Method for exploring fault occurrence and fault projection based on ground directional drilling technology

Abstract

The invention discloses a method for exploring fault occurrence and fault projection based on a ground directional drilling technology, and the method specifically comprises the following steps: carrying out the primary selection of a treatment horizon according to the supplementary exploration drilling logging information of a treatment region; further selecting a layer with the minimum average thickness greater than or equal to the thickness of the water-resisting layer of the coal seam from the average thicknesses between the primarily selected treatment layers and the coal seam as a probing treatment layer, carrying out construction by adopting a directional drilling technology, drilling a main hole and at least three horizontal branch holes, finding out drilling fault points of the branch holes, and carrying out drilling treatment on the main hole and the at least three horizontal branch holes; and recording the spatial position coordinates of the drilling fault point, calculating the azimuth angle and dip angle of the fault according to the coordinates, and calculating the plane projection distance of the fault strike projected to the coal mining layer position according to the fault dip angle and the elevation coordinate height difference between the contour line of the coal seam floor in the treatment area and the breakpoint. The method is used in the technical field of mine water disaster prevention and control methods, can accurately determine the fault position, and then determines the fault occurrence and the fault projection according to the fault position.

Description

Technical Field

[0001] The present invention belongs to the technical field of mine water hazard prevention and control methods, and specifically relates to a method for detecting fault occurrence based on ground directional drilling technology. The present invention also relates to a method for detecting fault projection based on ground directional drilling technology. Background Art

[0002] As the main energy source in my country, coal plays a key role in economic development. In the process of coal mining, faults are a common geological structure that seriously affects the mining of coal resources. Accurately detecting the location of faults, their water conductivity and other characteristics is of great significance for ensuring safe production in mines, improving the recovery rate of coal resources and mining efficiency.

[0003] At present, there are many types of fault exploration methods, mainly covering the following categories:

[0004] Ground geophysical exploration: such as ground 3D seismic exploration and ground electrical exploration. These methods can detect a large area and provide information such as the approximate location and direction of the fault, which is effective in identifying large faults. For example, ground 3D seismic exploration can preliminarily outline the contours of underground geological structures through the propagation and reflection of seismic waves, thereby determining the existence and approximate orientation of large faults. Ground electrical exploration is mainly sensitive to water-rich anomalies and can indirectly reflect the approximate location of the structure.

[0005] Supplementary ground exploration: By constructing vertical coring holes on the ground, faults can be visually identified. The core samples obtained by drilling can clearly show the characteristics of the rocks at the fault, providing a direct basis for fault analysis.

[0006] Underground exploration: including geophysical exploration such as working face slot wave, transient electromagnetic, audio frequency electric perspective, as well as underground advance drilling, tunnel exploration, etc. These methods work in the underground environment and can obtain fault information closer to the mining area.

[0007] However, the existing fault exploration technology has many defects and shortcomings:

[0008] Ground geophysical exploration technology: Taking seismic exploration as an example, although it can detect large areas, it is affected by many factors such as stratum geological conditions, acquisition conditions, data processing and interpretation personnel experience, and the recognition accuracy of small faults is low. It is difficult to determine the specific location and water conductivity of the fault, and drilling is often required for further verification. Ground electrical exploration is affected by the volume effect of aquifers, the degree of structural water filling, etc., and the accuracy of the location of abnormal bodies is limited, and it can only roughly reflect the location of the structure.

[0009] Traditional ground drilling and coring: Although it can visually identify faults, it is difficult to accurately and continuously determine fault information due to space limitations, and the positioning of faults is inaccurate under complex geological conditions. In addition, it is difficult to select the drilling location, the cost of supplementary survey is high, and the cycle is long.

[0010] Underground geophysical exploration method: Although it can be used for advance detection, it is affected by the complex underground environment, and the detection accuracy and distance are limited. Although underground advance drilling and tunnel exploration can directly obtain fault information, they need to be carried out after tunnel excavation, which is prone to encountering faults during excavation, thereby increasing safety risks.

[0011] Directional drilling technology on the ground can drill along a predetermined trajectory to obtain geological information at different depths and directions. However, the fault identification method based on this technology currently lacks systematicity, and the detection accuracy and efficiency need to be improved. Therefore, it is necessary to develop a fault detection method based on directive drilling technology to improve the accuracy and efficiency of advanced fault detection in the mine area. Summary of the invention

[0012] The purpose of the present invention is to provide a method for detecting fault occurrence based on ground directional drilling technology, which method can accurately detect the fault position and obtain fault occurrence data.

