A method for long-distance accurate drilling of ground directional drilling in thin-bedded limestone

Abstract

This invention discloses a method for long-distance, precise directional drilling in thin-layered limestone. First, hydrogeological parameters of the treatment area are collected. Then, exploratory boreholes are drilled on the surface to explore and obtain precise data for each stratum. Combined with data from rock cuttings returned during drilling, natural gamma-ray measurement during drilling, and drilling log data, the continuity and specific location of the borehole in the target stratum are comprehensively determined. The target rock stratum is then drilled, and the coordinate points recorded during the drilling process are used to form a drilling trajectory. Multiple drilling trajectories are connected to form a three-dimensional trajectory model, realizing the anticipated changes in the dip angle of the strata and guiding the actual drilling trajectory. By comprehensively utilizing hydrogeological parameters, exploratory borehole construction, drilling continuity monitoring, and three-dimensional trajectory establishment, the accuracy and safety of the drilling operation are ensured, and this method has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of drilling technology for thin layers of limestone in coal mine floors. Specifically, it is a method for long-distance, precise drilling using surface directional drilling in thin layers of limestone. Background Technology

[0002] With the development of surface directional drilling and grouting reinforcement technology, this technology has been increasingly widely used in mine water control projects, especially in the reinforcement and renovation of thin limestone layers in coal mine floors. The thickness of thin limestone layers is generally less than 6 meters, while the drilling section of horizontal holes can reach hundreds to thousands of meters, increasing the difficulty of precise positioning during drilling. Currently, the distribution of thin limestone layers often alternates with mudstone, sandstone, and other strata, with similar thicknesses and properties, making stratigraphic identification difficult. Furthermore, surface undulations and fault influences make accurately identifying target strata and ensuring precise drilling within thin limestone layers a pressing problem. Existing technologies in this field suffer from inaccurate positioning and difficulty in controlling the drilling trajectory. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to provide a method for long-distance and precise drilling in thin limestone layers by ground directional drilling, which can accurately identify and perform long-distance drilling on the ground.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for long-distance and precise drilling of directional boreholes in thin layers of limestone, comprising the following steps:

[0005] Step A: Collect hydrogeological parameters of the treatment area, including the thickness of the thin limestone layer, the interlayer spacing between the thin limestone layer and the coal seam, and the properties of the roof and floor rocks of the thin limestone layer;

[0006] Step B: Construct large-angle exploration holes on the ground into the treatment area to record and accurately determine the vertical depth, layer thickness, and spacing of each rock layer in the treatment area;

[0007] Step C: After confirming the target thin layer of limestone, raise the drill string, then drill horizontally into the target thin layer of limestone and drill along the target thin layer of limestone;

[0008] Step D: During the drilling operation in the target thin layer of limestone, the continuity and specific location of the borehole in the target thin layer of limestone are comprehensively confirmed by combining the data of the rock cuttings returned during drilling, the natural gamma measurement data while drilling, and the data of the drilling time logging.

[0009] Step E: During the horizontal drilling process, the coordinates of the current drilling tool are recorded at regular intervals. After the drilling is completed, the coordinates are connected in sequence to form the drilling trajectory A.

[0010] Step F: Construct branch boreholes adjacent to drilling trajectory A within the target thin layer of limestone. During the drilling of the branch boreholes, record the coordinates of the current drilling tool at regular intervals. After the construction is completed, connect the coordinates in sequence to form drilling trajectory B.

[0011] Step G: Connect the corresponding coordinate points of drilling trajectory A and drilling trajectory B to establish a three-dimensional trajectory model, thereby anticipating the changes in the dip angle of the strata;

[0012] Step H: When conducting actual drilling on the target thin layer of limestone, the drilling trajectory is guided by the three-dimensional trajectory model.

[0013] The above-mentioned method for long-distance and precise drilling of ground directional boreholes in thin limestone involves, in step A, collecting hydrogeological parameters of the treatment area, drawing a comprehensive columnar section, recording in detail the thickness and vertical depth of the coal seam, the thickness and vertical depth of each limestone layer, and calculating the interlayer spacing between the coal seam and each limestone layer.

[0014] In the above-mentioned method for long-distance and precise drilling of directional boreholes in thin limestone, during step B, the inclination of the exploratory borehole in the directional section is maintained at 60-70°.

[0015] The above-mentioned method for long-distance and precise drilling of directional boreholes in thin limestone layers involves step B, in which the exploratory boreholes sequentially penetrate each rock layer, record relevant data and perform calculations to obtain the specific vertical depth, layer thickness, and distance between each limestone layer and the coal seam, and compare and analyze the data with the data in step A, thereby accurately determining the location of the target thin limestone layer.

