A Multi-Dimensional Geological Steering Method for Horizontal Wells in Medium-Deep Coalbed Methane Formations

Abstract

This invention discloses a multi-dimensional geological steering method for horizontal wells in medium-deep coalbed methane formations, comprising the following steps: S1 establishing a three-dimensional seismic-geological model of the marker layer and the target coal seam; S2 determining the well inclination angle of each marker layer encountered; S3 predicting the depth, thickness, dip angle, and spatial distribution characteristics of the target coal seam; S4 using a layer-by-layer approximation method to ensure accurate target entry of the horizontal well; S5 comprehensively analyzing horizontal section data to ensure a high drilling success rate; S6 adjusting and optimizing the model. This invention is applicable to the field of coalbed methane development technology. It adopts a layer-by-layer approximation control technique for the well inclination angle of the marker layer to quantitatively determine the optimal well inclination angle for each marker layer. During actual drilling, geological steering personnel only need to determine whether the well inclination angle meets the design when each marker layer is encountered, simplifying the analysis content and steps, saving analysis time when there is a large deviation from the designed marker layer depth, and improving drilling efficiency.

Description

Technical Field

[0001] This invention belongs to the field of coalbed methane development technology, specifically a multi-dimensional geological steering method for horizontal wells in medium-deep coalbed methane formations. Background Technology

[0002] Medium-deep coalbed methane refers to unconventional natural gas, primarily composed of methane, that exists at depths of 1200–1800 meters, mainly in the form of adsorption on the surface of coal matrix particles. China possesses enormous medium-deep coalbed methane resources, estimated at 25 trillion cubic meters. Currently, the main development technology combines high-drill-rate horizontal well drilling with large-scale volumetric fracturing, with the high-drill-rate horizontal well drilling technology laying the foundation for the commercial development of medium-deep coalbed methane resources.

[0003] High-exposure-rate horizontal well drilling technology aims to ensure a high success rate in drilling the target coal seam. It employs horizontal well drilling geological steering technology to create horizontal wells within the target coal seam that conform to the drilling geological and engineering design. For example, the invention patent CN105740639A, published on July 6, 2016, entitled "A Three-Dimensional Geological Steering Method for Horizontal Wells," designs a three-dimensional geological steering method for horizontal wells. This patent utilizes parameters such as three-dimensional spatial stratigraphic correlation, sedimentary microfacies analysis, drilling parameter tracking and evaluation, and geological model optimization to achieve a shift from qualitative geological steering to semi-quantitative geological steering, maximizing the achievement of the horizontal well drilling objectives. However, the geological model is mainly based on the stratigraphic information revealed by the scattered drilled wells. The changes in geological characteristics between wells are only qualitatively analyzed and evaluated based on sedimentary microfacies analysis technology. This results in a large number of ambiguities and uncertainties, making it impossible to accurately predict the actual changes in the three-dimensional spatial depth, thickness, dip angle, and spatial distribution characteristics of the target layer. This makes it impossible to provide early warning prompts to geological guidance personnel so as to adjust the well trajectory in advance to achieve the drilling objectives, resulting in significant technical limitations. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-dimensional geological steering method for horizontal wells in medium-deep coalbed methane formations.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A multi-dimensional geological steering method for horizontal wells in medium-deep coalbed methane formations includes the following steps:

[0007] S1 Establish a three-dimensional seismic-geological model of the marker layer and the target coal seam;

[0008] S2 determines the well inclination angle of each marker layer encountered during drilling;

[0009] S3 predicts the depth, thickness, dip angle, and spatial distribution characteristics of the target coal seam;

[0010] S4 employs a layer-by-layer approximation method to ensure accurate target entry of horizontal wells;

[0011] S5 comprehensive analysis of horizontal segment data ensures a high drilling success rate;

[0012] S6 Adjustment and Optimization Model.

[0013] Preferably, step S1 specifically includes:

[0014] Based on 3D seismic data and adjacent well drilling data, multiple stratigraphic correlation framework profiles of the target area are first established to identify stable and well-developed marker layers in the target area. Then, synthetic record calibration technology is used to calibrate the marker layers to the 3D seismic data, identify the seismic reflection phase axes corresponding to each marker layer, and establish a 3D seismic-geological model of the marker layers and the target coal seam.

