A method for seismic calibration in horizontal wells while drilling

Abstract

The present invention relates to a well seismic calibration method during the drilling process of a horizontal well, and belongs to the technical field of seismic data interpretation. The specific steps are as follows: main data preparation work; performing time-depth conversion to clarify the structural absolute error value of each marker layer; obtaining the error grid of the layer-by-layer velocity field of each marker layer segment; correcting the layer-by-layer velocity field of each marker layer, and then performing three-dimensional spatial interpolation to obtain a new velocity field as the stacking velocity, performing projection comparative analysis, and clarifying the structural absolute error value of each upper stable marker layer; continuously correcting the interlayer velocity by comparing and obtaining the velocity error of each marker layer, and using the corrected velocity field to extract the velocity curve for well seismic calibration, so that the correlation coefficient after well seismic calibration gradually increases and reaches the target value and meets the structural relative error standard value, and the spatial position in the target layer can be finally obtained. This well seismic calibration method significantly improves the prediction accuracy and work efficiency of target entry.

Description

Technical Field

[0001] The invention relates to a well seismic calibration method in a horizontal well while drilling process, and belongs to the technical field of seismic data interpretation. Background Art

[0002] A horizontal well is a well with an inclination greater than 80° and a horizontal displacement greater than 10 times the target layer thickness when drilling into the target layer. It effectively increases the length of oil and gas layers encountered and the volume of oil and gas supplied after subsequent fracturing, thereby improving oil and gas recovery and becoming an effective means of increasing production. Geosteering technology is a technique for monitoring and controlling wellbore trajectory based on the establishment of a geological model using 3D seismic data, using logging-while-drilling technology, and combining it with engineering techniques such as logging and drilling. It integrates 3D seismic data, reservoir geology, logging, engineering technology, and computers to ensure that the actual wellbore penetrates the reservoir and is located at the optimal position within the oil and gas layer, thereby maximizing the oil and gas layer encounter rate in the horizontal section and ensuring subsequent development benefits. Geosteering technology originally belonged to the field of drilling, mainly using the measurement of engineering parameters such as well inclination, azimuth, and torque while drilling to ensure the construction process of horizontal wellbore trajectory. With the continuous development and integration of 3D seismic prediction technology, drilling, and logging technology, especially since the 1990s, the gradual update and iteration of drilling instruments such as MWD, LWD, and rotary steering, the lithology, oil content, trajectory and other parameters of the drilled formation can be recorded in a timely manner during the drilling process. How to combine these parameters with 3D seismic data for in-depth application, guide the optimization and adjustment of the trajectory during horizontal well drilling, and maximize the horizontal well reservoir drilling rate is the research background of this invention. Summary of the Invention

[0003] In order to solve the above-mentioned problems existing in the prior art, the present invention discloses a method for well seismic calibration during the drilling process of a horizontal well. The method can realize the in-depth application of geological data, establish a well-seismic correspondence in combination with three-dimensional seismic data, and solve the spatial projection of the trajectory on the three-dimensional seismic data, so as to predict the bottom hole drilling adjustment plan in advance and ensure that the trajectory of the horizontal well penetrates the effective reservoir to the maximum extent. This seismic geological guidance mode and method significantly improves the prediction accuracy and work efficiency of horizontal well targeting, and can effectively guide the trajectory optimization and adjustment work during the drilling process of the horizontal well. This work is directly related to whether the horizontal well can achieve the design purpose and the level of the horizontal well production capacity in the later stage.

[0004] To achieve the goal of using 3D seismic data to guide horizontal well optimization during drilling, the present invention adopts a technical solution: a wellbore seismic calibration method during drilling of a horizontal well, the specific steps of which are as follows:

[0005] Step 1: Prepare the main data before the horizontal well is drilled;

[0006] Step 2: Before entering the target, the time domain data volume is converted by stacking the velocity field to obtain a 3D seismic data volume in the depth domain, and the absolute structural error values ​​of each marker layer in the drilling horizontal well and adjacent wells are determined;

[0007] Step 3: Calculate the error grid of the along-layer velocity field of each marker layer segment using the time horizon of each marker layer in the 3D seismic time domain data volume and the absolute error value of each layer structure obtained in step 2;

