Method for judging core of ancient buried hill based on rock mechanical structure volatility

Abstract

The invention relates to the field of oil and gas field exploration and development, in particular to a method for judging the core of an ancient buried hill based on rock mechanical structure volatility. The method comprises the following steps: (1) carrying out high-precision geological geometric modeling; (2) pre-stack data drive inversion of the initial model; (3) performing current dynamic rock mechanical parameter three-dimensional distribution data volume inversion; (4) current static rock mechanical parameter three-dimensional distribution data volume conversion; (5) calculating the spatial volatility of the rock mechanical structure; (6) judging the development scale of the tectonic fracture; and (7) determining the core of the ancient buried hill. The invention provides a method for judging the ancient and buried hill core based on rock mechanics structure volatility. A judgment result has certain reference significance in multiple aspects of ancient and modern rock mechanics parameter inversion, tectonic fracture distribution prediction, geological dessert evaluation and the like.

Description

Technical Field

[0001] The invention relates to the field of oil and gas field exploration and development, in particular to a method for judging the core of an ancient buried hill based on the volatility of rock mechanics structure. Background Art

[0002] The formation of geological "sweet spots" in oil and gas reservoirs must have certain structural conditions. Paleomorphology has a significant control effect on the distribution of high-quality reservoirs and the sedimentary system of oil and gas basins. The core of ancient buried hills usually develops high-quality reservoirs. Current research relies on the residual thickness method and backstripping method. The restoration results are basically the paleomorphic characteristics of a specific stratum or a specific period. Moreover, it is difficult to quantitatively study the paleomorphic characteristics, and the steps are cumbersome and have great inaccuracy. Therefore, how to quickly and accurately determine the core of the ancient buried hill is a practical problem faced in oil and gas geology. The patent of this invention proposes a method for determining the core of the ancient buried hill based on the volatility of rock mechanical structure. The identification results are accurate and can effectively guide the evaluation of the geological "sweet spots" of buried hill reservoirs. Summary of the invention

[0003] The present invention aims to solve the above problems and provides a method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure. The method can determine the core of an ancient buried hill quickly and accurately.

[0004] The technical solution of the present invention is: a method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure, and the specific steps are as follows:

[0005] S1 high-precision geological geometry modeling determines the current structural morphology based on well logging data, mud logging data, pre-stack seismic data and geological data. After multiple modifications and adjustments, a high-precision geological geometry model is established. The high-precision geological geometry model is a model constructed based on the fault model and the top and internal interface model of the work area. The fault model is established based on the fault plane obtained by interpreting seismic data, and the top and internal interfaces are fitted based on the top and internal interfaces of the work area obtained by structural interpretation. The grid unit size of the high-precision geological model is 1-8 meters.

[0006] S2 pre-stack data driven inversion initial model, based on pre-stack seismic data and geological stratification data, the initial model is established, and the P-wave and S-wave reflectivity terms and density reflectivity terms corresponding to the initial model are obtained according to the Aki-Richards approximate equation. The obtained reflectivity terms are convolved with the wavelets extracted from the work area to obtain a synthetic artificial gather. The residual is obtained by comparing it with the actual gather data, and the initial model is modified according to the residual to finally obtain the initial model. The initial model includes a P-wave velocity model, a S-wave velocity model, and a density model. The Aki-Richards approximate equation is:

[0007]

[0008] In formula (1), R PPθ is the reflection coefficient of the synthetic seismic record, dimensionless; θ is the incident angle, °; R P is the longitudinal wave velocity reflectivity term, dimensionless; R S is the shear wave velocity reflectivity term, dimensionless; R D is the density reflectivity term, dimensionless; V P is the longitudinal wave velocity, m / μs; V S is the shear wave velocity, m / μs.

