Method for establishing high-precision stratum model profile through well-seismic combination

Abstract

The invention belongs to the technical field of oil and gas reservoir development, and particularly discloses a method for establishing a high-precision stratum model profile through well-seismic combination, and the method sequentially comprises the following steps: S1, establishing an initial geologic model; s2, calculating a layering line of the geological small layer; and S3, generating a new geological model. The high-precision stratum model of the horizontal well to be drilled is provided on the basis of seismic data and the drilled vertical well, is suitable for a complex model of a single well, multiple wells and multiple stratums and can provide a basis for seismic geosteering work of horizontal well drilling, the drilling rate of a reservoir'box 'is increased, and the drilling engineering risk is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas reservoir development, and relates to a method for establishing a high-precision formation model section by combining well and seismic data. Background Art

[0002] In recent years, unconventional exploration has become a hot spot in oil and gas exploration, such as exploration of shale oil, shale gas, tight sandstone, coalbed methane, etc. Unconventional reservoirs are characterized by low porosity and low permeability, and the oil and gas contained in them are almost stagnant. It is necessary to drill as many reservoirs as possible through horizontal well drilling, and then transform the reservoirs to extract oil and gas. The project is difficult, so the drilling-while-drilling geosteering technology came into being during the drilling process.

[0003] For example, the existing technologies represented by the simulation modeling of the Starsteer geosteering software mainly focus on the establishment and adjustment of 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 seismic layer as a structural morphology basis, or no seismic layer data. The premise of the assumption is that the target layer is laterally stable and unchanged, and the established model is inconsistent with the actual geological conditions, which will bring many inconveniences or unexpected conditions to subsequent exploration operations.

[0004] In actual production, there is an urgent need to comprehensively combine seismic information with geological information such as drilling to establish a model that is more consistent with the actual complex geological conditions underground. Summary of the invention

[0005] The purpose of the present invention is to provide a method for establishing a high-precision formation model profile by combining well-seismic data, so as to increase the drilling rate of the reservoir "box" and reduce the risk of drilling engineering.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for establishing a high-precision stratigraphic model profile by combining well and seismic data is performed in the following order:

[0008] S1. Establishing the initial geological model

[0009] Generate an initial geological model using interpreted faults and corrected interpreted horizons;

[0010] The corrected interpretation horizon refers to the depth domain horizon corrected by well stratification;

[0011] S2. Calculate the stratification line of geological layers

[0012] Divide each geological block of the initial geological model into high-precision geological layers in proportion to obtain stratification lines;

[0013] S3. Generate new geological model

[0014] Generate new geological models 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 section, the characteristics of the event axis are used to interpret the horizon and fault to obtain the interpreted horizon and interpreted fault;

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

[0019] S12, determining the corresponding relationship between the interpreted horizon and the well stratification;

[0020] In this process, the marker layer is first determined; for the well layers other than the marker layer in the well layer, the two sets of interpretation layers between which each layer is located are calculated according to the depth relationship;

[0021] Among them, the marker layer refers to the well layer that is the same set of strata as a certain set of interpreted horizons;

[0022] S13, fitting the interpretation horizons with the marker layers so that each interpretation horizon intersects with the corresponding well layers, and obtaining the fitted interpretation horizons, i.e., the corrected interpretation horizons;

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

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

[0025] S131, interpolating and extending the interpreted horizon;

[0026] S132, obtaining the intersection point of the reference well trajectory and the interpreted layer, and calculating the distance between the intersection point and the marked layer corresponding to the interpreted layer;

[0027] S133, Use marker stratification to perform trend fitting on interpreted horizons

[0028] In this process, the longitudinal offset of each trace on the interpretation horizon is calculated by linear interpolation using the distance obtained in step S132 to obtain the fitted interpretation horizon;

[0029] Among them, the depth coordinates of the intersection points of two adjacent reference wells and the interpreted horizon are y n1 ,y h2 The depth coordinates of the well layers corresponding to the interpreted horizons are y t1 ,y t2 , the number of channels between two adjacent reference wells is x 12, the number of channels from the calculation point to the left reference well is x i , then the offset of this point is Δy i for

[0030]

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

[0032] Δy i =(y h -y t ) ②

[0033] The depth coordinate of the intersection of the reference well and the interpretation layer is y h The depth coordinate of the well layer corresponding to the interpretation layer is y t .

