A dynamic shale gas horizontal well formation dip angle prediction method

Abstract

The application discloses a dynamic shale gas horizontal well stratum dip angle prediction method, which comprises the following steps: establishing a shale reservoir velocity model; preparing a shale reservoir structure map, and designing depths of target points A and B of a shale gas horizontal well, wherein the target point A is a starting position of a horizontal section of the shale gas horizontal well, and the target point B is an ending position of the horizontal section of the shale gas horizontal well; calculating a stratum dip angle alpha of the whole horizontal section according to a horizontal distance and a longitudinal distance between the target points A and B; after entering the target point A, a stratum dip angle beta is predicted by using depth data of first and last points of a preset distance drilled this time, the velocity model is updated by using the depth data of the first and last points of the preset distance drilled this time, the structure map is prepared again, a stratum dip angle gamma of a next drilling distance of the horizontal section is predicted by using the prepared structure map again, and a reference stratum dip angle theta of the next drilling distance of the horizontal section is determined according to the three stratum dip angles alpha, beta and gamma, so as to serve as a guide for drilling of the horizontal well. The method can effectively improve a high-quality shale drilling ratio of the shale gas horizontal well, improve drilling efficiency of the horizontal well and save drilling cost.

Description

Technical Field

[0001] This invention relates to the field of shale gas exploration and development technology, and in particular to a dynamic method for predicting the dip angle of formations in horizontal wells for shale gas exploration and development. Background Technology

[0002] Formation dip angle prediction is a crucial step in the directional drilling process for shale gas horizontal wells, and a vital guarantee for the economic viability of shale gas exploration and development. High-quality horizontal well guidance requires accurate formation dip angle data, which helps improve drilling speed and save costs. However, in reality, although formation dip angle data predicted based on previous seismic data is always available during geological briefings, its accuracy is generally low. This often leads to the horizontal well trajectory traversing non-high-quality shale sections, resulting in low production after drilling and fracturing, and ultimately hindering efficient shale gas development. Currently, formation dip angle data for shale gas horizontal wells is mainly predicted by combining existing seismic data with the coordinates of the designed horizontal well target points A and B. However, the underlying strata are complex and variable, containing many micro-folds and faults, leading to inaccurate formation dip angle predictions from the original seismic data. This results in decision-making errors during the directional drilling process, causing the drill bit to deviate from the target window and enter non-high-quality shale sections, leading to lower shale gas production. Summary of the Invention

[0003] To address the aforementioned technical problems, at least one embodiment of the present invention provides a dynamic method for predicting the dip angle of shale gas horizontal well formations, thereby solving the problems.

[0004] In some optional embodiments, the method includes the following steps:

[0005] A shale reservoir velocity model was established based on seismic data from the study area.

[0006] Compile a structural map of the shale reservoir and design the depths of target points A and B for the shale gas horizontal well. Target point A is the starting position of the horizontal section of the shale gas horizontal well, and target point B is the ending position of the horizontal section of the shale gas horizontal well.

[0007] Calculate the dip angle α of the entire horizontal segment based on the horizontal and vertical distances between target points A and B;

[0008] After entering target point A, perform the following steps after each preset drilling distance:

[0009] Predict the formation dip angle β using the data from this drilling operation;

[0010] The velocity model is updated using the drilling data, the structural map is re-compiled, and the dip angle γ of the formation in the next drilling in the horizontal section is predicted using the re-compiled structural map.

[0011] Based on the three formation dip angles α, β, and γ, the reference formation dip angle θ for the next drilling in the horizontal section is determined, serving as the guiding basis for horizontal well drilling.

[0012] In some optional embodiments, establishing a shale reservoir velocity model based on seismic data of the study area includes:

[0013] Based on seismic data from the study area, the shale reservoir was structurally interpreted, the fracture and stratigraphic characteristics of the shale reservoir were analyzed, and a time-depth conversion velocity model was established.

[0014] In some optional embodiments, the compilation of shale reservoir structural maps includes:

[0015] The velocity model was used to perform time-depth conversion on the interpretation horizon, and the resulting sub-sea level structural map of the shale reservoir was compiled.

[0016] In some optional embodiments, the dip angle α of the entire horizontal segment is calculated according to the following formula, based on the horizontal and vertical distances between target points A and B.

[0017] α = arctan(H / L);

[0018] In the formula, L is the horizontal distance between target points A and B, and H is the vertical distance between target points A and B.

[0019] In some optional embodiments, the drilling data includes depth data at the beginning and end points of a preset drilling distance.

[0020] In some optional embodiments, after predicting the formation dip angle β using the drilling data, the method further includes:

[0021] The predicted formation dip angle β is compared with the formation dip angle α predicted based on target points A and B to determine the formation's downdip trend.