[0013] Another object of the present invention is to provide a method for exploring fault projection based on ground directional drilling technology.

[0014] The technical solution adopted by the present invention is a method for detecting the occurrence of faults based on ground directional drilling technology, comprising the following steps:

[0015] Step 1: Selecting a stratum or stratum combination with a different natural gamma value from the adjacent stratum section as a preliminary treatment stratum based on the drilling and logging data of the treatment area;

[0016] Step 2: Calculate the thickness of the impermeable layer required for coal seam recovery according to the "Detailed Rules for Coal Mine Water Prevention and Control", calculate the average thickness of each preliminary treatment layer to the coal seam, and determine the preliminary treatment layer with the smallest average thickness that is not less than the thickness of the impermeable layer as the exploration treatment layer;

[0017] Step 3: Carry out construction based on ground directional drilling technology, drill the main hole, drill the bottom of the main hole to the exploration and treatment layer, collect the main hole logging data during the drilling process, and establish a standard database based on the main hole logging data;

[0018] Step 4, drilling at least three parallel horizontal branch holes at the bottom of the main hole, recording the logging data of each branch hole during the drilling process, comparing them with the standard database, determining the drilling fault point, and reading the spatial position coordinate information of the drilling fault point;

[0019] Step 5: Calculate the fault plane dip azimuth θ and inclination β based on the spatial position coordinate information of the fault points encountered by each branch hole.

[0020] The present invention is also characterized in that:

[0021] The difference between the average natural gamma value of the primary treatment layer and the average natural gamma value of the adjacent formation segment is ≥50API.

[0022] The main hole consists of a first vertical section and a second inclined section. The first vertical section is from the hole mouth vertically downward to the top of the bedrock, and the second inclined section is from the top of the bedrock to the exploration and management layer.

[0023] The logging data include lithology of flowback cuttings, formation thickness, gamma while drilling, and drilling fluid consumption.

[0024] The fault point encountered during drilling is determined by the discontinuity of the returned cuttings, the change of the gamma value while drilling, and the increase of the consumption of drilling fluid.

[0025] The drilling method of the horizontal branch hole is to first drill a horizontal branch hole. When the horizontal branch hole encounters a fault, other horizontal branch holes are drilled in its adjacent position. The distance between adjacent horizontal branch holes is 40 to 60m.

[0026] Step 5 is as follows:

[0027] Step 5.1, select the spatial coordinates of the breakpoints encountered by three branch holes, record them as A(x1, y1, z1), B(x2, y2, z2), and C(x3, y3, z3), and obtain the vector in the fault plane and vector coordinate,

[0028]

[0029] Step 5.2, according to the vector and vector Calculate the fault plane normal vector Its coordinates are in:

[0030] a=(y2-y1)(z3-z1)-(y3-y1)(z2-z1),

[0031] b=(z2-z1)(x3-x1)-(z3-z1)(x2-x1),

[0032] c=(x2-x1)(y3-y1)-(x3-x1)(y2-y1);

[0033] Step 5.3, let the horizontal plane projection vector be

[0034] Step 5.4, the fault azimuth θ is The clockwise angle with the north direction, first calculate The angle α with the positive direction of the X-axis is calculated according to formula (1), and then according to The quadrant determines θ:

[0035]

[0036] When a>0, b>0, θ=α,

[0037] When a<0, θ=π+α,

[0038] When a>0, b<0, θ=2π+α;

[0039] Step 5.5, let the fault plane dip angle be β and the spatial vertical unit vector be Then the fault plane normal vector and the vertical unit vector The angle between them is β,

[0040] Another technical solution of the present invention is a method for detecting fault projection based on ground directional drilling technology, which specifically includes the following steps:

[0041] Step 1, calculate the difference H between the elevation coordinates of the coal seam floor contour line in the treatment area and the fault point;

[0042] Step 2: Calculate the plane projection distance L of the fault point according to the following formula (2):

[0043]

[0044] Step 3: Calculate the plane projection distance of each fault point according to step 2, and finally project the fault position to the target coal seam.

