A method for constructing a horizontal well formation model

Abstract

The present application relates to the technical field of oil exploration, in particular to a kind of horizontal well formation model construction method.The present application uses seismic stratum line as the overall trend line of formation, controls the overall fluctuation form of formation, avoids the multi-solution of angle adjustment in previous method;The stratum interface of formation model is calibrated using the true dip angle of formation obtained by while-drilling azimuthal imaging logging, so that the precision of formation dip angle is improved.Through the method, the workload of artificial modeling is greatly reduced, and the modeling precision is improved.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, and in particular to a method for constructing a formation model for a horizontal well. Background Technology

[0002] Horizontal well formation model construction is fundamental to horizontal well processing and interpretation. Accurate model construction is crucial for horizontal well interpretation and is one of the key core functions of various horizontal well processing and interpretation software products. Currently, the most common method for constructing horizontal well formation models is based on the pilot well formation model. This method uses a homogeneous formation model and interactively performs real-time forward modeling using the current model's logging response. The forward model curve is compared with the measured curve, and through continuous interactive adjustments, the forward model curve is made consistent with the measured curve. At this point, the obtained model is considered the final geological formation model. This method is currently the mainstream approach, but it has several drawbacks:

[0003] 1. The adjustment of the model relies entirely on the interpreter's experience, and the scale of model adjustment is mostly impossible to quantify, resulting in multiple solutions to the model.

[0004] 2. The model needs to be finely adjusted. The accuracy of the model depends on the number of control points to be adjusted. Therefore, a large amount of work is required to obtain a high-accuracy model.

[0005] 3. Since the initial model established using adjacent wells often starts with adjustments to horizontal formations, it is often inaccurate in terms of formation dip trends;

[0006] 4. Because this method is related to the experience of the interpreters and the angles of the strata are not accurate, it is only suitable for qualitative interpretation and the accuracy is often not high. Summary of the Invention

[0007] To address the above problems, this invention provides a method for constructing a horizontal well formation model.

[0008] A method for constructing a formation model for a horizontal well, the method comprising:

[0009] The well trajectory and formation lines are unfolded along the trajectory to obtain a joint display profile of the well trajectory and formation, and the formation interface is obtained;

[0010] An initial stratigraphic model is constructed, and seismic horizons are mapped to stratigraphic interfaces to obtain a depth-matched stratigraphic model.

[0011] Calculate the true dip angle of the formation, and adjust the depth-matched formation model according to the true dip angle so that the formation angle at the corresponding formation model profile position is transformed into the true dip angle.

[0012] Furthermore, stratigraphic lines include:

[0013] The intersection of well trajectory surfaces with seismic interpretation planes is used to obtain the intersection line as the stratigraphic line.

[0014] Furthermore, the well trajectory and formation lines are unfolded along the trajectory, including:

[0015] When the seismic plane is three-dimensional, the three-dimensional spatial stratigraphic lines are aligned with the well trajectory plane.

[0016] Furthermore, the well trajectory and formation lines are unfolded along the trajectory, including:

[0017] When the seismic plane is two-dimensional, the stratigraphic lines interpreted from the two-dimensional seismic profile coincide with the well trajectory.

[0018] Furthermore, an initial formation model is constructed, including:

[0019] Square wave conversion is performed using logging curves from pilot wells or adjacent wells to form an initial formation model.

[0020] Furthermore, the seismic horizons are correlated with stratigraphic boundaries, including:

[0021] Square wave conversion was performed using the natural gamma curves of adjacent wells, and the square wave interface corresponding to the layer depth of the seismic plane was marked, as well as the location of the marker layer.

[0022] The depth of the stratigraphic interface is matched with that of the marker layer. Using the marker layer as a reference, the stratigraphic interface is shifted to make the two positions consistent.

[0023] Further, the true dip angle of the formation is calculated, including:

[0024] Pick up the formation interface of the drilling azimuth imaging data and specify the formation corresponding to the interface;

[0025] Calculate the true dip angle of the corresponding formation based on the well trajectory and the picked interface angle and dip.

