Well pattern layout and drainage control method for high-steep coal seam development

Abstract

The present invention discloses a well network layout structure and drainage control method for the development of high-steep coal seams, including an integrated well platform and a horizontal well group, including a plurality of wellheads concentrated in the same area in the high-steep coal seam area, the horizontal well group including at least three horizontal wells spaced apart along the inclination direction of the coal seam, the horizontal sections of the horizontal wells being arranged along the direction of the coal seam, and the hydraulic fractures generated by the horizontal wells developing within the coal seam along the inclination direction of the coal seam, each horizontal well being matched with a wellhead, the present invention distributes the setting positions of the horizontal wells at intervals according to the inclination direction of the coal seam, and enables the hydraulic fractures generated by the horizontal wells to develop along the inclination direction of the coal seam, thereby achieving the maximum degree of transformation of the coal seam and improving production capacity, and the adopted drainage control method can reduce the replacement frequency of drainage pipe strings, reduce drainage costs, ensure the stability of the production system, and improve the comprehensive development effect.

Description

Technical Field

[0001] The present invention relates to the technical field of coalbed methane development, and in particular to a well pattern arrangement structure and a drainage and production control method for high-steep coal seam development. Background Art

[0002] The steepness of coal seams presents certain difficulties for coalbed methane (CBM) development. Due to the inherently poor permeability of steep coal seams, reservoir modification is necessary to increase their conductivity during development. Due to the steepness of coal seams, artificial fractures created in the seams tend to extend toward higher structural levels. Furthermore, during CBM production, differences in gas and water density lead to gas-water differentiation during the flow of gas and water within the coal seam. Gas, with its low density, tends to flow toward higher structural levels, while water, with its higher density, tends to flow toward lower structural levels. This gas-water differentiation leads to gas accumulation in higher structural levels, increasing pressure and hindering the further desorption of CBM from these higher structural levels. Water accumulation in lower structural levels hinders gas flow.

[0003] Research has found that coalbed methane production can generally be divided into six stages: drainage, gas / water production, first stable production, first production decline, second stable production, and second decline. Due to the complex production patterns of coalbed methane, the gas and water volumes vary significantly between stages, and the production process often requires replacement of drainage strings. This not only reduces production time and increases operating costs, but also leads to poor drainage effectiveness due to the discontinuous drainage system, affecting overall production. For high-steep coalbed methane, directional wells constructed along the dip of the coal seam are generally used for development. The corresponding buried depths of the reservoir sections vary greatly, making it easy for different sections in the same well to be in different production stages, further increasing the difficulty of drainage and reducing production efficiency.

[0004] Therefore, there is an urgent need for a well network layout structure and drainage control method for high-steep coal seam development to solve the above technical problems. Summary of the Invention

[0005] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problem that the drainage pipes need to be replaced frequently during the existing production process of high-steep coal seams, which not only reduces the production time rate and increases the operating costs, but also leads to poor drainage effect due to the discontinuous drainage system, affecting the overall output; and for high-steep coalbed methane, directional wells built along the coal seam dip are generally used for development. The corresponding burial depths of the reservoir sections vary greatly, and it is easy for different sections at different positions in the same well to be in different production stages, further increasing the difficulty of drainage and low production efficiency.

[0006] To this end, in a first aspect, the present invention provides a well network arrangement structure for the development of high-steep coal seams, comprising an integrated well platform and a horizontal well group, wherein the integrated well platform comprises a plurality of wellheads concentrated in the same area of ​​the high-steep coal seam area, the horizontal well group comprises at least three horizontal wells arranged at intervals along the inclination direction of the coal seam, the horizontal sections of the horizontal wells are arranged along the strike of the coal seam, and the hydraulic fractures generated by the horizontal wells develop within the coal seam along the inclination direction of the coal seam, and each of the horizontal wells is matched with a wellhead.

[0007] In the specific implementation of the well network arrangement structure for the development of the above-mentioned high-steep coal seam, the high-steep coal seam area is divided into an upper area, a middle area and a lower area along the inclination direction of the coal seam according to the gas and water distribution law of the high-steep coal seam, and the upper area, the middle area and the lower area each contain at least one horizontal well in the horizontal well group.