[0045] The beneficial effects of the present invention are:

[0046] 1. The present invention uses ground directional drilling technology to accurately control the drilling trajectory and directly reach the target fault area, reducing exploration errors, so that the fault position can be accurately determined, and then the fault occurrence can be determined based on the fault position. The present invention provides a reliable basis for the formulation of coal mining plans by exploring fault characteristics in advance, which helps to improve resource recovery rate and reduce mining costs.

[0047] 2. When detecting the occurrence and projection of faults, the present invention allows workers to work on the ground, thus avoiding the workers from entering a complex and dangerous underground environment, thereby reducing the risk of mining accidents and ensuring the safety of the workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a schematic diagram of the preliminary selection results of the exploration and treatment layer in Example 1 of the present invention;

[0049] Figure 2 is a schematic diagram of the directional drilling structure in Example 1 of the present invention;

[0050] Figure 3 is a gamma curve diagram of the main hole section while drilling in Example 1 of the present invention;

[0051] Figure 4 is a graph showing the consumption of drilling fluid in the main hole section in Example 1 of the present invention;

[0052] Figure 5 This is a cross-sectional schematic diagram of the breakpoint position of the branch hole drilled in Example 1 of the present invention;

[0053] Figure 6 It is a schematic diagram of the projection plane position of the breakpoint encountered when drilling the branch hole in Example 1 of the present invention. DETAILED DESCRIPTION

[0054] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] The method for detecting fault occurrence and fault projection based on ground directional drilling technology of the present invention is specifically implemented according to the following steps:

[0056] Step 1: Exploration of the initial selection of governance layers:

[0057] Based on the supplementary drilling and logging data of the treatment area, the strata or strata combination with the natural gamma value difference of ≥50API with the adjacent strata are selected as the primary treatment layers.

[0058] Step 2: Determine the final exploration and treatment layer:

[0059] Calculate the average thickness between each preliminary treatment layer and the coal seam in step 1, and then calculate the thickness of the impermeable layer required for coal seam mining according to the "Detailed Rules for Coal Mine Water Prevention and Control", and compare the average thickness of each preliminary treatment layer from the coal seam with the thickness of the impermeable layer. Finally, the preliminary treatment layer with an average thickness greater than or equal to the thickness of the impermeable layer and the smallest average thickness is determined as the exploration treatment layer.

[0060] Step 3: Data collection of directional drilling construction results:

[0061] Directional drilling technology is used for construction. The main hole is drilled first, and the bottom of the main hole is connected to the exploration and treatment layer determined in step 1. The main hole logging data is collected during the drilling process. The logging data includes the lithology of the returned cuttings, formation thickness, gamma while drilling, and drilling fluid consumption. A standard database is established based on the main hole logging data; further, the lithology content of the returned cuttings should be corrected according to the actual hole depth position corresponding to the cuttings according to the late arrival time.

[0062] The directional drilling structure mainly consists of two parts: the main hole and the horizontal branch hole. The main hole is divided into a first vertical hole section and a second inclined hole section. The opening of the first vertical hole section is vertically downward to the top of the bedrock, and the casing is lowered after the drilling is completed; the opening of the second inclined hole section is inclined from the top of the bedrock to the exploration and treatment layer, and the casing is lowered after the drilling is completed.

[0063] Step 4, determination of fault point location:

[0064] Horizontal branch holes are drilled from the bottom of the secondary casing of the main hole to each target area. The logging data of the branch holes during the drilling process are recorded and compared with the standard database. If the return cuttings are discontinuous and the gamma value changes with drilling, accompanied by an increase in the consumption of drilling fluid, it can be determined that a fault point has been encountered, and the spatial position coordinate information of the fault point can be read.

[0065] Specifically, a horizontal branch hole is drilled first. When the horizontal branch hole encounters a fault, other horizontal branch holes are drilled in its adjacent position. The total number of branch holes is not less than 3. The spacing between each horizontal branch hole is 40 to 60m, and the drilling trajectory remains parallel to the completed branch holes. The drilling elevation of each horizontal branch hole needs to be adjusted in time according to the formation trend to meet the needs of following layer drilling.

