Geosteering parameter modeling method suitable for complex thin layer

Abstract

The invention belongs to the technical field of petroleum and natural gas drilling exploration and development, and discloses a geosteering parameter modeling method suitable for a complex thin layer, which comprises the steps of seismic data collection and geological profile evaluation, geological data analysis and target window feature determination, drilling trajectory guiding model establishment, drilling dynamic tracking, real-time borehole correction and the like. And accurate guiding is realized. Target window control is carried out by combining a layer thickness method and a segmentation method, and a drilling trajectory is monitored in real time by adopting a'five maps and one table 'tracking method, so that efficient passing of a drill bit in a target reservoir is ensured. According to the method, the drilling rate under the narrow target window geological condition is remarkably improved, the drilling risk is reduced, and the development efficiency and economic benefits of the shale gas well are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas drilling exploration and development, and in particular relates to a method for modeling guiding parameters of complex thin-layer geology. Background Art

[0002] In the field of oil and gas exploration and development, with the increasing depletion of conventional oil and gas resources, more difficult unconventional oil and gas resources (such as shale gas, tight oil and gas, etc.) have gradually become the focus of development, especially in narrow target window geological areas with very limited thickness and width. These unconventional resources are usually found under complex geological conditions, especially narrow target window geology, that is, the target reservoir thickness and width are extremely limited, which may be only a few meters or even smaller. Such geological conditions have brought huge challenges to drilling projects. The existing technology mainly uses conventional geosteering tools while drilling for trajectory control, but the accuracy is still insufficient in narrow target window geology, and there are problems such as the drill bit easily deviating from the target window, short residence time in the target window, and failure to fully drill into the oil and gas layer. Summary of the invention

[0003] The present invention aims to provide a method for modeling geological steering parameters suitable for complex thin layers. By establishing a fine geological steering model and combining real-time drilling monitoring and wellbore correction technology, it ensures that the drill bit can be accurately guided in the target layer, thereby improving the drilling rate and economic benefits.

[0004] To achieve the above object, the present invention provides a method for geosteering parameter modeling applicable to complex thin layers, comprising the following steps:

[0005] S1, Seismic data collection and drilling geological profile evaluation:

[0006] Collect 2D and 3D seismic data: Collect 2D and 3D seismic data in the work area, fully cover the target strata, and ensure the accuracy and integrity of the seismic data;

[0007] Conduct drilling geological profile evaluation and analysis: Identify formation characteristics, clarify formation interfaces and structural morphology through seismic data analysis. Combined with well logging curves, analyze the lithology characteristics, gas-bearing characteristics, formation pressure and its changing patterns of each formation;

[0008] Drilling trajectory trend prediction: Based on the geological profile, predict the structural changes and formation inclinations that may be encountered during the drilling process, and preliminarily determine the drilling trajectory design plan;

[0009] S2, geological data analysis and target window feature determination:

[0010] Collect geological data: collect existing geological reports, well logging data, core analysis results, etc. in the work area.

[0011] Analyze the sedimentary characteristics and reservoir characteristics of the target layer: analyze the sedimentary environment, reservoir properties, and gas-bearing characteristics of the target layer to clarify the storage capacity and production capacity of the target layer; divide the target layer into small layers, determine the landmark points and formation occurrence, and facilitate the determination of the target window and guidance control in the subsequent geological guidance;

[0012] S3, establish drilling trajectory guidance model:

[0013] Integrated seismic and geological data: Combine 2D and 3D seismic data with geological data in the work area to establish a 3D geological model; use seismic inversion technology to predict stratum distribution characteristics and make comprehensive predictions on the fine features of the target window;

[0014] Drilling trajectory guidance model: Based on the geological model, a drilling trajectory guidance model is established to simulate the ideal trajectory of the wellbore within the target window; the target window position, shape and geological characteristics are modeled to ensure the maximum section length of the wellbore trajectory within the target window;

[0015] S4, dynamic tracking of drilling and real-time wellbore correction:

[0016] Real-time drilling tracking: During the drilling process, dynamically obtain logging data and geological parameters while drilling, track logging and mud logging information during the actual drilling process; compare the measured data with the predicted data in the geological model, and verify the entry of the target window;

[0017] Real-time wellbore monitoring and correction: Use geosteering software to analyze real-time geological data, and use gamma logging or resistivity logging to evaluate the relative position of the wellbore to the target window in real time; when the wellbore deviates from the target window, use the rotary steerable system (RSS) to correct the trajectory to ensure that the horizontal well is accurately targeted, allowing the wellbore to pass through high-quality reservoirs and remain in the optimal position.