[0022] In some optional embodiments, the preset distance is a constant value.

[0023] At least one embodiment of the present invention also provides a dynamic shale gas horizontal well formation dip prediction device, characterized in that it comprises:

[0024] The model building module is used to build shale reservoir velocity models based on seismic data of the study area.

[0025] The structural map compilation module is used to compile structural maps of shale reservoirs and design the depths of target points A and B in shale gas horizontal wells. Target point A is the starting position of the horizontal section of the shale gas horizontal well, and target point B is the ending position of the horizontal section of the shale gas horizontal well.

[0026] Design a dip angle module to calculate the dip angle α of the entire horizontal segment based on the horizontal and vertical distances between target points A and B;

[0027] The dip angle adjustment module is used to perform the following steps after entering target point A and drilling a preset distance: predict the formation dip angle β using the drilling data; update the velocity model using the drilling data, recompile the structural map, and predict the formation dip angle γ for the next drilling in the horizontal section using the recompile structural map; determine the reference formation dip angle θ for the next drilling in the horizontal section based on the three formation dip angles α, β, and γ, as the guiding basis for horizontal well drilling.

[0028] At least one embodiment of the present invention also provides an electronic device, characterized in that it comprises:

[0029] At least one processor; and,

[0030] A memory communicatively connected to the at least one processor; wherein,

[0031] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the dynamic shale gas horizontal well formation dip prediction method as described above.

[0032] At least one embodiment of the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the dynamic shale gas horizontal well formation dip prediction method as described above.

[0033] At least one embodiment of the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the dynamic shale gas horizontal well formation dip prediction method as described above.

[0034] Compared with existing technologies, the dynamic shale gas horizontal well formation dip angle prediction method provided by the embodiments of the present invention has unique advantages. Utilizing current geological data during the horizontal well drilling process, combined with geophysical data such as seismic data, well logging data, and velocity models, the method updates the velocity model and structural map, confirming the occurrence and depth of un-drilled formations in the horizontal well. This method overcomes the shortcomings of existing technologies, not only enabling timely understanding of drilling progress but also allowing for dynamic prediction of the subsequent formation dip angle of the horizontal well trajectory. This effectively improves the encounter rate of high-quality shale in shale gas horizontal wells, enhances drilling efficiency, and saves drilling costs. Attached Figure Description

[0035] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.

[0036] Figure 1 This is a flowchart illustrating the steps of the dynamic shale gas horizontal well formation dip angle prediction method used in Embodiment 1 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of the present invention to facilitate a better understanding of the invention. However, the technical solutions claimed in the present invention can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0038] As mentioned earlier, to address the technical problem of large errors in the prediction of formation dip angles for dynamic shale gas horizontal wells in existing technologies, this invention proposes a dynamic method for predicting formation dip angles for shale gas horizontal wells. The implementation details of this method are described below through examples. These details are provided for ease of understanding and are not essential for implementing this solution.

[0039] Example 1:

[0040] like Figure 1 As shown in the figure, this embodiment provides a dynamic method for predicting the dip angle of shale gas horizontal wells. The method mainly includes the following steps:

[0041] Using seismic data from the study area, we conducted a structural interpretation of the shale reservoir, identified the fault and stratigraphic characteristics of the shale reservoir, and established an initial velocity model for time-depth conversion.

[0042] Compile a structural map of the shale reservoir below sea level and design the target depths A and B of the shale gas horizontal well (target point A refers to the beginning of the horizontal section of the shale gas horizontal well, and target point B refers to the end of the horizontal section of the shale gas horizontal well).

[0043] The dip angle α = arctan(H / L) is calculated using the horizontal distance L between target points A and B and the longitudinal distance H between target points A and B.

[0044] After the shale gas horizontal well successfully enters target point A, every 20 meters of drilling (only one example in this embodiment), the depth data of the first and last two points of these 20 meters are used to predict the formation dip angle β, and the predicted formation dip angle β is compared with the formation dip angle α predicted based on the original target points A and B to determine the formation downdip trend.

[0045] While proceeding with the previous step, the initial velocity model established based on the structural interpretation was updated based on the drilling depth of 20 meters, and a new local structural map of the drilling area was compiled. The new structural map was used to predict the dip angle γ of the formation in the horizontal section from 20 meters to 40 meters.

[0046] Thus, during the drilling process, the dip angles of the three formations α, β, and γ are comprehensively considered, and the geological and structural characteristics of the study area are combined to comprehensively evaluate the reference formation dip angle θ of the 20-meter to 40-meter horizontal section, which serves as a reference for guiding the horizontal well drilling.

[0047] This prediction is repeated every 20 meters, and the drill bit direction is adjusted promptly if there are any changes, until the drilling is completed.