[0066] Step 5, calculate fault occurrence data:

[0067] Determine the spatial coordinate information of the fault points encountered by each branch hole, and calculate the fault plane dip azimuth θ and dip angle β according to the coordinate information. The specific steps are as follows:

[0068] Step 5.1, select the spatial coordinates of three fault points, record them as A(x1,y1,z1), B(x2,y2,z2), and C(x3,y3,z3), and obtain the vector in the fault plane and vector coordinate,

[0069]

[0070] Step 5.2, according to the vector and vector Calculate the fault plane normal vector Its coordinates are in:

[0071] a=(y2-y1)(z3-z1)-(y3-y1)(z2-z1),

[0072] b=(z2-z1)(x3-x1)-(z3-z10(x2-x1),

[0073] c=(x2-x1)(y3-y1)-(x3-x1)(y2-y1);

[0074] Step 5.3, calculate the horizontal plane projection vector: Let the horizontal plane projection vector be

[0075] Step 5.4, calculate the fault azimuth: The azimuth θ is The clockwise angle with the north direction can be calculated first. The angle α with the positive direction of the X-axis is calculated according to formula (1), and then according to The quadrant determines θ:

[0076]

[0077] When a>0, b>0, θ=α,

[0078] When a<0, θ=π+α,

[0079] When a>0, b<0, θ=2π+α;

[0080] Step 5.5, calculate the dip angle: Assume the dip angle of the fault plane is β, and the vertical unit vector in space is Then the fault plane normal vector and the vertical unit vector The angle between them is β:

[0081] but so

[0082] Step 6: Project the fault strike to the recovered coal seam level:

[0083] According to the coal seam floor contour and fault occurrence data, the fault strike is projected to the coal seam level, which specifically includes the following steps:

[0084] Step 6.1, calculate the height difference H between the projected target layer and the fault point, where H is the difference between the contour line of the coal seam floor in the treatment area and the elevation coordinates at the fault point;

[0085] Step 6.2, calculate the plane projection distance L according to the following formula (2):

[0086]

[0087] Step 6.3, calculate the projection distance of each fault point according to step 6.2, and finally project the fault position to the target coal seam.

[0088] Example 1

[0089] In the Pingshuo mining area, the fault exploration method based on ground directional drilling technology was carried out in the Dongpo coal mine treatment area. The specific steps are as follows:

[0090] Step 1, preliminary selection of exploration and governance layers;

[0091] The gamma value while drilling is an intuitive reflection of the physical properties of the formation and a strong proof of the stratigraphic information encountered during drilling. Through statistical analysis of the logging data of the supplementary exploration boreholes in the treatment area, it is found that the gamma value of the top formation of the Ordovician limestone is generally small, with a gamma value within 20API, and most of them within 10API, reflecting the overall stability of the formation. The interface between the top of the Ordovician limestone and the adjacent formations of the Benxi Formation is relatively unstable. Affected by the weathering of the formation, the content of mud components is relatively high, and the gamma value fluctuates between 20 and 80API. The gamma value of bauxite is the largest in the formation, most of which are greater than 100API, and the peak value is even close to 280API, which has obvious characteristics. The API of K1 limestone is about 20 to 60API. This layer is close to normal sandy mudstone formations and coal seams, but its rock debris composition has obvious characteristics. In addition, the sandy mudstone layer immediately above the K1 limestone is a rare stratum with a relatively high gamma value. The gamma value is mainly 100-140 API, and the peak value can reach 200 API, which is slightly close to the bauxite layer, but the distribution is unstable. In summary, the gamma values ​​are ranked from large to small as follows: bauxite > sandy mudstone layer immediately above the top of K1 limestone (local occurrence) > sandy mudstone layer above the top of Ordovician limestone at the bottom of bauxite (local occurrence) > sandy mudstone layer of coal-bearing strata, coal seam > K1 mudstone > Ordovician limestone. Based on this, strata with obvious differences in natural gamma values ​​from their adjacent strata were selected, namely K1 limestone, bauxite, and Ordovician limestone, a total of 3 strata, such as Figure 1 As shown, these three layers are initially selected as the exploration and management layers.

[0092] Step 2, determine the final exploration and treatment layer;

[0093] The thickness of the coal floor waterproof layer is calculated according to the calculation formula (3) of the water inrush coefficient in Appendix 5 of the "Detailed Rules for Coal Mine Water Prevention and Control":

[0094] p s =T s M (3)

[0095] Where: P s is the safety head value of the bottom plate waterproof layer, MPa; M is the thickness of the bottom plate waterproof layer, m; T s T is the critical water inrush coefficient, MPa / m. s The value is determined based on the data of this area. Under normal circumstances, the section where the bottom plate is structurally damaged is calculated as 0.06MPa / m, and the section where the aquiclude is intact with no fractures or structural damage is calculated as 0.1MPa / m.

