Shale gas tectonic geologic model correction method based on well track and layered data

Abstract

The invention discloses a shale gas structure geologic model correction method based on a well track and layered data. The method comprises the following steps: constructing a stratum thickness model; obtaining small-layer apparent thickness plane data; establishing a penetrating mode of the well track in each small layer; calculating the specific space position of the interface of each small layer according to the established penetrating mode of the well track in each small layer and the apparent thickness plane data of each small layer; judging whether a spatial position result is continuous and smooth or not according to the calculated spatial position result of the small-layer interface; and when the spatial position result is not smooth, adjusting the thickness data of the small-layer apparent thickness plane data and the depth data of the specific spatial position of each small-layer interface. According to the geologic model correction method, related information of the horizontal well can be well utilized to carry out rapid and efficient batch well data processing, so that the seismic horizon is corrected, the structural model can be well matched with the spatial position relation of horizontal well passing, and a reliable data basis is provided for next attribute modeling and numerical simulation.

Description

Technical Field

[0001] The present invention relates to the field of shale gas development, and in particular to a shale gas structural geological model correction method based on wellbore trajectory and layering data. Background Art

[0002] Currently, research on structural geological modeling technology is primarily focused on conventional oil and gas reservoirs such as clastic rocks and carbonates, while shale gas reservoirs are still in their infancy, and related modeling methods still rely on conventional oil and gas reservoir modeling concepts and methods. Shale gas reservoirs are generally developed using horizontal wells, making it difficult to utilize horizontal well information in structural geological modeling. Conventional seismic horizon calibration methods, which rely on vertical wells, are not highly applicable to horizontal wells and, in most cases, require manual adjustments. Therefore, there is an urgent need to develop a calibration method that can fully utilize horizontal well data for fast and efficient batch processing. Summary of the Invention

[0003] The main purpose of the present invention is to provide a shale gas structural geological model correction method based on wellbore trajectory and layered data, aiming to accurately create a high-precision structural geological model that fully matches the horizontal well penetration of the entire area.

[0004] To achieve the above objectives, the present invention provides a shale gas structure geological model correction method based on wellbore trajectory and layer data, comprising the following steps: Construct a formation thickness model based on horizontal well layer data and seismic layer data; The scattered point data of the apparent thickness of the small layer is obtained according to the stratum thickness model, and the scattered point interpolation is constrained by combining the distribution of the seismic response plane characteristics to obtain the plane data of the apparent thickness of the small layer; According to the wellbore trajectory and horizontal well layer data, the wellbore trajectory through each layer is established and simplified into a geometric function relationship; By establishing the wellbore trajectory through each layer and combining it with the apparent thickness plane data of the layer, the specific spatial position of each layer interface is calculated; According to the calculated spatial position results of the small layer interface, determine whether the spatial position results are continuous and smooth; When the spatial position results are not smooth, adjust the thickness data of the small layer apparent thickness plane data and the depth data of the specific spatial position of each small layer interface.

[0005] Preferably, after the step of judging whether the calculated spatial position result of the small layer interface is continuous and smooth, the method further comprises: When the spatial position results are smooth, the small layer results that meet the requirements are output to correct the seismic horizons to improve a reasonable and reliable structural model.

[0006] Preferably, in the step of constructing a formation thickness model based on horizontal well stratification data and seismic layer data, when the lateral change in formation thickness is greater than a preset change rate, equal thickness treatment of small layers is adopted; when the lateral change in formation thickness is greater than a preset change rate, the horizontal well inclined well formation penetration mode is used to estimate the apparent thickness of each small layer through stratification data and wellbore trajectory.

[0007] Preferably, the apparent thickness of each layer is estimated using the following formula based on the layered data and the wellbore trajectory: ; Where, It is the altitude difference between the intersection of the top and bottom interfaces of the formation and the wellbore trajectory; is the stratigraphic dip between stratification points; is the bathymetric difference between stratification points; is the apparent thickness of the formation at the stratification point. When the plus sign is taken, the direction of the wellbore trajectory is the same as the formation dip; when the minus sign is taken, the direction of the wellbore trajectory is opposite to the formation dip.

[0008] Preferably, in the step of establishing the wellbore trajectory's travel pattern in each sub-layer based on the wellbore trajectory and horizontal well stratification data, and simplifying it into a geometric function relationship, when judging the contact relationship between the front and rear strata of the current formation, if the front and rear strata are the same, it means that the wellbore trajectory does not penetrate the current formation, and is a travel pattern that penetrates out and then returns to the original formation; if the front and rear strata are different, it means that the wellbore trajectory penetrates the current formation, and is a penetrating travel pattern.