[0048] In this embodiment, the method predicts the formation dip angle of the horizontal well once every certain preset drilling distance, which enables timely and effective dynamic adjustment, ensuring high-speed drilling of shale gas horizontal wells, shortening the drilling cycle of shale gas horizontal wells, saving drilling costs, providing support for high-quality exploration and development of shale gas, and ensuring national energy security.

[0049] It should be noted that in the formation dip angle prediction method provided by the present invention, the preset distance for each drilling operation can remain constant or vary, and this is not limited here.

[0050] Example 2

[0051] The technical solution of the present invention and its beneficial effects will be further illustrated below with a specific example.

[0052] In this embodiment, a shale gas horizontal well is taken as an example in the DS area of ​​the Sichuan Basin. The DS area of ​​the Sichuan Basin is a favorable area for shale gas exploration. However, during the drilling of shale gas horizontal wells, due to its location on the edge of the basin, the burial depth and occurrence of shale strata change rapidly, making it difficult to predict the accurate formation dip angle. This results in slow drilling speed or difficulty in drilling high-quality shale sections, leading to extremely high drilling costs. Now, taking the SY4 well in the Nanchuan area as an example, a detailed explanation of the dynamic shale gas horizontal well formation dip angle prediction method of the present invention will be given.

[0053] In this embodiment, the implementation process of the dynamic shale gas horizontal well formation dip angle prediction method of the present invention is as follows.

[0054] Step 1: Using pre-stack depth migration seismic data from the DS area, conduct structural interpretation of the Longmaxi Formation shale to determine the fault development and stratigraphic planar distribution characteristics of the Longmaxi Formation shale reservoir. Then, using the logging data from completed wells such as SY1, SY21, and SY3, well strata, and interpreted stratigraphic positions, establish an initial velocity model for time-depth conversion.

[0055] Step 2: Use the velocity model to perform time-depth conversion on the interpretation layer. After conversion, compile a structural map of the shale reservoir below sea level. Based on the structural map, design the SY4 well location. Design the horizontal well with target point A depth of 3550 meters and target point B depth of 3718 meters (target point A refers to the beginning of the horizontal section of the shale gas horizontal well, and target point B refers to the complete horizontal section of the shale gas horizontal well). The designed horizontal section length is 1300 meters.

[0056] Step 3: Using the horizontal distance of 1300 meters between target points A and B and the longitudinal distance of 168 meters between target points A and B, the dip angle of the strata is calculated to be 7.36° downward.

[0057] Step 4: After the shale gas horizontal well successfully enters target point A, drill forward 20 meters. The vertical depth of the high-quality shale section of the drill bit is 3,552.52 meters, which is 2.52 meters higher than that of target point A. Using this data, the formation dip angle is calculated to be 7.20°, which is somewhat different from the original design of 7.36°, indicating that the downdip trend of the formation has slowed down.

[0058] Step 5: In order to constrain the formation dip angle calculation with the information from the seismic data, the actual drilling data of the horizontal well was used to update the velocity model, and then a new local structural map of the drilling area was compiled. From the newly compiled local structural map, the formation dip angle of the 20-meter to 40-meter horizontal section was determined to be 7.25°.

[0059] Step Six: Taking into account the original design dip of 7.36°, the actual drilling dip of 7.20°, and the seismic constraint of 7.25°, the reference stratum dip angle is set to 7.25°, which is used as the stratum dip angle for drilling in the horizontal section from 20 meters to 40 degrees.

[0060] In this way, a dynamic prediction is made every 20 meters of drilling to ensure a more accurate formation dip angle for determining the horizontal well drilling.

[0061] In the above embodiment, well SY4 utilizes a dynamic horizontal well target prediction method to obtain a more accurate formation dip angle. The horizontal section from target point A to target point B is 1300 meters long. Drilling took 6 days, with a daily drilling depth of 216.6 meters. Compared with other wells in the previous work area, the average daily drilling length was 150-180 meters, and the drilling speed was significantly improved, effectively saving 350,000 yuan in drilling time costs.

[0062] The above embodiments fully demonstrate that applying the dynamic shale gas horizontal well formation dip angle prediction method provided by the present invention to other work areas will greatly improve the efficiency of shale gas exploration and development in the DS area.

[0063] Example 3

[0064] Another embodiment of the present invention relates to a dynamic shale gas horizontal well formation dip prediction device, comprising:

[0065] The model building module is used to build shale reservoir velocity models based on seismic data of the study area.

[0066] The structural map compilation module is used to compile structural maps of shale reservoirs and design the depths of target points A and B in shale gas horizontal wells. Target point A is the starting position of the horizontal section of the shale gas horizontal well, and target point B is the ending position of the horizontal section of the shale gas horizontal well.