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

[0035] S21, obtaining each geological block of the initial geological model;

[0036] S22, combining the correspondence between the interpretation horizon and the well layers determined in step S12, determining which well layers each geological block spans;

[0037] S23, perform the following two operations

[0038] c. For each well layer spanned by a geological block, calculate the ratio of these well layers between the upper and lower marker layers to obtain the layer ratio;

[0039] Among them, the well layer T is between the upper and lower marker layers T up and T Bottom The ratio between

[0040]

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

[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 layering ratio and the top and bottom interfaces, and calculating the layering line corresponding to each geological block according to formula ④, the layering line is an extended layering line;

[0044]

[0045] Where (x, y) is the coordinate of a point on the stratification line, x1 is the reference well position on the left side of the point, x2 is the reference well position on the right side of the point, r1 is the stratification ratio of the well on the left side of the point, r2 is the stratification ratio of the well on the right side 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, the ratio of the nearest reference well is used. In this case, formula ④ is as follows:

[0047] y=r1*(y2-y1)+y1⑤

[0048] If a point on the stratification line is located to the right of the rightmost reference well, the ratio of the nearest reference well is used. In this case, formula ④ is as follows:

[0049] y=r2*(y2-y1)+y1⑥

[0050] S25, cutting the extended stratification line with the geological block to ensure that the stratification line is within the geological block;

[0051] Steps S23-S25 are repeated until complete layer lines corresponding to all well layers selected in step S12 for which geological models need to be established are obtained.

[0052] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0053] (1) Based on seismic data and drilled vertical wells, the present invention provides a high-precision stratigraphic 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 formations. It can provide a basis for seismic geological guidance work for horizontal well drilling, improve the drilling rate of reservoir "boxes", reduce drilling engineering risks, and ultimately achieve the purpose of increasing the productivity of a single well;

[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) The present invention generates an initial geological model using the corrected interpreted horizons and faults, which can reflect a large set of strata with seismic accuracy;

[0056] (4) The present invention generates a new geological model through layering lines and faults, which can provide assistance for drilling decisions of horizontal wells in target layers.

[0057] The invention belongs to the technical field of oil and gas reservoir development, and can improve the drilling rate of reservoir "boxes" and improve the single well production capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0059] In the attached picture:

[0060] Figure 1 is a flow chart of an embodiment of the present invention;

[0061] Figure 2 This is a schematic diagram of the process of establishing a high-precision formation model profile by combining well-seismic analysis according to an embodiment of the present invention;

[0062] in, Figure 2 (a) A schematic diagram of the interpreted horizon and interpreted fault obtained in an embodiment of the present invention;

[0063] Figure 2 (b) is a schematic diagram of fitting the interpreted horizons using the marker well stratification according to an embodiment of the present invention;

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

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

[0066] Figure 2 (e) 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 a layering line extended by cutting a geological block according to an embodiment of the present invention;

[0068] Figure 2 (g) is a schematic diagram of a complete layered line obtained by performing operations (d) to (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 layering lines and interpreted faults according to an embodiment of the present invention. DETAILED DESCRIPTION

[0070] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0071] Embodiment A method for establishing a high-precision formation model profile by combining well-seismic data

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

[0073] S1. Establish an initial geological model;

[0074] S2, calculate the stratification line of geological layers;

[0075] S3. Generate a new geological model.

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

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

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

[0079] S11. Perform the following two operations

[0080] a. On the seismic section, the characteristics of the event axis are used to interpret the horizon and fault, and the interpreted horizon and fault are obtained, 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 well layers for which geological models need to be established;

[0082] In this embodiment, the two reference wellheads are Well1 and Well2, and the well layers for which the geological model needs to be established 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, determining the corresponding relationship between the interpreted horizon and the well stratification;

[0084] In this process, the marker layer is first determined; for the well layers other than the marker layer in the well layer, the two sets of interpretation layers between which each layer is located are calculated according to the depth relationship;

[0085] Among them, the marker layer refers to the well layer that is the same set of strata as a certain set of interpreted horizons;

[0086] In this embodiment, the marker layers are Top1 and Top5 of Well1, and Top1 and Top5 of Well2, where two Top1s correspond to the interpretation layer H1, two Top5s correspond to the interpretation layer H2, and the remaining two Top2s, two Top3s, and two Top4s are located between the two interpretation layers H1 and H2;

[0087] S13, fitting the interpretation horizon with the marker layer, so that each interpretation horizon intersects with the corresponding well layer, and obtaining the fitted interpretation horizon, that is, the corrected interpretation horizon, such as Figure 2 (b) After fitting, H1 obviously moves down and fits with the two Top1s;

[0088] S14, such as Figure 2 (c) Generate an initial geological model using interpreted faults and corrected interpreted horizons.