[0015] Preferably, step S2 specifically includes:

[0016] The design horizontal well trajectory data is imported into the 3D seismic data. The well inclination angle of each marker layer encountered by the design horizontal well trajectory is determined layer by layer from deep to shallow, and the depth of each marker layer is predicted to ensure that the horizontal well successfully enters the target coal seam at the designed well inclination angle.

[0017] Preferably, step S3 specifically includes:

[0018] Along the designed horizontal wellbore trajectory, the phase axis of the calibrated target coal seam is laterally traced and interpreted in the 3D seismic data. The depth and thickness of the target coal seam along the horizontal wellbore trajectory are predicted at certain intervals. Potential local anomalies are identified, control points for the horizontal section are determined, the dip angle of each section of the target coal seam is calculated, the three-dimensional spatial distribution characteristics of the target coal seam are finely depicted, and wellbore trajectory adjustment measures are formulated in advance.

[0019] Preferably, step S4 specifically includes:

[0020] S41 uses logging cuttings data, gas logging data, measurement while drilling data and adjacent well data to determine the current drilling formation in real time, compares and analyzes the deviation between the actual drilling inclination angle and the designed well inclination angle of each marker layer, and formulates a wellbore trajectory adjustment plan.

[0021] If the actual drilling inclination angle is less than the designed inclination angle, increase the wellbore build-up rate to ensure that the inclination angle of the next marker layer meets the designed inclination angle.

[0022] If the actual drilling inclination angle is equal to the designed well inclination angle, then continue drilling according to the designed wellbore build-up rate;

[0023] If the actual drilling inclination angle is greater than the designed inclination angle, the wellbore build-up rate should be adjusted appropriately according to the predicted vertical thickness between the upper and lower marker layers to avoid the drilling failure caused by an excessively large inclination angle when encountering the next marker layer.

[0024] S42 adopts the method of step S41, comparing and analyzing layer by layer from shallow to deep, and adjusting the wellbore trajectory in real time to gradually approach the target coal seam to ensure accurate target entry.

[0025] Preferably, step S5 specifically includes:

[0026] Based on the coal seam structure, coal seam GR, coal seam interbedded GR, and roof and floor GR characteristics of the target coal seam in the adjacent well, S51 combines the upper and lower gamma data measured during drilling, cuttings data, gas logging data, and drilling time data to comprehensively analyze and determine the current coal seam location of the drill bit.

[0027] S52 comparative analysis examines the deviation between the predicted coal seam dip angle and the actual drilled coal seam dip angle, evaluates the accuracy of the predicted coal seam dip angle and the three-dimensional spatial distribution characteristics of the coal seam, provides a basis for subsequent wellbore trajectory adjustment schemes, and ensures a high drilling rate of the target coal seam in horizontal wells.

[0028] Preferably, step S6 specifically includes:

[0029] After drilling is completed, a deviation analysis between the design and actual drilling is performed. If the preset trajectory is not met, steps S2-S5 are repeated to adjust and optimize the model.

[0030] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0031] 1. In this invention, the well inclination angle of the marker layer is approached layer by layer to control the target entry technology, which quantitatively determines the optimal well inclination angle of each marker layer. During the actual drilling process, the geological guidance personnel only need to judge whether the well inclination angle meets the design when each marker layer is encountered, which simplifies the analysis content and steps, saves the analysis time when there is a large deviation from the design marker layer depth, and improves drilling efficiency.

[0032] 2. This invention, based on a reliable three-dimensional geological model, develops a geological steering technology for horizontal wells with high drilling success rates in medium-deep coalbed methane formations. Using three-dimensional seismic data, the dip angle of the coal seam along the well trajectory in the horizontal section is quantitatively predicted in advance. Anomalies in coal seam development within the horizontal section are identified, control points are set, and well trajectory adjustment measures are formulated. During actual drilling, based on multi-dimensional data such as coal seam structure data from adjacent wells, LWD (Low-Drilling Measurement) data, cuttings data, gas logging data, and drilling time data, the location of the drill bit in the coal seam is determined in real time. The accuracy of the predicted coal seam dip angle and anomalies is evaluated, and the well trajectory adjustment scheme is optimized to ensure a high drilling success rate for the target coal seam in the horizontal well. Attached Figure Description

