Method for improving simulation accuracy of three-dimensional stress field of lift seam hole type reservoir

Abstract

The application discloses a method for improving the simulation accuracy of a three-dimensional ground stress field of a fracture-vug type oil reservoir, and comprises the following steps: collecting seismic data of a target block; identifying the seismic data to find out fault displays in the seismic data; drilling wells at different positions of the faults according to the positions of the identified faults, and taking out fault cores at the corresponding positions; drilling wells at different positions outside the positions of the faults according to the positions of the identified faults, and taking out non-fault cores at the corresponding positions at the depth of the same fault core in the previous step; performing rock mechanics parameter test experiments on the taken-out fault cores and non-fault cores to respectively obtain a plurality of mechanics parameters of the fault cores and a plurality of mechanics parameters of the non-fault cores; obtaining the size relationship between the fault cores and the non-fault cores from the corresponding same mechanics parameters of the fault cores and the non-fault cores, and assigning the size relationship to a geological model to be used for the simulation of a three-dimensional ground stress field.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and specifically to a method for improving the accuracy of geostress field simulation in fractured-vuggy reservoirs. Background Technology

[0002] Fractured-vuggy reservoirs occupy a vital position in global oil and gas resources; statistics show that over one-third of the world's carbonate reservoirs are of this type. The three-dimensional in-situ stress field of fractured-vuggy reservoirs is closely related to hydrocarbon accumulation, reservoir permeability, fracturing design, and well placement. Therefore, 3D in-situ stress field simulation has significant theoretical guidance and practical implications for oil and gas exploration and development. However, when conducting 3D in-situ stress field simulations of fractured-vuggy reservoirs, the influence of faults on the local stress field must be fully considered. Therefore, before conducting 3D in-situ stress field simulations of fractured-vuggy reservoirs, it is essential to effectively characterize the fault parameters.

[0003] In the prior art, the invention patent "A Coherence Enhancement Fault Identification Method Based on Seismic Analytical Trace under Stratified Constraints" (application number: 201910854606.4) discloses a coherence enhancement fault identification method based on seismic analytical traces under stratified constraints. This method improves the conventional similar coherence algorithm by dividing the input seismic data into two parts: processed result data and analytical trace data after Hilbert transformation, thus obtaining a coherence algorithm based on seismic analytical traces. The vertical drift of the seismic interpretation horizon of the target layer is used as the analysis time window, and the coherence attribute is calculated using the coherence algorithm based on seismic analytical traces. The obtained coherence attribute is used as input, and the coherence attribute is enhanced using the histogram equalization method. This enhanced coherence attribute is used to identify the fault development characteristics of the target segment, thereby improving the fault identification effect. The invention patent "Method for Fault Identification and Model Training Method and Apparatus" (application number: 201911078637.1) discloses a method for fault identification and a model training method and apparatus, relating to the field of fault diagnosis. The model training method includes: acquiring fault attribute data of the fault region; generating a sample dataset based on the fault attribute data; inputting the sample dataset into a preset support vector machine model for training; performing calculations on the support vector machine model using a particle swarm optimization algorithm, and obtaining a model for fault identification when the calculation result meets a preset threshold; outputting the fault identification result by inputting the fault attribute data to be identified into the pre-trained fault identification model; and obtaining the fault identification model by training using the improved attribute data as input data.

[0004] Most existing fault identification methods analyze seismic data to obtain fault strike, displacement, and other attribute parameters. However, these methods cannot characterize the mechanical properties of different regions of the fault, resulting in poor accuracy in the three-dimensional in-situ stress field inversion calculation of the fault region. Furthermore, the interrelationships of mechanical properties across the entire stratigraphic region are not extensively studied, which significantly reduces the accuracy of the subsequent three-dimensional in-situ stress field simulation, hindering the development of fractured-vuggy reservoirs.

[0005] Therefore, for those skilled in the art, how to provide a method to improve the accuracy of simulations has become an urgent technical problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs, comprising the following steps:

[0007] (1) Collect seismic data of the target block;

[0008] (2) Identify the earthquake data and find the faults in the earthquake data;

[0009] (3) Identify the location of the fault according to step (2), drill wells at different locations of the fault, and extract fault cores at the corresponding locations;

[0010] (4) Based on the location of the fault identified in step (2), drill wells at different locations outside the location of the fault, and extract non-fault cores at the corresponding depths of the same fault cores in step (3).

