Shale oil pressure crack height extension simulation method and system

By establishing a fine geological and fracture model, inverting the impact factor of the stratified joint and fracturing fluid filtration loss coefficient, and characterizing the joint net distribution, the problem of uncertainty and insufficient differential characterization when simulating the impact of micro-fractures in shale oil reservoirs in the existing technology is solved, and the accuracy of the joint net model after shale oil volume fracturing and the credibility of reservoir numerical simulation is achieved.

CN119830507APending Publication Date: 2025-04-15CHINA PETROLEUM & CHEMICAL CORP +1
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Patent Information

Application Number
CN202311326489.7
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2023-10-13
Publication Date
2025-04-15

AI Technical Summary

Technical Problem

The prior art has strong uncertainty in fracture parameters when simulating the micro-fracture effects of shale oil reservoirs and lacks differential characterization methods, which leads to rough numerical simulation results of fracturing and the impact of stratification on fracture expansion cannot be fully considered.

Method used

By establishing a fine reservoir geological model, geological mechanic model, natural fracture model and ground stress model, combining the one-dimensional and three-dimensional layered joint density attribute model of single well, the impact factor of the stratified joint and the filtration loss coefficient of the fracturing fluid are inverted, the seam network distribution is portrayed, and a post-fracted reservoir geological model is established on the seam network distribution.

Benefits of technology

The accurate description of the artificial seam model after the volume fracturing of the shale oil in the laminated seam is achieved, which improves the credibility of the numerical simulation of the reservoir and can consider the impact of the shale on the fracturing effect more carefully.

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Abstract

The invention provides a shale oil pressure fracture height extension simulation method and system, and the simulation method comprises the steps: building a fine reservoir geologic model, a geomechanical model, a natural fracture model and a ground stress model according to the actual block data; single-well one-dimensional natural bedding fracture relative density logging interpretation is carried out; establishing a three-dimensional natural bedding seam density attribute model; establishing an artificial hydraulic fracture network model; according to the artificial hydraulic seam network model, inversion of bedding seam influence factors related to bedding density is carried out; according to the bedding seam influence factor, a fracturing fluid filtration coefficient considering bedding seam influence is inversed; according to the bedding seam influence factor and the fracturing fluid filtration coefficient, seam net distribution is depicted; and establishing a fractured reservoir geologic model on the fracture net distribution. An artificial fracture network model after bedding fracture shale oil volume fracturing is accurately described, and the credibility of reservoir numerical simulation is improved.
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Description

Technical Field

[0001] The invention relates to the field of numerical simulation research on geological reservoirs for petroleum development, and in particular to a method and system for simulating the height expansion of shale oil fractures. Background Art

[0002] Compared with matrix-type shale oil, the reservoir space types of shale oil reservoirs in Jiyang Depression of Shengli Oilfield include two categories: pores and microcracks, among which microcracks are mainly structural fractures, overpressure fractures, bedding fractures and grain edge fractures.

[0003] The pore-fracture systems of different lithofacies are obviously different. Combining different testing methods, the "sandwich" structure of laminated gray shale has a pore-fracture network system integrating "source, reservoir and permeability", in which the "source" is the organic-rich mudstone laminae, and the "reservoir and permeability" are bright crystal and cryptocrystalline gray laminae. The organic-rich laminated gray shale / lime-containing shale phase is mainly distributed in the center of the basin, and the laminated gray shale phase is the optimal reservoir phase. Therefore, after the shale oil fracturing transformation in the Jiyang Depression, an extremely complex combined fracture network of artificial fractures + natural fractures will be formed under the influence of the complex pore-fracture system.