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

[0090] S131, interpolating and extending the interpretation horizons H1 and H2;

[0091] Since the interpreted horizon is not continuous on the section, it is necessary to interpolate the interpreted horizon;

[0092] S132, obtaining the intersection point of the reference well trajectory and the interpreted layer, and calculating the distance between the intersection point and the marked layer corresponding to the interpreted layer;

[0093] S133, Use marker stratification to perform trend fitting on interpreted horizons

[0094] Use the marker layers Top1 and Top5 corresponding to the two reference wells Well1 and Well2 to fit the interpretation layers H1 and H2 respectively, so that the intersection point of the interpretation layer H1 and the reference well Well1 is the Top1 of Well1, the intersection point of the interpretation layer H1 and the reference well Well2 is the Top1 of Well2, the intersection point of the interpretation layer H2 and the reference well Well1 is the Top5 of Well1, and the intersection point of the interpretation layer H2 and the reference well Well2 is the Top5 of Well2;

[0095] In this process, the longitudinal offset of each trace on the interpretation horizon is calculated by linear interpolation using the distance obtained in step S132 to obtain the fitted interpretation horizon;

[0096] Among them, the depth coordinates of the intersection points of two adjacent reference wells and the interpreted horizon are y h1 ,y h2 The depth coordinates of the well layers corresponding to the interpreted horizons are y t1 ,y t2 , the number of channels between two adjacent reference wells is x 12, the number of channels from the calculation point to the left reference well Well1 is x i , then the offset of this point is Δy i for

[0097]

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

[0099] Δy i =(y h -y t ) ②

[0100] The depth coordinate of the intersection of the reference well and the interpretation layer is y h The depth coordinate of the well layer corresponding to the interpretation layer is y t .

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

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

[0103] S21, obtaining each geological block of the initial geological model;

[0104] S22, combining the correspondence between the interpretation horizon and the well layer determined in step S12, determining which well layers each geological block spans; the upper and lower boundaries of the geological block are part of the interpretation horizon, and it can be concluded through the correspondence between the marker layer and the interpretation horizon, as well as the well layer depth, that each geological block in this embodiment spans the Top2, Top3 and Top4 layers;

[0105] S23, perform the following two operations

[0106] c. For each well layer spanned by a geological block, calculate the ratio of these well layers between the upper and lower marker layers to obtain the layer ratio;

[0107] Among them, the well layer T is between the upper and lower marker layers T up and T Bottom The ratio between

[0108]

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

[0110] In this embodiment, the two marking layers T up and T Bottom are Top1 and Top5 respectively; therefore, formula ③ can be expressed as Among them, y is the depth value of the well layer T, y H1 is the depth value of the upper marker layer Top1 closest to the well layer, y H5 The depth value of the Top5 lower marker layer closest to the well layer;

[0111] d. Figure 2 (d) calculating the top and bottom interfaces of each geological block in the initial geological model and extending the top and bottom interfaces;

[0112] S24, such as Figure 2 (e) Combined with the layering ratio and the top and bottom interfaces, the layering line corresponding to each geological block is calculated according to formula ④. The layering line at this time is also an extended layering line;

[0113]

[0114] Where (x, y) is the coordinate of a point on the stratification line, x1 is the reference well position on the left side of the point, x2 is the reference well position on the right side of the point, r1 is the stratification ratio of the well on the left side of the point, r2 is the stratification ratio of the well on the right side 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 refers to Well1, and the right reference well refers to Well2. In practice, the left reference well and the right reference well are the reference wells closest to the layering line on both sides of the layering line in the cross-section diagram;

[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, the ratio of the nearest reference well is used; for example, in some cases, if a point on the stratification line is located to the left of Well1, the ratio of Well1 is used. In this case, formula ④ becomes

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

[0118] For example, in some cases, if a point on the stratification line is on the right side of Well2, the ratio of Well2 is used. In this case, formula ④ becomes

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

[0120] S25, such as Figure 2 (f) cutting the extended layering line with the geological block to ensure that the layering line is within the geological block;

[0121] like Figure 2 (g) Repeat steps S24-S26 for each geological block. Figure 2 (d)- Figure 2 (f) is performed until the complete layer lines corresponding to all the well layers selected in step S12 for which the geological model needs to be established are obtained.

[0122] like Figure 2 (h), in the final step S3, a new geological model is generated for the through-layering lines and interpreted faults;

[0123] This new geological model contains seismic and well layer information and is a high-precision geological model that combines well and seismic data. Seismic data can provide real-time analysis of drilled wells and pre-drilling predictions for horizontal well drilling projects, guiding the smooth implementation of drilling trajectories. It comprehensively and systematically supports static geological evaluation and dynamic engineering implementation, and plays a bridging role, connecting geology and engineering to guide horizontal well drilling.

