment step, it comprises: based on the subdivided close-to-parabolic base fracturing stitching strategy and the fracturing stitching parameters after differential optimization of the normal sweet spot sections and the local special sections, an overall fracturing stitching scheme of the horizontal well is formed, substituted into the corresponding productivity prediction calculation model, and the fracturing stitching parameters are optimized according to the productivity calculation result in combination with the numerical calculation result of the fracture propagation morphology model; for the reservoir with small stress difference between the reservoir and the barrier and thin barrier thickness, there is a need to avoid crossing the layer, the fracturing construction discharge and the fracturing fluid viscosity are reduced according to the set proportion, so that the reservoirs with high stress difference and high barrier thickness reach the designed fracture length with the same average fracture height; and for the case of crossing the layer, the discharge can be increased, and the fracturing fluid volume can be appropriately increased to reach the designed fracture length.

2. The method of claim 1, wherein, in the geological feature analysis step, the collected geological and engineering data include: well logging data, porosity and permeability data, structural surface data and seismic interpretation data of the target horizontal well and adjacent wells; the analyzed engineering geological features include: porosity, permeability, oil saturation, gas saturation, water saturation, shale content, reservoir thickness, barrier thickness, natural fracture development density and bedding fracture density geological feature data; and Young's modulus, Poisson's ratio, brittleness index, horizontal stress difference coefficient and reservoir-barrier stress difference engineering characteristic parameters.

3. The method of claim 1, wherein, in the section division step, it comprises: applying analytic hierarchy process and grey correlation analysis to determine the influence weight of each factor in the geological engineering feature parameters on productivity, constructing a comprehensive sweet spot calculation model of the well section based thereon, and then calculating the comprehensive sweet degree value of each section along the horizontal well section by using the calculation model.

4. The method of claim 3, wherein, In the section division step, the well section meeting the following conditions is set as a local special section in combination with the geological engineering data and the logging data: The section with the comprehensive sweetness value meeting the set condition and the distance from the wellbore exceeding the set value; The section with the comprehensive sweetness value meeting the set condition and the scattered and discontinuous distribution; The section with the fracture pressure exceeding the set value.

5. The method of claim 1, wherein, In the difference optimization step, if the optimization target section is a normal sweet spot section, the difference optimization is realized according to the following steps: The optimization principle is to improve the fracturing reconstruction degree and the fracture network complexity of the normal sweet spot section. Based on the specified basic fracturing distribution strategy and the engineering geological characteristics of the current section, a plurality of sets of fracturing distribution parameters are set. The fracturing distribution parameters are substituted into the productivity prediction calculation model. The fracturing distribution parameter that optimizes the productivity calculation result of the current section is selected as the fracturing distribution strategy after the difference optimization.

6. The method of claim 1, wherein, In the difference optimization step, if the optimization target section is a local special section, the difference optimization is realized according to the following steps: It is judged whether the duration of the local special section meets the set condition. If yes, a corresponding virtual homogeneous independent geological model is constructed based on the engineering address characteristics of the section. A corresponding section productivity prediction calculation model is constructed. Different sets of finely cut parabolic fracturing distribution parameters are substituted into the section productivity prediction calculation. The fracturing distribution parameters matched with the section are determined based on the engineering geological characteristics and the productivity prediction result. The fracturing distribution parameters are used as the basic fracturing distribution strategy of the current local special section. If the duration of the local special section does not meet the set condition, a plurality of sets of fracturing distribution parameters are set based on the specified basic fracturing distribution strategy and the engineering geological characteristics of the current section. The fracturing distribution parameters are substituted into the productivity prediction calculation model. The fracturing distribution parameter that optimizes the productivity calculation result of the current section is selected as the fracturing distribution strategy after the difference optimization.

7. The method of claim 1, wherein, In the productivity comprehensive adjustment step, the process of optimizing the fracturing distribution parameters based on the numerical calculation result of the fracture propagation morphology model includes: The productivity of the fracture network morphology scheme formed after the historical fracturing distribution design parameters, the increased fracture spacing according to different set adjustment coefficients and / or the fracture spacing and fracture length adjusted according to different set adjustment coefficients are simulated respectively. The optimal scheme is determined again based on the productivity prediction.

8. A storage medium, characterized by The storage medium has program code for realizing the method of any one of claims 1-7.

9. A close-cuts parabolic differential fracturing striding system, characterized in that, The system executes the method of any one of claims 1-7, and the system comprises: a geological feature analysis module configured to collect the geological and engineering data of the target horizontal well and adjacent wells, and analyze the engineering geological characteristics of each horizontal section of the target horizontal well; a basic fracturing design module configured to establish a hypothetical homogeneous model of the current horizontal well based on the overall engineering geological characteristics of the target horizontal well, and develop a finely cut parabolic basic fracturing distribution strategy corresponding to the hypothetical homogeneous model in combination with the productivity prediction result; a section division module configured to divide the fracturing reconstruction local special section and the normal sweet spot section based on the engineering geological characteristics and the productivity prediction result of each section; The differential seam optimization module is configured to, for each normal dessert section and local special section, respectively based on the formulated base fracturing seam strategy, further perform targeted intra-section fracturing seam optimization according to the engineering geological characteristics corresponding to the current horizontal well section and the fracturing seam optimization principle. The productivity comprehensive adjustment module is configured to, based on the productivity prediction result, optimize the differential optimized fracturing seam parameters of each horizontal well section, and form the target close-to-parabolic differential fracturing seam parameters with the optimal productivity of different well sections of the current heterogeneous horizontal well.

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