[0004] At present, the modeling methods of natural fractures have limitations such as strong uncertainty in fracture parameters and lack of differential characterization methods for different types of natural fractures, which leads to the inability to fully consider the influence of various fractures, especially bedding fractures, during the fracturing numerical simulation process. Patents such as "A method for numerical simulation of hydraulic fracture expansion in deep oil and gas reservoirs", "A method for numerical simulation of production dynamics of fracturing well groups in shale gas reservoirs", and "A method for simulating the formation process of complex fracture networks in hydraulic fracturing of unconventional oil and gas reservoirs" only consider the influence of natural structural fractures on fracture expansion, and fail to consider the development of bedding fractures in the matrix and their influence on fracture expansion. Although the importance of bedding fracture interface slip to fracture expansion has long been recognized, this mechanism is rarely considered in hydraulic fracturing simulators. The fracture height growth model considering bedding planes currently exists in hydraulic fracturing simulators, but it can only simulate the influence of bedding fractures on fracture height, fracture width and fracturing pressure, and cannot characterize the complex fracture network generated by bedding fractures. Therefore, the fracturing numerical simulation method based on the natural fracture model cannot be applied to the fracturing development of shale oil in the Jiyang Depression where bedding fractures are highly developed. At the same time, the post-fracture geological model established by the equivalent fracture network simulation method cannot fully utilize the results of the field fracturing construction data and microseismic monitoring data interpretation, and cannot fully consider the reservoir heterogeneity within the fracture network transformation area after fracturing. The simulation method is simple and the simulation results are rough. This is not conducive to the subsequent numerical simulation of the reservoir, creating great fitting difficulties and limiting the accuracy of numerical simulation. Summary of the invention

[0005] In view of the above problems, the present invention is proposed to provide a shale oil fracture height expansion simulation method and system that overcomes the above problems or at least partially solves the above problems.

[0006] According to one aspect of the present invention, a method for simulating the height extension of shale oil fractures is provided, the simulation method comprising:

[0007] Step S1: Establish a detailed reservoir geological model, geomechanical model, natural fracture model and geostress model based on actual block data;

[0008] Step S2: single well one-dimensional natural bedding fracture relative density logging interpretation;

[0009] Step S3: establishing a three-dimensional natural bedding fracture density attribute model;

[0010] Step S4: establishing an artificial hydraulic seam network model;

[0011] Step S5: inverting the bedding fracture influencing factors related to the bedding density according to the artificial hydraulic fracture network model;

[0012] Step S6: inverting the fracturing fluid loss coefficient considering the influence of bedding fractures according to the bedding fracture influence factor;

[0013] Step S7: Describing the distribution of the fracture network according to the bedding fracture influencing factor and the fracturing fluid loss coefficient;

[0014] Step S8: establishing a post-fracture reservoir geological model on the fracture network.

[0015] Optionally, the step S2: single well one-dimensional natural bedding fracture relative density logging interpretation specifically includes:

[0016] Based on the core bedding fracture scale, a natural bedding fracture density interpretation model was established using dipole acoustic logging to interpret the one-dimensional natural bedding fracture density of a single well.

[0017] Optionally, the step S3: establishing a three-dimensional natural bedding fracture density attribute model specifically includes:

[0018] A three-dimensional natural bedding fracture density attribute model is established using a difference method based on the relative density logging interpretation.

[0019] Optionally, the step S4: establishing an artificial hydraulic seam network model specifically includes:

[0020] According to the detailed reservoir geological model, geomechanical model, natural fracture model, geostress model and three-dimensional natural bedding fracture density attribute model, the fracturing process is fitted through fracturing simulation software to establish a dynamic expansion model of artificial hydraulic fractures.

[0021] Optionally, the step S5: inverting the bedding fracture influencing factors related to the bedding density according to the artificial hydraulic fracture network model specifically includes:

[0022] According to the artificial hydraulic fracture network model, the actual hydraulic fracture height of the mine is fitted, and the bedding fracture influencing factor related to the bedding fracture density is inverted to characterize the mechanism of the bedding fracture containment fracture height expansion in the mine.

[0023] Optionally, the step S6: inverting the fracturing fluid loss coefficient considering the influence of bedding fractures according to the bedding fracture influence factor specifically includes:

[0024] According to the bedding fracture influencing factor, the total usage of the mine proppant and fracturing fluid is input into the simulator, the mine fracture length monitoring data is fitted, and the fracturing fluid loss coefficient considering the influence of the bedding fracture is inverted.

[0025] Optionally, the step S7: characterizing the fracture network distribution according to the bedding fracture influencing factor and the fracturing fluid loss coefficient specifically includes:

[0026] According to the bedding fracture influencing factor and the fracturing fluid loss coefficient, the microseismic interpretation results of the fracture height and the fracture length are fitted simultaneously to finely characterize the fracture network distribution.

[0027] Optionally, after the step S7: describing the fracture network distribution according to the bedding fracture influence factor and the fracturing fluid loss coefficient, the following steps may be further performed:

[0028] The fine characterization and prediction of the fracture network morphology can be achieved through model control.