[0009] Preferably, the travel pattern of the established wellbore trajectory in each small layer includes two wellbore trajectory travel patterns: the A and B layer points corresponding to the formation contact different formations; and the A and B layer points corresponding to the formation contact the same formation.

[0010] Preferably, when the A and B layer points corresponding to the stratum contact different strata, The specific position of the well trajectory in the layer is calculated using the following formula: ;in, , ; In the above formula, is the vertical distance from the wellbore position to the top or bottom of the formation; is the formation thickness; 、 、 They are the depth measurements corresponding to the wellbore trajectory point and the layer point A and layer point B respectively; when the strata contacted by points A and B are from new to old, they represent the distance from the bottom of the stratum; otherwise, they represent the distance from the top of the stratum.

[0011] Preferably, when the A and B layer points corresponding to the stratum contact the same stratum, The specific position of the well trajectory in the layer is calculated using the following formula: ;in, , ; When the strata contacted by points A and B are from new to old, it represents the distance from the bottom of the stratum; otherwise, it represents the distance from the top of the stratum.

[0012] Preferably, the following formula is used to calculate the altitude depth of each sub-layer interface based on the specific position of the well trajectory in the sub-layer: ; Where, is the altitude depth of a small layer corresponding to the measuring point, is the altitude depth of the measuring point, It is the thickness from the stratum where the measuring point is located to a certain sublayer.

[0013] Preferably, after the calculated spatial position result of the sub-layer interface is obtained, the sub-layer altitude depth corresponding to all the measuring points of the horizontal well is smoothed to control the spatial position result of the sub-layer interface within a preset range.

[0014] The shale gas structural geological model correction method based on wellbore trajectory and layered data proposed in the present invention can make good use of horizontal well related information to perform fast and efficient batch well data processing, thereby correcting seismic horizons, so that the structural model can well match the spatial position relationship of the horizontal wells, providing a reliable data basis for the next step of attribute modeling and numerical simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the flow of the shale gas structure geological model correction method based on wellbore trajectory and layered data of the present invention; Figure 2 This is a stratum thickness model diagram for the shale gas structural geological model correction method based on wellbore trajectory and layered data of the present invention when the stratum dip is the same as the drilling direction in the inclined well section; Figure 3 This is a stratum thickness model diagram for the shale gas structural geological model correction method based on wellbore trajectory and layered data of the present invention when the stratum dip is opposite to the drilling direction in the inclined well section; Figure 4 A diagram showing the formation penetration pattern of the horizontal well trajectory in the formation penetration mode in the shale gas structure geological model correction method based on the wellbore trajectory and layered data of the present invention; Figure 5This is a formation penetration pattern diagram of the horizontal well trajectory in the shale gas structure geological model correction method based on wellbore trajectory and layered data of the present invention when the horizontal well trajectory does not penetrate the formation mode.

[0016] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0017] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] In this preferred embodiment, referring to Figure 1 A shale gas structure geological model correction method based on wellbore trajectory and layering data includes the following steps: Step S1, constructing a formation thickness model based on horizontal well layer data and seismic layer data; Step S2, obtaining scattered point data of apparent thickness of small layers according to the stratum thickness model, and obtaining plane data of apparent thickness of small layers by constraining scattered point interpolation in combination with the characteristic distribution of seismic response plane; Step S3: Based on the wellbore trajectory and horizontal well layer data, the wellbore trajectory travel pattern in each layer is established and simplified into a geometric function relationship (such as Figure 2 and Figure 3 shown); Step S4, calculating the specific spatial position of each sub-layer interface by combining the established wellbore trajectory through each sub-layer with the sub-layer apparent thickness plane data; Step S5, judging whether the spatial position result is continuous and smooth based on the calculated spatial position result of the small layer interface; if the spatial position result is not smooth, executing step S6 and returning to executing step S5 until the spatial position result is continuous and smooth; Step S6, adjusting the thickness data of the small layer apparent thickness plane data and the depth data of the specific spatial position of each small layer interface.

[0019] After step S5, the following steps are also included: When the spatial position result is not smooth, execute step S7; Step S7: Output the sub-layer results that meet the requirements to correct the seismic horizons to improve a reasonable and reliable structural model.

[0020] In the updated structural model, the wellbore data and seismic horizons are completely consistent.

