Thin sandstone reservoir horizontal well mining structure and mining method

Abstract

The invention relates to the technical field of well production, in particular to a thin sandstone reservoir horizontal well production structure and method. The thin sandstone reservoir horizontal well mining structure comprises an upper rock stratum and a bottom rock stratum, a first vertical well is formed downwards from the top of the upper rock stratum, and a second vertical well formed to the bottom rock stratum is formed downwards from the bottom of the first vertical well. The horizontal well is formed in the bottom rock stratum from the bottom end of the second vertical well in the horizontal direction, an inclined well is arranged between the horizontal well and the bottom end of the second vertical well, a first step part is arranged at the bottom end of the first vertical well, a second step part is arranged at the bottom end of the second vertical well, a buffer hole is formed in the inclined well, and the buffer hole is communicated with the inclined well. The buffer hole and the second vertical well are located on the same vertical line, the flexible drill bit can deflect after being buffered and blocked by the spherical surface, and it is guaranteed that the opened horizontal well does not deflect greatly when tunneling continues.

Description

Technical Field

[0001] The invention relates to the technical field of well production, and in particular to a thin sandstone reservoir horizontal well production structure and a production method. Background Art

[0002] The advantage of horizontal well mining in sandstone reservoirs is that drilling horizontally from the side toward the sampling environment allows the well channel to reach the sampling environment in a more direct way to continuously obtain materials, thereby continuously extracting materials. When drilling, it is necessary to first drill a vertical well of a certain depth on the upper soil, then penetrate the flexible drill bit into the bottom of the vertical well, and use the gyroscope to adjust the drill bit to a horizontal excavation method to reach the sampling environment.

[0003] After the flexible drill is dropped to the bottom of the vertical well, the bottom end of the drill bit is acted upon by the reverse force from the bottom of the well and is very likely to deflect, resulting in a large deviation in the excavation direction of the horizontal well, which is difficult to adjust. If water seepage occurs in the horizontal well after horizontal excavation, it is difficult to drain, affecting the construction progress. Summary of the invention

[0004] In order to solve the above problems, the present invention provides the following technical solutions: A thin sandstone reservoir horizontal well mining structure comprises an upper rock formation and a bottom rock formation, a first vertical well is opened downward from the top of the upper rock formation, a second vertical well is opened downward from the bottom of the first vertical well to the bottom rock formation, a horizontal well is opened on the bottom rock formation along the horizontal direction from the bottom end of the second vertical well, an inclined well is arranged between the bottom ends of the horizontal well and the second vertical well, a first step is arranged at the bottom end of the first vertical well, a second step is arranged at the bottom end of the second vertical well, a buffer hole is arranged on the inclined well, the buffer hole and the second vertical well are on the same vertical line, a third step is arranged in the middle of the buffer hole, the top surface of the third step coincides with the surface of the inclined well, and a There is a pressure tube, a rubber plug is removably installed in the tube cavity of the pressure tube, a first pressure ring is fixed on the pressure tube, a first spring is arranged between the first pressure ring and the second step portion, a groove is opened on the upper rock formation, one end of the groove is communicated with the first step portion, and the other end of the groove is directly connected to the outside of the upper rock formation, the buffer hole is filled with a buffer tube, a second pressure ring is fixed on the buffer tube, the second pressure ring is located above the third step portion, a second spring is arranged between the second pressure ring and the third step portion, a row of holes is opened on the first pressure ring, the row of holes is communicated with the second vertical well, the inclined well and the horizontal well, and the top of the buffer tube is provided with a spherical surface protruding in the inclined well.

[0005] Preferably, the inner surface of the inclined well is a rounded surface connected between the first vertical well and the horizontal well, and the spherical surface protrudes on the inner side of the inclined well along the rounded surface.

[0006] Preferably, the first vertical well is filled with a reinforcement pipe, the bottom end of the reinforcement pipe falls on the first step portion, a through hole communicating with the inclined well is opened at the bottom end of the reinforcement pipe, a circular plate is welded to the bottom end of the reinforcement pipe, the through hole is opened on the circular plate, and the bottom end of the circular plate falls on the first step portion.

