A method for quickly and quantitatively predicting planar distribution of offshore carbonate buried hill reservoirs

Abstract

This invention discloses a rapid quantitative prediction method for the planar distribution of carbonate buried hill reservoirs at sea, comprising the following steps: identifying the development pattern of carbonate buried hills; calculating tectonic inversion factors; calculating paleogeomorphic factors; calculating the comprehensive reservoir influence factor A; calculating the reservoir sensitivity factor F; conducting F-A pre-stack inversion; establishing a regression relationship between net-to-gross ratio and fused attributes; and calculating a net-to-gross ratio map, thereby achieving rapid quantitative prediction of the planar distribution of carbonate buried hill reservoirs. This invention uses tectonic inversion factors and paleogeomorphic factors as variables to calculate and construct a comprehensive influence factor for carbonate reservoirs. By introducing the comprehensive reservoir influence factor and the three parameters of P-wave velocity and density into the pre-stack inversion, the three-parameter fused attributes are obtained, establishing a correlation with the net-to-gross ratio of drilled wells, and calculating the net-to-gross ratio map, thus achieving rapid quantitative prediction of the planar distribution of carbonate buried hill reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and development technology, and in particular relates to a rapid quantitative prediction method for the planar distribution of offshore carbonate buried hill reservoirs. Background Technology

[0002] Currently, the industry generally believes that the reservoir genesis of carbonate buried hills is extremely complex, exhibiting strong heterogeneity under the control of factors such as paleogeography, structure, lithology, weathering time, and deep hydrothermal fluids. This is especially true in offshore oil and gas exploration and development, where there is a relatively small number of appraisal wells.

[0003] Currently, most experts and scholars use single-factor reservoir prediction methods, such as paleogeomorphology, fracture prediction, and pre-stack inversion. These methods are mostly qualitative analyses, lacking quantitative research and failing to establish relationships between the various factors. Therefore, an effective, rapid, quantitative prediction method for inter-well operations is currently lacking. Summary of the Invention

[0004] The problem to be solved by this invention is to provide a rapid quantitative prediction method for the planar distribution of offshore carbonate buried hill reservoirs. This method can scientifically, rationally and effectively reflect the planar distribution characteristics of carbonate buried hill reservoirs and can be used as the basis for determining the planar thickness of reservoirs, thereby realizing the quantitative characterization of the planar distribution of offshore carbonate buried hill reservoirs.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a rapid quantitative prediction method for the planar distribution of offshore carbonate buried hill reservoirs, comprising the following steps: S1: Identify the development pattern of carbonate buried hills; S2: Calculate the structural inversion factor ; S3: Calculation of paleogeographic factors ; S4: Calculate the comprehensive influence factor A of the reservoir; S5: Calculate the reservoir sensitivity factor F; S6: Conduct FA pre-stack inversion; S7: Establish the regression relationship between net gross weight ratio and fusion attribute; S8: The net-to-gross ratio map is calculated, enabling rapid quantitative prediction of the planar distribution of carbonate buried hill reservoirs.

[0006] Furthermore, S1 includes the following steps: S11: Taking into account paleogeography, structure, lithology and weathering time, the carbonate buried hills in the study area are determined to be either fault-block buried hills controlled by tectonics or residual hills controlled by paleogeography. S12: Determine the coefficient values ​​of tectonic inversion factor a and paleogeomorphological factor b in the comprehensive reservoir influencing factors based on the buried hill development model.

[0007] Furthermore, in S12, if it is a fault-block buried hill, then a > b; if it is a residual hill buried hill, then b > a, where a + b = 1.

[0008] Furthermore, step S2 includes the following steps: S21: Paleomorphology before tectonic reversal is normalized using the following formula (Ⅰ), and paleomorphology after tectonic reversal is normalized using the following formula (Ⅱ). (I), (II) In the formula, ΔH is the difference between the maximum and minimum current structural height of the Paleozoic buried mountain top, in meters; Δh is the difference between the maximum and minimum residual thickness of the Paleozoic strata, in meters. S22: Subtract the paleogeography before and after tectonic reversal using the following formula (Ⅲ) to obtain the normalized tectonic reversal amount. (Ⅲ), In the formula, To construct the reversal factor.