Claims

1. A method for establishing a high-precision formation model profile by combining well and seismic data, characterized in that: Follow these steps in order: S1. Establishing the initial geological model Generate an initial geological model using interpreted faults and corrected interpreted horizons; The corrected interpretation horizon refers to the depth domain horizon corrected by well stratification; S2. Calculate the stratification line of geological layers Divide each geological block of the initial geological model into high-precision geological layers in proportion to obtain stratification lines; S3. Generate new geological model Generate new geological models by layering lines and interpreting faults.

2. The method for establishing a high-precision formation model section by combining well and seismic data according to claim 1, characterized in that: The step S1 is performed in the following order: S11. Perform the following two operations a. On the seismic section, the characteristics of the event axis are used to interpret the horizon and fault to obtain the interpreted horizon and interpreted fault; b. Select reference wells and well layers for which geological models need to be established; S12, determining the corresponding relationship between the interpreted horizon and the well stratification; In this process, the marker layer is first determined; for the well layers other than the marker layer in the well layer, the two sets of interpretation layers between which each layer is located are calculated according to the depth relationship; Among them, the marker layer refers to the well layer that is the same set of strata as a certain set of interpreted horizons; S13, fitting the interpretation horizons with the marker layers so that each interpretation horizon intersects with the corresponding well layers, and obtaining the fitted interpretation horizons, i.e., the corrected interpretation horizons; S14. Generate an initial geological model using the interpreted faults and the corrected interpreted horizons.

3. The method for establishing a high-precision formation model section by combining well and seismic data according to claim 2, characterized in that: The step S13 is performed in the following order: S131, interpolating and extending the interpreted horizon; S132, obtaining the intersection point of the reference well trajectory and the interpreted layer, and calculating the distance between the intersection point and the marked layer corresponding to the interpreted layer; S133, Use marker stratification to perform trend fitting on interpreted horizons In this process, the longitudinal offset of each trace on the interpretation horizon is calculated by linear interpolation using the distance obtained in step S132 to obtain the fitted interpretation horizon; Among them, the depth coordinates of the intersection points of two adjacent reference wells and the interpreted horizon are y h1 ,y h2 The depth coordinates of the well layers corresponding to the interpreted horizons are y t1 ,y t2 , the number of channels between two adjacent reference wells is x 12 , the number of channels from the calculation point to the left reference well is x i , then the offset of this point is Δy i for If there is only one reference well and only one corresponding interpretation horizon, it is equivalent to the translation of the interpretation horizon. Δy i =(y h -y t ) ② The depth coordinate of the intersection of the reference well and the interpretation layer is y h The depth coordinate of the well layer corresponding to the interpretation layer is y t .

4. A method for establishing a high-precision formation model profile by combining well and seismic data according to claim 2 or 3, characterized in that: The step S2 is performed in the following order: S21, obtaining each geological block of the initial geological model; S22, combining the correspondence between the interpretation horizon and the well layers determined in step S12, determining which well layers each geological block spans; S23, perform the following two operations c. For each well layer spanned by a geological block, calculate the ratio of these well layers between the upper and lower marker layers to obtain the layer ratio; Among them, the well layer T is between the upper and lower marker layers T up and T Bottom The ratio between Among them, y is the depth value of the well layer T, y up The upper marker layer T is the layer closest to the well layer. up The depth value, y Bottom The lower marker layer T is the closest to the well layer. Bottom The depth value of 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 layering ratio and the top and bottom interfaces, and calculating the layering line corresponding to each geological block according to formula ④, the layering line is an extended layering line; Where (x, y) is the coordinate of a point on the stratification line, x1 is the reference well position on the left side of the point, x2 is the reference well position on the right side of the point, r1 is the stratification ratio of the well on the left side of the point, r2 is the stratification ratio of the well on the right side 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; If a point on the stratification line is located to the left of the leftmost reference well, the ratio of the nearest reference well is used. In this case, formula ④ is as follows: y=r1*(y2-y1)+y1⑤ If a point on the stratification line is located to the right of the rightmost reference well, the ratio of the nearest reference well is used. In this case, formula ④ is as follows: y=r2*(y2-y1)+y1⑥ S25, cutting the extended stratification line with the geological block to ensure that the stratification line is within the geological block; Steps S23-S25 are repeated until complete layer lines corresponding to all well layers selected in step S12 for which geological models need to be established are obtained.

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