[0007] Preferably, a guide plate is provided at the top end of the pressing tube, and the guide plate is slidably fitted on the cavity wall of the reinforcing tube.

[0008] Preferably, the top surface of the groove is in vertical communication with the top surface of the upper rock formation. The present invention also provides a method for mining a thin sandstone reservoir horizontal well, which is applicable to the above-mentioned thin sandstone reservoir horizontal well mining structure, and comprises the following steps: Step S01, drilling the first vertical well downward from the upper rock formation, with the bottom of the first vertical well reaching the bottom rock formation as a reference; Step S02, drilling the second vertical well from the bottom end of the first vertical well to the bottom rock formation, when selecting a drill bit, the diameter of the drill bit in step S02 is smaller than the diameter of the drill bit in step S01, so that the first step is formed between the first vertical well and the second vertical well; Step S03, inserting the reinforcement pipe into the first vertical well until the bottom end of the reinforcement pipe falls on the first step; Step S04, replace a drill bit that is smaller than that in step S02, and during drilling, first use a drill bit with a larger diameter to expand the hole downward from the bottom end of the second vertical well, so that a second step portion is formed between the expanded hole and the bottom end of the second vertical well, and the lower half of the buffer hole is drilled downward on the bottom rock formation along the bottom end of the second vertical well, and a larger drill bit is replaced to drill the upper half of the buffer hole along the lower half of the buffer hole, so that a third step portion is formed in the middle of the buffer hole; Step S05, placing the second spring on the third step portion through the first vertical well and the second vertical well, installing the buffer tube into the buffer hole, and pressing the second pressure ring on the second spring; Step S06, placing the first spring in the second vertical well so that the bottom end of the first spring falls on the second step portion, inserting the pressing tube into the reinforcing tube along the through hole so that the bottom end of the pressing tube extends into the second vertical well, and at the same time pressing the first pressing ring on the top end of the first spring; Step S07, replace the flexible drill, and move the drill bit along the lumen of the pressure tube into the bottom end of the second vertical well, and use the bottom end of the second vertical well as a starting point to drill the inclined well downward, the drill bit of the flexible drill turns after being restricted by the spherical surface, and drills the horizontal well on the bottom rock formation along the length direction, and the drilling operation is completed; Step S08, installing the rubber plug into the pressure tube, and opening the groove on the upper rock formation, wherein the inner end of the groove is communicated with the second vertical well, and the inner end of the groove is communicated with the row of holes on the first pressure ring in an up-and-down manner; Step S09, pressing the rubber plug, the rubber plug pushes the pressure tube down, the pressure tube pushes the first pressure ring down, so that pressure is formed in the second vertical well, so that the liquid refluxed in the inclined well when drilling the horizontal well rises, and the rising liquid passes through the drainage hole into the channel, and is finally discharged outward from the channel; Step S10, removing the rubber plug, passing the flexible tube through the lumen of the compression tube into the second vertical well, and inserting the flexible tube into the horizontal well after being deflected by the spherical surface.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. A buffer hole is set at the bottom end of the vertical well. During construction, the buffer tube is placed in the buffer hole. The bottom section of the buffer tube passes through the second spring and is inserted into the lower half of the buffer hole. The second pressure ring on the buffer tube presses on the second spring. The spherical surface at the top of the buffer tube protrudes in the upper half of the inclined well. The flexible drill bit is replaced and the flexible drill bit is pushed into the upper part of the inclined well by the flexible rod. The bottom end of the flexible drill bit falls on the spherical surface. Under the action of the buffer tube and the second spring, the spherical surface not only provides a buffering effect to the flexible drill bit, but also uses reverse buffering to adjust the flexible drill bit so that the flexible drill bit can drill a horizontal well in the horizontal direction as shown in the figure. After being blocked by the spherical buffer, the flexible drill bit can be deflected, so that the horizontal well opened will not be significantly deflected when continuing to excavate.

