A quantitative prediction method for reservoir geomechanical parameters in complex structural superposition areas

Abstract

This invention provides a quantitative prediction method for reservoir geomechanical parameters in complex tectonic superposition areas, applicable to the fields of petroleum and natural gas geology and rock mechanics. First, core samples, conventional logging, imaging logging, and 3D seismic data are collected from the complex tectonic superposition area. Rock mechanical parameters are calculated using experimental and logging data, and a single-well rock mechanical parameter profile S0 is constructed. Then, fracture parameters are extracted, and the relationships f1 and f2 between fracture density in the hanging wall and footwall and distance from the fault, as well as a fracture-weakened rock mechanical property model F, are established. Subsequently, S0 is transformed into a rock mechanical parameter profile S1 under actual fractured formation conditions, and its relationship with seismic attributes is established. Finally, the natural fracture field and rock mechanical field of the complex tectonic superposition area are constructed, achieving quantitative prediction of reservoir geomechanical parameters. This method is comprehensive, rigorous, highly operable, and yields highly reliable prediction results.

Description

Technical Field

[0001] This invention relates to the fields of petroleum and natural gas geology and rock mechanics, specifically to a method for quantitative prediction of reservoir geomechanical parameters in complex structural superposition zones. Background Technology

[0002] The Kuqa Depression, influenced by intense tectonic activity and the presence of superimposed Kumegliemu Group gypsum-salt rock layers, has developed a series of thrust-nappe tectonic systems, characterized by "north-south zonation, east-west segmentation, and vertical superposition." In complex tectonic superposition areas such as the Kuqa Depression, quantitative prediction of the development and distribution of reservoir geomechanical parameters is crucial for oil and gas development.

[0003] Previous studies have largely focused on analyzing the characteristics of north-south zonation and east-west segmentation, with few targeted studies addressing vertical overlay characteristics. Chinese invention patent application CN112764097A proposes a spatial overlay three-dimensional structural modeling method, device, and computer storage medium. This method acquires seismic interpretation data in the depth domain, groups adjacent strata with identical fault development, establishes cross-section and bedding plane models within each structural model, spatially overlays the cross-section models of adjacent structural models to obtain a complete set of three-dimensional cross-section models, and spatially overlays the bedding plane models of adjacent structural models to obtain a complete set of three-dimensional bedding plane models. Chinese invention patent application CN116411942A proposes a high-angle well trajectory design method for complex overlay reservoirs. This method refines the target stratigraphic units based on existing exploration data, establishes a high-precision sequence cycle correspondence between reservoir stratigraphic units, and determines the optimal drilling azimuth for multi-layered three-dimensional exploration. Chinese invention patent CN103913774A proposes a method for inverting reservoir geomechanical parameters based on microseismic events. This method includes steps such as processing the microseismic event cloud with a Gaussian distribution function, selecting a prediction model, calculating the Kalman filter factor, updating the reservoir geomechanical parameters, and obtaining the actual reservoir geomechanical parameters to establish an accurate underlying reservoir geomechanical model. However, it fails to consider the characteristics of complex superimposed structures and is not applicable in areas with complex superimposed structures such as the Kuqa Depression. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a quantitative prediction method for reservoir geomechanical parameters in complex tectonic superposition areas that comprehensively considers various factors and yields highly reliable results. It comprehensively considers the distance from the fault, the rock mechanical property model weakened by fractures, and combines experimental testing, well logging interpretation, and 3D seismic data to construct the natural fracture field and rock mechanical field in complex tectonic superposition areas, thereby achieving quantitative prediction.

[0005] To achieve the above objectives, this invention provides a method for quantitative prediction of reservoir geomechanical parameters in complex tectonic superposition areas. First, core samples, conventional logging, imaging logging, and 3D seismic data from the complex tectonic superposition area are collected. Rock mechanical parameters are calculated using experimental and logging data, and a single-well rock mechanical parameter profile S0 is constructed. Then, fracture parameters are extracted, and the relationships f1 and f2 between fracture density in the hanging wall and footwall and distance from the fault, as well as a fracture-weakened rock mechanical property model F, are established. Subsequently, S0 is transformed into a rock mechanical parameter profile S1 under actual fractured strata conditions, and its relationship with seismic attributes is established. Finally, the natural fracture field and rock mechanical field of the complex tectonic superposition area are constructed, achieving quantitative prediction of reservoir geomechanical parameters.