[0026] Furthermore, based on the extracted apparent dip angle and the well inclination and azimuth values ​​of the well trajectory corresponding to the current formation, the true dip angle of the formation is calculated, using the following formula:

[0027]

[0028]

[0029] ψ=azim±arccos(tan(α+β) / tanθ)

[0030] Where θ represents the true dip angle. α represents the true dip, β represents the complementary angle of the inclination angle, azim represents the inclination azimuth, and α represents the complementary angle of the apparent dip. The angle between the apparent dip line and the drilling trajectory is represented by γ, which is an intermediate variable.

[0031] Furthermore, the formation interface of the drilling azimuth imaging data is picked up, and the formation corresponding to the interface is specified, including:

[0032] The location of the formation interface is obtained using a sine curve method.

[0033] Furthermore, it also includes:

[0034] The square wave depth is extended parallel to the formation interface to obtain a parallel formation model with a trend, and the adjacent well depth position of the square wave is recorded in the formation.

[0035] The adjacent well curve values ​​are obtained based on the depth of the adjacent wells. The formation is then assigned values ​​to obtain the formation model, thus completing the construction of the formation model.

[0036] This invention has at least the following beneficial effects:

[0037] This invention uses seismic stratigraphic lines as the overall trend lines of the formation, controlling the overall undulation of the formation and avoiding the multiple solutions inherent in angle adjustments used in previous methods. It also utilizes the true dip angles of the formations obtained from drilling azimuth imaging logging to calibrate the formation interfaces of the formation model, thereby improving the accuracy of the formation dip angles. This method significantly reduces the workload of manual modeling and improves the accuracy of the modeling.

[0038] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a flowchart illustrating the construction method of an embodiment of the present invention;

[0041] Figure 2 This is a detailed flowchart of the implementation of the present invention;

[0042] Figure 3 A three-dimensional schematic diagram of the intersection between the well trajectory profile and the seismically interpreted strata;

[0043] Figure 4This is a combined profile of seismic strata and well trajectory;

[0044] Figure 5 Initial model construction and example diagram corresponding to seismic horizons;

[0045] Figure 6 This is a schematic diagram showing the relationship between the true tilt angle and the apparent tilt angle.

[0046] Figure 7 The true dip angle constrains the interface angle of the formation model.

[0047] Figure 8 This is a schematic diagram of the subdivided stratigraphic model. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0049] To address the shortcomings of existing stratigraphic model construction methods, this invention utilizes seismic interpretation data to control the overall trend of strata in the stratigraphic model and employs drilling-while-drilling azimuth imaging data to calculate the true dip angle of the strata, thereby obtaining the true angle of the strata. By automatically constructing the stratigraphic model through the calculation of stratigraphic trend and true dip angle, the problem of multiple solutions in model construction is reduced. Furthermore, the automated model construction method significantly saves model adjustment time.

[0050] like Figure 1 As shown, the present invention provides a method for constructing a horizontal well formation model, the method comprising:

[0051] S101, unfold the well trajectory and formation line along the trajectory to obtain a joint display profile of the well trajectory and formation, and obtain the formation interface;

[0052] S102, Construct an initial stratigraphic model, correlate seismic horizons with stratigraphic interfaces, and obtain a depth-matched stratigraphic model;

[0053] S103, calculate the true dip angle of the formation, and adjust the depth-matched formation model according to the true dip angle so that the formation angle at the corresponding formation model profile position is transformed into the true dip angle.

[0054] In practice, the detailed process is as follows: Figure 2 As shown, the following steps are taken:

[0055] 1. Load data. Data types to load include: well trajectory data, seismic interpretation layer data, azimuth gamma ray while drilling, density or resistivity imaging data (one of the following), other horizontal well logging curve data, and adjacent well or pilot well data;

[0056] 2. The intersection of the well trajectory with the seismic interpretation plane is used as the stratigraphic line;

[0057] 3. Unfold the well trajectory and the formation lines obtained in step 2 along the trajectory to form an initial two-dimensional formation interface;

[0058] 4. Use the natural gamma curve of the adjacent well to perform square wave conversion, mark the square wave interface at the layer depth corresponding to the seismic plane, and mark the location of the marker layer at the same time.