[0010] 2. According to the rock and mineral conditions, the spherical surface on the buffer tube is set to be slightly upward in the direction of the horizontal well. When the flexible drill bit falls on the spherical surface, in addition to being adjusted to excavate in the direction of the horizontal well, its excavation direction is also slightly upward, so that the drilled horizontal well will be slightly inclined upward. After drilling the horizontal well along the bottom rock layer in this way, the flexible drill is raised upward. If there is moisture on the surface of the flexible drill, it proves that there is indeed water seepage when excavating the horizontal well. As the flexible drill and the flexible power rod are raised, most of the moisture will be removed due to the horizontal well moving toward the inclined well. One side tilts downward and flows back into the inclined well. At this time, a groove is first opened downward along the top surface of the upper rock layer. The depth of the groove reaches the first pressure ring as shown in the figure, and all the drainage holes on the first pressure ring are leaked, and then the rubber plug is inserted into the pressure tube. Under the support of the first spring on the first pressure ring, a distance is formed between the bottom end of the pressure tube and the inclined well. The rubber plug is frequently stepped on, and the bottom end of the pressure tube is pushed by the rubber plug to be frequently inserted into the inclined well, so that the water level in the inclined well continues to rise. After reaching the first pressure ring, it flows into the groove from the drainage holes and is then discharged outward from the groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic diagram of a thin sandstone reservoir horizontal well mining structure provided by an embodiment of the present invention; Figure 2 A thin sandstone reservoir horizontal well mining structure provided by the embodiment of the present invention is composed of Figure 1 The derived top view plan diagram; Figure 3 A thin sandstone reservoir horizontal well mining structure provided by the embodiment of the present invention is composed of Figure 2 The A-section diagram is shown below; Figure 4 A thin sandstone reservoir horizontal well mining structure provided by the embodiment of the present invention is composed of Figure 3 The enlarged schematic diagram of the B part is shown; Figure 5 A thin sandstone reservoir horizontal well mining structure provided by the embodiment of the present invention is composed of Figure 3 The enlarged schematic diagram of the C part is shown; Figure 6 A schematic diagram of a partially cut-away thin sandstone reservoir horizontal well production structure provided in an embodiment of the present invention.

[0012] In the figure: 1, upper rock layer; 2, bottom rock layer; 3, first vertical well; 4, second vertical well; 5, horizontal well; 6, inclined well; 7, first step; 8, second step; 9, buffer hole; 10, third step; 11, pressure tube; 12, rubber plug; 13, first pressure ring; 14, first spring; 15, groove; 16, buffer tube; 17, second pressure ring; 18, second spring; 19, row hole; 20, reinforcement tube; 21, through hole; 22, guide plate; 23, spherical surface; 24, circular plate. DETAILED DESCRIPTION

[0013] The above and other embodiments and advantages of the present invention are described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments.

[0014] In one embodiment, if Figure 1-Figure 6 As shown: The present embodiment provides a thin sandstone reservoir horizontal well mining structure, including an upper rock layer 1 and a bottom rock layer 2, a first vertical well 3 is opened downward from the top of the upper rock layer 1, a second vertical well 4 is opened downward from the bottom of the first vertical well 3 to the bottom rock layer 2, a horizontal well 5 is opened on the bottom rock layer 2 along the horizontal direction from the bottom end of the second vertical well 4, an inclined well 6 is arranged between the horizontal well 5 and the bottom end of the second vertical well 4, a first step 7 is arranged at the bottom end of the first vertical well 3, a second step 8 is arranged at the bottom end of the second vertical well 4, a buffer hole 9 is opened on the inclined well 6, the buffer hole 9 and the second vertical well 4 are on the same vertical line, a third step 10 is arranged in the middle of the buffer hole 9, the top surface of the third step 10 coincides with the surface of the inclined well 6, and a pressure pipe is arranged in the first vertical well 3. 11, a rubber plug 12 is removably installed in the lumen of the pressure tube 11, a first pressure ring 13 is fixed on the pressure tube 11, a first spring 14 is arranged between the first pressure ring 13 and the second step portion 8, a groove 15 is opened on the upper rock layer 1, one end of the groove 15 is communicated with the first step portion 7, and the other end of the groove 15 is directly connected to the outside of the upper rock layer 1, the buffer hole 9 is filled with a buffer tube 16, a second pressure ring 17 is fixed on the buffer tube 16, the second pressure ring 17 is located above the third step portion 10, a second spring 18 is arranged between the second pressure ring 17 and the third step portion 10, a row of holes 19 is opened on the first pressure ring 13, the row of holes 19 are communicated with the second vertical well 4, the inclined well 6 and the horizontal well 5, and the top of the buffer tube 16 is provided with a spherical surface 23 protruding in the inclined well 6.