[0009] S3 Inversion of the current three-dimensional distribution data of dynamic rock mechanics parameters. Substitute the P-wave velocity model, S-wave velocity model and density model into the rock mechanics parameter calculation formula to calculate the dynamic rock mechanics parameters and invert the current three-dimensional distribution data of dynamic rock mechanics parameters. The rock mechanics parameter calculation formula refers to:

[0010]

[0011] In formulas (2)-(3), E d is the dynamic Young's modulus of rock, GPa; μ d is the dynamic Poisson's ratio of rock, dimensionless; ρ b is the density model, g / cm 3 ; Δt p is the longitudinal wave velocity model, μs / m; Δt s is the shear wave velocity model, μs / m.

[0012] S4 converts the current three-dimensional distribution data body of static rock mechanics parameters, conducts triaxial rock mechanics experiments under in-situ stress environment of underground rocks, tests the corresponding static rock mechanics parameters, determines the dynamic-static conversion model of rock mechanics parameters, substitutes the determined dynamic-static conversion model of rock mechanics parameters into the current three-dimensional distribution data body of dynamic rock mechanics parameters, and establishes the current three-dimensional distribution data body of static rock mechanics parameters; the dynamic-static conversion model of rock mechanics parameters is: conduct intersection analysis on dynamic rock mechanics parameters and static rock mechanics parameters, and establish the numerical relationship between the two.

[0013] S5: Calculation of spatial volatility of rock mechanical structure, reading the average value of rock mechanical parameters in each longitudinal grid unit, and calculating the spatial volatility of rock mechanical structure of the longitudinal grid unit; the calculation of spatial volatility of rock mechanical structure of the longitudinal grid unit is:

[0014]

[0015] In formulas (4)-(5), is the average value of rock mechanical parameters, N iis the rock mechanical parameter within each grid unit, m is the number of grid units in the vertical direction, dimensionless; σ is the spatial volatility of the rock mechanical structure of the vertical grid unit.

[0016] S6 Determination of the scale of development of structural fractures, based on the spatial volatility of the rock mechanical structure of the longitudinal grid unit, the scale of development of structural fractures at different structural positions on the plane is determined; the scale of development of structural fractures is: divided into micro-scale, small-scale, medium-scale and large-scale structural fractures according to the difference in rock mechanical structure volatility. When the rock mechanical volatility is between 0 and 300, it is the area of ​​development of micro-scale structural fractures; when the rock mechanical volatility is between 300 and 500, it is the area of ​​development of small-scale structural fractures; when the rock mechanical volatility is between 500 and 800, it is the area of ​​development of medium-scale structural fractures; when the rock mechanical volatility is between 800 and 1000, it is the area of ​​development of large-scale structural fractures.

[0017] The core of the S7 ancient buried hill was determined based on the scale of structural fracture development at different structural positions on the plane. The area with large structural fracture scale and small density was the core of the ancient buried hill, and the area with small structural fracture scale and large density was the ancient structural low area.

[0018] The beneficial effects of the present invention are as follows: through high-precision geological geometric modeling, combined with the three-dimensional distribution data body of current static rock mechanical parameters obtained from pre-stack data and in-situ rock mechanics experiments, the fluctuation of rock mechanical structure in different structural parts is calculated, the volatility of rock mechanical structure is clarified, the development scale of structural fractures in different structural parts is identified, and the core of the ancient buried hill is judged through the development scale of structural fractures in different structural parts.

[0019] The present invention proposes a method for judging the core of an ancient buried hill based on the volatility of rock mechanics structure. The method has high practical value, low judgment cost and strong operability, and can greatly reduce the expenditure of manpower and financial resources. The judgment result has certain reference significance for the inversion of ancient and modern rock mechanics parameters, the prediction of structural fracture distribution and the evaluation of "geological sweet spots". BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of a method for determining the core of an ancient buried hill based on the spatial volatility of rock mechanical structure.

[0021] Figure 2 It is a high-precision geological model of the Bohai X well area.

[0022] Figure 3 The longitudinal wave, shear wave and density model of the Bohai X well area: (a) longitudinal wave; (b) shear wave; (c) density.

[0023] Figure 4 The distribution of three-dimensional dynamic rock mechanical parameters inverted in the Bozhong x well area: (a) Young's modulus of rock; (b) Poisson's ratio of rock.

