A method for establishing a high-precision stratigraphic model profile by combining well and seismic data

Abstract

This invention belongs to the field of oil and gas reservoir development technology, specifically disclosing a method for establishing a high-precision stratigraphic model profile through well-seismic integration. The method comprises the following steps: S1, establishing an initial geological model; S2, calculating the stratigraphic lines of geological sub-layers; and S3, generating a new geological model. Based on seismic data and drilled vertical wells, this invention provides a high-precision stratigraphic model for horizontal wells to be drilled. It is suitable for complex models of single wells, multiple wells, and multiple stratigraphic layers, providing a basis for seismic geological guidance work during horizontal well drilling, improving the drilling rate of reservoir "boxes," and reducing drilling engineering risks.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas reservoir development technology, and relates to a method for establishing a high-precision formation model profile by combining well and seismic testing. Background Technology

[0002] In recent years, unconventional exploration has become a hot topic in oil and gas exploration, such as the exploration of shale oil, shale gas, tight sandstone, and coalbed methane. Unconventional reservoirs are characterized by low porosity and low permeability, and the oil and gas they contain are almost non-flowing. It is necessary to drill as many reservoirs as possible through horizontal well drilling, and then stimulate the reservoirs to extract oil and gas. This is a very difficult engineering process, so geological steering technology during drilling has emerged.

[0003] For example, existing technologies, such as the Starsteer geosteering software simulation modeling, mainly focus on establishing and adjusting the stratigraphic model of the horizontal section of the target layer. However, the stratigraphic models in these geosteering technologies are all based on a single vertical well as a reference well, a single seismic horizon as the structural basis, or no seismic horizon data. The premise is that the target layer is laterally stable and unchanging. The established model does not match the actual geological conditions well, which can lead to many inconveniences or unpredictable situations in subsequent exploration operations.

[0004] In actual production, there is an urgent need for a model that fully integrates seismic information with geological information such as drilling data to establish a model that more closely matches the complex geological conditions underground. Summary of the Invention

[0005] The purpose of this invention is to provide a method for establishing a high-precision formation model profile by combining well and seismic drilling, so as to improve the drilling encounter rate of reservoir "boxes" and reduce drilling engineering risks.

[0006] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0007] A method for establishing a high-precision formation model profile by combining well and seismic analysis, comprising the following steps in sequence:

[0008] S1. Establishing the initial geological model

[0009] An initial geological model was generated using interpreted faults and corrected interpreted horizons.

[0010] The corrected interpretation horizon refers to the depth domain horizon corrected by well-level stratification.

[0011] S2, Calculate the stratigraphic lines of geological sublayers

[0012] Each geological block in the initial geological model is divided into high-precision geological layers according to proportions to obtain the layer lines;

[0013] S3, Generate a new geological model

[0014] New geological models are generated by layering lines and interpreting faults.

[0015] As a limitation, step S1 is performed in the following order:

[0016] S11. Perform the following two operations.

[0017] a. On the seismic profile, the characteristics of the same phase axis are used to interpret the horizon and fault, and the interpreted horizon and interpreted fault are obtained.

[0018] b. Select reference wells and wells for which geological models need to be built;

[0019] S12. Determine the correspondence between the interpretation stratigraphic position and the well stratigraphic layer;

[0020] In this process, the marker layers are first determined; for well layers other than the marker layers, their respective positions between two interpretation layers are calculated according to their depth relationships.

[0021] Among them, marker stratification refers to well stratification that belongs to the same set of strata as a certain set of interpretation strata;

[0022] S13. Use the marker layer to fit the interpretation layer so that each interpretation layer intersects with the corresponding well layer, and obtain the fitted interpretation layer, that is, the corrected interpretation layer;

[0023] S14. Generate an initial geological model using the interpreted faults and corrected interpreted horizons.

[0024] As a further limitation, step S13 is performed in the following order:

[0025] S131. Interpolate and extend the interpretation layer;

[0026] S132. Obtain the intersection of the reference well trajectory and the interpretation layer, and calculate the distance between the intersection and the marker layer corresponding to the interpretation layer;

[0027] S133. Using stratification of markers to perform trend fitting on explanatory strata.

[0028] In this process, the longitudinal offset of each trace on the interpretation layer is calculated using the distance linear interpolation obtained in step S132, and the fitted interpretation layer is obtained.