[0015] Preferably, the inner surface of the inclined well 6 is a fillet surface that is continuous between the first straight well 3 and the horizontal well 5 , and the spherical surface 23 protrudes on the inner side of the inclined well 6 along the fillet surface.

[0016] Preferably, the first straight shaft 3 is filled with a reinforcement pipe 20 , the bottom end of the reinforcement pipe 20 falls on the first step 7 , and a through hole 21 communicating with the inclined shaft 6 is opened at the bottom end of the reinforcement pipe 20 .

[0017] Preferably, a guide plate 22 is provided at the top end of the pressing tube 11 , and the guide plate 22 is slidably fitted on the cavity wall of the reinforcing tube 20 .

[0018] Preferably, the top surface of the groove 15 is in vertical communication with the top surface of the upper rock layer 1 . Before construction, a drilling point is selected, and a straight drilling tool is used to drill along the upper rock layer 1 as the starting point, and a first straight well 3 is drilled. A drill bit thinner than the first straight well 3 is replaced, and the drill is drilled along the bottom end of the first straight well 3, and a second straight well 4 is drilled, so that a first step 7 is formed between the top of the second straight well 4 and the bottom end of the first straight well 3. A drill bit thinner than the second straight well 4 is replaced and the drill is drilled along the bottom end of the second straight well 4, and the top part of the inclined well 6 is drilled, so that the bottom end of the second vertical well 4 and the top section of the inclined well 6 form a second step 8. A fine drill bit is replaced to drill a buffer hole 9 in a straight drilling manner, and a third step 10 is drilled on the buffer hole 9 in the same way as above, and the straight drilling tool is used to drill the buffer hole 9. The second spring 18 is placed on the third step 10, the buffer tube 16 is placed in the buffer hole 9, the bottom section of the buffer tube 16 passes through the second spring 18 and is inserted into the lower half of the buffer hole 9, the second pressure ring 17 on the buffer tube 16 is pressed on the second spring 18, the spherical surface 23 at the top of the buffer tube 16 protrudes in the upper half of the inclined well 6, the flexible drill bit is replaced, and the flexible drill bit is pushed into the upper part of the inclined well 6 by the flexible rod, and the bottom end of the flexible drill bit falls on the spherical surface 23. Under the action of the buffer tube 16 and the second spring 18, the spherical surface 23 not only provides a buffering effect to the flexible drill bit, but also uses reverse buffering to adjust the flexible drill bit so that the flexible drill bit is pressed. Figure 3 In the manner shown, the horizontal well 5 is drilled in the horizontal direction. After being buffered and blocked by the spherical surface 23, the flexible drill bit can be deflected, and when the excavation continues, it is ensured that the horizontal well 5 drilled will not deviate significantly.

[0019] When the flexible drill is advancing, its flexible power rod rotates in the first vertical shaft 3 and the second vertical shaft 4. In order to prevent the first vertical shaft 3 (the upper rock layer 1 of the thin sandstone is relatively soft) from collapsing, the reinforcement pipe 20 is erected in the first vertical shaft 3 before the flexible drill bit is drilled down, and the bottom end of the reinforcement pipe 20 falls on the first step 7 to form a stable support.