[0011] (5) Conduct rock mechanics parameter testing experiments on the fault cores and non-fault cores taken out in steps (3) and (4) respectively to obtain several mechanical parameters of the fault cores and several mechanical parameters of the non-fault cores.

[0012] (6) The magnitude relationship between the corresponding mechanical parameters of the fault core and the non-fault core obtained in step (5) can be obtained, and the magnitude relationship is assigned to the geological model for simulation of the three-dimensional geodynamic field.

[0013] Preferably, in step (5), the mechanical parameters are compressive strength, elastic modulus, Poisson's ratio, and tensile strength. These mechanical parameters of the fault core are denoted as P1, E1, μ1, and T1, respectively, and these mechanical parameters of the non-fault core are denoted as P2, E2, μ2, and T2, respectively.

[0014] Preferably, in step six, the size relationship is as follows:

[0015] (P2-P1) / P2>0.4, (E2-E1) / E2>0.3, (μ1-μ2) / μ1>0.1, (T2-T1) / T2>0.5.

[0016] Preferably, in step (3), based on the location of the fault identified in step (2), wells are drilled at different locations of the fault, and fault cores are extracted. The core extraction location is the intersection of the well and the fault identified in step (2).

[0017] Preferably, the fault has a length direction, and drilling is performed at different locations on the fault in step (3), the different locations referring to the two ends of the fault along the length direction, the interior of the fault, and the side of the fault.

[0018] Preferably, in step (4), drilling is carried out at different locations outside the location of the fault, which refers to locations with different vertical distances from the central axis of the fault.

[0019] Preferably, in steps (3) and (4), the removal of the fault core and the non-fault core refers to the removal of a full-diameter core with the same diameter as the well.

[0020] Preferably, the structures of the fault core and the non-fault core are the actual structures of the reservoir at the drilling location.

[0021] The method for improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs provided by this invention has the following technical effects:

[0022] By obtaining the relationship between fault cores and non-fault cores and assigning it to the subsequent three-dimensional geostress field simulation, the accuracy of the simulation can be greatly improved, which has significant reference value for subsequent oil and gas extraction. Moreover, it avoids the limitation of uniformly assigning mechanical parameters to fault areas of the strata, introduces the distribution characteristics of mechanical property parameters in different areas of the fault, and makes the subsequent differential assignment of values ​​to different areas, including fault and non-fault areas, more consistent with the actual situation, thus enhancing the accuracy of subsequent geostress field simulation.

[0023] Preferably, the mechanical parameters are compressive strength, elastic modulus, Poisson's ratio, and tensile strength, which are sufficient to reflect the mechanical properties of the core. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating a method for improving the accuracy of three-dimensional geostress field simulation in fractured-vuggy reservoirs provided by the present invention.

[0025] Figure 2Seismic data from Embodiment 1 of the method for improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs provided by the present invention;

[0026] Figure 3 Seismic data from Example 2 of the method for improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs provided by the present invention.

[0027] Figure 4 A schematic diagram of a three-dimensional geological model for the method of improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs provided by the present invention.

[0028] Figure 5 This is a schematic diagram of a model for the method of improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs provided by the present invention, showing different regions of the fault. Detailed Implementation

[0029] like Figure 1 As shown, the present invention provides a method for improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs, comprising the following steps:

[0030] (1) Collect seismic data of the target block;

[0031] (2) Identify the earthquake data and find the faults in the earthquake data;

[0032] (3) Identify the location of the fault according to step (2), drill wells at different locations of the fault, and extract fault cores at the corresponding locations;

[0033] (4) Based on the location of the fault identified in step (2), drill wells at different locations outside the location of the fault, and extract non-fault cores at the corresponding depths of the same fault cores in step (3).

[0034] (5) Conduct rock mechanics parameter testing experiments on the fault cores and non-fault cores taken out in steps (3) and (4) respectively to obtain several mechanical parameters of the fault cores and several mechanical parameters of the non-fault cores.

[0035] (6) The magnitude relationship between the corresponding mechanical parameters of the fault core and the non-fault core obtained in step (5) can be obtained, and the magnitude relationship is assigned to the geological model for simulation of the three-dimensional geodynamic field.