[0029] Optionally, the step S6: inverting the fracturing fluid loss coefficient considering the influence of bedding fractures according to the bedding fracture influence factor specifically includes:

[0030] According to the bedding fracture influencing factor, the mine fracture height monitoring data is fitted to invert the bedding fracture influencing factor, and the bedding fracture influencing factor and the bedding fracture relative density model established in step 3 are used together to calculate the artificial fracture height expansion in the fracturing simulation.

[0031] The present invention also provides a shale oil pressure fracture height expansion simulation system, which uses the above-mentioned shale oil pressure fracture height expansion simulation method, and the simulation system includes:

[0032] The geological model building module builds a detailed reservoir geological model, geomechanical model, natural fracture model and geostress model based on actual block data;

[0033] Well logging interpretation module, used for single well one-dimensional natural bedding fracture relative density logging interpretation;

[0034] Attribute model building module, used to build a three-dimensional natural bedding fracture density attribute model;

[0035] Artificial hydraulic fracture network model building module, used to build an artificial hydraulic fracture network model;

[0036] A bedding fracture influencing factor inversion module, used for inverting the bedding fracture influencing factor related to the bedding density according to the artificial hydraulic fracture network model;

[0037] A fracturing fluid loss coefficient inversion module, used to invert the fracturing fluid loss coefficient taking into account the influence of bedding fractures according to the bedding fracture influence factor;

[0038] A fracture network distribution characterization module, used to characterize the fracture network distribution according to the bedding fracture influencing factor and the fracturing fluid loss coefficient;

[0039] The post-fracture reservoir geological model establishment module is used to establish the post-fracture reservoir geological model on the fracture network layout.

[0040] The present invention provides a method and system for simulating the high expansion of shale oil fractures, the simulation method comprising: step S1: establishing a fine reservoir geological model, a geomechanical model, a natural fracture model and a geostress model according to actual block data; step S2: well logging interpretation of the relative density of one-dimensional natural bedding fractures in a single well; step S3: establishing a three-dimensional natural bedding fracture density attribute model; step S4: establishing an artificial hydraulic fracture network model; step S5: inverting the bedding fracture influence factor related to the bedding density according to the artificial hydraulic fracture network model; step S6: inverting the fracturing fluid loss coefficient considering the influence of bedding fractures according to the bedding fracture influence factor; step S7: depicting the fracture network distribution according to the bedding fracture influence factor and the fracturing fluid loss coefficient; step S8: establishing a reservoir geological model after fracturing on the fracture network distribution. Accurately depicting the artificial fracture network model after volume fracturing of bedding fracture shale oil improves the credibility of reservoir numerical simulation.

[0041] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0043] Figure 1 It is a flow chart of a shale oil fracture height expansion simulation method provided by an embodiment of the present invention;

[0044] Figure 2It is a geological model provided by an embodiment of the present invention - taking a permeability attribute model as an example;

[0045] Figure 3 The geostress model provided in the embodiment of the present invention - taking the maximum horizontal principal stress model as an example;

[0046] Figure 4 The bedding fracture density interpretation model provided by the embodiment of the present invention;

[0047] Figure 5 A three-dimensional bedding fracture density model provided by an embodiment of the present invention;

[0048] Figure 6 A crack propagation model provided by an embodiment of the present invention;

[0049] Figure 7 An embodiment of the present invention provides a discrete fracture network model after fracturing. DETAILED DESCRIPTION

[0050] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0051] The terms "comprises" and "having" and any variations thereof in the description embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0052] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0053] Example 1

[0054] like Figure 1 As shown, the present invention provides a shale oil hydraulic fracture network expansion simulation method that takes into account the influence of natural bedding fractures, uses microseismic data to reconstruct a hydraulic fracture model, and focuses on reflecting the influence of bedding fractures in the hydraulic fracture model, and combines it with the artificial hydraulic fracture fracturing simulation workflow to establish a more refined and accurate complex fracture network model. Due to the inherent complexity of the interaction between hydraulic fracturing and bedding interfaces, it is difficult to develop a comprehensive model suitable for general applications. The present invention uses a bedding fracture density attribute model to equivalently characterize the natural bedding fractures of the actual reservoir, and simulates the formation of a complex artificial fracture network under this influence. By optimizing the integrated geological and engineering fracturing simulation method and combining the results of microseismic monitoring data interpretation, it is possible to achieve a detailed characterization of the scope and morphology of the fracture network transformation area after volume fracturing.

[0055] Step (1) According to the requirements of basic geological research and reservoir numerical simulation, a detailed reservoir geological model and geomechanical model are established, and on this basis, a geostress simulation is carried out to establish a geostress model, which is the basis for integrated geological and engineering fracturing simulation.