[0020] Before the flexible drilling operation, in addition to placing the reinforcement pipe 20 into the first vertical well 3, it is also necessary to insert the first spring 14 into the reinforcement pipe 20 in advance, and then insert the pressure pipe 11 into the second vertical well 4. The first pressure ring 13 on the pressure pipe 11 presses on the first spring 14, so that the pressure pipe 11 is in a buffer state. The flexible power rod passes through the pressure pipe 11. When the flexible power rod carries the drill bit to drill the horizontal well 5, the rotation of the flexible power rod is restricted in the pressure pipe 11 to ensure stable rotation. The impact generated by the rotation of the flexible action rod will also act on the pressure pipe 11, which is transmitted from the pressure pipe 11 to the first spring 14 to achieve buffering.

[0021] In another embodiment, according to the actual conditions of the rock and mine (especially the bottom rock layer 2), the spherical surface 23 is slightly upturned toward the horizontal well 5. When the flexible drill bit falls on the spherical surface 23, in addition to being adjusted to excavate in the direction of the horizontal well 5, its excavation direction is also slightly upturned, so that the drilled horizontal well 5 will be slightly inclined upward. After drilling the horizontal well 5 along the bottom rock layer 2 in this way, the flexible drill is raised upward. If there is moisture on the surface of the flexible drill, it proves that there is indeed water seepage when excavating the horizontal well 5. As the flexible drill and the flexible power rod are raised, most of the moisture will flow back into the inclined well 6 because the horizontal well 5 is tilted downward toward one side of the inclined well 6. At this time, a groove 15 is first opened downward along the top surface of the upper rock layer 1, and the depth of the groove 15 is Figure 6 As shown, the water reaches the first pressure ring 13 and makes all the drainage holes 19 on the first pressure ring 13 leak out, and then the rubber plug 12 is inserted into the pressure tube 11. Under the support of the first spring 14 on the first pressure ring 13, a distance is formed between the bottom end of the pressure tube 11 and the inclined well 6. The rubber plug 12 is stepped on frequently, and the bottom end of the pressure tube 11 is pushed by the rubber plug 12 to be frequently inserted into the inclined well 6, so that the water level in the inclined well 6 continues to rise. After reaching the first pressure ring 13, the water flows from the drainage holes 19 to the groove 15, and then is discharged outward from the groove 15.

[0022] The present invention also provides a method for mining a thin sandstone reservoir horizontal well, which is applicable to the above-mentioned thin sandstone reservoir horizontal well mining structure, and comprises the following steps: Step S01, drilling a first vertical well 3 downward from the upper rock layer 1, with the bottom end of the first vertical well 3 reaching the bottom rock layer 2 as a reference; Step S02, drilling a second vertical well 4 from the bottom end of the first vertical well 3 to the bottom rock layer 2, when selecting a drill bit, the diameter of the drill bit in step S02 is smaller than the diameter of the drill bit in step S01, so that a first step 7 is formed between the first vertical well 3 and the second vertical well 4; Step S03, insert the reinforcement pipe 20 into the first vertical well 3 until the bottom end of the reinforcement pipe 20 falls on the first step 7; Step S04, replace a drill bit smaller than that in step S02, and during drilling, first use a drill bit with a larger diameter to expand the hole downward from the bottom end of the second vertical well 4, so that a second step 8 is formed between the expanded hole and the bottom end of the second vertical well 4, and drill the lower half of the buffer hole 9 downward on the bottom rock layer 2 along the bottom end of the second vertical well 4, and replace a larger drill bit to drill the upper half of the buffer hole 9 along the lower half of the buffer hole 9, so that a third step 10 is formed in the middle of the buffer hole 9; Step S05, placing the second spring 18 on the third step portion 10 through the first vertical well 3 and the second vertical well 4, installing the buffer tube 16 into the buffer hole 9, and at the same time pressing the second pressure ring 17 on the second spring 18; Step S06, placing the first spring 14 in the second vertical well 4, making the bottom end of the first spring 14 fall on the second step 8, inserting the pressing tube 11 into the reinforcing tube 20 along the through hole 21, making the bottom end of the pressing tube 11 extend into the second vertical well 4, and at the same time making the first pressing ring 13 press on the top end of the first spring 14; Step S07, replace the flexible drill, and move the drill bit along the lumen of the pressure tube 11 into the bottom end of the second vertical well 4, and use the bottom end of the second vertical well 4 as a starting point to drill the inclined well 6 downwards, the drill bit of the flexible drill turns after being blocked and restricted by the spherical surface 23, and drills a horizontal well 5 on the bottom rock layer 2 along the length direction, and the drilling operation is completed; Step S08, insert the rubber plug 12 into the pressure tube 11, and open a groove 15 on the upper rock layer 1, the inner end of the groove 15 is connected to the second vertical well 4, and the inner end of the groove 15 is connected to the row of holes 19 on the first pressure ring 13 in an upper and lower direction; Step S09, pressing the rubber plug 12, the rubber plug 12 pushes the pressure tube 11 down, and the pressure tube 11 pushes the first pressure ring 13 down, so that pressure is formed in the second vertical well 4, so that the liquid refluxed in the inclined well 6 when drilling the horizontal well 5 rises, and the rising liquid passes through the drainage hole 19 into the groove 15, and is finally discharged outward from the groove 15; Step S010, remove the rubber plug 12, pass the flexible tube through the lumen of the pressure tube 11 into the second vertical well 4, and insert it into the horizontal well 5 after being blocked by the spherical surface 23. The above orientation designations do not represent the specific orientations of the components in this embodiment. This embodiment is only for the convenience of describing the scheme, and the orientations are described and set relatively with reference to the drawings. In essence, the specific orientations of the components are described according to their actual installation and actual use, as well as the customary orientations of those skilled in the art. This is hereby explained.

