Well curve automatic generation method for pre-drilling well

Abstract

The invention provides a method for automatically generating a well curve of a pre-drilled well, and relates to the technical field of drilling exploration and development, the method comprises the following steps: selecting a standard well, and obtaining an MD domain geological stratification, a well curve and a well trajectory of the standard well; the MD domain geological stratification and the well trajectory of the pre-drilled well are obtained; geological layering and well curve indexes are converted into TVD from MD according to well trajectories of the standard well and the pre-drilled well; longitudinal layered section movement, variable-proportion stretching and compression are adopted in the TVD domain, and a well curve of the TVD domain of the pre-drilled well is obtained; carrying out compaction correction on a speed curve and a density curve by utilizing a compaction trend line recovery method under a TVD domain; the well curve of the TVD domain is converted into a well curve of the MD domain, and a pre-drilling well logging curve under the conventional MD index is obtained. According to the method, the pre-drilling curve with high precision and relatively accurate longitudinal direction can be conveniently and quickly obtained, so that quick calculation of three pressures is realized, and the drilling safety is ensured.

Description

Technical Field

[0001] This invention relates to the field of drilling exploration and development technology, and in particular to a method for automatically generating well curves for pre-drilled wells. Background Technology

[0002] Drilling safety is receiving increasing attention, and predicting the three pressures in drilling is a crucial means of ensuring it. This prediction requires logging data from pre-drilled wells, and the timeliness and accuracy of this data directly impact the precision and reliability of the prediction.

[0003] The applicant has discovered that the prior art has at least the following technical problems:

[0004] Due to limitations in current research findings on the target layer and the accuracy of seismic velocity, conventional methods cannot quickly obtain logging curves for pre-drilled wells and the accuracy of logging curves for the entire well section, resulting in an inability to effectively avoid drilling risks. Summary of the Invention

[0005] The purpose of this invention is to provide an automatic method for generating well logging curves for pre-drilled wells, thereby addressing the technical problem in existing technologies where limitations imposed by current research findings on the target layer and the accuracy of seismic velocity result in the inability to quickly obtain well logging curves for pre-drilled wells and insufficient accuracy of well logging curves for the entire well section using conventional methods, thus hindering effective mitigation of drilling risks. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for automatically generating well curves in pre-drilled wells, comprising:

[0008] Select a standard well and obtain the MD domain geological stratification, well curve, and well trajectory of the standard well;

[0009] Obtain the geological stratification and well trajectory of the MD domain in the pre-drilled well;

[0010] Geological stratification and well curve indexing were converted from MD to TVD based on the well trajectories of standard wells and pre-drilled wells;

[0011] In the TVD domain, longitudinal segmented movement, variable-proportion stretching, and compression are used to obtain the well curve of the pre-drilled TVD domain.

[0012] The compaction correction of velocity and density curves was performed using the compaction trend line recovery method under the TVD domain.

[0013] Convert the well curves in the TVD domain to the well curves in the MD domain to obtain the pre-drilling logging curves under the conventional MD index.

[0014] Preferably, the step of converting geological stratification and well curve indexing from MD to TVD based on the well trajectories of standard wells and pre-drilled wells includes:

[0015] The mean angle method is used to convert the geological stratification of the drilled well into TVD stratification and well curves indexed by TVD based on the well trajectory, and the TVD depth geological stratification of the pre-drilled well is obtained.

[0016] Preferably, the step of using the mean angle method to convert the geological stratification of the drilled well into TVD stratification and well curves indexed by TVD based on the well trajectory, and obtaining the TVD depth geological stratification of the pre-drilled well, specifically includes:

[0017] Let the file format on the well trajectory be MD, the inclination angle be θ, and the azimuth angle be β. Using the average angle method and trigonometric functions, the TVD depth at the (n+1)th sampling point, the sounding point Dm, can be expressed by the formula:

[0018]

[0019] TVD m ΔD represents the TVD depth corresponding to the (n+1)th sampling point, in meters; ΔD represents the length between the (n+1)th sampling point and the nth sampling point on the well trajectory, in meters; θ n+1 and θ n Let represent the well inclination angle of the (n+1)th sampling point and the well inclination angle of the nth sampling point, in degrees.

[0020] Preferably, the step of obtaining the well profile of the pre-drilled TVD domain by employing longitudinal segmented movement, variable-scale stretching, and compression within the TVD domain includes:

[0021] Based on the maximum TVD depth of the pre-drilled well, delete the TVD sampling point data below that depth in the converted file.