[0036] By obtaining the relationship between fault cores and non-fault cores and assigning it to the subsequent three-dimensional geostress field simulation, the accuracy of the simulation can be greatly improved, which has significant reference value for subsequent oil and gas extraction. Moreover, it avoids the limitation of uniformly assigning mechanical parameters to fault areas of the strata, and introduces the distribution characteristics of mechanical property parameters in different areas of the fault. This allows for more realistic and differentiated assignment of values ​​to different areas, including fault and non-fault areas, thus enhancing the accuracy of subsequent geostress field simulation.

[0037] In some embodiments, in step (5), the mechanical parameters are compressive strength, elastic modulus, Poisson's ratio, and tensile strength. The mechanical parameters of the fault core are respectively denoted as P1, E1, μ1, and T1, and the mechanical parameters of the non-fault core are respectively denoted as P2, E2, μ2, and T2.

[0038] The mechanical parameters are compressive strength, elastic modulus, Poisson's ratio, and tensile strength, which are sufficient to reflect the mechanical properties of the rock core.

[0039] In step six, the size relationship is as follows:

[0040] (P2-P1) / P2>0.4, (E2-E1) / E2>0.3, (μ1-μ2) / μ1>0.1, (T2-T1) / T2>0.5.

[0041] In some embodiments, in step (3), based on the location of the fault identified in step (2), wells are drilled at different locations of the fault, and fault cores are extracted. The core extraction location is the intersection of the well and the fault identified in step (2).

[0042] Furthermore, the fault has a length direction, and in step (3), drilling is performed at different locations on the fault, the different locations referring to the two ends of the fault along the length direction, the interior of the fault, and the side of the fault.

[0043] Preferably, in step (4), drilling is carried out at different locations outside the location of the fault, which refers to locations with different vertical distances from the central axis of the fault.

[0044] In steps (3) and (4), the fault core and the non-fault core are retrieved, referring to the retrieved full-diameter cores with the same diameter as the well. The structures of the fault core and the non-fault core are the actual structures of the reservoir at the drilling location.

[0045] Example 1:

[0046] A. Collect seismic data for the target area, as shown in the attached document. Figure 2 As shown;

[0047] B. Identify earthquake data and locate fault indications within the data. Figure 2 A clear discontinuity in amplitude can be observed within the area circled by the ellipse in the longitudinal section, which is preliminarily identified as the location of the fault.

[0048] C. Based on the fault location identified in step (B), as shown in the attached... Figure 4 As shown, a well is drilled at the location of the fault, and a core sample is taken from the fault location. Figure 5 The image shows the intersection of the well and the fault, and the coring location is at this point (inside the fault ①).

[0049] D. Based on the fault location identified in step (B), drill a well at any location other than the fault location, as shown in the attached diagram. Figure 5 As shown, core samples were taken from the same core depth in step (C) (away from the fault area ①);

[0050] E. The compressive strength, elastic modulus, Poisson's ratio, and tensile strength of the core samples taken in steps (C) and (D) are tested. The compressive strength, elastic modulus, Poisson's ratio, and tensile strength of the core samples from step (C) are denoted as P1, E1, μ1, and T1, respectively. The compressive strength, elastic modulus, Poisson's ratio, and tensile strength of the core samples from step (D) are denoted as P2, E2, μ2, and T2, respectively. The measured values ​​of P1, E1, μ1, and T1 are 70 MPa, 3 × 10⁻⁶ MPa, and 3 × 10⁻⁶ MPa, respectively. 4 MPa, 0.25, 4 MPa, and P2, E2, μ2, and T2 were measured to be 120 MPa, 5 × 10 MPa, 0.25 MPa, 4 MPa, 0.25 MPa, 0.25 MPa, 4 MPa, and P2, E2, μ2, and T2 were 5 × 10 MPa, 0.25 MPa, 0.25 MPa, 4 MPa, 0.25 ... 4 MPa, 0.2, 10MPa.

[0051] F. The distribution characteristics of mechanical property parameters in different regions of the fault are: (P2-P1) / P2>0.4, (E2-E1) / E2>0.3, (μ1-μ2) / μ1>0.1, (T2-T1) / T2>0.5.