[0006] The specific steps are as follows:

[0007] Step 1: Collect cross-fault core samples from complex structural superposition areas and gather conventional logging, imaging logging, and 3D seismic data;

[0008] Step 2: Using the drilling core and conventional logging data obtained in Step 1, triaxial rock mechanics experiments and logging rock mechanics parameter calculations are carried out to obtain static and dynamic rock mechanics parameters. Then, a dynamic-static rock mechanics parameter conversion model is established to construct a single-well rock mechanics parameter profile S0.

[0009] Step 3: Extract natural fracture parameters using the imaging logging data obtained in Step 1, calculate fracture density, and statistically establish the relationship between fracture density and distance from the fault in the hanging wall and footwall, f1 and f2, respectively. Based on this, construct a fracture field in the complex structural superposition zone based on fracture density and distance from the fault.

[0010] Step 4: Construct a mechanical property model F of fracture-weakened rock based on theoretical analysis;

[0011] Step 5: Using the relationships f1 and f2 obtained in Step 3 and the model F obtained in Step 4, the rock mechanics profile S0 constructed in Step 1 is converted into the rock mechanics parameter profile S1 under the actual strata with fractures.

[0012] Step 6: Extract the seismic attribute volume using the three-dimensional seismic data obtained in Step 1, establish its relationship with the rock mechanics profile S1 obtained in Step 5, and construct the rock mechanics field of the complex tectonic superposition zone.

[0013] Furthermore, the drilling cores collected in step 1 need to be processed into dimensions of 25mm in diameter and 50mm in height. Conventional logging data should include at least gamma ray (GR), acoustic transit time (AC), density (DEN) curves, and core fill elevation and core fill height. The 3D seismic data should be depth domain data.

[0014] Furthermore, in step 2, the calculation of rock mechanical parameters using conventional well logging data is mainly performed using the following formula:

[0015]

[0016]

[0017] In the formula: μ is the Poisson's ratio of the rock, E is the elastic modulus of the rock, and Δt s and Δt p ρ represents the transverse and longitudinal wave time differences of the strata, respectively, and ρ is the rock density.

[0018] Furthermore, in step 3, the crack density is expressed in the form of linear density, that is, the number of cracks per unit length:

[0019]

[0020] In the formula: f d denoted as crack density, n as the number of cracks, and l as the length of the measurement section.

[0021] The relationships between fracture density and fault distance in the hanging wall and footwall, f1 and f2, are as follows:

[0022]

[0023] In the formula: f1 and f2 are the fracture densities of the hanging wall and footwall of the fault, respectively; g1 and g2 are the relationship between the distances of f1 and f2 from the fault; and d is the distance of the measurement point from the fault.

[0024] Furthermore, the fracture-weakening rock mechanical property model F constructed in step 4, taking two sets of fractures as examples, is as follows:

[0025]

[0026]

[0027] In the formula: E eq and μ eq E and μ are the equivalent rock elastic modulus, respectively; E and μ are the elastic modulus and Poisson's ratio of intact rock, respectively; α and β are the acute angles between the first group of cracks and the horizontal plane, and between the second group of cracks and the first group of cracks, respectively; S1 and S2 are the spacings between the second group of cracks and the first group of cracks, respectively; K is the equivalent rock elastic modulus, respectively. n1 and K n2 The normal stiffness of the second and first groups of cracks, respectively, K s1 and K s2 These are the shear stiffnesses of the second and first groups of cracks, respectively.

[0028] Furthermore, in step 6, the seismic attributes include at least coherent volume and wave impedance, establishing the following relationship:

[0029]

[0030] In the formula: Eeq and μ eq Here, X represents the equivalent rock elastic modulus, X represents the coherent volume property, and P represents the wave impedance property.

[0031] The beneficial effects of this invention are as follows:

[0032] Currently, there are no research methods for reservoir geomechanical parameters in areas with complex superimposed structures. In order to quantitatively characterize the features of complex superimposed structures and predict reservoir geomechanical parameters, this invention patent comprehensively considers the distance from the fault and the rock mechanical property model weakened by fractures to achieve quantitative prediction of the distribution of underground natural fractures and accurate characterization of rock mechanical properties. By combining experimental testing, well logging interpretation, and 3D seismic data, a natural fracture field and rock mechanical field in complex superimposed structures are constructed to achieve quantitative prediction of reservoir geomechanical parameters. This method considers comprehensive and rigorous factors, is highly operable, and has high reliability in prediction results, solving the problem of low prediction accuracy of reservoir geomechanical parameters in areas with complex superimposed structures. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram illustrating the process of a method for quantitative prediction of reservoir geomechanical parameters in complex structural superimposed areas provided by the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figure 1As shown, the present invention provides a method for quantitative prediction of reservoir geomechanical parameters in complex tectonic superposition areas. First, core samples, conventional logging, imaging logging, and 3D seismic data from the complex tectonic superposition area are collected. Rock mechanical parameters are calculated using experimental and logging data, and a single-well rock mechanical parameter profile S0 is constructed. Then, fracture parameters are collected, and the relationships f1 and f2 between fracture density in the hanging wall and footwall and distance from the fault, as well as a fracture-weakened rock mechanical property model F, are established. Subsequently, S0 is converted into a rock mechanical parameter profile S1 under actual fractured strata conditions, and its relationship with seismic attributes is established. Finally, the natural fracture field and rock mechanical field of the complex tectonic superposition area are constructed, achieving quantitative prediction of reservoir geomechanical parameters.

[0037] The specific steps are as follows:

[0038] Step 1: Collect cross-fault core samples from complex structural superposition areas and gather conventional logging, imaging logging, and 3D seismic data;

[0039] The collected drilling cores need to be processed into dimensions of 25mm in diameter and 50mm in height. Conventional logging data should include at least gamma ray (GR), acoustic transit time (AC), density (DEN) curves, and core fill elevation and core fill height. 3D seismic data should be depth domain data.

[0040] Step 2: Using the drilling core and conventional logging data obtained in Step 1, triaxial rock mechanics experiments and logging rock mechanics parameter calculations are carried out to obtain static and dynamic rock mechanics parameters. Then, a dynamic-static rock mechanics parameter conversion model is established to construct a single-well rock mechanics parameter profile S0.

[0041] Rock mechanics parameters are mainly calculated from conventional well logging data using the following formulas:

[0042]

[0043]

[0044] In the formula: μ is the Poisson's ratio of the rock, E is the elastic modulus of the rock, and Δt s and Δt p ρ represents the transverse and longitudinal wave time differences of the strata, respectively, and ρ is the rock density.

[0045] Step 3: Extract natural fracture parameters using the imaging logging data obtained in Step 1, calculate fracture density, and statistically establish the relationship between fracture density and distance from the fault in the hanging wall and footwall, f1 and f2, respectively. Based on this, construct a fracture field in the complex structural superposition zone based on fracture density and distance from the fault.

[0046] Crack density is expressed in linear density form, which is the number of cracks per unit length:

[0047]

[0048] In the formula: f d denoted as crack density, n as the number of cracks, and l as the length of the measurement section.

[0049] The relationships between fracture density and fault distance in the hanging wall and footwall, f1 and f2, are as follows:

[0050]

[0051] In the formula: f1 and f2 are the fracture densities of the hanging wall and footwall of the fault, respectively; g1 and g2 are the relationship between the distances of f1 and f2 from the fault; and d is the distance of the measurement point from the fault.

[0052] Step 4: Construct a mechanical property model F of fracture-weakened rock based on theoretical analysis;

[0053] The expression for the fracture-weakened rock mechanical property model F, constructed using two sets of fractures as an example, is as follows:

[0054]

[0055]

[0056] In the formula: E eq and μ eq E and μ are the equivalent rock elastic modulus, respectively; E and μ are the elastic modulus and Poisson's ratio of intact rock, respectively; α and β are the acute angles between the first group of cracks and the horizontal plane, and between the second group of cracks and the first group of cracks, respectively; S1 and S2 are the spacings between the second group of cracks and the first group of cracks, respectively; K is the equivalent rock elastic modulus, respectively. n1 and K n2 The normal stiffness of the second and first groups of cracks, respectively, K s1 and K s2 These are the shear stiffnesses of the second and first groups of cracks, respectively.

[0057] Step 5: Using the relationships f1 and f2 obtained in Step 3 and the model F obtained in Step 4, the rock mechanics profile S0 constructed in Step 1 is converted into the rock mechanics parameter profile S1 under the actual strata with fractures.

[0058] Step 6: Extract the seismic attribute volume using the three-dimensional seismic data obtained in Step 1, establish its relationship with the rock mechanics profile S1 obtained in Step 5, and construct the rock mechanics field of the complex tectonic superposition zone.