[0033] Figure 1 This is a flowchart of the present invention;

[0034] Figure 2 This is a schematic diagram of the well inclination angle control and layer-by-layer approximation control target entry in this invention;

[0035] Figure 3 This is a schematic diagram illustrating the determination of the location of the coal seam encountered during horizontal drilling in this invention;

[0036] Figure 4 This is a characteristic map of the seismic reflection axis of the marker layer in the Yushe-Wuxiang block of this invention;

[0037] Figure 5 This is an overlay diagram of the designed wellbore trajectory of Well X and the seismic profile in this invention;

[0038] Figure 6 This is a map showing the dip angle and control point distribution of the target coal seam in the horizontal section of well X in this invention;

[0039] Figure 7 This is the accurate target entry diagram for the layer-by-layer approximation of the inclination angle control of the X well's directional drilling section in this invention;

[0040] Figure 8 This is a diagram of the actual drilling trajectory of the horizontal section of Well X in this invention. Detailed Implementation

[0041] The specific embodiments of the present invention are described in detail below.

[0042] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0044] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0045] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0047] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0048] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0049] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0050] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0051] The following embodiments further illustrate specific implementations of the multi-dimensional geological steering method for medium-deep coalbed methane horizontal wells according to the present invention. The multi-dimensional geological steering method for medium-deep coalbed methane horizontal wells of the present invention is not limited to the descriptions in the following embodiments.

[0052] Example 1:

[0053] A multi-dimensional geological steering method for horizontal wells in medium-deep coalbed methane formations, such as Figure 1 As shown, it includes the following steps:

[0054] Step 1: Establish a reliable geological model

[0055] Based on 3D seismic data and adjacent well drilling data, multiple stratigraphic correlation framework profiles of the target area are first established, stable marker layers in the target area are identified, and synthetic record calibration technology is used to calibrate the marker layers to the 3D seismic data. The seismic reflection phase axes corresponding to each marker layer are identified, and a reliable 3D seismic-geological model of the marker layers and the target coal seam is established.

[0056] Step 2: Determine the inclination angle of each marker layer encountered during drilling.

[0057] Import the design horizontal wellbore trajectory data into the 3D seismic data, and determine the well inclination angle of each marker layer encountered by the design horizontal wellbore trajectory from deep to shallow, and predict the depth of each marker layer, to ensure that the horizontal well successfully enters the target coal seam at the designed well inclination angle.

[0058] Step 3: Predict the depth, thickness, dip angle, and spatial distribution characteristics of the target coal seam.

[0059] Along the designed horizontal wellbore trajectory, the phase axis of the calibrated target coal seam is laterally traced and interpreted in the 3D seismic data. The depth and thickness of the target coal seam along the horizontal wellbore trajectory are predicted at certain intervals. Potential local anomalies are identified, control points for the horizontal section are determined, the dip angle of each section of the target coal seam is calculated, the three-dimensional spatial distribution characteristics of the target coal seam are finely depicted, and wellbore trajectory adjustment measures are formulated in advance.

[0060] Step Four: As Figure 2 As shown, a layer-by-layer approximation method is used to ensure accurate target entry of the horizontal well.

[0061] During actual drilling, the current drilling layer is determined in real time using logging cuttings data, gas logging data, measurement-while-drilling data, and data from adjacent wells. The deviation between the actual drilling inclination angle and the designed inclination angle of each marker layer is compared and analyzed to formulate a wellbore trajectory adjustment plan: if the actual drilling inclination angle is less than the designed inclination angle, the wellbore build-up rate needs to be increased to ensure that the inclination angle of the next marker layer matches the designed inclination angle; if the actual drilling inclination angle is equal to the designed inclination angle, drilling continues at the designed wellbore build-up rate; if the actual drilling inclination angle is greater than the designed inclination angle, the wellbore build-up rate needs to be adjusted appropriately according to the predicted vertical thickness between the upper and lower marker layers to avoid excessive inclination angle when encountering the next marker layer, which could lead to target failure. Using the above method, from shallow to deep, layer-by-layer comparative analysis is conducted, and the wellbore trajectory is adjusted in real time to gradually approach the target coal seam, ensuring accurate target entry.