[0024] Figure 5 Dynamic-static conversion model of rock mechanical parameters: (a) dynamic-static conversion model of rock Young's modulus; (b) dynamic-static conversion model of rock Poisson's ratio.

[0025] Figure 6 The three-dimensional static rock mechanical parameter distribution of Bozhong x well area: (a) Young's modulus of rock; (b) Poisson's ratio of rock.

[0026] Figure 7 This is the spatial fluctuation of rock mechanical structure in the study area of ​​Bozhong x well area.

[0027] Figure 8 It is the core location of the ancient buried hill in the study area of ​​Bozhong x well area. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, this embodiment provides a method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure, comprising the following steps:

[0030] S1 high-precision geological geometry modeling, based on well logging data, mud logging data, pre-stack seismic data and geological data to determine the current structural morphology, after multiple modifications and adjustments to establish a high-precision geological geometry model. The specific process is: based on the Bozhong x well area fault model and the Bozhong x well area top and internal interface model to build the model, the fault model is based on the fault plane obtained by the interpretation of the Bozhong x well area seismic data, the top and internal interface is based on the Bozhong x well area top and internal interface obtained by structural interpretation Fit, get Figure 2 Meter-level high-precision geological geometry model of the Bohai X well area.

[0031] S2 pre-stack data driven inversion initial model, based on pre-stack seismic data and geological stratification data, the initial model is established, and the P- and S-wave reflectivity terms and density reflectivity terms corresponding to the initial model are obtained according to the Aki-Richards approximate equation. The obtained reflectivity terms are convolved with the wavelets extracted from the work area to obtain synthetic artificial gathers. The residuals are obtained by comparing them with the actual gather data, and the initial model is modified according to the residuals after repeated iterations, and finally the initial model is obtained. The specific process is: based on the pre-stack seismic data and geological stratification data of the Bohai x well area, the initial model is established, and the P- and S-wave reflectivity terms and density reflectivity terms corresponding to the initial model are obtained according to the Aki-Richards approximate equation:

[0032]

[0033] In formula (1), R PPθ is the reflection coefficient of the synthetic seismic record, dimensionless; θ is the incident angle, °; R P is the longitudinal wave velocity reflectivity term, dimensionless; R S is the shear wave velocity reflectivity term, dimensionless; R D is the density reflectivity term, dimensionless; V P is the longitudinal wave velocity, m / μs; V S is the shear wave velocity, m / μs.

[0034] The obtained reflectivity term is convolved with the wavelet extracted from the Bohai X well area to obtain a synthetic artificial gather. The residual is obtained by comparing it with the actual gather data, repeating the iteration several times and correcting the initial model according to the residual, and finally obtaining Figure 3 P-wave velocity model, S-wave velocity model and density model of Bozhong x well area.

[0035] S3 Inversion of the current dynamic rock mechanics parameter three-dimensional distribution data body, substitute the P-wave velocity model, S-wave velocity model, and density model into the rock mechanics parameter calculation formula, calculate the dynamic rock mechanics parameters, and invert the current dynamic rock mechanics parameter three-dimensional distribution data body. The specific process is: Substitute the P-wave velocity and S-wave velocity and density of the Bozhong x well area into the rock mechanics parameter calculation formula:

[0036]

[0037] In formulas (2)-(3), E d is the dynamic Young's modulus of rock, GPa; μ d is the dynamic Poisson's ratio of rock, dimensionless; ρ b is the density model, g / cm 3 ; Δt p is the longitudinal wave velocity model, μs / m; Δt s is the shear wave velocity model, μs / m. Calculate the dynamic rock mechanics parameters and get Figure 4 The three-dimensional distribution data volume of current dynamic rock mechanical parameters in the Bozhong x well area.