[0096] The No. 9 coal seam in the treatment area of ​​this embodiment is mined under water pressure with Ordovician limestone, and the maximum water pressure on the coal seam floor is 2.5Mpa. According to the critical water inrush coefficient of the floor section with structural damage, the thickness of the waterproof layer of the No. 9 coal floor is calculated to be not less than 41.67m. This thickness standard is compared with the average thickness of the No. 9 coal seam floor from the three preliminarily selected layers, and it can be seen that the three preliminarily selected layers can meet the waterproof layer thickness requirements. Therefore, the K1 limestone closest to the surface is selected as the final exploration and treatment layer.

[0097] In another embodiment of the present invention, when the thickness of the several preliminary selected exploration and treatment layers is not less than the thickness of the coal floor waterproof layer, the final exploration and treatment layer selected should also be more conducive to structural discrimination and meet the controllability of grouting. The following mainly compares the preliminary selected layers from three aspects: structural discrimination, drilling follow-up rate, and grouting controllability, as shown in Table 1.

[0098] Table 1 Comparison of advantages and disadvantages of the initial selected layers

[0099]

[0100] From the above comparison results, it can be seen that the K1 limestone layer is conducive to structural identification, but it is relatively difficult to drill into the layer in the complex structural area, and the grouting property is good; the bauxite layer is conducive to structural identification, but the discontinuous distribution increases the difficulty of following the layer, and the grouting property is relatively poor; the Ordovician limestone layer is not conducive to structural identification, with a wide distribution and large thickness, which is conducive to drilling into the layer and has strong grouting property, but it is easy to cause uneven diffusion of slurry and increase costs. Under the premise of naturally meeting the thickness requirements of the aquiclude, the focus of the exploration and treatment project becomes structural exploration and the blocking of vertical water-bearing channels. Based on this, the K1 limestone and its underlying strata are selected as the exploration and treatment layers.

[0101] Step 3: Data collection of directional drilling construction results;

[0102] Directional drilling was used to construct the D500 main hole in the southwest corner of the treatment area. The main hole was divided into a vertical hole section and a second inclined hole section: the first hole structure: hole depth 0.00~59.77m, hole diameter Φ345mm, lower Φ

[0103] 273.1*8.89mm casing 60.07m, using P.O42.5 cement slurry for cementing; Second opening drilling structure: 59.77m~511.90m, hole diameter Φ244.5mm, Φ193.7*8.33mm casing 523.67m, using P.O42.5 cement slurry for cementing, such as Figure 2 shown.

[0104] The hole entered the bedrock stratum from 30.70m, and a bag of rock cuttings was collected every 1m. The drilling fluid consumption was observed once every hour during the drilling process, and the normal value of the observed consumption was 0.36-1.92m 3 / h; the overall gamma value while drilling is in the range of 4.53 to 203.75API, among which, K1 limestone is encountered in the range of 415 to 432m, and the gamma value while drilling is 16.98 to 59.99API; bauxite mudstone is encountered in the range of 436 to 458m, and the gamma value while drilling is 97.35 to 203.75API; Ordovician limestone is encountered in the range of 458 to 511.9m, and the gamma value while drilling is 6.79 to 26.04API. Overall, the strata encountered from top to bottom in this hole are the Quaternary (Q), Permian (P), Taiyuan Formation (C3t) of the Upper Carboniferous, Benxi Formation (C2b) of the Middle Carboniferous, and Majiagou Formation (O2m) of the Ordovician.

[0105] According to the construction results of the first and second main hole openings, the standard database of the cuttings lithology and formation thickness (i.e., hole depth) of each marker layer in the treatment area was obtained, as shown in Table 2; the standard database of the gamma value characteristics while drilling and formation thickness (i.e., hole depth) was obtained, as shown in Figure 3 As shown; the standard database of drilling fluid consumption and formation thickness (i.e. hole depth), such as Figure 4 As shown;

[0106] Table 2 Standard database of rock fragments lithology and stratigraphic thickness of each marker layer in the treatment area

[0107]

[0108]

[0109] Step 4, determination of the fault point location;