[0022] Preferably, the step of converting the well curve in the TVD domain to the well curve in the MD domain to obtain the pre-drilling logging curve under the conventional MD index includes:

[0023] The depth index of the well curve of the target well in the TVD domain is converted into the well curve of the MD index using the average angle method, thereby obtaining the target well logging curve under the conventional MD index.

[0024] Preferably, the depth index of the well curve of the pre-drilled well in the TVD domain is converted into the well curve of the MD index using the mean angle method, including the following formula:

[0025]

[0026] Among them, MD n+1 The measurement depth corresponding to the (n+1)th sampling point is represented in meters (m); ΔH n+1The value m represents the difference between the (n+1)th sampling point and the nth sampling point under the TVD depth index; θ n+1 and θ n This represents the well inclination angle of the (n+1)th sampling point and the well inclination angle of the nth sampling point.

[0027] Preferably, the compaction correction of the velocity and density curves using the compaction trend line recovery method under the TVD domain includes:

[0028] In the TVD domain, the difference between the compaction trend line of the standard well's TVD domain velocity or density after longitudinal stretching and compression and the pseudo-compaction trend line is used to perform compaction correction on the corresponding curve of the pre-drilled well.

[0029] Preferably, selecting a standard well and obtaining the MD domain geological stratification, well curve, and well trajectory of the standard well further includes:

[0030] Obtain or generate the mudstone compaction trend line of the standard well.

[0031] The present invention provides an automatic method for generating well curves in pre-drilled wells, comprising: selecting a standard well and obtaining the geological stratification, well curve, and well trajectory of the standard well in the MD domain; obtaining the geological stratification and well trajectory of the pre-drilled well in the MD domain; converting the geological stratification and well curve index from MD to TVD based on the well trajectory of the standard well and the pre-drilled well; obtaining the well curve of the pre-drilled well in the TVD domain by using longitudinal segment movement, variable-scale stretching, and compression; performing compaction correction of velocity and density curves using the compaction trend line recovery method under the TVD domain; and converting the well curve of the TVD domain to the well curve of the MD domain to obtain the pre-drilled well logging curve under the conventional MD index. It features simple data requirements, convenient well curve acquisition, and a simple technical process, making it easy to implement quickly. It also boasts high computational efficiency and reliability, effectively meeting the time-sensitive requirements of drilling. Layer movement and layered stretching and compression within the TVD domain can address variations in formation thickness, enabling rapid compaction correction of velocity and density. The conversion between the MD and TVD domains effectively addresses rapid changes in well trajectories for different well types. Furthermore, it is highly versatile and adaptable, providing convenient and quick access to high-precision and accurate pre-drilling curves, thereby facilitating rapid calculation of the three pressures to ensure drilling safety. Attached Figure Description

[0032] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1This is a flowchart of the method for automatically generating well curves in pre-drilled wells according to the present invention;

[0034] Figure 2 This is a flowchart of the method for automatically generating well curves in pre-drilled wells according to the present invention;

[0035] Figure 3 This is a schematic diagram of the stretching and compression of a standard well and a pre-drilled well in the automatic well curve generation method of the pre-drilled well of the present invention;

[0036] Figure 4 This is a comparison diagram of the well curves of the standard well and the pre-drilled well in the TVD domain of the automatic generation method of well curves for pre-drilled wells in this invention.

[0037] Figure 5 This is a comparison diagram of the well curves of the standard well and the pre-drilled well in the MD domain of the automatic generation method of well curves for pre-drilled wells in this invention.

[0038] Figure 6 This is a comparison chart of the generated curve and the measured curve in the automatic well curve generation method of the pre-drilled well of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] Figure 1 This is a flowchart of the method for automatically generating well curves in pre-drilled wells according to the present invention, as shown below. Figure 1 As shown, this invention provides an automatic method for generating well curves in pre-drilled wells, which solves the problem of conveniently and quickly obtaining pre-drilled well curves with high longitudinal precision and accuracy, thereby enabling rapid calculation of the three pressures. The automatic method for generating well curves in pre-drilled wells includes the following steps:

[0041] S101: Select a standard well and obtain the geological stratification, well curve, and well trajectory of the standard well in the MD (measured depth) domain;

[0042] S102: Obtain the geological stratification and well trajectory of the MD domain of the pre-drilled well;

[0043] S103: Based on the well trajectories of standard wells and pre-drilled wells, convert the geological stratification and well curve index from MD to TVD (truevertical depth);

[0044] S104: In the TVD domain, longitudinal segmented movement, variable-proportion stretching and compression are used to obtain the well curve of the pre-drilled TVD domain;

[0045] S105: Compaction correction of velocity and density curves is performed using the compaction trend line recovery method under the TVD domain.