[0038] S4 converts the current static rock mechanics parameter three-dimensional distribution data volume, conducts rock triaxial mechanics experiments under the in-situ stress environment of underground rocks, tests the corresponding static rock mechanics parameters, determines the dynamic-static conversion model of rock mechanics parameters, substitutes the determined dynamic-static conversion model of rock mechanics parameters into the current dynamic rock mechanics parameter three-dimensional distribution data volume, and establishes the current static rock mechanics parameter three-dimensional distribution data volume. The specific process is: conduct rock triaxial mechanics experiments under the in-situ stress environment of underground rocks in Bohai X well area, test the corresponding static rock mechanics parameters, conduct intersection analysis on dynamic rock mechanics parameters and static rock mechanics parameters, establish the numerical relationship between the two, and obtain Figure 5 The dynamic-static conversion model of rock mechanical parameters is substituted into the three-dimensional distribution data of the current dynamic rock mechanical parameters in the Bozhong x well area to establish Figure 6 The three-dimensional distribution data volume of current static rock mechanical parameters in the Bozhong x well area.

[0039] S5 rock mechanics structure spatial volatility calculation, read the average value of rock mechanics parameters in each longitudinal grid unit, and calculate the spatial volatility of rock mechanics structure of longitudinal grid unit. The specific process is: read the average value of rock mechanics parameters in each longitudinal grid unit of Bozhong x well area, and calculate the spatial volatility of rock mechanics structure of longitudinal grid unit of Bozhong x well area:

[0040]

[0041] In formulas (4)-(5), is the average value of rock mechanical parameters, N i is the average value of the rock mechanical parameters in each grid unit, m is the number of grid units in the vertical direction, dimensionless; σ is the spatial volatility of the rock mechanical structure. Figure 7 Spatial volatility of rock mechanical structure in Bozhong x well area.

[0042] S6 Determination of the scale of structural fracture development: Determine the scale of structural fracture development at different structural positions on the plane based on the spatial volatility of the rock mechanical structure of the longitudinal grid unit. The specific process is: Determine the scale of structural fracture development at different structural positions on the plane based on the spatial volatility of the rock mechanical structure of the Bozhong x well area. When the rock mechanical volatility is between 0 and 300, it is the microscopic structural fracture development area of ​​the Bozhong x well area. When the rock mechanical volatility is between 300 and 500, it is the small-scale structural fracture development area of ​​the Bozhong x well area. When the rock mechanical volatility is between 500 and 800, it is the medium-scale structural fracture development area of ​​the Bozhong x well area. When the rock mechanical volatility is between 800 and 1000, it is the large-scale structural fracture development area of ​​the Bozhong x well area.

[0043] S7 Ancient buried hill core determination, based on the scale of structural fracture development at different structural positions on the plane, the part with large structural fracture scale and small density is the ancient buried hill core, and the part with small structural fracture scale and large density is the ancient structural low part. The specific process is: Based on the scale of structural fracture development at different structural positions on the plane of Bozhong x well area, the ancient buried hill core is determined. The part with large structural fracture scale and small density is the ancient buried hill core, and the part with small structural fracture scale and large density is the ancient structural low part. Figure 8 The location of the core of the ancient buried hill in the Bozhong x well area.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure, characterized in that: The method specifically comprises the following steps: S1 high-precision geological geometry modeling, based on well logging data, mud logging data, pre-stack seismic data and geological data to determine the current structural morphology and establish a high-precision geological geometry model; S2 Pre-stack data driven inversion initial model: Based on pre-stack seismic data and geological stratification data, the initial model is established. The P-wave and S-wave reflectivity terms and density reflectivity terms corresponding to the initial model are obtained according to the Aki-Richards approximate equation. The obtained reflectivity terms are convolved with the wavelets extracted from the work area to obtain synthetic artificial gathers. The residuals are obtained by comparing the synthetic artificial gathers with the actual gather data, and the initial model is modified according to the residuals after repeated iterations. Finally, the initial model is obtained. S3 Inversion of the current three-dimensional distribution data of dynamic rock mechanics parameters. Substitute the P-wave velocity model, S-wave velocity model and density model into the rock mechanics parameter calculation formula, calculate the dynamic rock mechanics parameters and invert the current three-dimensional distribution data of dynamic rock mechanics parameters. S4 Convert the current static rock mechanics parameter three-dimensional distribution data body, carry out rock triaxial mechanics experiments under the in-situ stress environment of underground rocks, test the corresponding static rock mechanics parameters, determine the dynamic-static conversion model of rock mechanics parameters, substitute the determined dynamic-static conversion model of rock mechanics parameters into the current dynamic rock mechanics parameter three-dimensional distribution data body, and establish the current static rock mechanics parameter three-dimensional distribution data body; S5: Calculation of spatial fluctuation of rock mechanical structure, reading the average value of rock mechanical parameters in each longitudinal grid unit, and calculating the spatial fluctuation of rock mechanical structure of the longitudinal grid unit; S6 Determination of the scale of structural fracture development: Determine the scale of structural fracture development at different structural positions on the plane based on the spatial volatility of the rock mechanical structure of the vertical grid unit; The core of the S7 ancient buried hill was determined based on the scale of structural fracture development at different structural positions on the plane. The area with large structural fracture scale and small density was the core of the ancient buried hill, and the area with small structural fracture scale and large density was the ancient structural low area.