[0016] In the above-mentioned method for long-distance and precise drilling of directional boreholes in thin limestone, during the exploration borehole drilling process, the drilling fluid carries rock cuttings back to the wellhead on the surface, rock cuttings samples are collected, and the rock cuttings samples are analyzed by titration with dilute hydrochloric acid to determine the properties of the rock cuttings samples.

[0017] In the above-mentioned method for long-distance and precise drilling of ground directional boreholes in thin limestone, in steps E and F, during the drilling process, the drilling tool is used to measure the inclination every 10 meters and record the borehole depth, inclination, azimuth, and east-west displacement data of the current point to form a coordinate point.

[0018] In the above-mentioned method for long-distance and precise drilling of ground directional boreholes in thin limestone, step D involves analyzing the natural gamma measurement data while drilling, monitoring the surrounding rock properties of the borehole trajectory in real time, and determining the continuity of borehole drilling in thin limestone by considering the different radioactive properties of different rocks.

[0019] In the above-mentioned method for long-distance and precise drilling in thin limestone by directional drilling, in step D, the properties of the rock cut by the drill bit are determined based on the drilling log data, and the formation in which the drill bit is located is determined.

[0020] The technical solution of the present invention achieves the following beneficial technical effects:

[0021] 1. By comprehensively utilizing hydrogeological parameters, exploration hole construction, drilling continuity monitoring, and three-dimensional trajectory establishment, the accuracy and safety of drilling construction are ensured, which has broad application prospects.

[0022] 2. By utilizing multiple judgment methods, we ensure accurate directional horizontal drilling within the target rock strata. Practical testing has shown that in actual applications, the average limestone bedding rate in thin limestone drilling reaches as high as 95%. Attached Figure Description

[0023] Figure 1 A schematic diagram of the exploration hole construction of this invention;

[0024] Figure 2 A schematic diagram of the three-dimensional stratigraphic model of this invention. Detailed Implementation

[0025] This embodiment takes a directional horizontal borehole thin-layer limestone cement high-pressure grouting project in a construction area as an application example. It adopts a method of long-distance precision drilling in thin-layer limestone using ground directional drilling, and specifically includes the following steps:

[0026] Step A: Collect hydrogeological parameters of the treatment area, including the thickness of the thin limestone layer, the interlayer spacing between the thin limestone layer and the coal seam, and the properties of the roof and floor rocks of the thin limestone layer. Draw a comprehensive columnar section, record the thickness and vertical depth of the coal seam and the thickness and vertical depth of each limestone layer in detail, and calculate the interlayer spacing between the coal seam and each limestone layer.

[0027] Step B: Drill large-angle exploratory boreholes into the treatment area on the ground. The borehole inclination of the exploratory borehole is maintained at 60-70°. The exploratory boreholes are drilled through each rock layer in sequence. The vertical depth, layer thickness and spacing of each rock layer in the treatment area are recorded and accurately determined. The data are compared and analyzed with the data in Step A to accurately determine the location of the target thin layer of limestone.

[0028] Step C: After confirming the target thin layer of limestone, raise the drill string, then drill horizontally into the target thin layer of limestone and drill along the target thin layer of limestone;

[0029] Step D: During drilling operations within the target thin layer of limestone, the continuity and specific location of the borehole in the thin layer of limestone are comprehensively confirmed by combining the data from the rock cuttings returned during drilling, the natural gamma measurement data while drilling, and the data from the drilling log. The well fluid carries the rock cuttings back to the wellhead on the surface, and rock cuttings samples are collected. The rock cuttings samples are then analyzed by titration with dilute hydrochloric acid to determine their properties. The chemical reaction formula between limestone and dilute hydrochloric acid is as follows: CaCO3 + 2HCl = CaCl2 + CO2↑ + H2O.

[0030] By analyzing the natural gamma measurement data while drilling, the properties of the surrounding rock along the borehole trajectory can be monitored in real time. The continuity of drilling in thin limestone layers can be determined by the different radioactivity properties of different rocks. The properties of rocks in different strata vary greatly, and the drilling speed of the borehole in limestone, coal seam, sandstone and mudstone is different. The strata can be determined by using the data recorded during drilling.

[0031] Table 1: Drilling Logging Parameters

[0032] rock name color Reaction of hydrochloric acid Gamma Data Drilling time limestone Gray, off-white violent reaction 20～50 7~12min / m Sandstone and mudstone Dark black, gray Basically no reaction 51～300 4~6min / m coal seam black No response 10～20 1~3min / m

[0033] Step E: During drilling, the drill bit is surveyed every 10 meters, and the hole depth, inclination, azimuth, and east-west displacement data at the current point are recorded to form coordinate points. The coordinate points of the current drill bit are also recorded. After drilling is completed, the coordinate points are connected sequentially to form drilling trajectory A. Then, adjacent branch boreholes are drilled. After the adjacent branch boreholes are completed, the coordinate points recorded in the branch boreholes are connected sequentially to form drilling trajectory B. The corresponding coordinate points of drilling trajectory A and drilling trajectory B are connected to establish a three-dimensional trajectory model, forming a trajectory surface, which allows for the prediction of changes in the dip angle of the formation.