[0018] By collecting and analyzing seismic data and logging data, a detailed description of the stratigraphic profile is established, the geological characteristics of each layer are identified, and the specific location and characteristics of the target window target layer are determined. Accurate geological profile evaluation can improve the accuracy of wellbore trajectory planning and effectively reduce the risks in drilling and the possibility of non-target window layer penetration. The systematic analysis of geological data is to gain a deep understanding of the physical properties, sedimentary environment and reservoir characteristics of the target layer, which directly affect the establishment of wellbore trajectory planning and guidance models. By analyzing sedimentary characteristics and reservoir properties, the accurate positioning of the target window can be improved, the wellbore trajectory can be matched with high-quality reservoirs, and the drilling rate can be improved. By combining geological and seismic data, the stratigraphic characteristics are inverted and predicted, and a fine guidance model is established. The guidance model can simulate the ideal trajectory of the wellbore in the target window, ensure that the wellbore can stay in the target window for the maximum length, and improve the efficiency of drilling. Using logging while drilling data and geological guidance software, the trajectory deviation of the wellbore is monitored in real time, and timely corrections are made in combination with the rotary guidance system. Real-time monitoring and correction can ensure that the wellbore is accurately placed in the target layer, achieve maximum drilling of high-quality reservoirs, and improve resource recovery.

[0019] Furthermore, in step S4, the determination of marker layers and marker points during the drilling process is to find the geological marker layers and marker points based on the overall structural relationship of the work area and the differences in the electrical characteristics of the formations, so as to use them as reference points for geological guidance; the precise target entry control method is to combine the layer thickness method and the segmentation method for precise target entry control, and through the precise measurement of the formation thickness, ensure that the drill bit remains in the effective target reservoir when entering the target window; the segmentation control technology subdivides the drilling process into multiple control nodes according to the changes in different geological conditions in the target window, and each node is monitored and adjusted in real time to ensure a high drilling rate in the overall target window.

[0020] By accurately determining the marker layer and marker point, and combining the layer thickness method with the segmentation method to control the target, the wellbore trajectory is ensured to be stable within the target window. This method ensures the accuracy of geosteering and effectively improves the drilling rate of the target layer in the narrow target window.

[0021] Further, in step S4, the "five Figure 1 The tracking method of "table" is used to analyze and judge the drill bit tendency according to the gamma data of the near-bit azimuth, update the penetration formation inclination in real time, and control the drilling tendency in real time in combination with the trajectory guidance model to ensure efficient penetration. The drilling process is tracked and analyzed in detail through five charts and a tracking table to ensure real-time grasp of formation changes. This method can more intuitively monitor the geological and trajectory changes during the drilling process, improve the accuracy of guidance, and reduce the risks that may be encountered during the drilling process.

[0022] Further, in step S4, the actual drilling logging parameters include logging parameters during drilling, cuttings logging parameters, gas logging parameters, and near-bit natural gamma parameters. Comprehensive information on formation characteristics can be obtained through comprehensive analysis of different types of logging parameters. Real-time monitoring of multiple parameters can effectively predict geological changes and provide data support for timely adjustment of wellbore trajectory.

[0023] Furthermore, the vertical depth calculation of the target point of the marker layer in the layer thickness method is shown as follows:

[0024] Case 1: For the well area in front of the target formation with a formation dip angle within 1°, the vertical depth of the target point = a + h;

[0025] Case 2: For the well area in front of the target formation with a formation dip angle greater than 1°, the vertical depth of the target point = a + △h*sinα + d*tanα;

[0026] Case 3: For the well area in front of the target formation where the formation dip angle changes complexly, the vertical depth of the target point = a + △h*sinα + △d*tanα.