[0023] The specific implementation methods described above further describe the invention purpose, technical solutions, and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thin sandstone reservoir horizontal well mining structure, characterized in that: The invention comprises an upper rock layer (1) and a bottom rock layer (2), wherein a first vertical well (3) is opened downward from the top of the upper rock layer (1), a second vertical well (4) is opened downward from the bottom of the first vertical well (3) to the bottom rock layer (2), a horizontal well (5) is opened on the bottom rock layer (2) along the horizontal direction from the bottom end of the second vertical well (4), an inclined well (6) is provided between the horizontal well (5) and the bottom end of the second vertical well (4), and a vertical well (6) is provided at the bottom end of the first vertical well (3). The first vertical well (3) has a first stepped portion (7), the second vertical well (4) has a second stepped portion (8) at its bottom end, the inclined well (6) has a buffer hole (9), the buffer hole (9) and the second vertical well (4) are on the same vertical line, a third stepped portion (10) is provided in the middle of the buffer hole (9), the top surface of the third stepped portion (10) coincides with the surface of the inclined well (6), a pressure tube (11) is provided in the first vertical well (3), and a removable pressure tube (11) is installed in the tube cavity of the pressure tube (11) The rubber plug (12) is provided with a first pressure ring (13) fixed on the pressure tube (11), a first spring (14) is provided between the first pressure ring (13) and the second stepped portion (8), a groove (15) is provided on the upper rock layer (1), one end of the groove (15) is communicated with the first stepped portion (7), and the other end of the groove (15) is directly connected to the outside of the upper rock layer (1), and a buffer tube (16) is filled in the buffer hole (9), and the buffer tube (16) is fixed on the buffer tube (16). A second pressure ring (17) is provided, the second pressure ring (17) is located above the third step portion (10), a second spring (18) is provided between the second pressure ring (17) and the third step portion (10), a row of holes (19) is opened on the first pressure ring (13), the row of holes (19) is communicated with the second vertical well (4), the inclined well (6) and the horizontal well (5), and the top end of the buffer tube (16) is provided with a spherical surface (23) protruding in the inclined well (6).

2. The thin sandstone reservoir horizontal well mining structure according to claim 1 is characterized in that: The inner surface of the inclined well (6) is a rounded surface connected between the first vertical well (3) and the horizontal well (5), and the spherical surface (23) protrudes on the inner side of the inclined well (6) along the rounded surface.