[0062] Step 5: Comprehensive analysis of horizontal segment data to ensure a high drilling success rate.

[0063] Based on the coal seam structure, coal seam gravitational density (GR), interbedded rock gravitational density (GR), and roof and floor gravitational density (GR) characteristics of the target coal seam in adjacent wells, and combined with LWD (Low-Drilling Width Measurement) upper and lower gamma data, cuttings data, gas logging data, and drilling time data, a comprehensive analysis is conducted to determine the current location of the drill bit in the coal seam (e.g., Figure 3(As shown); By comparing and analyzing the deviation between the predicted coal seam dip angle and the actual drilled coal seam dip angle, the accuracy of the predicted coal seam dip angle and the three-dimensional spatial distribution characteristics of the coal seam is evaluated, providing a basis for subsequent wellbore trajectory adjustment schemes and ensuring a high drilling rate of the target coal seam in horizontal wells.

[0064] Step Six: Adjust and Optimize the Model

[0065] After drilling is completed, a deviation analysis between the design and the actual drilling is conducted in a timely manner, and the model is adjusted and optimized.

[0066] By adopting the above technical solution:

[0067] This multi-dimensional geological steering method, centered on controlling the well inclination angle to achieve accurate target entry layer by layer and controlling the horizontal section wellbore trajectory adjustment by predicting the dip angle of the coal seam in the horizontal section in real time, relies on 3D seismic data, actual drilling data from adjacent wells, actual drilling cuttings data, gas logging data, drilling time data, and LWD (Low-Drilling Width) measurement data to achieve accurate target entry and high coal seam encounter rate in the horizontal section. Based on 3D seismic data and data from adjacent wells, the method first predicts the well inclination angle of each major marker layer encountered and the dip angle of the coal seam along the horizontal section wellbore trajectory. Then, by comparing and analyzing the deviation between the actual drilling inclination angle and the predicted well inclination angle of each major marker layer, trajectory adjustment measures are formulated layer by layer to achieve accurate target entry according to the designed well inclination angle. Secondly, during horizontal section drilling, the location of the drilled coal seam and the actual dip angle of the drilled coal seam are determined segment by segment based on the coal seam structure of adjacent wells and LWD measurement data, and the horizontal section wellbore trajectory and adjustment plan are corrected in real time. It is simple to operate, real-time and efficient, and enhances the role of 3D seismic data in the horizontal well drilling process. Based on multiple data, it ensures the coal seam drilling rate and greatly improves the horizontal well construction cycle.

[0068] Example 2:

[0069] The technical means of this invention were implemented in the Yushe-Wuxiang block, located in the central-eastern part of the Qinshui Basin. The main coal seam, Taiyuan Formation No. 15, is buried at a depth of 1200m–1800m and has a thickness of 4m–7m, making it a typical medium-deep coalbed methane block. Three-dimensional seismic data confirms that the Yushe-Wuxiang block exhibits east-west zonation: the western part shows a NE-trending syncline structure with alternating uplift and depression; the eastern part shows a west-dipping monocline structure. Fault structures with displacements greater than 10m are not well-developed, making it suitable for large-scale development using horizontal wells. The multi-dimensional geological steering method for medium-deep coalbed methane horizontal wells proposed in this invention was successfully applied in this area.

[0070] Well X is located on the eastern slope of the Yushe-Wuxiang block, designed as a horizontal well with a designed depth of 2771.60m. Through the implementation of the geological steering method of this invention, the Taiyuan Formation No. 15 coal seam was accurately hit in one go, achieving a 100% drilling success rate in the horizontal section. The implementation steps are as follows:

[0071] Step 1: As Figure 4 As shown, regional stratigraphic correlation was performed to identify stable marker layers and pinpoint their seismic reflection phase axes.

[0072] Stratigraphic correlation through 28 vertical wells confirmed that four stable correlation marker layers are developed above the No. 15 coal seam of the Taiyuan Formation in the Yushe-Wuxiang block, from deep to shallow: the K2 limestone, K4 limestone, and No. 9 coal seam of the Taiyuan Formation, and the No. 3 coal seam of the Shanxi Formation. These four marker layers exhibit clear seismic reflection in-phase axis reflection characteristics, making them easy to track and interpret across the entire area. Therefore, these four marker layers were selected as key target layers.