[0027] Different vertical depth calculation methods are used according to the inclination of the formation to ensure the accuracy of the target position. Through accurate vertical depth calculation, the risk of the wellbore deviating from the target window during drilling is minimized.

[0028] Furthermore, the “Five Figure 1 The tracking methods of the "Five Tables" include single well logging comprehensive histogram, horizontal section trajectory model diagram, well connection comparison diagram, well trajectory projection structural plan diagram, well trajectory projection seismic profile diagram, drilling well tracking analysis and undrilled formation prediction table. Figure 1 The tracking method of "table" provides a comprehensive and integrated tracking and analysis system for geological guidance, which can effectively monitor and guide the drilling process in different dimensions. Intuitive data display: The formation, wellbore trajectory and geological characteristics are intuitively displayed through charts, which is convenient for quick judgment and decision-making. Real-time adjustment capability: Combined with actual drilling logging data and adjacent well data, through comparative analysis and real-time monitoring, the drilling trajectory can be adjusted in real time to ensure that the wellbore maintains the maximum section length in the high-quality reservoir. Improve guidance accuracy: Through multi-dimensional comparison and tracking, the accuracy of wellbore drilling in narrow target windows is effectively improved, and the risk of crossing non-target formations is reduced.

[0029] "five Figure 1 The "table" tracking method is a method that comprehensively utilizes multi-dimensional data to monitor and analyze the drilling process in real time. By combining five charts and a prediction table, the wellbore trajectory and formation changes are fully tracked to ensure accurate guidance of the drilling process.

[0030] 1. Comprehensive histogram of single well logging

[0031] Content: Including logging parameters such as drilling time, cuttings, gas logging, and comprehensive display of logging while drilling data.

[0032] The characteristics and parameter changes of each stratum are presented intuitively in the form of a bar graph.

[0033] Uses and advantages: The comprehensive histogram of single well logging can help geological guidance personnel fully understand the geological characteristics of each layer in the current drilling and adjust the wellbore trajectory according to the measured data. Through this comprehensive display method, the drilling time changes, cuttings characteristics and gas content of different strata can be intuitively compared and analyzed to determine whether the wellbore is in a high-quality reservoir.

[0034] 2. Horizontal segment trajectory model diagram

[0035] Content: Describes the trajectory of horizontal drilling and shows the relative position of the wellbore to the target layer. Including the relationship between the depth range, shape, thickness, etc. of the target reservoir and the actual wellbore trajectory.

[0036] Uses and advantages: Used to track the movement of the horizontal section of the wellbore within the target window to ensure that the wellbore trajectory remains in the target layer. By comparing the wellbore trajectory and the target layer position, the geosteering personnel can adjust the drilling direction in time to stay in the high-quality reservoir.

[0037] 3. Comparison of wells

[0038] Content: Contains stratigraphic comparison maps of multiple adjacent wells, showing the stratigraphic division, marker layer depth, wellbore trajectory and reservoir characteristics of each well.

[0039] Uses and advantages: By comparing the data of adjacent wells, we can understand the spatial changes and connectivity of the formations in the work area, so as to adjust and optimize the trajectory of the current well. It can help determine the occurrence changes and extension of the target layer between different wells and improve the drilling rate.

[0040] 4. Well trajectory projection structural plan

[0041] Content: Displays the projection of the wellbore trajectory in the structural plane, including the structural morphology, dip angle and distribution of marker points of the target layer.

[0042] Uses and advantages: Used to understand the relative position of the wellbore trajectory in the horizontal structural plane, especially the relationship between the wellbore and the formation structure. Ensure that the wellbore trajectory matches the structural characteristics, effectively avoid formation faults and non-target areas, thereby improving drilling efficiency.

[0043] 5. Well trajectory projection seismic profile

[0044] Content: Combined with seismic data, the projection of the wellbore trajectory in the seismic section is displayed, showing the depth and changes relative to the formation during the wellbore's travel.

[0045] Uses and advantages: Used to track the movement of the wellbore in the formation on the seismic profile, helping to determine whether the wellbore is in the target reservoir. This projection method can directly show the matching of the wellbore trajectory and the formation, ensuring that the wellbore moves along the expected trajectory of the seismic profile.