[0110] Three horizontal branch holes D501, D502 and D503 were drilled at the bottom of the second casing of the main hole. The logging information during the drilling of the D501 branch hole was statistically analyzed and it was found that the drilling fluid consumption suddenly increased to 7.2m at a hole depth of 1326.33m. 3 / h, compared with the normal strata in the standard database 0.36~1.92m 3 / h is obviously higher; at the same time, the gamma value of drilling at this point has decreased significantly, which is consistent with the gamma value characteristics of the Ordovician limestone formation in the standard database; in addition, the lithology of the cuttings before and after the abnormal point changes from K1 limestone to Ordovician limestone layer, which is a discontinuous change. It is comprehensively judged that the abnormal point is caused by the impact of the drilling fault, and then the spatial position coordinate information of the breakpoint is read, such as Figure 5 Then implement D502 and D503 branch holes, the horizontal distance between them and D501 branch hole is 40 to 60m, and they are parallel to D501 branch hole, as shown in Figure 1. Figure 6As shown, the spatial position coordinate information of the breakpoints encountered when drilling the branch holes D502 and D503 is recorded.

[0111] Step 5, calculating fault occurrence data;

[0112] The spatial position coordinate information of the three breakpoints in step 4 is shown in Table 3.

[0113] Table 3 Breakpoint coordinates list

[0114] Breakpoint number X Y Z Breakpoint A 4366773.285 622449.02 764.69 Breakpoint B 4366826.513 622371.9756 954.8 Breakpoint C 4366964.093 622503.3602 824.7

[0115] Using the spatial coordinates of the three points, the vector inside the fracture surface can be obtained: and vector coordinate: pass Vector Sum Vector calculation to obtain the fracture surface normal vector The coordinates are (-5, 11, 6), then the horizontal plane projection vector The coordinates are (-5, 11, 0), and the calculation is The angle α with the positive direction of the X-axis is -65°. Since a<0, the azimuth θ=π+(-65°), and the calculated azimuth is 115°. Assuming the fault plane dip is β, the spatial vertical unit vector Then the fault plane normal vector The angle between the vertical unit vector and The calculated fault plane dip angle β is 63.59°, which is rounded to 64°.

[0116] Step 6, projecting the fault strike to the recovered coal seam level;

[0117] According to the elevation coordinates of the coal seam floor in the treatment area and the breakpoint, the height difference between the projected target layer and the breakpoint position is calculated to be H = 50.21m. Substituting H and β into formula (2), the plane projection distance L = 24.5m is calculated. Finally, the fault position is projected to the target coal seam, as shown in Figure 6 shown.

[0118] The present invention also provides a method for determining the water conductivity of a fault: the aquifers that are more closely related to the mining of the No. 9 coal seam in the mine are mainly the sandstone fissure aquifers in the coal-bearing rock system in the top and bottom plates of the coal seams and the Ordovician limestone aquifers at the bottom. According to the supplementary drilling hydrological data of the treatment area and the mine hydrological observation system data, the static water level elevation of the sandstone fissure aquifers in the coal-bearing rock system in the top and bottom plates of the coal seams is +1111.55m, and the Ordovician limestone water level elevation within the treatment area is +1052.35m.

[0119] After drilling the fault point in each horizontal branch hole, start drilling, and observe the water level in the hole for more than 8 to 12 hours. The cumulative number of observations should be no less than 3 times, with an interval of no less than 8 hours. Each observation should be measured 2 to 3 times, and the average value should be taken as the observation result. The difference between two adjacent measurements should not exceed ±2cm. If it exceeds, it needs to be re-measured and recorded. The water level elevation of each horizontal branch hole is accurately measured: the water level elevation of the D501 branch hole is +1055.53m, the water level elevation of the D502 branch hole is +1055.39m, and the water level elevation of the D503 branch hole is +1053.16m. Combined with the previous construction drilling water level observation data and hydrogeological test results in the treatment area, the following judgment standard is obtained, see Table 4 for details. This standard is not universal and can be obtained based on actual test data in different regions.

[0120] Table 4 Fault water conductivity identification table

[0121]

[0122] The water level differences among the branch holes D501, D502 and D503 are all less than 10m, and the water level differences with the Ordovician ash in the area are less than 10m, which conforms to the third situation. It is determined that the drilled fault as a whole has a certain degree of water conductivity.

[0123] According to step 5, in the direction of drilling, the branch hole encountered stratum lithology from the K1 layer to the Ordovician limestone layer. Combined with the standard database of stratum thickness established in step 3, it can be seen that the distance between the top of K1 limestone and the top of Ordovician limestone is 42.11m, which indicates that the fault drop is greater than 42.11m.