[0009] Furthermore, in S3, the paleomorphology is obtained through the residual thickness method, that is, by subtracting the bottom and top surfaces of the Paleozoic strata to obtain the residual stratum thickness of the Paleozoic strata, which is used to characterize the paleomorphology of the Paleozoic strata. The residual stratum thickness is a paleomorphological factor. .

[0010] Furthermore, S4 includes the following steps: S41: The reservoir comprehensive influence factor A is calculated according to the following formula (Ⅳ). (Ⅳ); S42: Construct the correlation between the comprehensive reservoir influence factor A and the net-to-gross ratio of the well-revealed reservoir, achieving a correlation coefficient of 0.9 or higher.

[0011] Furthermore, S5 includes the following steps: S51: Through analysis of rock physics sensitive parameters, P-wave velocity and density are introduced as reservoir sensitive rock physics parameters; S52: The reservoir sensitivity factor F is calculated using the following formula (V), with units of m. 5 / (kg·s 2 ) (V); In the formula, The longitudinal wave velocity is expressed in m / s. Density, unit: kg / m³ 3 .

[0012] Furthermore, step S6 includes the following steps: S61: Perform pre-stack elastic parameter inversion to obtain a three-dimensional data volume that fuses the square of the longitudinal wave velocity and the density; S62: Introducing the reservoir comprehensive influence factor as a constraint, the inversion results are corrected using the following formula (VI) to obtain " - -A” Inversion fusion attribute map, (VI); In the formula, Density, unit: kg / m³ 3 ; denoted as P-wave velocity in m / s; A is the reservoir comprehensive influence factor, dimensionless; n is the constraint coefficient, dimensionless.

[0013] Furthermore, in step S7, the normalized inversion data is intersected with the net-to-gross ratio of drilled wells to establish a formula for determining the correlation between the two.

[0014] Furthermore, in S8, the net-to-gross ratio contour map of the effective reservoir of Paleozoic carbonate buried hills is calculated by normalized inversion data and the correlation formula of the net-to-gross ratio of drilled wells, so as to realize rapid quantitative prediction of carbonate reservoirs in planar plane.

[0015] The advantages and positive effects of this invention are: This invention constructs a comprehensive influence factor for carbonate reservoirs by using inversion factors and paleogeographic factors as variables. By introducing the comprehensive influence factor of the reservoir and the three parameters of P-wave velocity and density for pre-stack inversion, the three-parameter fusion attributes are obtained, and a correlation with the net-to-gross ratio of drilled wells is established. The net-to-gross ratio map is calculated, enabling rapid quantitative prediction of the planar distribution of carbonate buried hill reservoirs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall process of an embodiment of the present invention.

[0017] Figure 2 This is a diagram illustrating the structural evolution of the study area in an embodiment of the present invention.

[0018] Figure 3 This is a topographic map before inversion and a normalized map constructed according to an embodiment of the present invention.

[0019] Figure 4This is a reversed topographic map and a normalized map constructed according to an embodiment of the present invention.

[0020] Figure 5 This is the normalized construction inversion graph of the present invention.

[0021] Figure 6 This is a thickness map of the Paleozoic residual strata in the study area of ​​this invention embodiment.

[0022] Figure 7 This is a distribution diagram of reservoir comprehensive influence factors according to an embodiment of the present invention.

[0023] Figure 8 This is a reservoir sensitive parameter analysis diagram according to an embodiment of the present invention.

[0024] Figure 9 This is the attribute map obtained by parameter fusion and inversion in embodiment three of the present invention.

[0025] Figure 10 This is a graph showing the correlation between the fusion attribute and the net-to-gross ratio of drilled wells in an embodiment of the present invention.

[0026] Figure 11 This is a contour map of the reservoir net-to-gross ratio in the study area of ​​this invention embodiment. Detailed Implementation

[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0028] The embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 1 As shown, a rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs includes the following steps: S1: Identify the development pattern of carbonate buried hills. Specifically, S1 includes the following steps. S11: Taking into account paleogeography, structure, lithology and weathering time, the carbonate buried hills in the study area are determined to be either fault-block buried hills controlled by tectonics or residual hills controlled by paleogeography. S12: Determine the values ​​of the tectonic inversion factor coefficient a and the paleogeomorphological factor coefficient b in the comprehensive influence factors of the reservoir based on the buried hill development model. If it is a fault-block type buried hill, then a > b; if it is a residual hill type buried hill, then b > a, where a + b = 1.

