Construction method of horizontal well stratum model

Abstract

The invention relates to the technical field of oil exploration, in particular to a construction method of a horizontal well stratum model. According to the method, the seismic stratigraphic line is adopted as the overall trend line of the stratigraphic, the overall fluctuation form of the stratigraphic is controlled, and the multiplicity of solution of angle adjustment in a previous method is avoided; the stratum interface of the stratum model is calibrated through the stratum true dip angle obtained through while-drilling azimuth imaging logging, so that the precision of the stratum dip angle is improved. Through the method, the workload of manual modeling is greatly reduced, and the modeling precision is improved.

Description

Technical Field

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

[0002] The construction of horizontal well formation model is the basis of horizontal well processing and interpretation. Accurate model construction is an important task for horizontal well interpretation, and it is also one of the key core functions of various horizontal well processing and interpretation software products. For the construction of horizontal well formation model, at present, the commonly used method for horizontal well formation model is based on the pilot well formation model construction method. This method adopts a uniform formation model, and interactively uses the logging response of the current model for real-time forward modeling, compares the forward modeling curve with the measured curve, and makes the forward modeling curve consistent with the measured curve through continuous model interaction adjustment. At this time, the obtained model is considered to be the final formation geological model. This method is also the current mainstream method, but it has the following disadvantages:

[0003] 1. The adjustment of the model depends entirely on the interpretation experience of the interpreter. The adjustment scale of the model cannot be quantified in most cases, and the model has multiple solutions;

[0004] 2. The adjustment of the model requires fine adjustment. The accuracy of the model depends on the number of control points of the adjusted model. Therefore, in order to obtain a model with higher accuracy, a large amount of work is required;

[0005] 3. Since the initial model established using adjacent wells often uses horizontal formations for adjustment, it is often inaccurate for the formation inclination trend;

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

[0007] In view of the above problems, the present invention provides a method for constructing a horizontal well formation model.

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

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

[0010] Construct an initial stratigraphic model, match the seismic horizons with the stratigraphic interfaces, and obtain a depth-matched stratigraphic model;

[0011] The true dip of the formation is calculated, and according to the true dip of the formation, the formation model of depth matching is adjusted so that the formation angle corresponding to the section position of the formation model is transformed into the true dip.

[0012] Further, the stratigraphic lines include:

[0013] The well trajectory is used to intersect the seismic interpretation plane, and the intersection line obtained is used as the stratigraphic line.

[0014] Further, the well trajectory and the formation line are unfolded along the trajectory, including:

[0015] When the seismic plane is a three-dimensional plane, the three-dimensional spatial stratigraphic line is overlapped with the well trajectory plane.

[0016] Further, the well trajectory and the formation line are unfolded along the trajectory, including:

[0017] When the seismic plane is a two-dimensional plane, 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] The logging curves of the pilot well or adjacent wells are converted into square waves to form an initial formation model.

[0020] Furthermore, the seismic horizons are matched to the stratigraphic interfaces, including:

[0021] The natural gamma curve of the adjacent well is used for square wave conversion, and the square wave interface at the layer depth position corresponding to the seismic layer is marked, and the position of the marker layer is marked;

[0022] The depth of the formation interface is matched with the depth of the marker layer position, and the formation interface is translated based on the marker layer position to make the two positions consistent.

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

[0024] Pick up the stratigraphic interface of the azimuthal imaging data while drilling, and specify the stratigraphic layer corresponding to the interface;

[0025] According to the well trajectory and the picked interface angle and inclination, the true inclination of the corresponding formation is calculated.

[0026] Furthermore, the true dip of the formation is obtained according to 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:

[0027]

[0028]

[0029] ψ=azim±arccos(tan(α+β) / tanθ)

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

[0031] Furthermore, picking up the stratigraphic interface of the azimuthal imaging data while drilling and specifying the stratigraphic interface corresponding to the stratigraphic interface includes:

[0032] The position of the formation interface is obtained by using the sine line method.

[0033] Furthermore, it also includes:

[0034] Extend the square wave depth parallel to the formation interface to obtain a parallel formation model with trend, and record the adjacent well depth position of the square wave into the formation;

[0035] The adjacent well curve value is obtained according to the adjacent well depth, the formation is assigned a value, the formation model is obtained, and the construction of the formation model is completed.