[0029] The depth coordinates of the intersection points between two adjacent reference wells and the interpretation layer are y and y, respectively. n1 y h2 The depth coordinates of the well layers corresponding to the stratigraphic positions are y and y respectively. t1 y t2 The number of traces between two adjacent reference wells is x. 12The number of traces from the calculation point to the left reference well is x. i Then the offset Δy at that point i for

[0030]

[0031] If there is only one reference well and only one corresponding interpretation horizon, it is equivalent to a translation of the interpretation horizon.

[0032] Δy i =(y h -y t ) ②

[0033] The depth coordinate of the intersection point between the reference well and the interpretation layer is y. h The depth coordinates of the well layers corresponding to the stratigraphic positions are y. t .

[0034] As a limitation on step S2, step S2 is performed in the following order:

[0035] S21. Obtain each geological block of the initial geological model;

[0036] S22. Based on the correspondence between the interpretation horizons and well layers determined in step S12, determine which well layers each geological block spans.

[0037] S23. Perform the following two operations.

[0038] c. For each geological block that spans well layers, calculate the proportion of these well layers between the upper and lower marker layers to obtain the layer ratio.

[0039] Among them, well layer T is marked by two layers T above and below. up and T Bottom The ratio between is

[0040]

[0041] Where y is the depth value of well layer T, y up The upper marker layer T is the closest to the well layer. up The depth value, y Bottom The lower marker layer T closest to the well strata Bottom The depth value;

[0042] d. Calculate the top and bottom interfaces of each geological block in the initial geological model, and extend the top and bottom interfaces;

[0043] S24. Combining the stratification ratio and the top and bottom interfaces, calculate the stratification line corresponding to each geological block according to Equation ④. This stratification line is an extended stratification line.

[0044]

[0045] Where (x, y) are the coordinates of a point on the stratification line, x1 is the position of the reference well to the left of the point, x2 is the position of the reference well to the right of the point, r1 is the stratification ratio of the well to the left of the point, r2 is the stratification ratio of the well to the right of the point, y1 is the depth value of the upper boundary of the geological block at the point, and y2 is the depth value of the lower boundary of the geological block at the point.

[0046] If a point on the stratification line is located to the left of the leftmost reference well, then the proportion of the nearest reference well is used. In this case, formula ④ becomes the following expression.

[0047] y = r1*(y2-y1) + y1 ⑤

[0048] If a point on the stratification line is located to the right of the rightmost reference well, then the proportion of the nearest reference well is used. In this case, formula ④ becomes the following expression.

[0049] y = r2*(y2-y1)+y1 ⑥

[0050] S25. Use geological blocks to cut extended stratification lines, ensuring that the stratification lines are within the geological blocks;

[0051] Repeat steps S23-S25 until the complete stratigraphic lines corresponding to all the well stratigraphic layers selected in step S12 that require the establishment of geological models are obtained.

[0052] The present invention, by adopting the above-described technical solution, achieves the following technical advancements compared to existing technologies:

[0053] (1) Based on seismic data and drilled vertical wells, this invention provides a high-precision formation model for a horizontal well to be drilled, which more realistically reflects the underground structure and is suitable for complex models of single wells, multiple wells and multiple sets of formations. It can provide a basis for seismic geological guidance work in horizontal well drilling, improve the drilling rate of reservoir "boxes", reduce drilling engineering risks, and ultimately achieve the goal of improving single well productivity.

[0054] (2) The method provided by the present invention can be applied in computer software to predict the actual geological conditions of the section to be drilled, so as to adjust the drilling trajectory in real time.

[0055] (3) This invention uses the corrected interpretation horizons and faults to generate an initial geological model that can reflect a large set of strata with earthquake accuracy;

[0056] (4) This invention generates new geological models by using stratification lines and faults, which can help with drilling decisions for horizontal wells in the target strata.

[0057] This invention belongs to the field of oil and gas reservoir development technology and can improve the drilling rate of reservoir "boxes" and increase the productivity of single wells. Attached Figure Description

[0058] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0059] In the attached diagram:

[0060] Figure 1 This is a flowchart of an embodiment of the present invention;

[0061] Figure 2 This is a schematic diagram illustrating the process of establishing a high-precision formation model profile using a combination of well and seismic testing in an embodiment of the present invention.