[0029] S2: Calculate the structural inversion factor Specifically, S2 includes the following steps: S21: Paleomorphology before tectonic reversal is normalized using the following formula (Ⅰ), and paleomorphology after tectonic reversal is normalized using the following formula (Ⅱ). (I), (II) In the formula, ΔH is the difference between the maximum and minimum current structural height of the Paleozoic buried mountain top, in meters; Δh is the difference between the maximum and minimum residual thickness of the Paleozoic strata, in meters. S22: Subtract the paleogeography before and after tectonic reversal using the following formula (Ⅲ) to obtain the normalized tectonic reversal amount. (Ⅲ), In the formula, To construct the reversal factor.

[0030] S3: Calculation of paleogeographic factors Specifically, paleomorphology is obtained through the residual thickness method, which involves subtracting the bottom and top surfaces of the Paleozoic strata to obtain the residual stratum thickness, used to characterize the paleomorphology of the Paleozoic strata. This residual stratum thickness is a paleomorphological factor. .

[0031] S4: Calculate the reservoir's comprehensive impact factor A. Specifically, S4 includes the following steps. S41: The reservoir comprehensive influence factor A is calculated according to the following formula (Ⅳ). (Ⅳ); S42: Construct the correlation between the comprehensive reservoir influence factor A and the net-to-gross ratio of the well-revealed reservoir, achieving a correlation coefficient of 0.9 or higher.

[0032] S5: Calculate the reservoir sensitivity factor F. Specifically, S5 includes the following steps: S51: Through analysis of rock physics sensitive parameters, P-wave velocity and density are introduced as reservoir sensitive rock physics parameters; S52: The reservoir sensitivity factor F is calculated using the following formula (V), with units of m. 5 / (kg·s 2 ), (V); In the formula, The longitudinal wave velocity is expressed in m / s. Density, unit: kg / m³ 3 .

[0033] S6: Perform pre-stack FA inversion. Specifically, S6 includes the following steps: S61: Perform pre-stack elastic parameter inversion to obtain a three-dimensional data volume that fuses the square of the longitudinal wave velocity and the density; S62: Introducing the reservoir comprehensive influence factor as a constraint, the inversion results are corrected using the following formula (VI) to obtain " - -A” Inversion fusion attribute map, (VI); In the formula, Density, unit: kg / m³ 3 ; denoted as P-wave velocity in m / s; A is the reservoir comprehensive influence factor, dimensionless; n is the constraint coefficient, dimensionless.

[0034] S7: Establish the regression relationship between net gross ratio and fusion attribute. Specifically, use normalized inversion data and the net gross ratio of drilled wells to perform cross-interaction and establish a formula to determine the correlation between the two.

[0035] S8: The net-to-gross ratio map is calculated to enable rapid quantitative prediction of the planar distribution of carbonate buried hill reservoirs. Specifically, the net-to-gross ratio contour map of effective Paleozoic carbonate buried hill reservoirs is calculated by using the correlation formula between normalized inversion data and the net-to-gross ratio of drilled wells, thus enabling rapid quantitative prediction of carbonate reservoir planar distribution.

[0036] The present invention will be specifically described below using the determination of oilfield C in the study area as an example: S1: Identifying the development model of carbonate buried hills. Specifically, considering factors such as paleogeography, structure, lithology, and weathering time, and based on drilling data, the C oilfield in the study area was determined to be a fault-block carbonate buried hill reservoir controlled primarily by structure and co-controlled by paleogeography. This led to the determination of the tectonic reversal factor coefficient 'a' and the paleogeographic factor coefficient 'b' in the comprehensive reservoir influencing factors, with the relationship being a > b.

[0037] S2: Calculate the structural inversion factor Specifically, regional tectonic evolution reveals that the Paleozoic strata in the study area underwent tectonic inversion under the intense extensional stress of the Early Yanshanian period. The tectonic evolution model of the study area is shown in the diagram below. Figure 2 As shown.