[0021] In step S1, when the lateral change of the formation thickness is greater than the preset change rate, the small layer equal thickness treatment is adopted; when the lateral change of the formation thickness is greater than the preset change rate, the horizontal well and inclined well formation penetration mode are used to estimate the apparent thickness of each small layer through the layered data and wellbore trajectory.

[0022] Specifically, the apparent thickness of each layer is estimated using the following formula based on the layered data and wellbore trajectory: ; (1) Where, It is the altitude difference between the intersection of the top and bottom interfaces of the formation and the wellbore trajectory; is the stratigraphic dip between stratification points; is the bathymetric difference between stratification points; is the apparent thickness of the formation at the delamination point, where the plus sign indicates that the wellbore trajectory direction is the same as the formation dip (e.g. Figure 2 As shown in the formula, when the minus sign is taken, the direction of the wellbore trajectory is opposite to the formation dip (such as Figure 3 shown).

[0023] In step S2, conventional seismic response characteristics usually reflect the impedance difference between the upper and lower layers of the stratum interface, which is difficult to establish a direct connection with the stratum thickness. Currently, it can only be controlled by manually adding control points.

[0024] In step S3, when determining the contact relationship between the front and rear strata of the current stratum, if the front and rear strata are the same, it means that the wellbore trajectory does not penetrate the current stratum and is a penetration mode that penetrates out and then penetrates back to the original stratum (e.g. Figure 5 If the previous and next formations are different, it means that the wellbore trajectory penetrates the current formation, which is a penetrating penetration mode (such as Figure 4 shown).

[0025] In order to facilitate the judgment of the Boolean values ​​0 and 1 in the calculation program, when the strata above and below the stratum are the same, the stratum can be defined as 0, otherwise it can be defined as 1.

[0026] In step S4, the established wellbore trajectory travel patterns in each sub-layer include two wellbore trajectory travel patterns: one in which the A and B layer points corresponding to the formation contact different formations; and the other in which the A and B layer points corresponding to the formation contact the same formation.

[0027] Specifically, when the contact strata of the A and B strata corresponding to the strata are different, The specific position of the well trajectory in the layer is calculated using the following formula: ;in, , ; (2) In the above formula, It is the vertical distance from the wellbore position to the top or bottom of the formation; is the formation thickness; 、 、 are the measured depths corresponding to the wellbore trajectory point and the layer point A and layer point B, respectively. In formula (2), when the strata contacted by points A and B are from new to old, represents the distance from the bottom of the stratum; otherwise, represents the distance from the top of the stratum.

[0028] When the contact strata of the A and B layer points corresponding to the stratum are the same, The specific position of the well trajectory in the layer is calculated using the following formula: ;in, , ; (3) In formula (3), when the strata contacted by points A and B are from new to old, it represents the distance from the bottom of the stratum; otherwise, it represents the distance from the top of the stratum.

[0029] The following formula is used to calculate the elevation depth of each sub-layer interface based on the specific location of the well trajectory in the sub-layer: ; Where, is the altitude depth of a small layer corresponding to the measuring point, is the altitude depth of the measuring point, It is the thickness from the stratum where the measuring point is located to a certain sublayer.

[0030] In step S4, the spatial position of each measuring point (wellbore trajectory) in the formation is calculated based on the well's different traversal patterns in each formation. The apparent thickness of each sub-layer corresponding to each measuring point's coordinates is then read, thereby calculating the elevation depth corresponding to each sub-layer interface at each measuring point. The ratio of the elevation depth to the measured depth for each adjacent point in a sub-layer within the well is calculated (derivative of elevation with respect to measured depth). If the slope value is within the allowable range, it is not modified. If it does not meet the requirements, the slopes of the preceding and following points are checked for consistency (second-order derivative of elevation with respect to measured depth). If they do not meet the requirements and exceed the allowable range, the elevation value is iteratively adjusted until the requirements are met. The thickness of each sub-layer corresponding to that point is then recalculated using the adjusted elevation value.

[0031] In step S5, based on the calculated spatial position of the sub-layer interface, the sub-layer elevation depth corresponding to all horizontal well measurement points is smoothed to keep the spatial position of the sub-layer interface within a preset range. Smoothing involves taking the derivative and second-order derivative of the elevation depth with respect to the measured depth, and controlling the results within a certain range.

[0032] The shale gas structural geological model correction method based on wellbore trajectory and layered data proposed in the present invention can make good use of horizontal well related information to perform fast and efficient batch well data processing, thereby correcting seismic horizons, so that the structural model can well match the spatial position relationship of the horizontal wells, providing a reliable data basis for the next step of attribute modeling and numerical simulation.