[0059] 5. Perform depth matching between the stratigraphic interface obtained in step 3 and the depth of the location marked in step 4. Using the location in step 4 as a reference, translate the stratigraphic interface to make the two locations consistent.

[0060] 6. Pick up the formation interface of the drilling azimuth imaging data and specify the formation corresponding to the interface;

[0061] 7. Calculate the true dip angle of the corresponding formation based on the well trajectory and the picked interface angle and dip.

[0062] 8. Based on the formation dip angle calculated in step 7, constrain the formation interface in step 5, and adjust the formation interface at the dip angle position picked in step 6 to the angle in step 7.

[0063] 9. Extend the square wave depth obtained in step 4 parallel to the formation interface obtained in step 8 to obtain a parallel formation model with a trend, and record the adjacent well depth position of the square wave in the formation.

[0064] 10. Obtain the curve values ​​of adjacent wells based on their depths, assign values ​​to the formation obtained in step 9, and obtain the formation model, thus completing the construction of the formation model.

[0065] To enable those skilled in the art to better understand the present invention, the principles of the present invention are explained below in conjunction with the accompanying drawings:

[0066] In step S1, various types of data are loaded, including well trajectory data, seismic interpretation layer data, drilling azimuth imaging data, logging curves from other horizontal wells, and data from adjacent or pilot wells. Generally, seismic interpretation layer data is one of the seismic interpretation results, and it is three-dimensional layer data. However, in some cases, when using two-dimensional seismic profiles, the layer data is a two-dimensional interpretation result. Regardless, the provided seismic interpretation layer is in the depth domain. Drilling azimuth imaging data generally includes drilling azimuth gamma imaging data, drilling density imaging data, and drilling resistivity imaging data; this method only requires one of these. For pilot well or adjacent well data, pilot well data is preferred, but adjacent well data with more complete data can also be used. The data should be as comprehensive as possible.

[0067] In step S2, the well trajectory profile intersects with the formation interface.

[0068] If S3 represents a three-dimensional seismic level, it would be a three-dimensional spatial stratigraphic line coinciding with the well trajectory plane, as shown in the attached figure. Figure 3 The image shows a profile of the well trajectory. If the stratigraphic lines are directly interpreted from a 2D seismic profile, they are directly combined with the well trajectory. Through this process, a combined display profile of the well trajectory and the stratigraphy is formed, as shown in the attached image. Figure 4 As shown. (Initial two-dimensional stratigraphic interface)

[0069] In step S4, square wave conversion is performed using logging curves from pilot wells or adjacent wells. Square wave conversion typically employs the activity method, which is not within the scope of this invention; similar methods exist in some literature. This square wave conversion then forms the initial formation model.

[0070] The horizontal direction of the S5 square wave indicates the depth location of the initial formation model. The seismic horizons are correlated with the horizons of the pilot well, as shown in the attached figure. Figure 5 As shown in the diagram, L1, L2, and L3 represent the locations of geological interfaces. The seismic planes are matched with these geological layers. This corresponds to step S5 in the workflow.

[0071] In step S6, formation interfaces are picked up by selecting drilling azimuth imaging data. This is generally done manually, although there are also automatic methods in current patents. However, these are not the main technical content of this patent. The formation interface position is obtained by using a sine curve.

[0072] In step S7, the true dip angle of the formation is calculated based on the apparent dip angle extracted in S6 and the well inclination and azimuth values ​​of the well trajectory corresponding to the current formation. The specific formula is as follows:

[0073]

[0074]

[0075] ψ=azim±arccos(tan(α+β) / tanθ)

[0076] Where θ: true inclination angle, True tilt, β: complementary angle of inclination, azim: azimuth of inclination, α: complementary angle of apparent tilt. The angle between the apparent dip line and the drilling trajectory.