[0038] The paleogeography before and after tectonic reversal was normalized using formulas (I) and (II). Specifically, as follows... Figure 3 As shown, the geomorphological map before inversion and the normalization process are presented, where... Figure 3 Figure (1) in the figure is a geomorphological map before tectonic reversal. Figure 3 Figure (2) in the figure is a geomorphic map before tectonic reversal after normalization. Figure 4 It is a topographic map after tectonic inversion and normalization processing, in which Figure 4Figure (1) in the figure is a landform map after tectonic reversal. Figure 4 Figure (2) in the figure is a normalized tectonic inversion topographic map. Formulas (I) and (II) are as follows: (I); (II); In the formula, ΔH is the difference between the maximum and minimum current structural height of the Paleozoic buried mountain top, in meters, and Δh is the difference between the maximum and minimum residual thickness of the Paleozoic strata, in meters.

[0039] The normalized pre-tectonic landform and the normalized post-tectonic landform are subtracted using formula (III) to obtain the normalized post-tectonic inversion amount. Figure 5 This is the normalized construction inversion quantity. Formula 3 is as follows: (III); In the formula, To construct the reversal factor.

[0040] S3: Calculation of paleogeographic factors Paleomorphology is obtained through the residual thickness method, which involves subtracting the bottom and top surfaces of the Paleozoic strata to obtain the residual strata thickness, used to characterize Paleozoic paleomorphology, such as... Figure 6 The figure shown is a thickness map of the residual Paleozoic strata in the study area.

[0041] S4: Optimize the comprehensive reservoir influencing factor A. The study area is a fault-block carbonate buried hill reservoir. Therefore, the coefficient of tectonic inversion factor a > paleogeomorphic factor b in the comprehensive reservoir influencing factor is determined.

[0042] The reservoir comprehensive influence factor A is calculated according to formula (Ⅳ). a takes a value of 0.60; b takes a value of 0.40; formula (Ⅳ) is as follows: (Ⅳ); The correlation between the reservoir comprehensive impact factor A and the net-to-gross ratio of the well revealed by drilling was constructed, achieving a correlation coefficient of 0.918. For example... Figure 7 The figure shown is a distribution map of the comprehensive influence factors of the reservoir.

[0043] S5: Calculate the reservoir sensitivity factor F. Through rock physics sensitivity parameter analysis, P-wave velocity and density are introduced as reservoir-sensitive rock physics parameters; the reservoir sensitivity factor F is calculated according to formula (V), with units of m. 5 / (kg·s 2 );like Figure 8 The figure shown is a diagram of reservoir sensitive parameters. Formula (V) is as follows. (V); In the formula, The longitudinal wave velocity is expressed in m / s. Density, unit: kg / m³ 3 .

[0044] S6: Perform FA pre-stack inversion. - Based on pre-stack inversion, a comprehensive influence factor A based on reservoir controlling factors was introduced to construct a " - The "-A" three-parameter fusion attribute is used to predict the distribution of Paleozoic vertical flow zones. For example... Figure 9 The image shown is a three-parameter fusion inversion attribute map. Formula (VI) is as follows: (VI); In the formula, Density, unit: kg / m³ 3 ; denoted as P-wave velocity in m / s; A is the reservoir comprehensive influence factor, dimensionless; n is the constraint coefficient, dimensionless.

[0045] S7: Establish a regression relationship between net hair ratio and fusion attributes. For example... Figure 10 The figure shows the correlation between the fusion attribute and the net-to-gross ratio of drilled wells. A correlation formula is established by intersecting the inversion data with the net-to-gross ratio of drilled wells.

[0046] S8: The net-to-gross ratio map is calculated, enabling rapid quantitative prediction of the planar distribution of carbonate buried hill reservoirs. For example... Figure 11 The image shows a contour map of the net-to-gross ratio of the reservoir in the study area.

[0047] In summary, this invention constructs a comprehensive reservoir influencing factor by combining tectonic inversion and paleogeomorphological factors, which are the main controlling factors for carbonate buried hill reservoir development. By introducing pre-stack inversion of this comprehensive reservoir factor and establishing a regression relationship with the net-to-gross ratio, rapid quantitative prediction of carbonate buried hill reservoirs is achieved. This method can scientifically, rationally, and effectively reflect the planar distribution characteristics of carbonate buried hill reservoirs and can serve as a basis for determining reservoir planar thickness prediction, thus realizing a quantitative characterization of the planar distribution of offshore carbonate buried hill reservoirs.