[0062] in, Figure 2 (a) Schematic diagram of the interpreted stratigraphic level and interpreted fault obtained in the embodiments of the present invention;

[0063] Figure 2 (b) is a schematic diagram of stratigraphic fitting using marker wells in an embodiment of the present invention;

[0064] Figure 2 (c) is a schematic diagram of generating an initial geological model using the corrected interpretable horizons and interpretable faults in an embodiment of the present invention;

[0065] Figure 2 (d) is a schematic diagram of the top and bottom interfaces of the initial geological model block calculated according to an embodiment of the present invention, and the top and bottom interfaces are extended;

[0066] Figure 2 (e) is a schematic diagram of the layering lines of a geological block calculated according to an embodiment of the present invention;

[0067] Figure 2 (f) is a schematic diagram of the layering line extended by cutting geological blocks in an embodiment of the present invention;

[0068] Figure 2 (g) is a schematic diagram of the complete layer lines obtained by performing operations (d)-(f) on each block in an embodiment of the present invention;

[0069] Figure 2 (h) is a schematic diagram of generating a new geological model using layered lines and interpreting faults in an embodiment of the present invention. Detailed Implementation

[0070] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0071] Example 1: A method for establishing a high-precision formation model profile using a combination of well and seismic testing

[0072] like Figure 1 As shown, this embodiment includes the following steps performed sequentially:

[0073] S1. Establish an initial geological model;

[0074] S2. Calculate the stratigraphic lines of geological sublayers;

[0075] S3. Generate a new geological model.

[0076] In step S1, an initial geological model is generated using the interpreted faults and corrected interpreted horizons;

[0077] Among them, the corrected interpretation horizon refers to the depth domain horizon corrected by well layering;

[0078] Specifically, in combination Figure 1 As shown, step S1 is performed in the following order:

[0079] S11. Perform the following two operations.

[0080] a. On seismic profiles, the characteristics of phase axes are used to interpret horizons and faults, resulting in interpreted horizons and faults, such as... Figure 2 As shown in (a), the interpreted horizons obtained in this embodiment are H1 and H2, and the interpreted fault is F1;

[0081] b. Select reference wells and wells for which geological models need to be built;

[0082] In this embodiment, the two reference wellheads are Well1 and Well2. The well layers that need to be established for the geological model are the five well layers Top1, Top2, Top3, Top4 and Top5 included in Well1, and the five well layers Top1, Top2, Top3, Top4 and Top5 included in Well2.

[0083] S12. Determine the correspondence between the interpretation stratigraphic position and the well stratigraphic layer;

[0084] In this process, the marker layers are first determined; for well layers other than the marker layers, their respective positions between two interpretation layers are calculated according to their depth relationships.

[0085] Among them, marker stratification refers to well stratification that belongs to the same set of strata as a certain set of interpretation strata;

[0086] In this embodiment, the marker layers are Top1 and Top5 of Well1 and Top1 and Top5 of Well2, where the two Top1 correspond to the interpretation layer H1, the two Top5 correspond to the interpretation layer H2, and the remaining two Top2, two Top3 and two Top4 are located between the two interpretation layers H1 and H2.

[0087] S13. Fit the interpretation horizons using marker stratification, ensuring that each interpretation horizon intersects with its corresponding well stratification, to obtain the fitted interpretation horizons, i.e., the corrected interpretation horizons, such as... Figure 2 (b) After fitting, H1 shifts significantly downwards and achieves a good fit with the two Top1 values;

[0088] S14, such as Figure 2 (c) An initial geological model is generated using the interpreted faults and corrected interpreted horizons.

[0089] In the above process, step S13 is performed in the following order:

[0090] S131. Interpolate and extend the interpretation layers H1 and H2;

[0091] Because the interpretable horizons are discontinuous in the cross section, interpolation of the interpretable horizons is required;

[0092] S132. Obtain the intersection of the reference well trajectory and the interpretation layer, and calculate the distance between the intersection and the marker layer corresponding to the interpretation layer;

[0093] S133. Using stratification of markers to perform trend fitting on explanatory strata.

[0094] The top 1 and top 5 marker layers corresponding to the two reference wells Well1 and Well2 are used to fit the interpretation horizons H1 and H2 respectively, so that the intersection of interpretation horizon H1 and reference well Well1 is the top 1 of Well1, the intersection of interpretation horizon H1 and reference well Well2 is the top 1 of Well2, the intersection of interpretation horizon H2 and reference well Well1 is the top 5 of Well1, and the intersection of interpretation horizon H2 and reference well Well2 is the top 5 of Well2.

[0095] In this process, the longitudinal offset of each trace on the interpretation layer is calculated using the distance linear interpolation obtained in step S132, and the fitted interpretation layer is obtained.