[0046] 6. Tracking analysis of drilling wells and prediction table of undrilled formations

[0047] Content: Contains analysis of actual drilling data of the current well, crossing of formation marker layers, and prediction information of undrilled formations. Provides geological characteristics and risk assessment of undrilled formations, and infers based on existing seismic and adjacent well data.

[0048] Uses and advantages: Used to track and record the current drilling, including the prediction of the strata that have been traversed and the strata that have not been drilled. It helps geologists to predict the characteristics of the strata to be encountered, adjust the drilling parameters, reduce the drilling risks, and ensure the efficient crossing of the strata. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A flowchart of a process for applying for an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a layer thickness method according to an embodiment of the present invention; DETAILED DESCRIPTION

[0051] The following is further described in detail through specific implementation methods:

[0052] Example: During the drilling of shale gas wells in the Hongxing area, due to the narrow and thin target window, the wellbore trajectory must be accurately controlled to ensure that the wellbore enters and remains in the target layer for a long time. In order to achieve this goal, this example uses a combination of layer thickness method and segmentation method to guide the wellbore, ensuring that the drill bit achieves the maximum drilling encounter in high-quality reservoirs.

[0053] Step 1: Steering control of the deflection section

[0054] Determination of the depth of the marker layer during actual drilling: Collect regional 2D and 3D seismic data and adjacent well data to determine the depth of the important marker layer in the build-up section. Verify and correct the position of the marker layer in real time through logging data to ensure that the marker layer is accurately identified during the actual drilling process.

[0055] Determination of the thickness of the pre-target marking layer:

[0056] According to the seismic inversion results and formation logging curves, the thickness of the marker layer in front of the target window is determined. The marker layer is a key reference point in drilling guidance, and ensuring its thickness is accurate can significantly improve the accuracy of target entry.

[0057] Target vertical depth calculation (layer thickness method):

[0058] The vertical depth of the target is calculated using the layer thickness method: Case 1: For areas with gentle formation dip in front of the target (formation dip angle within 1°), the equal thickness method is used. The calculation formula for the target vertical depth is: target vertical depth = a + h, where a is the vertical depth of the bottom well marker layer, and h is the difference between the vertical depths of the marker layer and the target layer.

[0059] Case 2: For well areas with large formation dip angles, the equal thickness method combined with the overall formation dip angle method is used. The target vertical depth calculation formula is: target vertical depth = a + Δh·sinα + d·tanα, where α is the vertical depth of the bottom well marker layer, Δh is the vertical thickness between the marker layer and the target layer, d is the distance before the target, and α is the formation dip angle.

[0060] Case 3: For areas with complex formation dip angle changes, the equal thickness combined with the overall formation dip angle method is used. The target vertical depth calculation formula is: target vertical depth = a + Δh·sinα + Δd·tanα; where a is the bottom hole vertical depth, d is the remaining target front distance, Δd is the target front distance of the next mark point, h is the vertical thickness of the two mark points in the standard well, and Δh is the vertical thickness of the two mark points in the build-up section.

[0061] Establish a steering model for the deflection section: Combine the vertical depth calculation of the target point and the seismic structural characteristics to establish a geological steering model for the deflection section. The model includes the depth, thickness and inclination of the target layer, and guides the trajectory design and adjustment of the deflection section.

[0062] Correct the target entry guidance model: During the drilling process, the accuracy of the model is verified through the data collected in real time by logging while drilling. When the actual parameters of the formation do not match the prediction, the guidance model is readjusted and the wellbore trajectory is corrected to ensure smooth target entry in the deflection section.

[0063] Redesign the wellbore trajectory: According to the correction results of the guidance model, redesign the wellbore trajectory, adjust the well inclination angle and wellbore direction to ensure accurate target entry.

[0064] Step 2: Horizontal Segment Guidance Control

[0065] Analysis of formation rock electrical characteristics: Analyze the rock electrical characteristics of the target layer through gamma logging and resistivity logging data to ensure that the wellbore can always remain at the target layer during horizontal drilling.

[0066] Pre-target occurrence prediction and marker layer identification (segmentation method): Before entering the horizontal section, the electrical characteristics of the formation and the occurrence prediction are combined to identify important marker layers, which serve as key reference points in drilling guidance.