[0073] Step 2: As Figure 5 As shown, the horizontal wellbore trajectory design determines the inclination angles of four key target layers.

[0074] With a target well inclination angle of 88°–90°, a three- or five-segment horizontal wellbore trajectory design method was adopted. The wellbore trajectory was designed and projected onto three-dimensional seismic data to determine the well inclination angles at the intersections of the wellbore trajectory with four key layers: 47° for the top well of coal seam No. 3 in Shanxi Formation, 60° for the top well of coal seam No. 9 in Taiyuan Formation, 62° for the top well of limestone K4 in Taiyuan Formation, and 72° for the top well of limestone K2 in Taiyuan Formation.

[0075] Step 3: As Figure 6 As shown, the dip angle of the target coal seam is predicted and control points are identified, and adjustment measures are formulated.

[0076] Along the designed trajectory direction of the horizontal section, at 20m intervals, the depth difference h between the top surface of the target coal seam between two interval points is read. The dip angle of the coal seam at each interval point is calculated using the formula arctan = h / 20 and marked on the seismic reflection phase axis of the top surface of the coal seam. At the same time, the trend of the dip angle change is analyzed, and points where the dip angle increases sharply are identified as trajectory adjustment control points. Inclination operations are carried out in advance to prevent coal from being produced from the bottom plate and to ensure that the wellbore trajectory always remains inside the coal seam.

[0077] Step 4: As Figure 7 As shown, well inclination angle control allows for accurate target entry by approaching the target layer by layer.

[0078] Before reaching the Shanxi Formation, the wellbore trajectory proceeded normally according to the design. After reaching the Shanxi Formation, real-time comparisons were made between logging cuttings data, gas logging data, drilling time data, and data from adjacent wells. The depth data of the four key target layers were collected and provided to the geological steering personnel for comparison of the actual well inclination angle with the designed well inclination angle. When Well X encountered the No. 3 coal seam of the Shanxi Formation, the actual well inclination angle was 49°, 2° higher than the designed well inclination angle. Based on the predicted vertical distance of approximately 60m to the No. 9 coal seam of the Taiyuan Formation, a build-up rate of 5° / 30m was sufficient to adjust the well inclination to 60°. Therefore, drilling continued at a 5° / 30m build-up rate. This method was applied layer by layer, comparing the well inclination angle deviation and adjusting the build-up rate in real-time until the top well inclination angle of the target layer, the No. 15 coal seam of the Taiyuan Formation, reached 89°, achieving accurate target entry.

[0079] Step 5: As Figure 8 As shown, the horizontal segment is used to correct the predicted coal seam dip angle in real time and optimize trajectory adjustment measures.

[0080] During horizontal drilling along the predicted coal seam dip angle, the location of the drill bit in the coal seam is determined in real time based on LWD (Low-Drilling Measurement) data, cuttings logging data, gas logging data, drilling time data, and coal seam structure data from adjacent wells. Furthermore, the calculated coal seam dip angle based on LWD data is 7° updip, which is close to the predicted coal seam dip angle. Therefore, during horizontal drilling, trajectory adjustments are only made at control points according to the trajectory adjustment plan. The coal seam encounter rate in this well is 100%, and the well construction period is 20 days.

[0081] Step 6: Post-drilling evaluation

[0082] The actual drilling process of Well X confirms that the multi-dimensional geological steering method proposed in this invention is reliable, with reasonable parameter selection and model, and can be used for geological steering of horizontal well drilling.

[0083] By adopting the above technical solution:

[0084] Based on 3D seismic data and adjacent well drilling data, the inclination angle of each major marker layer and the dip angle of the target coal seam along the well trajectory direction in the horizontal section are quantitatively determined. A reliable geological model is established and the depth, thickness, dip angle, and spatial distribution characteristics of the target coal seam are predicted. Combining various parameters such as drilling cuttings data, gas logging data, drilling time data, and LWD measurement-while-drilling data, the stratigraphic position encountered by the actual drilled well, the inclination angle, and the location of the target coal seam in the horizontal section of the well trajectory are accurately determined. The deviation between the actual drilling data and the designed well trajectory is analyzed, and a well trajectory adjustment plan is formulated to achieve accurate target entry of the horizontal well and a high drilling rate of the target coal seam in the horizontal section, thus meeting the purpose of rapid well construction and drilling of a single horizontal well.