[0008] Step 4: Using the error grid of the along-layer velocity field of each marker layer obtained in step 3, the along-layer velocity field of each marker layer obtained from the stacking velocity field corresponding to the 3D seismic data volume is corrected to obtain the corrected along-layer velocity field of each marker layer;

[0009] Step 5: Use the velocity fields of each marker layer corrected in step 4 to perform three-dimensional spatial interpolation to obtain a new velocity field as the stacking velocity, and perform time-depth conversion on the 3D seismic time domain data volume to convert it into a 3D seismic data volume in the depth domain;

[0010] Step 6: Perform projection comparison analysis on the depth domain 3D seismic data volume obtained in step 5 for the well being drilled, analyze the degree of consistency between the horizontal well being drilled and the adjacent wells and the structural and seismic profile reflection characteristics, and determine the absolute structural error values ​​of each upper marker layer;

[0011] Step 7: Repeat steps 3 to 5, and continuously correct the interlayer velocity between the horizontal well being drilled and the adjacent wells by comparing and obtaining the velocity errors of each marker layer. Use the corrected velocity field to extract the velocity curve as the velocity of the horizontal well being drilled, and perform well-seismic calibration on the time domain data volume. The correlation coefficient after well-seismic calibration is gradually improved and reaches the target value, gradually conforming to the geological and seismic understanding and meeting the standard value of structural relative error. Finally, the spatial position of the horizontal well being drilled in the target layer can be obtained.

[0012] Furthermore, in step 1, the main data preparation before the horizontal well enters the target includes understanding the logging instruments and zero length of the drilling equipment; collecting the altitude, logging, mud recording, 3D seismic time domain data volume, and stacked velocity field corresponding to the 3D seismic data volume of all adjacent wells in the drilling area of ​​the horizontal well being drilled, laying a data foundation for subsequent analysis.

[0013] In step 2, the horizontal well being drilled and the adjacent wells are projected and compared on the depth domain 3D seismic data volume. The purpose of comparing and analyzing the degree of agreement between the trajectory of the actual horizontal well and the structural and seismic profile reflection characteristics is to obtain the structural absolute error value of each marker layer.

[0014] Furthermore, in step 7, the target value of the correlation coefficient must be at least greater than 0.8.

[0015] Furthermore, in step 7, the relative error standard value is less than 1‰.

[0016] In step 7, the spatial position of the horizontal well in the target layer is finally obtained. Combined with the spatial position prediction and timely adjustment of the well inclination, a basis is provided for trajectory optimization and the well trajectory drilling plan is optimized. Through continuous correction, the consistency between the designed trajectory and the actual drilling results is ensured, so that the effective reservoir is always drilled and the reservoir drilling rate is guaranteed.

[0017] The present invention discloses a method for well seismic calibration during the drilling process of a horizontal well. The method has the beneficial effect of fully combining the actual drilling curve and the results of 3D seismic data processing and interpretation, for the first time considering the introduction of the vertical and horizontal resolutions of 3D seismic data into the horizontal well steering technology while drilling, combining key parameters such as seismic interpretation and drilling data, and establishing a method for well seismic calibration during the drilling process of a horizontal well. This method can achieve in-depth application of geological and seismic data, establish a well-seismic relationship in combination with 3D seismic data, solve the spatial projection position of the trajectory of the drilling horizontal well in the target layer of the 3D seismic data, combine the spatial position prediction and timely adjust the well inclination, provide a basis for trajectory optimization, optimize the well trajectory drilling plan, and ensure that the trajectory of the horizontal well penetrates the effective reservoir to the maximum extent. This method significantly improves the prediction accuracy and work efficiency of the horizontal well entering the target, and can effectively guide the trajectory optimization and adjustment work during the drilling of the horizontal well. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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 any creative labor.