Claims

1. A method for detecting fault occurrence based on ground directional drilling technology, characterized in that: The following steps are involved: Step 1: Selecting a stratum or stratum combination with a different natural gamma value from the adjacent stratum section as a preliminary treatment stratum based on the drilling and logging data of the treatment area; Step 2: Calculate the thickness of the impermeable layer required for coal seam recovery according to the "Detailed Rules for Coal Mine Water Prevention and Control", calculate the average thickness of each preliminary treatment layer to the coal seam, and determine the preliminary treatment layer with the smallest average thickness that is not less than the thickness of the impermeable layer as the exploration treatment layer; Step 3: Carry out construction based on ground directional drilling technology, drill the main hole, drill the bottom of the main hole to the exploration and treatment layer, collect the main hole logging data during the drilling process, and establish a standard database based on the main hole logging data; Step 4, drilling at least three parallel horizontal branch holes at the bottom of the main hole, recording the logging data of each branch hole during the drilling process, comparing them with the standard database, determining the drilling fault point, and reading the spatial position coordinate information of the drilling fault point; Step 5: Calculate the fault plane dip azimuth θ and inclination β based on the spatial position coordinate information of the fault points encountered by each branch hole.

2. The method for detecting fault occurrence based on ground directional drilling technology according to claim 1, characterized in that: The difference between the average natural gamma value of the primary selected treatment layer and the average natural gamma value of the adjacent formation segment is ≥50API.

3. The method for detecting fault occurrence based on ground directional drilling technology according to claim 1, characterized in that: The main hole includes a first vertical section and a second inclined section. The first vertical section is a hole opening vertically downward to the top of the bedrock, and the second inclined section is an inclined section from the top of the bedrock to the exploration and management layer.

4. The method for detecting fault occurrence based on ground directional drilling technology according to claim 1, characterized in that: The logging data include lithology of flowback cuttings, formation thickness, gamma while drilling, and drilling fluid consumption.

5. The method for detecting fault occurrence based on ground directional drilling technology according to claim 4, characterized in that: The method for determining the drilling fault point is that the backflow cuttings are discontinuous, the gamma value changes while drilling, and the drilling fluid consumption increases in the formation.

6. The method for detecting fault occurrence based on ground directional drilling technology according to claim 1, characterized in that: The drilling method of the horizontal branch holes is to first drill a horizontal branch hole, and when the horizontal branch hole encounters a fault, drill other horizontal branch holes at adjacent positions thereof, and the distance between adjacent horizontal branch holes is 40 to 60 m.

7. The method for detecting fault occurrence based on ground directional drilling technology according to claim 1, characterized in that: The step 5 is specifically as follows: Step 5.1, select the spatial coordinates of the breakpoints encountered by three branch holes, record them as A(x1, y1, z1), B(x2, y2, z2), and C(x3, y3, z3), and obtain the vector in the fault plane and vector coordinate, Step 5.2, according to the vector and vector Calculate the fault plane normal vector Its coordinates are in: a=(y2-y1)(z3-z1)-(y3-y1)(z2-z1), b=(z2-z1)(x3-x1)-(z3-z1)(x2-x1), c=(x2-x1)(y3-y1)-(x3-x1)(y2-y1); Step 5.3, let the horizontal plane projection vector be Step 5.4, the fault azimuth θ is The clockwise angle with the north direction, first calculate The angle α with the positive direction of the X-axis is calculated according to formula (1), and then according to The quadrant determines θ: When a>0, b>0, θ=α, When a<0, θ=π+α, When a>0, b<0, θ=2π+α; Step 5.5, let the fault plane dip angle be β and the spatial vertical unit vector be Then the fault plane normal vector and the vertical unit vector The angle between them is β, 8. A method for detecting fault projection based on ground directional drilling technology, characterized in that: The method for detecting fault occurrence based on ground directional drilling technology according to any one of claims 1 to 7 specifically comprises the following steps: Step 1, calculate the difference H between the elevation coordinates of the coal seam floor contour line in the treatment area and the fault point; Step 2: Calculate the plane projection distance L of the fault point according to the following formula (2): Step 3: Calculate the plane projection distance of each fault point according to step 2, and finally project the fault position to the target coal seam.

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