[0033] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied to other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A shale gas structural geological model correction method based on wellbore trajectory and layered data, characterized in that: The following steps are involved: Construct a formation thickness model based on horizontal well layer data and seismic layer data; The scattered point data of the apparent thickness of the small layer is obtained according to the stratum thickness model, and the scattered point interpolation is constrained by combining the distribution of the seismic response plane characteristics to obtain the plane data of the apparent thickness of the small layer; According to the wellbore trajectory and horizontal well layer data, the wellbore trajectory through each layer is established and simplified into a geometric function relationship; By establishing the wellbore trajectory through each layer and combining it with the apparent thickness plane data of the layer, the specific spatial position of each layer interface is calculated; According to the calculated spatial position results of the small layer interface, determine whether the spatial position results are continuous and smooth; When the spatial position results are not smooth, adjust the thickness data of the small layer apparent thickness plane data and the depth data of the specific spatial position of each small layer interface.

2. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 1, characterized in that: After the step of judging whether the calculated spatial position result of the small layer interface is continuous and smooth, the following steps are further included: When the spatial position results are smooth, the small layer results that meet the requirements are output to correct the seismic horizons to improve a reasonable and reliable structural model.

3. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 1, characterized in that: In the step of constructing a formation thickness model based on horizontal well stratification data and seismic layer data, when the lateral change of the formation thickness is greater than a preset change rate, equal thickness treatment of the small layers is adopted; when the lateral change of the formation thickness is greater than the preset change rate, the horizontal well inclined well formation penetration mode is used to estimate the apparent thickness of each small layer through the stratification data and the wellbore trajectory.

4. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 3, characterized in that: The apparent thickness of each layer is estimated using the following formula based on the layer data and wellbore trajectory: ； Where, It is the altitude difference between the intersection of the top and bottom interfaces of the formation and the wellbore trajectory; is the stratigraphic dip between stratification points; is the bathymetric difference between stratification points; is the apparent thickness of the formation at the stratification point. When the plus sign is taken, the direction of the wellbore trajectory is the same as the formation dip; when the minus sign is taken, the direction of the wellbore trajectory is opposite to the formation dip.

5. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 1, characterized in that: In the step of establishing the wellbore trajectory's travel pattern in each sub-layer based on the wellbore trajectory and horizontal well stratification data and simplifying it into a geometric function relationship, when judging the contact relationship between the front and rear strata of the current formation, if the front and rear strata are the same, it means that the wellbore trajectory does not penetrate the current formation, and is a travel pattern that penetrates out and then penetrates back to the original formation; if the front and rear strata are different, it means that the wellbore trajectory penetrates the current formation, and is a penetrating travel pattern.

6. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 1, characterized in that: The established wellbore trajectory travel patterns in each sub-layer include two wellbore trajectory travel patterns: one in which the A and B layer points corresponding to the formation contact different formations; and the other in which the A and B layer points corresponding to the formation contact the same formation.

7. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 6, characterized in that: When the contact strata of the A and B layer points corresponding to the stratum are different, The specific position of the well trajectory in the layer is calculated using the following formula: ;in, , ; In the above formula, is the vertical distance from the wellbore position to the top or bottom of the formation; is the formation thickness; 、 、 They are the depth measurements corresponding to the wellbore trajectory point and the layer point A and layer point B respectively; when the strata contacted by points A and B are from new to old, they represent the distance from the bottom of the stratum; otherwise, they represent the distance from the top of the stratum.

8. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 7, characterized in that: When the contact strata of the A and B layer points corresponding to the stratum are the same, The specific position of the well trajectory in the layer is calculated using the following formula: ;in, , ; When the strata contacted by points A and B are from new to old, it represents the distance from the bottom of the stratum; otherwise, it represents the distance from the top of the stratum.

9. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to claim 8, characterized in that: The following formula is used to calculate the elevation depth of each sub-layer interface based on the specific location of the well trajectory in the sub-layer: ； Where, is the altitude depth of a small layer corresponding to the measuring point, is the altitude depth of the measuring point, It is the thickness from the stratum where the measuring point is located to a certain sublayer.

10. The shale gas structure geological model correction method based on wellbore trajectory and layered data according to any one of claims 1 to 9, characterized in that: According to the calculated results of the spatial position of the small layer interface, the small layer altitude depth corresponding to all the measuring points of the horizontal well is smoothed to control the spatial position results of the small layer interface within the preset range.

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