[0019] Figure 1 The figure shows the vertical depth comparison analysis with the adjacent well Y56-1;

[0020] Figure 2 Shown is the along-layer velocity error grid diagram for wells such as Y22-8-3;

[0021] Figure 3 Shown is the synthetic seismic record section and correlation coefficient diagram of Y22-8-3 well;

[0022] Figure 4 The figure shows the seismic profile of the well Y22-8-3 after synthetic record calibration and superposition of the well trajectory;

[0023] Figure 5 Shown is a comparison chart of the actual measurement of Y22-8-3 well (black) and the calculation and calibration using this method (blue). Specific implementation methods

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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 only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Because horizontal well logging while drilling (LWD) data only includes natural gamma, resistivity, and well trajectory data, but no acoustic time difference curves, the key to ensuring the reservoir encounter rate of horizontal wells is to relatively accurately establish a well-seismic relationship by combining 3D seismic data and accurately determine the spatial projection position of the trajectory on 3D seismic data. This allows for early prediction and formulation of downhole drilling adjustment plans to ensure that the horizontal well trajectory penetrates the effective reservoir to the greatest extent possible. This method provides a relatively accurate method for determining the spatial projection position of the horizontal well trajectory on 3D seismic data.

[0026] In order to further understand the content of the present invention, the present invention is further described below in conjunction with specific implementation methods.

[0027] Unless otherwise specified, the methods used in the following examples are all conventional methods. Specific embodiments of the present invention are further described in detail below with reference to the flow charts.

[0028] Example 1: Taking the Y22-8-3 horizontal well implemented in a certain work area as an example, the application effect of the well seismic calibration method in the horizontal well while drilling process is described in detail.

[0029] like Figures 1 to 5 As shown, this embodiment provides a method for well seismic calibration during drilling of a horizontal well, and the specific steps are as follows:

[0030] Step 1: Main data preparation before horizontal well drilling: Understand the logging instruments and zero length of the drilling equipment; collect the elevation, well logging, mud logging, 3D seismic time domain data volume, and stacked velocity field corresponding to the 3D seismic data volume of all adjacent wells in the drilling area of ​​the horizontal well being drilled;

[0031] Step 2: If Figure 1Comparative analysis with the adjacent well Y56-1 clarified the actual formation position of the adjacent well drilled at the bottom of the well. Through comparative analysis, it is believed that when the vertical depth of Well Y22-8-3 was 2682m (the inclined depth was 2853m), it was equivalent to the vertical depth of Well Y56-1 being encountered at 2674m. After comparison, it was found that the absolute structural error value of the first marker layer closest to the vertical depth of 2682m in the upper part of Well Y22-8-3 was 1.65m.

[0032] Step 3: If Figure 2 As shown in the figure, combined with the actual drilling results of Well Y22-8-3, the interval velocity error of the first marker layer in the upper part of Well Y22-8-3 closest to the vertical depth of 2682m is obtained. The obtained interval velocity error is used to re-establish the velocity error grid of adjacent wells such as Well Y56-1 and Well Y22-8-3.

[0033] Step 4: Using the error grid of the along-layer velocity field of each marker layer obtained in step 3, the along-layer velocity field of each marker layer obtained from the stacking velocity field corresponding to the 3D seismic data volume is corrected to obtain the corrected along-layer velocity field of each marker layer. The corrected velocity field can further improve the accuracy of along-layer velocity due to the addition of actual drilling results.

[0034] Step 5: Use the velocity fields of each marker layer corrected in step 4 to perform three-dimensional spatial interpolation to obtain a new velocity field as the stacking velocity, and perform time-depth conversion on the 3D seismic time domain data volume to convert it into a 3D seismic data volume in the depth domain;

[0035] Step 6: Perform projection comparison analysis on the depth domain 3D seismic data volume obtained in step 5 for the well being drilled, analyze the degree of consistency between the horizontal well being drilled and the adjacent wells and the structural and seismic profile reflection characteristics, and determine the absolute structural error values ​​of each upper marker layer;