[0067] A statistical analysis was performed based on the vertical difference between the key well inclination marker layer inside the bottom of the Changxing Formation and the upper target frame of the target layer: the marker point at a vertical depth of about 35 meters above the bottom of the Changxing Formation: the well inclination was controlled at about 60°, serving as the control node for entering the horizontal section; the well inclination at the bottom of the Changxing Formation: controlled at about 77.5°, and adjusted in conjunction with the marker point of the Wu II section for auxiliary purposes.

[0068] Establish a horizontal section steering model: Combine the formation rock electrical characteristics and adjacent well data to establish a horizontal section steering model. The model includes the depth, thickness, occurrence and geological changes of the target layer. During the drilling process, the model will be modified in real time to adapt to the actual geological conditions to ensure that the wellbore trajectory remains in the best position.

[0069] Real-time drilling data acquisition and adjustment: During horizontal drilling, real-time acquisition of gamma logging, density logging and cuttings data is performed to determine whether the current wellbore position is within the target reservoir. The wellbore trajectory is adjusted according to changes in formation inclination and occurrence to keep the drill bit in the target reservoir.

[0070] Application of segmented control method: The segmented method is used to finely control the wellbore trajectory, and the horizontal drilling process in the target window is divided into multiple control nodes: Node 1: Using the upper mark point on the bottom of the Changxing Formation, the well inclination angle is adjusted within a vertical depth of 35 meters, maintaining a well inclination angle of 60° to enter the target layer; Node 2: The well inclination at the bottom of the Changxing Formation is controlled at about 77.5° to ensure that the wellbore can smoothly pass through the high-quality reservoir; Node 3: Combined with the Wu II section mark point, further auxiliary adjustments are made to ensure that the wellbore trajectory of each segment is maintained in the optimal position within the target window.

[0071] Real-time model correction and trajectory adjustment: Based on the comparison of geological data collected while drilling and the steering model, the steering model is corrected in real time. The deflection angle of the rotary steerable system (RSS) is adjusted to ensure that the wellbore trajectory is always within the target reservoir to maximize the drilling rate of the reservoir section.

[0072] Summarize the adjustment rules of complex strata:

[0073] After drilling is completed, the actual changes in the formation are compared with the geological model, the adjustment process of the wellbore in the complex formation is analyzed, and the regularity of the horizontal section guidance is summarized to provide experience support for the construction of subsequent wells.

[0074] Implementation Effect

[0075] Improve the drilling rate of high-quality reservoirs: By combining the layer thickness method and the segmentation method, the wellbore trajectory is accurately controlled to ensure the efficient movement of the wellbore within the target window, effectively increasing the probability of drilling into high-quality reservoirs.

[0076] Reduce the risk of deviation from the target: Combine the marker layer and segment control to ensure that the wellbore trajectory matches the formation characteristics, reducing the risk of deviation from the target window target layer.

[0077] Improve drilling efficiency and economic benefits: Accurate target vertical depth calculation, real-time model correction and trajectory adjustment significantly improve drilling efficiency, reduce ineffective drilling and formation crossing errors, and improve the economic benefits of shale gas well development.

[0078] Real-time adjustment and correction: During the drilling process, the use of logging while drilling, geological imaging, real-time data fusion and guidance model correction can achieve dynamic adjustment of the wellbore trajectory and reduce the risk of wellbore deviation.

[0079] Improve the level of steering management: By establishing and modifying the steering model and adjusting the wellbore trajectory, a systematic steering management process has been built to achieve fine control of the drilling process under complex geological conditions.