[0077] Appendix Figure 6 This is a schematic diagram showing the relationship between the true tilt angle and the apparent tilt angle.

[0078] In step S8, the true dip angle of the formation calculated in S7 is used to constrain the depth-matched formation model obtained in S5, so that the formation angle at the corresponding formation model profile position is transformed into the true dip angle. (See attached...) Figure 7 As shown.

[0079] In step S9, the square wave depth line formed in step S4 is used as the stratigraphic subdivision interface depth. The subdivision extends along the stratigraphic lines created in previous steps, forming subdivided strata. Square wave values ​​are then assigned to each subdivided stratum (corresponding to step S10) as attribute values ​​for the stratigraphic model. This results in the final model, as shown in the attached figure. Figure 8 As shown.

[0080] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a horizontal well formation model, characterized in that, The method includes: The well trajectory and formation lines are unfolded along the trajectory to obtain a joint display profile of the well trajectory and formation, and the formation interface is obtained; An initial stratigraphic model is constructed, and seismic horizons are mapped to stratigraphic interfaces to obtain a depth-matched stratigraphic model. Calculate the true dip angle of the formation, and adjust the depth-matched formation model according to the true dip angle so that the formation angle at the corresponding formation model profile position is transformed into the true dip angle. Constructing an initial formation model includes: Square wave conversion is performed using logging curves from pilot wells or adjacent wells to form an initial formation model; Corresponding seismic horizons to stratigraphic boundaries includes: Square wave conversion was performed using the natural gamma curves of adjacent wells, and the square wave interface corresponding to the layer depth of the seismic plane was marked, as well as the location of the marker layer. The depth of the stratigraphic interface is matched with that of the marker layer. Using the marker layer as a reference, the stratigraphic interface is shifted to make the two positions consistent. Also includes: The square wave depth is extended parallel to the formation interface to obtain a parallel formation model with a trend, and the adjacent well depth position of the square wave is recorded in the formation. The adjacent well curve values ​​are obtained based on the depth of the adjacent wells. The formation is then assigned values ​​to obtain the formation model, thus completing the construction of the formation model.

2. The method for constructing a horizontal well formation model according to claim 1, characterized in that, Stratigraphic lines, including: The intersection of well trajectory surfaces with seismic interpretation planes is used to obtain the intersection line as the stratigraphic line.

3. The method for constructing a horizontal well formation model according to claim 1, characterized in that, Unfold the well trajectory and formation lines along the trajectory, including: When the seismic plane is three-dimensional, the three-dimensional spatial stratigraphic lines are aligned with the well trajectory plane.

4. The method for constructing a horizontal well formation model according to claim 1, characterized in that, Unfold the well trajectory and formation lines along the trajectory, including: When the seismic plane is two-dimensional, the stratigraphic lines interpreted from the two-dimensional seismic profile coincide with the well trajectory.

5. The method for constructing a horizontal well formation model according to claim 1, characterized in that, Calculating the true dip angle of the formation includes: Pick up the formation interface of the drilling azimuth imaging data and specify the formation corresponding to the interface; Calculate the true dip angle of the corresponding formation based on the well trajectory and the picked interface angle and dip.

6. The method for constructing a horizontal well formation model according to claim 5, characterized in that, The true dip angle of the formation is calculated based on the extracted apparent dip angle and the well inclination and azimuth values ​​of the well trajectory corresponding to the current formation. The specific formula is as follows: Where θ represents the true dip angle, φ represents the true dip direction, β represents the complementary angle of the well inclination angle, azim represents the well inclination azimuth angle, α represents the complementary angle of the apparent dip angle, φ' represents the angle between the apparent dip line and the drilling trajectory, and γ is an intermediate variable.

7. The method for constructing a horizontal well formation model according to claim 5, characterized in that, Pick up the formation interface of the drilling azimuth imaging data and specify the formation corresponding to the interface, including: The location of the formation interface is obtained using a sine curve method.

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