[0096] The depth coordinates of the intersection points between two adjacent reference wells and the interpretation layer are y and y, respectively. h1 y h2 The depth coordinates of the well layers corresponding to the stratigraphic positions are y and y respectively. t1 y t2 The number of traces between two adjacent reference wells is x. 12The number of traces from the point to the left reference well Well1 is calculated as x. i Then the offset Δy at that point i for

[0097]

[0098] If there is only one reference well and only one corresponding interpretation horizon, it is equivalent to a translation of the interpretation horizon.

[0099] Δy i =(y h -y t ) ②

[0100] The depth coordinate of the intersection point between the reference well and the interpretation layer is y. h The depth coordinates of the well layers corresponding to the stratigraphic positions are y. t .

[0101] In step S2, each geological block of the initial geological model is divided into high-precision geological layers according to the proportions to obtain the layer lines.

[0102] Combination Figure 1 As shown, step S2 is performed in the following order:

[0103] S21. Obtain each geological block of the initial geological model;

[0104] S22. Based on the correspondence between the interpretation strata and well strata determined in step S12, determine which well strata each geological block crosses. The upper and lower boundaries of the geological block are part of the interpretation strata. By the correspondence between the marker strata and the interpretation strata, as well as the well strata depth, it can be concluded that in this embodiment, each geological block crosses the Top2, Top3 and Top4 strata.

[0105] S23. Perform the following two operations.

[0106] c. For each geological block that spans well layers, calculate the proportion of these well layers between the upper and lower marker layers to obtain the layer ratio.

[0107] Among them, well layer T is marked by two layers T above and below. up and T Bottom The ratio between is

[0108]

[0109] Where y is the depth value of well layer T, y up The upper marker layer T is the closest to the well layer. up The depth value, y Bottom The lower marker layer T closest to the well strata BottomThe depth value;

[0110] In this embodiment, the two markers are layered T up and T Bottom They are the Top 1 and Top 5 respectively; therefore, equation ③ can be expressed as Where y is the depth value of well layer T, y H1 y represents the depth value of Top1, the upper marker layer closest to the well strata. H5 This represents the depth of the Top 5 lower marker layers closest to the well stratum.

[0111] d. For example Figure 2 (d) Calculate the top and bottom interfaces of each geological block in the initial geological model and extend the top and bottom interfaces;

[0112] S24, such as Figure 2 (e) Combining the layering ratio and the top and bottom interfaces, calculate the layering line corresponding to each geological block according to Equation ④. At this time, the layering line is also an extended layering line.

[0113]

[0114] Where (x, y) are the coordinates of a point on the stratification line, x1 is the position of the reference well to the left of the point, x2 is the position of the reference well to the right of the point, r1 is the stratification ratio of the well to the left of the point, r2 is the stratification ratio of the well to the right of the point, y1 is the depth value of the upper boundary of the geological block at the point, and y2 is the depth value of the lower boundary of the geological block at the point.

[0115] In this embodiment, the left reference well is Well1 and the right reference well is Well2. In practice, the left reference well and the right reference well are the reference wells on both sides of the layer line in the cross-sectional view that are closest to the layer line.

[0116] If a point on the stratification line is located to the left of the leftmost reference well or to the right of the rightmost reference well, then the proportion of the nearest reference well is used; for example, in some cases, if a point on the stratification line is to the left of Well1, then the proportion of Well1 is used, and equation ④ becomes

[0117] y = r1*(y2-y1) + y1

[0118] For example, in some cases, if a point on the layer line is located to the right of Well2, then the proportion of Well2 is used, and equation ④ becomes...

[0119] y = r2*(y2-y1)+y1

[0120] S25, such as Figure 2 (f) Use geological blocks to cut extended stratification lines to ensure that the stratification lines are within the geological blocks;

[0121] like Figure 2 (g) Repeat steps S24-S26 to perform the following for each geological block: Figure 2 (d)- Figure 2 (f) continues until the complete stratigraphic lines corresponding to all the well stratigraphic layers selected in step S12 that require the establishment of geological models are obtained.

[0122] like Figure 2 (h), in the final step S3, a new geological model is generated by using layered lines and interpreting faults;

[0123] This new geological model incorporates seismic and well stratification information, making it a high-precision geological model combining well and seismic data. Seismic data can provide real-time drilled analysis and pre-drilling predictions for horizontal well drilling projects, guiding the smooth implementation of the drilling trajectory. It comprehensively and systematically supports static geological evaluation and dynamic engineering implementation, acting as a bridge between geology and engineering to guide horizontal well drilling.