[0036] Step 7: Figure 4 As shown in the figure, repeat steps 3 to 5, and continuously correct the interlayer velocity between the horizontal well being drilled and the adjacent wells by comparing and obtaining the velocity errors of each marker layer. Use the corrected velocity field to extract the velocity curve as the velocity of the horizontal well being drilled, and perform well-seismic calibration on the time domain data volume, so that the correlation coefficient after well-seismic calibration is greater than 0.8, as shown in the figure. Figure 3 As shown in the figure, it gradually conforms to the geological and seismic understanding and the standard value of the structural relative error is less than 1‰. At this time, it is considered that the interlayer velocity is reasonable, the structural error of the depth domain data volume is the smallest, and it is closest to the actual underground form. The spatial position of the drilling horizontal well in the target layer can be finally obtained. Combined with the spatial position prediction, the well inclination angle is adjusted in time, the well trajectory drilling plan is optimized, and a basis for trajectory optimization is provided; through continuous correction, the consistency of the designed trajectory and the actual drilling results is guaranteed, as shown in the figure. Figure 5 As shown, it is possible to always drill into effective reservoirs and ensure the reservoir drilling rate.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for seismic calibration during drilling of a horizontal well, characterized in that: The following steps are involved: Step 1: Prepare the main data before the horizontal well is drilled; Step 2: Before entering the target, the time domain data volume is converted by stacking the velocity field to obtain a 3D seismic data volume in the depth domain, and the absolute structural error values ​​of each marker layer of the drilling horizontal well and adjacent wells are determined; Step 3: Calculate the error grid of the along-layer velocity field of each marker layer segment by using the time horizon of each marker layer in the 3D seismic time domain data volume and the absolute error value of each marker layer structure obtained in step 2; Step 4: Using the error grid of the along-layer velocity field of each marker layer obtained in step 3, the along-layer velocity field of each marker layer obtained from the stacking velocity field corresponding to the 3D seismic data volume is corrected to obtain the corrected along-layer velocity field of each marker layer; Step 5: Use the velocity fields of each marker layer corrected in step 4 to perform three-dimensional spatial interpolation to obtain a new velocity field as the stacking velocity, and perform time-depth conversion on the 3D seismic time domain data volume to convert it into a 3D seismic data volume in the depth domain; Step 6: Perform projection comparison analysis on the depth domain 3D seismic data volume obtained in step 5 of the well being drilled to clarify the absolute structural error values ​​of each upper marker layer; Step 7: Repeat steps 3 to 5, and continuously correct the interlayer velocity between the horizontal well being drilled and the adjacent wells by comparing and obtaining the velocity errors of each marker layer. Use the corrected velocity field to extract the velocity curve as the velocity of the horizontal well being drilled, and perform well-seismic calibration on the time domain data volume. The correlation coefficient after well-seismic calibration is gradually improved and reaches the target value, gradually conforming to the geological and seismic understanding and meeting the standard value of structural relative error. Finally, the spatial position of the horizontal well being drilled in the target layer is obtained.

2. The method for seismic calibration of a horizontal well while drilling according to claim 1, characterized in that: In step 1, the main data preparation before the horizontal well is drilled includes understanding the logging instruments and zero length of the drilling equipment; collecting the elevation, logging, mud logging, 3D seismic time domain data volume, and stacked velocity field corresponding to the 3D seismic data volume of all adjacent wells in the drilling area of ​​the horizontal well being drilled.

3. The method for seismic calibration of a horizontal well while drilling according to claim 1, wherein: In step 2, the method for obtaining the structural absolute error value of each marker layer of the currently drilled horizontal well and the adjacent wells is to perform projection comparative analysis on the currently drilled horizontal well and the adjacent wells on the three-dimensional seismic data volume in the depth domain, analyze the degree of consistency between the currently drilled horizontal well and the adjacent wells and the structural and seismic profile reflection characteristics, and thus obtain the structural absolute error value of each marker layer.

4. The method for seismic calibration of a horizontal well while drilling according to claim 1, wherein: In step 6, the projection comparison analysis is based on the degree of consistency between the drilling horizontal well and the adjacent wells and the structural and seismic profile reflection characteristics, thereby obtaining the structural absolute error values ​​of the upper marker layers.

5. The method for seismic calibration of a horizontal well while drilling according to claim 1, wherein: In step 7, the target value of the correlation coefficient must be at least greater than 0.

8.

6. The method for seismic calibration of a horizontal well while drilling according to claim 1, wherein: In step 7, the relative error standard value is less than 1‰.

7. The method for seismic calibration of a horizontal well while drilling according to claim 1, wherein: In step 7, the spatial position of the horizontal well in the target layer is finally determined. Combined with the spatial position prediction and timely adjustment of the well inclination, this provides a basis for trajectory optimization and optimizes the well trajectory drilling plan. Through continuous correction, the consistency of the designed trajectory and the actual drilling results is ensured.

8. The method for well seismic calibration during drilling of a horizontal well according to claim 5, characterized in that: The correlation coefficient is 0.9.

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