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

[0037] The present invention uses seismic formation lines as the overall formation trend lines, controls the overall undulation of the formation, and avoids the multiple solutions of angle adjustment in previous methods; the formation interface of the formation model is calibrated using the true formation inclination angle obtained by azimuth imaging logging while drilling, so that the accuracy of the formation inclination angle is improved. This method greatly reduces the workload of manual modeling and improves the accuracy of modeling.

[0038] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A flow chart of a method for constructing an embodiment of the present invention;

[0041] Figure 2 It is a detailed implementation flow chart of the present invention;

[0042] Figure 3 It is a schematic diagram of the three-dimensional intersection of the well trajectory section and the seismic interpretation stratum;

[0043] Figure 4It is a combined section of seismic stratigraphy and well trajectory;

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

[0045] Figure 6 It is a schematic diagram of the relationship between true inclination and apparent inclination;

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

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

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In view of the shortcomings of the existing formation model construction method, the present invention uses seismic interpretation formation data to control the overall trend of the formation in the formation model, uses the while drilling azimuth imaging data, and adopts the calculation of the true dip angle of the formation to obtain the true angle of the formation. The formation model is automatically constructed by calculating the formation trend and true dip angle, reducing the multi-solution problem of model construction. At the same time, the model is constructed in an automatic way, which saves a lot of 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, unfolding the well trajectory and the formation line along the trajectory to obtain a joint display section of the well trajectory and the formation, and obtain the formation interface;

[0052] S102, constructing an initial formation model, matching the seismic horizon with the formation interface, and obtaining a depth-matched formation model;

[0053] S103, calculating the true dip of the formation, and adjusting the depth-matched formation model according to the true dip of the formation so that the formation angle corresponding to the section position of the formation model is transformed into the true dip.

[0054] When implementing it, the detailed process is as follows Figure 2 As shown, the following steps are taken:

[0055] 1. Load data. The loaded data types include: well trajectory data, seismic interpretation layer data, while drilling azimuth gamma, density or resistivity imaging data, other horizontal well logging curve data, adjacent well or pilot well data;

[0056] 2. Use the well trajectory to intersect the seismic interpretation layer, and the obtained intersection line is used as the stratigraphic line;

[0057] 3. Expand the well trajectory and the formation line 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 square wave, mark the square wave interface at the layer depth position corresponding to the seismic layer, and mark the position of the marker layer at the same time;

[0059] 5. Match the depth of the stratum interface obtained in step 3 with the depth of the position marked in step 4, and translate the stratum interface based on the position in step 4 to make the two positions consistent;

[0060] 6. Pick up the stratigraphic interface of the azimuthal imaging data while drilling, and specify the stratigraphic layer corresponding to the interface;

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

[0062] 8. Constrain the formation interface in step 5 according to the formation dip angle calculated in step 7, and adjust the formation interface at the position of the dip angle picked up in step 6 to the angle in step 7;

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

[0064] 10. Obtain the adjacent well curve value according to the adjacent well depth, assign a value to the formation obtained in step 9, obtain the formation model, and complete the construction of the formation model.

[0065] In order to enable those skilled in the art to better understand the present invention, the principle of the present invention is described as follows in conjunction with the accompanying drawings:

[0066] In step S1, various types of data are loaded, including well trajectory data, seismic interpretation layer data, azimuthal imaging while drilling data, other horizontal well logging curve data, and adjacent well or pilot well data. Among them, in general, seismic interpretation layer data is one of the results of seismic interpretation, which is three-dimensional layer data. But in some cases, when it is a two-dimensional seismic profile, the layer data is a two-dimensional interpretation result. In any case, the seismic interpretation layer provided is a depth domain. Azimuthal imaging while drilling data generally includes azimuthal gamma imaging data, density imaging data, and resistivity imaging data. For this method, one of them can be used. For pilot well or adjacent well data, it is best to use pilot well data, or adjacent well data with relatively complete data information can be used. The requirements for data should be as rich as possible.

[0067] In step S2, the cross section of the well trajectory is intersected with the formation interface.

[0068] If S3 is a three-dimensional seismic plane, it will be a three-dimensional spatial stratigraphic line that coincides with the well trajectory surface, as shown in the attached figure. Figure 3 The section shown is the well trajectory. If it is a stratum line directly interpreted from the 2D seismic section, it is directly combined with the well trajectory. Through the process of this step, a joint display section of the well trajectory and the stratum is formed, as shown in the attached figure. Figure 4 As shown. (Initial two-dimensional stratigraphic interface)

[0069] In step S4, the well logging curve of the pilot well or the adjacent well is used for square wave conversion. The square wave conversion generally adopts the activity method, which is not within the technical scope of the present invention, and there are similar articles in some literatures. The initial formation model is formed by square wave conversion.