Claims

1. A method for establishing a high-precision stratigraphic model profile by combining well and seismic analysis, characterized in that, Follow these steps in sequence: S1. Establishing the initial geological model An initial geological model was generated using interpreted faults and corrected interpreted horizons. The corrected interpretation horizon refers to the depth domain horizon corrected by well-level stratification. S2, Calculate the stratigraphic lines of geological sublayers Each geological block in the initial geological model is divided into high-precision geological layers according to proportions to obtain the layer lines; S3, Generate a new geological model New geological models are generated by layering lines and interpreting faults; Step S1 also includes determining the correspondence between the interpreted stratigraphic position and the well stratigraphic layer; Step S2 is performed in the following order: S21. Obtain each geological block of the initial geological model; S22. Based on the established correspondence between the interpretation stratigraphic positions and well strata, determine which well strata each geological block spans; S23. Perform the following two operations. c. For each geological block that spans well layers, calculate the proportion of these well layers between the upper and lower marker layers to obtain the layer ratio. Among them, well layer T is marked by two layers above and below. and The ratio between is ③ Where y is the depth value of well layer T. The upper marker stratum closest to this well stratum. The depth value, The lower marker layer closest to the well strata The depth value; d. Calculate the top and bottom interfaces of each geological block in the initial geological model, and extend the top and bottom interfaces; S24. Combining the stratification ratio and the top and bottom interfaces, calculate the stratification line corresponding to each geological block according to Equation ④. This stratification line is an extended stratification line. ④ Where (x, y) are the coordinates of a point on the layer line. This is the reference well location to the left of this point. This is the reference well location to the right of this point. The stratification ratio of the well to the left of this point. The stratification ratio of the well to the right of this point. This represents the depth value of the upper boundary of the geological block at that point. This represents the depth of the lower boundary of the geological block at that point. If a point on the stratification line is located to the left of the leftmost reference well, then the proportion of the nearest reference well is used. In this case, formula ④ becomes the following expression. ⑤ If a point on the stratification line is located to the right of the rightmost reference well, then the proportion of the nearest reference well is used. In this case, formula ④ becomes the following expression. ⑥ S25. Use geological blocks to cut extended stratification lines, ensuring that the stratification lines are within the geological blocks; Repeat steps S23-S25 until you obtain the complete stratigraphic lines corresponding to all the selected well stratigraphic layers for which geological models need to be built.

2. The method for establishing a high-precision formation model profile by combining well and seismic analysis according to claim 1, characterized in that, Step S1 is performed in the following order: S11. Perform the following two operations. a. On the seismic profile, the characteristics of the same phase axis are used to interpret the horizon and fault, and the interpreted horizon and interpreted fault are obtained. b. Select reference wells and wells for which geological models need to be built; S12. Determine the correspondence between the interpretation stratigraphic position and the well stratigraphic layer; In this process, the marker layers are first determined; for well layers other than the marker layers, their respective positions between two interpretation layers are calculated according to their depth relationships. Among them, marker stratification refers to well stratification that belongs to the same set of strata as a certain set of interpretation strata; S13. Use the marker layer to fit the interpretation layer so that each interpretation layer intersects with the corresponding well layer, and obtain the fitted interpretation layer, that is, the corrected interpretation layer; S14. Generate an initial geological model using the interpreted faults and corrected interpreted horizons.

3. The method for establishing a high-precision formation model profile by combining well and seismic analysis according to claim 2, characterized in that, Step S13 is performed in the following order: S131. Interpolate and extend the interpretation layer; S132. Obtain the intersection of the reference well trajectory and the interpretation layer, and calculate the distance between the intersection and the marker layer corresponding to the interpretation layer; S133. Using stratification of markers to perform trend fitting on explanatory strata. In this process, the longitudinal offset of each trace on the interpretation layer is calculated using the distance linear interpolation obtained in step S132, and the fitted interpretation layer is obtained. The depth coordinates of the intersection points between two adjacent reference wells and the interpretation layer are as follows: , The depth coordinates of the well layers corresponding to the stratigraphic positions are as follows: , The number of traces between two adjacent reference wells is The number of traces from the calculation point to the left reference well is Then the offset of that point for ① If there is only one reference well and only one corresponding interpretation horizon, it is equivalent to a translation of the interpretation horizon. ② The depth coordinates of the intersection point between the reference well and the interpretation layer are: The depth coordinates of the well layers corresponding to the stratigraphic positions are explained as follows: .

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