[0052] Example 2:

[0053] A. Collect seismic data for the target area, as shown in the attached document. Figure 3 As shown;

[0054] B. Perform preliminary identification of seismic data, locate fault indications within the seismic data, and attach... Figure 3 Within the area circled by the ellipse, a clear discontinuity in amplitude can be observed, which is preliminarily identified as the location of a fault.

[0055] C. Based on the fault location identified in step (B), as shown in the attached... Figure 4 As shown, a well is drilled at the location of the fault, and a core sample is taken from the fault location. Figure 5The image shows the intersection of the well and the fault, and the coring location is at this point (inside the fault ②).

[0056] D. Based on the fault location identified in step (B), drill a well at any location other than the fault location, as shown in the attached diagram. Figure 5 As shown, core samples were taken from the same core depth in step (C) (away from the fault area ②);

[0057] E. The compressive strength, elastic modulus, Poisson's ratio, and tensile strength of the core samples taken in steps (C) and (D) are tested. The compressive strength, elastic modulus, Poisson's ratio, and tensile strength of the core samples from step (C) are denoted as P1, E1, μ1, and T1, respectively. The compressive strength, elastic modulus, Poisson's ratio, and tensile strength of the core samples from step (D) are denoted as P2, E2, μ2, and T2, respectively. The measured values ​​of P1, E1, μ1, and T1 are 73 MPa, 3.2 × 10⁻⁶ MPa, and T1 are 3.2 × 10⁻⁶ MPa, respectively. 4 MPa, 0.26, 4.5 MPa, and P2, E2, μ2, and T2 were measured to be 125 MPa, 5 × 10 MPa, 0.26 MPa, 4.5 MPa, and P2, E2, μ2, and T2 were 5 × 10 MPa, 5 × 10 MPa, 0.26 MPa, 4.5 MPa, and 0.26 MPa, respectively. 4 MPa, 0.22, 10MPa.

[0058] F. The distribution characteristics of mechanical property parameters in different regions of the fault are: (P2-P1) / P2>0.4, (E2-E1) / E2>0.3, (μ1-μ2) / μ1>0.1, (T2-T1) / T2>0.5.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs, characterized in that, Includes the following steps: (1) Collect seismic data of the target block; (2) Identify the earthquake data and locate the faults in the earthquake data; (3) According to step (2), the location of the fault is identified, wells are drilled at different locations of the fault, and fault cores are taken out at the corresponding locations. In this step (3), according to the location of the fault identified in step (2), wells are drilled at different locations of the fault, and fault cores are taken out. The core location is the intersection of the well and the fault identified in step (2). The fault has a length direction. In this step (3), wells are drilled at different locations of the fault. The different locations refer to the two ends of the fault along the length direction, the interior of the fault, and the side of the fault. (4) Based on the location of the fault identified in step (2), drill wells at different locations outside the location of the fault, and extract non-fault cores at the same fault core depth as in step (3). In step (4), different locations outside the location of the fault refer to locations with different vertical distances from the central axis of the fault. (5) Conduct rock mechanics parameter testing experiments on the fault cores and non-fault cores taken out in steps (3) and (4) respectively, and obtain several mechanical parameters of the fault cores and several mechanical parameters of the non-fault cores. In step (5), the mechanical parameters are compressive strength, elastic modulus, Poisson's ratio and tensile strength. The mechanical parameters of the fault cores are recorded as P1, E1, μ1 and T1 respectively, and the mechanical parameters of the non-fault cores are recorded as P2, E2, μ2 and T2 respectively. (6) Based on the same mechanical parameters of the fault core and the non-fault core obtained in step (5), obtain the magnitude relationship between them, and assign the magnitude relationship to the geological model for simulation of the three-dimensional geostress field. The magnitude relationship is as follows: (P2-P1) / P2>0.4, (E2-E1) / E2>0.3, (μ1-μ2) / μ1>0.1, (T2-T1) / T2>0.5; The structures of the fault core and the non-fault core are the actual structures of the reservoir at the drilling location.

2. The method for improving the accuracy of three-dimensional geostress field simulation of fractured-vuggy reservoirs according to claim 1, characterized in that, In steps (3) and (4), the removal of the fault core and the non-fault core refers to the removal of a full-diameter core with the same diameter as the well.

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