[0067] Design a dip angle module to calculate the dip angle α of the entire horizontal segment based on the horizontal and vertical distances between target points A and B;

[0068] The dip angle adjustment module is used to perform the following steps after entering target point A and drilling a preset distance: predict the formation dip angle β using the drilling data; update the velocity model using the drilling data, recompile the structural map, and predict the formation dip angle γ for the next drilling in the horizontal section using the recompile structural map; determine the reference formation dip angle θ for the next drilling in the horizontal section based on the three formation dip angles α, β, and γ, as the guiding basis for horizontal well drilling.

[0069] Example 4:

[0070] Another embodiment of the present invention relates to an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the dynamic shale gas horizontal well formation dip prediction method of the above embodiments.

[0071] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0072] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0073] Example 5:

[0074] Another embodiment of the present invention relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the dynamic shale gas horizontal well formation dip prediction method of the above embodiments.

[0075] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0076] Example 6

[0077] Another embodiment of the present invention relates to a computer program product, including a computer program that, when executed by a processor, implements the steps of the dynamic shale gas horizontal well formation dip prediction method of the above embodiments.

[0078] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A dynamic method for predicting the dip angle of shale gas horizontal wells, characterized in that, include: A shale reservoir velocity model was established based on seismic data from the study area. Compile a structural map of the shale reservoir and design the depths of target points A and B for the shale gas horizontal well. Target point A is the starting position of the horizontal section of the shale gas horizontal well, and target point B is the ending position of the horizontal section of the shale gas horizontal well. Calculate the dip angle α of the entire horizontal segment based on the horizontal and vertical distances between target points A and B; After entering target point A, perform the following steps after each preset drilling distance: Predict the formation dip angle β using the data from this drilling operation; The velocity model is updated using the drilling data, the structural map is re-compiled, and the dip angle γ of the formation in the next drilling in the horizontal section is predicted using the re-compiled structural map. Based on the three formation dip angles α, β, and γ, the reference formation dip angle θ for the next drilling in the horizontal section is determined, serving as the guiding basis for horizontal well drilling.

2. The dynamic shale gas horizontal well formation dip prediction method according to claim 1, characterized in that, The establishment of a shale reservoir velocity model based on seismic data of the study area includes: Based on seismic data from the study area, the shale reservoir was structurally interpreted, the fracture and stratigraphic characteristics of the shale reservoir were analyzed, and a time-depth conversion velocity model was established.

3. The dynamic shale gas horizontal well formation dip prediction method according to claim 1, characterized in that, The compilation of shale reservoir structural maps includes: The velocity model was used to perform time-depth conversion on the interpretation horizon, and the resulting sub-sea level structural map of the shale reservoir was compiled.

4. The dynamic shale gas horizontal well formation dip prediction method according to claim 3, characterized in that, The dip angle α of the entire horizontal segment is calculated using the following formula, based on the horizontal and vertical distances between target points A and B. α = arctan(H / L); In the formula, L is the horizontal distance between target points A and B, and H is the vertical distance between target points A and B.

5. The dynamic shale gas horizontal well formation dip prediction method according to claim 1, characterized in that, The drilling data includes the depth data of the first and last points of the preset drilling distance.

6. The dynamic shale gas horizontal well formation dip prediction method according to claim 1, characterized in that, After predicting the formation dip angle β using the drilling data, the method further includes: The predicted formation dip angle β is compared with the formation dip angle α predicted based on target points A and B to determine the formation's downdip trend.

7. The dynamic shale gas horizontal well formation dip prediction method according to claim 1, characterized in that, The preset distance is a constant value.

8. A dynamic shale gas horizontal well formation dip angle prediction device, characterized in that, include: The model building module is used to build shale reservoir velocity models based on seismic data of the study area. The structural map compilation module is used to compile structural maps of shale reservoirs and design the depths of target points A and B in shale gas horizontal wells. Target point A is the starting position of the horizontal section of the shale gas horizontal well, and target point B is the ending position of the horizontal section of the shale gas horizontal well. Design a dip angle module to calculate the dip angle α of the entire horizontal segment based on the horizontal and vertical distances between target points A and B; The dip angle adjustment module is used to perform the following steps after entering target point A and drilling a preset distance: predict the formation dip angle β using the drilling data; update the velocity model using the drilling data, recompile the structural map, and predict the formation dip angle γ for the next drilling in the horizontal section using the recompile structural map; determine the reference formation dip angle θ for the next drilling in the horizontal section based on the three formation dip angles α, β, and γ, as the guiding basis for horizontal well drilling.

9. An electronic device, characterized in that, include: At least one processor; as well as, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the dynamic shale gas horizontal well formation dip prediction method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the dynamic shale gas horizontal well formation dip prediction method according to any one of claims 1 to 7.

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