[0059] Seismic properties include at least coherent volume and wave impedance, and the following relationship is established:

[0060]

[0061] In the formula: E eq and μ eq Here, X represents the equivalent rock elastic modulus, X represents the coherent volume property, and P represents the wave impedance property.

[0062] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for quantitative prediction of reservoir geomechanical parameters in complex structural superposition zones, characterized in that, Specifically, the following steps are included: Step 1: Collect cross-fault core samples from complex structural superposition areas and gather conventional logging, imaging logging, and 3D seismic data; Step 2: Using the drilling core and conventional logging data obtained in Step 1, triaxial rock mechanics experiments and logging rock mechanics parameter calculations are carried out to obtain static and dynamic rock mechanics parameters. Then, a dynamic-static rock mechanics parameter conversion model is established to construct a single-well rock mechanics parameter profile S0. Step 3: Extract natural fracture parameters using the imaging logging data obtained in Step 1, calculate fracture density, and statistically establish the relationship between fracture density and distance from the fault in the hanging wall and footwall, f1 and f2, respectively. Based on this, construct a fracture field in the complex structural superposition zone based on fracture density and distance from the fault. Step 4: Construct a mechanical property model F for fracture-weakened rocks based on theoretical analysis. The expression for the mechanical property model F for fracture-weakened rocks constructed in Step 4, taking two sets of fractures as examples, is as follows: In the formula: E eq and μ eq E and μ are the equivalent rock elastic modulus and equivalent rock Poisson's ratio, respectively; E and μ are the elastic modulus and Poisson's ratio of intact rock, respectively; α and β are the acute angles between the first group of cracks and the horizontal plane, and between the second group of cracks and the first group of cracks, respectively; S1 and S2 are the spacings between the second group of cracks and the first group of cracks, respectively; K is the equivalent rock elastic modulus and equivalent rock Poisson's ratio, respectively; E and μ are the equivalent rock elastic modulus and Poisson's ratio, respectively; α and β are the acute angles between the first group of cracks and the horizontal plane, respectively; S1 and S2 are the spacings between the second group of cracks and the first group of cracks, respectively; K is the equivalent rock elastic modulus and equivalent rock Poisson's ratio, respectively; α and β are the acute angles between the first group of cracks and the horizontal plane, respectively; S1 and S2 are the n1 and K n2 The normal stiffness of the second and first groups of cracks, respectively, K s1 and K s2 The shear stiffness of the second group and the first group of cracks are respectively; Step 5: Using the relationships f1 and f2 obtained in Step 3 and the model F obtained in Step 4, the rock mechanics profile S0 constructed in Step 1 is converted into the rock mechanics parameter profile S1 under the actual strata with fractures. Step 6: Extract the seismic attribute volume using the three-dimensional seismic data obtained in Step 1, establish its relationship with the rock mechanics profile S1 obtained in Step 5, and construct the rock mechanics field of the complex tectonic superposition zone.

2. The method according to claim 1, characterized in that, The drill core collected in step 1 needs to be processed into a size of 25mm in diameter × 50mm in height. Conventional logging data include gamma ray (GR), acoustic transit time (AC), density (DEN) curve, and core fill elevation and core fill height. The 3D seismic data needs to be depth domain data.

3. The method according to claim 1, characterized in that, In step 2, the rock mechanical parameters are calculated using conventional well logging data using the following formula: In the formula: μ is the Poisson's ratio of the rock, E is the elastic modulus of the rock, and Δt s and Δt p ρ represents the transverse and longitudinal wave time differences of the strata, ρ is the rock density, and γ is a coefficient.

4. The method according to claim 3, characterized in that, In step 3, the crack density is expressed in linear density form, that is, the number of cracks per unit length: In the formula: f d Where n is the crack density, n is the number of cracks, and l is the length of the measurement section; The relationships between fracture density and fault distance in the hanging wall and footwall, f1 and f2, are as follows: In the formula: f1 and f2 are the fracture densities of the hanging wall and footwall of the fault, respectively; g1 and g2 are the relationship between the distances of f1 and f2 from the fault; and d is the distance of the measurement point from the fault.

5. The method according to claim 4, characterized in that, In step 6, the seismic properties include coherence volume and wave impedance, and the following relationship is established: In the formula: E eq and μ eq Let X represent the equivalent rock elastic modulus and equivalent rock Poisson's ratio, respectively; X represent the coherent volume property; P represent the wave impedance property; and m1() and m2() represent the functional relationship.

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