3. The thin sandstone reservoir horizontal well mining structure according to claim 2 is characterized in that: The first vertical well (3) is filled with a reinforcing pipe (20), the bottom end of the reinforcing pipe (20) falls on the first stepped portion (7), the bottom end of the reinforcing pipe (20) is provided with a through hole (21) communicating with the inclined well (6), a circular plate (24) is welded to the bottom end of the reinforcing pipe (20), the through hole (21) is provided on the circular plate (24), and the bottom end of the circular plate (24) falls on the first stepped portion (7).

4. The thin sandstone reservoir horizontal well mining structure according to claim 3 is characterized in that: A guide plate (22) is provided at the top end of the pressing tube (11), and the guide plate (22) is slidably fitted on the cavity wall of the reinforcing tube (20).

5. The thin sandstone reservoir horizontal well mining structure according to claim 4 is characterized in that: The top surface of the groove (15) is in vertical communication with the top surface of the upper rock layer (1).

6. A method for mining a thin sandstone reservoir horizontal well, applicable to the thin sandstone reservoir horizontal well mining structure as claimed in claim 3, characterized in that: The following steps are involved: Step S01, drilling the first vertical well (3) downward from the upper rock layer (1), wherein the bottom end of the first vertical well (3) is based on reaching the bottom rock layer (2); Step S02, drilling the second vertical well (4) from the bottom end of the first vertical well (3) toward the bottom rock layer (2), and when selecting a drill bit, the diameter of the drill bit in step S02 is smaller than the diameter of the drill bit in step S01, so that the first step (7) is formed between the first vertical well (3) and the second vertical well (4); Step S03, inserting the reinforcement pipe (20) into the first vertical well (3) until the bottom end of the reinforcement pipe (20) falls on the first step portion (7); Step S04, replacing a drill bit smaller than that in step S02, and during drilling, first using a drill bit with a larger diameter to expand the hole downward from the bottom end of the second vertical well (4), so that the second step portion (8) is formed between the expanded hole and the bottom end of the second vertical well (4), and the lower half of the buffer hole (9) is drilled downward on the bottom rock formation (2) along the bottom end of the second vertical well (4), and replacing a drill bit with a larger diameter to drill the upper half of the buffer hole (9) along the lower half of the buffer hole (9), so that the third step portion (10) is formed in the middle of the buffer hole (9); Step S05, placing the second spring (18) on the third step portion (10) through the first vertical well (3) and the second vertical well (4), installing the buffer tube (16) into the buffer hole (9), and at the same time making the second pressure ring (17) press on the second spring (18); Step S06, placing the first spring (14) in the second vertical well (4) so ​​that the bottom end of the first spring (14) falls on the second step portion (8), inserting the pressing tube (11) into the reinforcing tube (20) along the through hole (21) so that the bottom end of the pressing tube (11) extends into the second vertical well (4), and at the same time, pressing the first pressing ring (13) on the top end of the first spring (14); Step S07, replace the flexible drill, and let the drill bit enter the bottom end of the second vertical well (4) along the lumen of the pressure tube (11), and use the bottom end of the second vertical well (4) as a starting point to drill the inclined well (6) downwards, the drill bit of the flexible drill turns after being blocked and restricted by the spherical surface (23), and drills the horizontal well (5) on the bottom rock layer (2) along the length direction, and the drilling operation is completed; Step S08, inserting the rubber stopper (12) into the pressure tube (11), and opening the groove (15) on the upper rock layer (1), wherein the inner end of the groove (15) is in communication with the second vertical well (4), and the inner end of the groove (15) is in communication with the row of holes (19) on the first pressure ring (13) in an upper and lower direction; Step S09, pressing the rubber plug (12), the rubber plug (12) pushes the pressure tube (11) down, the pressure tube (11) pushes the first pressure ring (13) down, so that pressure is formed in the second vertical well (4), so that the liquid that flows back into the inclined well (6) when drilling the horizontal well (5) rises, and the rising liquid passes through the drainage hole (19) into the groove (15), and is finally discharged outward from the groove (15); Step S010, remove the rubber stopper (12), pass the flexible tube through the lumen of the pressure tube (11) into the second vertical well (4), and insert it into the horizontal well (5) after being blocked and deflected by the spherical surface (23).

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