[0046] S106: Convert the well curve in the TVD domain to the well curve in the MD domain to obtain the pre-drilling logging curve under the conventional MD index.

[0047] This pre-drilling well curve automatic generation method features simple data requirements, convenient well curve acquisition, simple technical process, and easy and rapid implementation. At the same time, it is computationally efficient and highly reliable, which can better meet the high timeliness requirements of drilling. The segment movement and layer stretching and compression in the TVD domain can solve the changes in formation thickness, and can quickly realize the compaction correction of velocity and density. The mutual conversion between the MD domain and the TVD domain effectively solves the rapid changes in well trajectory of different well types. It is also highly versatile and adaptable, and can conveniently and quickly obtain pre-drilling curves with high vertical accuracy and relatively accurate results, thereby realizing the rapid calculation of three pressures to ensure drilling safety.

[0048] Specifically, Figure 2 This is a flowchart of the method for automatically generating well curves in pre-drilled wells according to this embodiment, as shown below. Figure 2 As shown, step S101: Select a standard well and obtain the MD domain geological stratification, well curve and well trajectory of the standard well; step S102: Obtain the MD domain geological stratification and well trajectory of the pre-drilled well to prepare basic data.

[0049] In the basic data preparation stage, preferably, wells with relatively complete vertical curves in the study area are selected as standard wells; if possible, vertical wells or low-angle directional wells should be selected. The MD geological stratification, well trajectory, and MD logging curves of the standard wells are obtained, and the mudstone compaction trend lines of the standard wells are collected or generated.

[0050] Step S103: Convert the geological stratification and well curve index from MD to TVD based on the well trajectory of the standard well and the pre-drilled well. This includes: using the mean angle method to convert the geological stratification of the drilled well into TVD stratification and well curve indexed by TVD based on the well trajectory, and obtaining the TVD depth geological stratification of the pre-drilled well.

[0051] Specifically, in this embodiment, the file format on the well trajectory is MD, the inclination angle is θ, and the azimuth angle is β. Using the average angle method and trigonometric functions, the (n+1)th sampling point and the depth D are... m The TVD depth at a point can be expressed by the formula:

[0052]

[0053] Among them, TVD m represents the TVD depth corresponding to the (n + 1)-th sampling point, in meters; ΔD represents the length between the (n + 1)-th sampling point and the n-th sampling point on the well trajectory, in meters; θ n+1 and θ n represent the well inclination angles of the (n + 1)-th sampling point and the n-th sampling point, in degrees.

[0054] According to the well trajectories of the standard well and the predicted well, the geological stratifications and well curve indexes are converted from MD depth to TVD depth. After comparison, the depth conversion error is about one ten-thousandth.

[0055] Step S104: Adopt longitudinal stratified section movement, variable ratio stretching and compression in the TVD domain to obtain the well curve in the TVD domain of the pre-drilled well; including: according to the maximum TVD depth of the pre-drilled well, delete the TVD sampling point data below this depth in the converted file.

[0056] Assume that the geological stratifications from top to bottom are T0, T1, T2, T3, …, Tn, Tm, the TVD depths of the geological stratifications of the standard well from top to bottom are a, b, c, d, …, n, m, and the corresponding geological stratifications of the pre-drilled well are a1, b1, c1, d1, …, n1, m1. The stratification comparison is shown in Table 1.

[0057] Table 1 Comparison Table of Geological Stratification (TVD) Depths of Standard Well and Predicted Well

[0058]

[0059] Then, the mapping relationship formula between the well curve corresponding to different depths TVD1 of the pre-drilled well and the standard well in the TVD domain can be expressed as:

[0060] When 0 < TVD <= a, then for the predicted well:

[0061]

[0062] When a < TVD <= b, then for the predicted well:

[0063]

[0064] When b < TVD <= c, then for the predicted well:

[0065]

[0066] [[ID=|45]]When c < TVD <= d, then for the predicted well:

[0067]

[0068] When m < TVD <= n, then for the predicted well:

[0069]

[0070] When n < TVD, then for the predicted well:

[0071]

[0072] Where, TVD1 is the vertical depth corresponding to the pre-drilled well, in meters; a, b, c, d,..., n, m are the vertical depths corresponding to the geological stratifications T0, T1, T2, T3,..., Tn, Tm of the standard well stratification, in meters; a1, b1, c1, d1,..., n1, m1 are the vertical depths corresponding to the geological stratifications T0, T1, T2, T3,..., Tn, Tm of the pre-drilled well, in meters; TVD is the vertical depth of the standard well, in meters.