2. A method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure according to claim 1, characterized in that: The high-precision geological geometric model in step S1 is: a model constructed based on a fault model and a top and internal interface model of the work area. The fault model is established based on the fault plane obtained by interpreting seismic data, and the top and internal interfaces are fitted based on the top and internal interfaces of the work area obtained by tectonic interpretation. The grid unit size of the high-precision geological model is 1-8 meters.

3. The method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure according to claim 1, characterized in that: The initial models in step S2 are: longitudinal wave velocity model, shear wave velocity model, and density model.

4. The method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure according to claim 1, characterized in that: The Aki-Richards approximation equation in step S2 is: In formula (1), R PPθ is the reflection coefficient of the synthetic seismic record, dimensionless; θ is the incident angle, °; R P is the longitudinal wave velocity reflectivity term, dimensionless; R S is the shear wave velocity reflectivity term, dimensionless; R D is the density reflectivity term, dimensionless; V P is the longitudinal wave velocity, m / μs; V S is the shear wave velocity, m / μs.

5. The method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure according to claim 1, characterized in that: The rock mechanics parameter calculation formula in step S3 is: In formulas (2)-(3), E d is the dynamic Young's modulus of rock, GPa; μ d is the dynamic Poisson's ratio of rock, dimensionless; ρ b is the density model, g / cm 3 ; Δt p is the longitudinal wave velocity model, μs / m; Δt s is the shear wave velocity model, μs / m.

6. The method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure according to claim 1, characterized in that: The rock mechanics parameter dynamic-static conversion model in step S4 is: performing intersection analysis on the dynamic rock mechanics parameters and the static rock mechanics parameters to establish a numerical relationship between the two.

7. The method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure according to claim 1, characterized in that: The calculation of the spatial volatility of the rock mechanical structure of the longitudinal grid unit in step S5 is: In formulas (4)-(5), is the average value of rock mechanical parameters, N i is the rock mechanical parameter within each grid unit, m is the number of grid units in the vertical direction, dimensionless; σ is the spatial volatility of the rock mechanical structure of the vertical grid unit.

8. The method for determining the core of an ancient buried hill based on the volatility of rock mechanical structure according to claim 1, characterized in that: The scale of structural fracture development in step S6 is: according to the difference in rock mechanical structural volatility, it is divided into micro-scale, small-scale, medium-scale and large-scale structural fractures. When the rock mechanical volatility is between 0 and 300, it is the micro-scale structural fracture development area, when the rock mechanical volatility is between 300 and 500, it is the small-scale structural fracture development area, when the rock mechanical volatility is between 500 and 800, it is the medium-scale structural fracture development area, and when the rock mechanical volatility is between 800 and 1000, it is the large-scale structural fracture development area.

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