[0085] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A multi-dimensional geosteering method for a mid-depth coal seam gas horizontal well, characterized in that, Includes the following steps: S1 Establish a three-dimensional seismic-geological model of the marker layer and the target coal seam; S2 determines the well inclination angle of each marker layer encountered during drilling; S3 predicts the depth, thickness, dip angle, and spatial distribution characteristics of the target coal seam; S4 employs a layer-by-layer approximation method to ensure accurate target entry of horizontal wells; S5 comprehensive analysis of horizontal segment data ensures a high drilling success rate; S6 Adjustment and Optimization Model; Step S2 specifically includes: Import the design horizontal wellbore trajectory data into the 3D seismic data, determine the well inclination angle of each marker layer encountered by the design horizontal wellbore trajectory from deep to shallow, and predict the depth of each marker layer to ensure that the horizontal well successfully enters the target coal seam at the designed well inclination angle; Step S3 specifically includes: Along the design horizontal wellbore trajectory, the phase axis of the calibrated target coal seam is laterally traced and interpreted in the 3D seismic data. The depth and thickness of the target coal seam along the horizontal wellbore trajectory are predicted at certain intervals. Potential local anomalies are identified, control points of the horizontal section are determined, the dip angle of each section of the target coal seam is calculated, the three-dimensional spatial distribution characteristics of the target coal seam are finely depicted, and wellbore trajectory adjustment measures are formulated in advance. Step S4 specifically includes: S41 uses logging cuttings data, gas logging data, measurement while drilling data and adjacent well data to determine the current drilling formation in real time, compares and analyzes the deviation between the actual drilling inclination angle and the designed well inclination angle of each marker layer, and formulates a wellbore trajectory adjustment plan. If the actual drilling inclination angle is less than the designed inclination angle, increase the wellbore build-up rate to ensure that the inclination angle of the next marker layer meets the designed inclination angle. If the actual drilling inclination angle is equal to the designed well inclination angle, then continue drilling according to the designed wellbore build-up rate; If the actual drilling inclination angle is greater than the designed inclination angle, the wellbore build-up rate should be adjusted appropriately according to the predicted vertical thickness between the upper and lower marker layers to avoid the drilling failure caused by an excessively large inclination angle when encountering the next marker layer. S42 adopts the method of step S41, from shallow to deep, layer by layer comparative analysis, and adjusts the wellbore trajectory in real time to gradually approach the target coal seam to ensure accurate target entry. Step S5 specifically includes: Based on the coal seam structure, coal seam GR, coal seam interbedded GR, and roof and floor GR characteristics of the target coal seam in the adjacent well, S51 combines the upper and lower gamma data measured during drilling, cuttings data, gas logging data, and drilling time data to comprehensively analyze and determine the current coal seam location of the drill bit. S52 comparative analysis examines the deviation between the predicted coal seam dip angle and the actual drilled coal seam dip angle, evaluates the accuracy of the predicted coal seam dip angle and the three-dimensional spatial distribution characteristics of the coal seam, provides a basis for subsequent wellbore trajectory adjustment schemes, and ensures a high drilling rate of the target coal seam in horizontal wells.

2. The multi-dimensional geological steering method for medium-deep coalbed methane horizontal wells as described in claim 1, characterized in that, Step S1 specifically includes: Based on 3D seismic data and adjacent well drilling data, multiple stratigraphic correlation framework profiles of the target area are first established to identify stable and well-developed marker layers in the target area. Then, synthetic record calibration technology is used to calibrate the marker layers to the 3D seismic data, identify the seismic reflection phase axes corresponding to each marker layer, and establish a 3D seismic-geological model of the marker layers and the target coal seam.

3. The multi-dimensional geological steering method for horizontal wells in medium-deep coalbed methane formations as described in claim 1, characterized in that... Step S6 specifically includes: After drilling is completed, a deviation analysis between the design and actual drilling is performed. If the preset trajectory is not met, steps S2-S5 are repeated to adjust and optimize the model.

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