[0073] Finally, according to the maximum vertical depth value of the pre-drilled well, delete the TVD sampling point data below its depth in the converted file.

[0074] Step S105: Perform compaction correction on the velocity and density curves using the compaction trend line restoration method in the TVD domain, including: In the TVD domain, perform compaction correction on the corresponding curves of the pre-drilled well using the difference between the pseudo-compaction trend line after vertical stretching and compression of the compaction trend line of the velocity or density in the TVD domain of the standard well.

[0075] In theory, for a basin or a block with the same compaction trend line of velocity and density, the compaction correction of the velocity and density curves can be achieved using the compaction trend line restoration method in the TVD domain, that is:

[0076] DEN 校 = DEN + (Trend_DEN 标准 - Trend_DEN 预钻井 ) (Formula 8)

[0077] Where, DEN 校 is the density after compaction correction in the TVD domain, g / cm 3 ; DEN is the density in the TVD domain generated by stretching and compression in the previous steps, g / cm 3 ; Trend_DEN 标准 is the density compaction trend line of the standard well, g / cm 3 ; Trend_DEN 标准 is the pseudo-density compaction trend line of the TVD domain of the pre-drilled well generated by stretching and compression of the density compaction trend line of the TVD domain of the standard well, g / cm 3 .

[0078] Similarly, the compaction correction of velocity or acoustic travel time can be achieved.

[0079] Step S106: Convert the well curve in the TVD domain to the well curve in the MD domain to obtain the pre-drilling logging curve under the conventional MD index, including: converting the depth index of the well curve of the target well in the TVD domain to the well curve of the MD index using the average angle method, thereby obtaining the logging curve of the target well under the conventional MD index.

[0080] In the TVD domain, using the mean angle method and trigonometric functions, the formula is:

[0081]

[0082] Among them, MD n+1 The measurement depth corresponding to the (n+1)th sampling point is represented in meters (m); ΔH n+1 The value m represents the difference between the (n+1)th sampling point and the nth sampling point under the TVD depth index; θ n+1 and θ n This represents the well inclination angle of the (n+1)th sampling point and the well inclination angle of the nth sampling point.

[0083] By converting the TVD depth index to the MD depth index, well curves at common measurement depths (MD) are obtained, thus achieving rapid and automatic generation of pre-drilling curves. The depth conversion error is approximately one ten-thousandth.

[0084] This embodiment takes the automatic generation method of well curves for pre-drilled wells as an example in the three-pressure prediction process of a certain block in the Bohai Sea. The application of the automatic generation technology of well curves for prediction wells is described in detail below:

[0085] Well X2, which has a relatively complete vertical curve, was selected as the standard well. If possible, vertical wells or directional wells with a small inclination were selected. Geological stratification, well curves and well trajectories of the conventional MD domain of X2 were collected, as well as geological stratification and well trajectory of the target well X21. The stratification comparison is shown in Table 2.

[0086] Table 2 Geological Stratification of Standard Wells and Predicted Wells (MD)

[0087] Layering Standard Well (MD) Predictive wells (MD) T1 1515 1985 T2 1733 2384 T3 2230 2905 T4 2465 3235 T5 2670 3525 Tm 2780 3660 Tn 2954 3708

[0088] Using Formula 1, well layers at MD depth are converted into well layers and curves at TVD depth, as shown in Table 3. Alternatively, existing software can be used to output well curve files with TVD depth indexes.

[0089] Table 3 Geological Stratification of Standard Wells and Predicted Wells (TVD)

[0090] Layering Standard well (TVD) TVD (Predictive Well) T1 1515 1521 T2 1733 1784 T3 2230 2171 T4 2465 2448 T5 2670 2688 Tm 27980 2802 Tn 2954 2843

[0091] By developing a small program, this method utilizes depth-based conditional judgments to process and transform the depth of TVD index sampling points in well curves using formulas 1 to 7 at the TVD depth. It also performs different depth-based scaling processing on well curves of different vertical segments, as illustrated in the diagram. Figure 3 As shown; based on the maximum TVD depth of pre-drilled well X21 being 2868m, the TVD sampling point data below the depth of 2868m in the file were deleted to obtain the well curve of the TVD domain of well X21.

[0092] Comparison of well curves and benchmark well curves within the TVD domain, for example Figure 4 As shown in the figure, the curves have similar shapes and unchanged value ranges; the depth index comparison of the obtained well curve files is shown in Table 4.