[0048] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs, characterized in that: Includes the following steps, S1: Identify the development pattern of carbonate buried hills; S2: Calculate the structural inversion factor ; S3: Calculation of paleogeographic factors ; S4: Calculate the comprehensive influence factor A of the reservoir; S5: Calculate the reservoir sensitivity factor F; S6: Conduct FA pre-stack inversion; S7: Establish the regression relationship between net gross weight ratio and fusion attribute; S8: The net-to-gross ratio map is calculated, enabling rapid quantitative prediction of the planar distribution of carbonate buried hill reservoirs.

2. The rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to claim 1, characterized in that: S1 includes the following steps: S11: Taking into account paleogeography, structure, lithology and weathering time, the carbonate buried hills in the study area are determined to be either fault-block buried hills controlled by tectonics or residual hills controlled by paleogeography. S12: Determine the coefficient values ​​of tectonic inversion factor a and paleogeomorphological factor b in the comprehensive reservoir influencing factors based on the buried hill development model.

3. The rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to claim 2, characterized in that: In S12, if it is a fault-block buried hill, then a > b; if it is a residual hill buried hill, then b > a, where a + b = 1.

4. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to any one of claims 1 to 3, characterized in that: S2 includes the following steps: S21: Paleomorphology before tectonic reversal is normalized using the following formula (Ⅰ), and paleomorphology after tectonic reversal is normalized using the following formula (Ⅱ). （Ⅰ）， （Ⅱ）， In the formula, ΔH is the difference between the maximum and minimum current structural height of the Paleozoic buried mountain top, in meters; Δh is the difference between the maximum and minimum residual thickness of the Paleozoic strata, in meters. S22: Subtract the paleogeography before and after tectonic reversal using the following formula (Ⅲ) to obtain the normalized tectonic reversal amount. （Ⅲ）， In the formula, To construct the reversal factor.

5. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to any one of claims 1 to 3, characterized in that: In S3, the paleomorphology is obtained through the residual thickness method, that is, the residual stratum thickness of the Paleozoic strata is obtained by subtracting the bottom and top surfaces of the Paleozoic strata, which is used to characterize the paleomorphology of the Paleozoic strata. The residual stratum thickness is a paleomorphological factor. .

6. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to any one of claims 1 to 3, characterized in that: S4 includes the following steps: S41: The reservoir comprehensive influence factor A is calculated according to the following formula (Ⅳ). （Ⅳ）； S42: Construct the correlation between the comprehensive reservoir influence factor A and the net-to-gross ratio of the well-revealed reservoir, achieving a correlation coefficient of 0.9 or higher.

7. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to any one of claims 1 to 3, characterized in that: S5 includes the following steps: S51: Through analysis of rock physics sensitive parameters, P-wave velocity and density are introduced as reservoir sensitive rock physics parameters; S52: The reservoir sensitivity factor F is calculated using the following formula (V), with units of m. 5 / (kg·s 2 ) （Ⅴ）； In the formula, The longitudinal wave velocity is expressed in m / s. Density, unit: kg / m³ 3 .

8. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to any one of claims 1 to 3, characterized in that: S6 includes the following steps: S61: Perform pre-stack elastic parameter inversion to obtain a three-dimensional data volume that fuses the square of the longitudinal wave velocity and the density; S62: Introducing the aforementioned reservoir comprehensive influence factor as a constraint, the inversion results are corrected using the following formula (VI) to obtain " - -A” Inversion fusion attribute map, （Ⅵ）； In the formula, Density, unit: kg / m³ 3 ; denoted as P-wave velocity in m / s; A is the reservoir comprehensive influence factor, dimensionless; n is the constraint coefficient, dimensionless.

9. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to any one of claims 1 to 3, characterized in that: In step S7, the normalized inversion data is intersected with the net-to-gross ratio of drilled wells to establish a formula for determining the correlation between the two.

10. A rapid quantitative prediction method for the planar distribution of marine carbonate buried hill reservoirs according to any one of claims 1 to 3, characterized in that: In S8, the net-to-gross ratio contour map of the effective reservoir of Paleozoic carbonate buried hills is calculated by normalized inversion data and the correlation formula of the net-to-gross ratio of drilled wells, so as to realize rapid quantitative prediction of carbonate reservoirs in planar plane.

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