[0080] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the present invention. The specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for geosteering parameter modeling suitable for complex thin layers, characterized in that: The following steps are involved: S1, Seismic data collection and drilling geological profile evaluation: Collect 2D and 3D seismic data: Collect 2D and 3D seismic data in the work area, fully cover the target strata, and ensure the accuracy and integrity of the seismic data; Conduct evaluation and analysis of drilling geological profiles: Identify stratigraphic characteristics, clarify stratigraphic interfaces and structural morphology through seismic data analysis. Combined with the well logging curve, analyze the lithology characteristics, gas-bearing characteristics, formation pressure and its changing laws of each formation; Drilling trajectory trend prediction: Based on the geological profile, predict the structural changes and formation inclinations that may be encountered during the drilling process, and preliminarily determine the drilling trajectory design plan; S2, geological data analysis and target window feature determination: Collect geological data: collect existing geological reports, well logging data, core analysis results, etc. in the work area. Analyze the sedimentary characteristics and reservoir characteristics of the target layer: Analyze the sedimentary environment, reservoir properties, and gas-bearing characteristics of the target layer to clarify the storage capacity and production capacity of the target layer; divide the target layer into small layers, determine the landmark points and formation occurrence, and facilitate the determination of the target window and guidance control in the subsequent geological guidance; S3, establish drilling trajectory guidance model: Integrated seismic and geological data: Combine 2D and 3D seismic data with geological data in the work area to establish a 3D geological model; use seismic inversion technology to predict stratum distribution characteristics and make comprehensive predictions on the fine features of the target window; Drilling trajectory guidance model: Based on the geological model, a drilling trajectory guidance model is established to simulate the ideal trajectory of the wellbore within the target window; the target window position, shape and geological characteristics are modeled to ensure the maximum section length of the wellbore trajectory within the target window; S4, dynamic tracking of drilling and real-time wellbore correction: Real-time drilling tracking: During the drilling process, dynamically obtain logging data and geological parameters while drilling, and track logging and mud logging information during the actual drilling process; Compare the measured data with the predicted data in the geological model to verify the entry of the target window; Real-time wellbore monitoring and correction: Use geosteering software to analyze real-time geological data, and use gamma logging or resistivity logging to evaluate the relative position of the wellbore to the target window in real time; when the wellbore deviates from the target window, use the rotary steerable system (RSS) to correct the trajectory to ensure that the horizontal well is accurately targeted, allowing the wellbore to pass through high-quality reservoirs and remain in the optimal position.

2. The method for geosteering parameter modeling applicable to complex thin layers according to claim 1, characterized in that: In step S4, the determination of the marker layer and the marker point during the drilling process is to find the geological marker layer and the marker point according to the overall structural relationship of the work area and the difference in the electrical characteristics of the formation, and use them as reference points for geological guidance; the precise target entry control method is to combine the layer thickness method and the segmentation method for precise target entry control, and ensure that the drill bit remains in the effective target reservoir when entering the target window through accurate measurement of the formation thickness; The segmented control technology divides the drilling process into multiple control nodes according to the changes in different geological conditions within the target window. Each node is monitored and adjusted in real time to ensure a high drilling rate within the overall target window.

3. The method for geosteering parameter modeling applicable to complex thin layers according to claim 1, characterized in that: In step S4, the "five-image-one-table" tracking method is adopted to analyze and judge the drill bit tendency based on the gamma data near the drill bit azimuth, update the penetration formation inclination in real time, and combine with the trajectory guidance model to control the drilling tendency in real time to ensure efficient penetration.

4. The method for geosteering parameter modeling applicable to complex thin layers according to claim 1, characterized in that: In step S4, the actual drilling logging parameters include logging parameters during drilling, cuttings logging parameters, gas logging parameters, and near-bit natural gamma parameters.

5. The method for geosteering parameter modeling applicable to complex thin layers according to claim 2, characterized in that: The calculation of vertical depth of target point of marker layer in the layer thickness method is shown as follows: Case 1: For the well area in front of the target formation with a formation dip angle within 1°, the vertical depth of the target point = a + h; Case 2: For the well area in front of the target formation with a formation dip angle greater than 1°, the vertical depth of the target point = a + △h*sinα + d*tanα; Case 3: For the well area in front of the target formation where the formation dip angle changes complexly, the vertical depth of the target point = a + △h*sinα + △d*tanα.

6. The method for geosteering parameter modeling applicable to complex thin layers according to claim 3, characterized in that: The "five pictures and one table" tracking method includes a single well logging comprehensive bar chart, a horizontal section travel trajectory model chart, a well connection comparison chart, a well trajectory projection structural plan chart, a well trajectory projection seismic profile chart, a drilling well tracking analysis, and an undrilled formation prediction table.

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