[0093] Table 4 Comparison of Depth Index Changes After Variable Scaling Conversion of Vertical Segments in TVD Domain

[0094]

[0095] As can be seen from Table 4, the numerical values ​​of the curves remain unchanged, while the depth and sampling rate of the original sampling points change between different layers.

[0096] The well logging curves under the MD index are obtained by transforming using Formula 8, as follows: Figure 5 As shown. A comparison is made between the wellbore curves for MD depth obtained using the above techniques and the measured curves. Figure 6 As shown.

[0097] The above methods can easily form programs to quickly and automatically generate well curves for pre-drilling and conveniently calculate the three pressures, etc.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for automatically generating well curves in pre-drilled wells, characterized in that, include: Select a standard well and obtain the MD domain geological stratification, well curve, and well trajectory of the standard well; Obtain the geological stratification and well trajectory of the MD domain in the pre-drilled well; Based on the well trajectories of the standard wells and the pre-drilled wells, the geological stratification and well curve indexes are converted from MD to TVD; In the TVD domain, longitudinal segmented movement, variable-proportion stretching, and compression are used to obtain the well curve of the pre-drilled TVD domain. The compaction correction of velocity and density curves was performed using the compaction trend line recovery method under the TVD domain. Convert the well curves in the TVD domain to the well curves in the MD domain to obtain the pre-drilling logging curves under the conventional MD index.

2. The method for automatically generating well curves in pre-drilled wells according to claim 1, characterized in that: The process of converting geological stratification and well curve indexing from MD to TVD based on the well trajectories of standard wells and pre-drilled wells includes: The mean angle method is used to convert the geological stratification of the drilled well into TVD stratification and well curves indexed by TVD based on the well trajectory, and the TVD depth geological stratification of the pre-drilled well is obtained.

3. The method for automatically generating well curves in pre-drilled wells according to claim 2, characterized in that: The method of using the mean angle method to convert the geological stratification of the drilled well into TVD stratification and well curves indexed by TVD based on the well trajectory, and to obtain the TVD depth geological stratification of the pre-drilled well, specifically includes: Let the file format on the well trajectory be MD, the inclination angle be θ, and the azimuth angle be β. Using the average angle method and trigonometric functions, the TVD depth at the (n+1)th sampling point, the sounding point Dm, can be expressed by the formula: TVD m ΔD represents the TVD depth corresponding to the (n+1)th sampling point, in meters; ΔD represents the length between the (n+1)th sampling point and the nth sampling point on the well trajectory, in meters; θ n+1 and θ n Let represent the well inclination angle of the (n+1)th sampling point and the well inclination angle of the nth sampling point, in degrees.

4. The method for automatically generating well curves in pre-drilled wells according to any one of claims 1-3, characterized in that: The method of obtaining the well profile of the pre-drilled TVD domain by employing longitudinal segmented movement, variable-scale stretching, and compression within the TVD domain includes: Based on the maximum TVD depth of the pre-drilled well, delete the TVD sampling point data below that depth in the converted file.

5. The method for automatically generating well curves in pre-drilled wells according to claim 4, characterized in that: The process of converting well curves in the TVD domain to well curves in the MD domain to obtain pre-drilling logging curves under a conventional MD index includes: The depth index of the well curve of the target well in the TVD domain is converted into the well curve of the MD index using the average angle method, thereby obtaining the target well logging curve under the conventional MD index.

6. The method for automatically generating well curves in pre-drilled wells according to claim 5, characterized in that: The depth index of the well curves of pre-drilled wells in the TVD domain is converted to the MD index well curves using the mean angle method, including the following formula: Among them, MD n+1 The measurement depth corresponding to the (n+1)th sampling point is represented in meters (m); ΔH n+1 The value m represents the difference between the (n+1)th sampling point and the nth sampling point under the TVD depth index; θ n+1 and θ n This represents the well inclination angle of the (n+1)th sampling point and the well inclination angle of the nth sampling point.

7. A method for automatically generating well curves in pre-drilled wells according to any one of claims 1-3, characterized in that: The compaction correction of velocity and density curves using the compaction trend line recovery method under the TVD domain includes: In the TVD domain, the difference between the compaction trend line of the standard well's TVD domain velocity or density after longitudinal stretching and compression and the pseudo-compaction trend line is used to perform compaction correction on the corresponding curve of the pre-drilled well.

8. A method for automatically generating well curves in pre-drilled wells according to any one of claims 1-3, characterized in that: Selecting a standard well and obtaining its MD domain geological stratification, well curves, and well trajectory, the method also includes: Obtain or generate the mudstone compaction trend line of the standard well.

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