[0070] The horizontal direction of the S5 square wave indicates the depth position of the initial stratigraphic model. The seismic horizon is matched with the horizon of the pilot well, as shown in the attached figure. Figure 5 As shown in the figure, L1, L2, and L3 are the positions of the stratum interfaces, and the seismic layers are matched with the stratum interfaces. The corresponding step in the process is S5.

[0071] In step S6, the azimuthal imaging data while drilling is selected to pick up the formation interface, which is generally done manually. Of course, the current patent also has an automatic method, which is not the main technical content of this patent. The position of the formation interface is obtained by using a sinusoidal line method.

[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, True dip, β: the complementary angle of the well inclination, azim: the well inclination azimuth, α: the complementary angle of the apparent dip, The angle between the apparent inclination line and the drilling trajectory.

[0077] Attached Figure 6 Schematic diagram of the relationship between true inclination and apparent inclination.

[0078] In step S8, the true dip angle of the formation calculated in S7 is used to constrain the formation model obtained in S5 with depth matching, so that the formation angle corresponding to the cross-sectional position of the formation model is transformed into the true dip angle. Figure 7 shown.

[0079] In step S9, the square wave depth line formed in step S4 is used as the depth of the stratum subdivision interface, and the stratum line created in the previous step is extended and subdivided to form a subdivided stratum, and the square wave value is assigned to each subdivided stratum (corresponding to step S10) as the attribute value of the stratum model. Thus, the final model is formed, as shown in the attached figure. Figure 8 shown.

[0080] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions 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 comprises: The well trajectory and the formation line are unfolded along the trajectory to obtain a joint display section of the well trajectory and the formation, and the formation interface is obtained; Construct an initial stratigraphic model, match the seismic horizons with the stratigraphic interfaces, and obtain a depth-matched stratigraphic model; The true dip of the formation is calculated, and according to the true dip of the formation, the formation model of depth matching is adjusted so that the formation angle corresponding to the section position of the formation model is transformed into the true dip.

2. The method for constructing a horizontal well formation model according to claim 1, characterized in that: Stratum lines, including: The well trajectory is used to intersect the seismic interpretation plane, and the intersection line obtained is used as the stratigraphic line.

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

4. The method for constructing a horizontal well formation model according to claim 1, characterized in that: Expand the well trajectory and formation line along the trajectory, including: When the seismic plane is a two-dimensional plane, 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: Construct an initial formation model, including: The logging curves of the pilot well or adjacent wells are converted into square waves to form an initial formation model.

6. The method for constructing a horizontal well formation model according to claim 5, characterized in that: Align seismic horizons with stratigraphic interfaces, including: The natural gamma curve of the adjacent well is used for square wave conversion, and the square wave interface at the layer depth position corresponding to the seismic layer is marked, and the position of the marker layer is marked; The depth of the formation interface is matched with the depth of the marker layer position, and the formation interface is translated based on the marker layer position to make the two positions consistent.

7. The method for constructing a horizontal well formation model according to claim 1, characterized in that: Calculate the true dip of the formation, including: Pick up the stratigraphic interface of the azimuthal imaging data while drilling, and specify the stratigraphic layer corresponding to the interface; According to the well trajectory and the picked interface angle and inclination, the true inclination of the corresponding formation is calculated.

8. The method for constructing a horizontal well formation model according to claim 7, characterized in that: According to 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. The specific formula is as follows: ψ=αzim±arccos(tan(α+β) / tan0) Where θ is the true inclination angle, represents the true dip, β represents the complementary angle of the well inclination, azim represents the well inclination azimuth, and α represents the complementary angle of the apparent dip. It represents the angle between the apparent inclination line and the drilling trajectory, and γ is an intermediate variable.

9. The method for constructing a horizontal well formation model according to claim 7, characterized in that: Pick up the stratigraphic interface of the azimuthal imaging data while drilling, and specify the stratigraphic layer corresponding to the interface, including: The position of the formation interface is obtained by using the sine line method.

10. The method for constructing a horizontal well formation model according to claim 1, characterized in that: Also includes: Extend the square wave depth parallel to the formation interface to obtain a parallel formation model with trend, and record the adjacent well depth position of the square wave into the formation; The adjacent well curve value is obtained according to the adjacent well depth, the formation is assigned a value, the formation model is obtained, and the construction of the formation model is completed.

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