[0034] Step F: When conducting actual drilling on the target thin layer of limestone, the drilling trajectory is guided by the three-dimensional trajectory model. Since the trajectory adjustment is limited by the rate of change of the full angle, it is necessary to guide the drilling trajectory according to the expected strata conditions, so as to ensure that the borehole can be drilled accurately over long distances in the thin layer of limestone.

[0035] Practical testing has shown that the average bedding rate of limestone in directional horizontal hole drilling of thin limestone is as high as 95%.

[0036] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for long-distance, precise drilling of directional boreholes in thin layers of limestone, characterized in that, Includes the following steps: Step A: Collect hydrogeological parameters of the treatment area, including the thickness of the thin limestone layer, the interlayer spacing between the thin limestone layer and the coal seam, and the properties of the roof and floor rocks of the thin limestone layer; Step B: Construct large-angle exploration holes on the ground into the treatment area to record and accurately determine the vertical depth, layer thickness, and spacing of each rock layer in the treatment area; Step C: After confirming the target thin layer of limestone, raise the drill string, then drill horizontally into the target thin layer of limestone and drill along the target thin layer of limestone; Step D: During the drilling operation in the target thin layer of limestone, the continuity and specific location of the borehole in the target thin layer of limestone are comprehensively confirmed by combining the data of the rock cuttings returned during drilling, the natural gamma measurement data while drilling, and the data of the drilling time logging. Step E: During the horizontal drilling process, the coordinates of the current drilling tool are recorded at regular intervals. After the drilling is completed, the coordinates are connected in sequence to form the drilling trajectory A. Step F: Construct branch boreholes adjacent to drilling trajectory A within the target thin layer of limestone. During the drilling of the branch boreholes, record the coordinates of the current drilling tool at regular intervals. After the construction is completed, connect the coordinates in sequence to form drilling trajectory B. Step G: Connect the corresponding coordinate points of drilling trajectory A and drilling trajectory B to establish a three-dimensional trajectory model, thereby anticipating the changes in the dip angle of the strata; Step H: When conducting actual drilling on the target thin layer of limestone, the drilling trajectory is guided by the three-dimensional trajectory model.

2. The method for long-distance, precise drilling in thin layers of limestone using directional drilling as described in claim 1, characterized in that, In step A, after collecting the hydrogeological parameters of the treatment area, a comprehensive columnar section is drawn, and the thickness and depth of the coal seam and the thickness and depth of each layer of limestone are recorded in detail. The interlayer spacing between the coal seam and each layer of limestone is also calculated.

3. The method for long-distance, precise drilling in thin layers of limestone using directional drilling as described in claim 1, characterized in that, In step B, during the construction of the exploratory borehole, the inclination of the exploratory borehole's directional section is maintained at 60–70°.

4. The method for long-distance, precise drilling in thin layers of limestone using directional drilling as described in claim 1, characterized in that, In step B, the exploration holes are drilled through each rock layer in sequence, relevant data are recorded and calculated to obtain the specific vertical depth, layer thickness, and distance between each layer of limestone and coal seam. The data is then compared and analyzed with the data in step A to accurately determine the location of the target thin layer of limestone.

5. The method for long-distance, precise drilling of directional boreholes in thin layers of limestone according to claim 1, characterized in that, In step D, during the exploration hole drilling process, the drilling fluid carries rock cuttings back to the surface wellhead, rock cuttings samples are collected, and the rock cuttings samples are analyzed by titration with dilute hydrochloric acid to determine the properties of the rock cuttings samples.

6. The method for long-distance, precise drilling of directional boreholes in thin layers of limestone according to claim 1, characterized in that, In steps E and F, during the drilling process, the drilling tool is used to measure the inclination every 10 meters, and the hole depth, well inclination, azimuth, and east-west displacement data of the current point are recorded to form a coordinate point.

7. The method for long-distance, precise drilling in thin layers of limestone using directional drilling as described in claim 1, characterized in that, In step D, the natural gamma measurement data while drilling is analyzed, and the properties of the surrounding rock along the borehole trajectory are monitored in real time. The continuity of drilling in thin limestone layers is determined by the different radioactive properties of different rocks.

8. The method for long-distance, precise drilling of directional boreholes in thin layers of limestone according to claim 1, characterized in that, In step D, the properties of the rock cut by the drill string are determined based on the drilling log data, and the formation in which the drill string is located is determined.

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