[0056] Step (2): The effect of bedding fractures on shear wave attenuation is much greater than that on P-wave attenuation. The P / S wave velocity ratio Vp / Vs increases in the formation where bedding fractures are developed. Based on the core bedding fracture scale, a natural bedding fracture density interpretation model is established using dipole acoustic logging to interpret the one-dimensional natural bedding fracture density of a single well.

[0057] Step (3): Based on the interpretation results in step (2), a three-dimensional natural bedding fracture density attribute model is established through constraint control using the geological model and rock mechanics model in step (1).

[0058] Step (4): Based on the geological engineering integrated fracturing numerical simulation software, according to the specific mine fracturing construction process, simulate the reservoir rupture process that occurs simultaneously and establish a dynamic expansion model of artificial hydraulic fractures.

[0059] Step (5): Based on the actual mine fracture height and reservoir bedding fracture density attribute model, invert the bedding fracture influencing factor related to the bedding fracture density, which can characterize the mechanism of bedding fracture containment fracture height expansion in the mine, and realize fracture height expansion fitting in the fracturing numerical simulation.

[0060] Step (6): Based on the fracture height simulation results in step (5), according to the actual field fracture length and bedding fracture density attribute model, invert the bedding fracture loss coefficient related to the bedding fracture density that can characterize the physical properties of the bedding fracture.

[0061] Step (7): Based on the fracturing numerical simulation technology, the crack propagation under actual mine construction conditions and the distribution of fracturing fluid and proppant in the fracture network transformation area are simulated, the interpretation results of the segmented microseismic monitoring data are fitted, and the simulation of the segmented fracture network spatial morphology and SRV volume fitting are realized in the fracturing simulation.

[0062] Step (8): Based on the fitted full-well section fracturing simulation results, a post-fracturing reservoir geological model is established to characterize the heterogeneous physical properties of the reservoir in the volume fracturing transformation area caused by the differential distribution of fracturing fluid and proppant.

[0063] Example 2

[0064] The method of the present invention is described in detail below with reference to the accompanying drawings (taking Fanyeping 1 well as an example), and the specific steps are as follows:

[0065] (1) Figure 2 Establish the reservoir geological model of the target block. The specific model parameters are as follows:

[0066] ① The grid step size is 25×25 meters,

[0067] ②The number of grid nodes is 296×144×74=3154176,

[0068] ③Complete attribute modeling and reserve calculation fitting;

[0069] (2) Figure 3 A three-dimensional geostress model is established based on the geological model. The main model attributes include: three-dimensional triaxial stress magnitude and direction, three-dimensional rock mechanical properties (Young's modulus, Poisson's ratio, etc.), three-dimensional pore pressure, etc.

[0070] (3) Figure 4 Establish a bedding fracture density interpretation model;

[0071] (4) Figure 5 Establish a three-dimensional bedding fracture density model;

[0072] (5) Figure 6 According to the specific construction process of the mine, carry out fracturing simulation and establish a post-fracturing fracture network model;

[0073] (6) Figure 7 A post-fracturing reservoir geological model was established based on the fitted fracturing simulation results. The permeability variation range within the reformed volume was between 0.3 and 37,000, and the reservoir physical property heterogeneity in the fracture reformed area affected by the differential distribution of proppants was precisely characterized.

[0074] Beneficial effects: The present invention is based on the innovation of conventional geological engineering integrated fracturing simulation technology, which can realize the numerical simulation of volume fracturing of shale oil in bedding fractures, and achieve the fine fitting of the interpretation results of microseismic monitoring data. The influence of the differential distribution of fracturing fluid and proppant in the transformation area under the influence of natural bedding fractures on the reservoir properties is fully considered, and the artificial fracture network model after volume fracturing of shale oil in bedding fractures can be accurately described, which improves the credibility of numerical simulation of oil reservoirs.

[0075] This method was applied in a mine and successfully simulated the expansion law of fracture height under the influence of bedding fractures, established a discrete fracture network model after volume fracturing transformation, and the fitting result conformity rate of the segmented microseismic monitoring data interpretation results was above 85%, which verified the reliability and practicality of the present invention in simulating the volume fracturing transformation area of ​​bedding fracture shale oil, and provided technical support for the preparation of shale oil development plans and dynamic adjustment of development with developed bedding fractures.

[0076] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for simulating the height expansion of shale oil fractures, characterized in that: The simulation method comprises: Step S1: Establish a detailed reservoir geological model, geomechanical model, natural fracture model and geostress model based on actual block data; Step S2: single well one-dimensional natural bedding fracture relative density logging interpretation; Step S3: establishing a three-dimensional natural bedding fracture density attribute model; Step S4: establishing an artificial hydraulic seam network model; Step S5: inverting the bedding fracture influencing factors related to the bedding density according to the artificial hydraulic fracture network model; Step S6: inverting the fracturing fluid loss coefficient considering the influence of bedding fractures according to the bedding fracture influence factor; Step S7: Describing the distribution of the fracture network according to the bedding fracture influencing factor and the fracturing fluid loss coefficient; Step S8: establishing a post-fracture reservoir geological model on the fracture network.

2. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S2: single well one-dimensional natural bedding fracture relative density logging interpretation specifically includes: Based on the core bedding fracture scale, a natural bedding fracture density interpretation model was established using dipole acoustic logging to interpret the one-dimensional natural bedding fracture density of a single well.

3. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S3: establishing a three-dimensional natural bedding fracture density attribute model specifically includes: A three-dimensional natural bedding fracture density attribute model is established using a difference method based on the relative density logging interpretation.

4. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S4: establishing the artificial hydraulic seam network model specifically includes: According to the detailed reservoir geological model, geomechanical model, natural fracture model, geostress model and three-dimensional natural bedding fracture density attribute model, the fracturing process is fitted through fracturing simulation software to establish a dynamic expansion model of artificial hydraulic fractures.

5. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S5: inverting the bedding fracture influencing factors related to the bedding density according to the artificial hydraulic fracture network model specifically includes: According to the artificial hydraulic fracture network model, the actual hydraulic fracture height of the mine is fitted, and the bedding fracture influencing factor related to the bedding fracture density is inverted to characterize the mechanism of the bedding fracture containment fracture height expansion in the mine.

6. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S6: inverting the fracturing fluid loss coefficient considering the influence of bedding fractures according to the bedding fracture influence factor specifically includes: According to the bedding fracture influencing factor, the total usage of the mine proppant and fracturing fluid is input into the simulator, the mine fracture length monitoring data is fitted, and the fracturing fluid loss coefficient considering the influence of the bedding fracture is inverted.

7. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S7: describing the fracture network distribution according to the bedding fracture influencing factor and the fracturing fluid loss coefficient specifically includes: According to the bedding fracture influencing factor and the fracturing fluid loss coefficient, the microseismic interpretation results of the fracture height and the fracture length are fitted simultaneously to finely characterize the fracture network distribution.

8. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S7: after describing the fracture network distribution according to the bedding fracture influence factor and the fracturing fluid loss coefficient, further comprises: The fine characterization and prediction of the fracture network morphology can be achieved through model control.

9. A shale oil fracture height expansion simulation method according to claim 1, characterized in that: The step S6: inverting the fracturing fluid loss coefficient considering the influence of bedding fractures according to the bedding fracture influence factor specifically includes: According to the bedding fracture influencing factor, the mine fracture height monitoring data is fitted to invert the bedding fracture influencing factor, and the bedding fracture influencing factor and the bedding fracture relative density model established in step 3 are used together to calculate the artificial fracture height expansion in the fracturing simulation.

10. A shale oil hydraulic fracture height expansion simulation system, using a shale oil hydraulic fracture height expansion simulation method according to any one of claims 1 to 9, characterized in that: The simulation system comprises: The geological model building module builds a detailed reservoir geological model, geomechanical model, natural fracture model and geostress model based on actual block data; Well logging interpretation module, used for single well one-dimensional natural bedding fracture relative density logging interpretation; Attribute model building module, used to build a three-dimensional natural bedding fracture density attribute model; Artificial hydraulic fracture network model building module, used to build an artificial hydraulic fracture network model; A bedding fracture influencing factor inversion module, used for inverting the bedding fracture influencing factor related to the bedding density according to the artificial hydraulic fracture network model; A fracturing fluid loss coefficient inversion module, used to invert the fracturing fluid loss coefficient taking into account the influence of bedding fractures according to the bedding fracture influence factor; A fracture network distribution characterization module, used to characterize the fracture network distribution according to the bedding fracture influencing factor and the fracturing fluid loss coefficient; The post-fracture reservoir geological model establishment module is used to establish the post-fracture reservoir geological model on the fracture network layout.