[0008] In a specific embodiment of the well pattern arrangement structure for developing high-steep coal seams, the horizontal wells in the lower area are installed with first drainage pipe strings during production.

[0009] In a specific embodiment of the well pattern arrangement structure for developing high-steep coal seams, the horizontal wells in the upper area are installed with a first gas production string during production, and the first gas production string is a self-flowing gas production string.

[0010] In the specific implementation of the well network arrangement structure for the development of high-steep coal seams, the horizontal wells in the central area are installed with corresponding second drainage pipe strings or second gas production pipe strings according to the gas production and liquid production during production, and the drainage volume of the second drainage pipe string is less than that of the first drainage pipe string.

[0011] In a specific embodiment of the well pattern arrangement structure for developing high-steep coal seams, there are two horizontal well groups, and the horizontal sections of the horizontal wells in the two horizontal well groups are in opposite directions.

[0012] In a second aspect, the present invention further provides a method for controlling production using the well pattern arrangement structure for high-steep coal seam development described in the first aspect, comprising the following steps:

[0013] During production, the wellhead pressure, liquid production and gas production of each horizontal well are obtained in real time;

[0014] According to the wellhead pressure, liquid production and gas production corresponding to the horizontal wells in the upper area, the lower area and the middle area, the first drainage pipe string corresponding to the horizontal wells in the upper area, the first gas production pipe string corresponding to the horizontal wells in the lower area and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal wells in the middle area are controlled to enter the drainage operation, and the horizontal wells in the lower area enter the drainage operation before the upper area, and the horizontal wells in the upper area enter the drainage operation before the middle area.

[0015] In a specific embodiment of the above-mentioned method for controlling the production of coal using a well pattern arrangement structure for high-steep coal seam development, the method further comprises:

[0016] If the liquid production of the horizontal wells in the middle area is greater than the first liquid production threshold, a second drainage string is installed in the horizontal wells in the middle area; or

[0017] If the gas production of the horizontal wells in the middle area is greater than the first gas production threshold, a second gas production string is installed in the horizontal wells in the middle area.

[0018] In a specific embodiment of the drainage and production control method for production using the well pattern arrangement structure for high-steep coal seam development, the step of "selectively controlling the first drainage pipe string corresponding to the horizontal wells in the upper area, the first gas production pipe string corresponding to the horizontal wells in the lower area, and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal wells in the middle area to enter drainage operations based on the wellhead pressure, liquid production, and gas production corresponding to the horizontal wells in the upper area, the lower area, and the middle area" specifically includes:

[0019] Determine whether the wellhead pressure value corresponding to the horizontal well in the lower area currently obtained is less than the wellhead pressure value obtained last time and whether the liquid production value is less than the liquid production value obtained last time;

[0020] If the current wellhead pressure value is less than the wellhead pressure value obtained last time and the liquid production value is less than the liquid production value obtained last time, then obtaining the wellhead pressure difference between the current wellhead pressure value and the last wellhead pressure value and obtaining the liquid production difference between the current liquid production value and the last liquid production value;

[0021] If the wellhead pressure difference is less than the preset pressure difference, and the liquid production difference is less than the preset liquid production difference, the first drainage pipe string corresponding to the horizontal well in the lower area is controlled to enter the drainage operation;

[0022] When all first drainage pipe strings in the lower area are activated, determining the difference between the wellhead pressure value of the horizontal well in the upper area and the first pressure threshold value, and the difference between the gas production and the second gas production threshold value;

[0023] If the wellhead pressure value corresponding to the horizontal well in the upper area is greater than the first pressure threshold and the gas production is greater than the second gas production threshold, the gas flow production string corresponding to the horizontal well in the upper area is controlled to enter the drainage operation;

[0024] When the first gas production string in the upper area is started, determining the difference between the wellhead pressure value of the horizontal well in the middle area and the second pressure threshold, and the difference between the gas production volume and the third gas production threshold;

[0025] If the wellhead pressure value corresponding to the horizontal well in the central area is greater than the second pressure threshold and the gas production is greater than the third gas production threshold, the second gas production string or the second drainage string corresponding to the horizontal well in the central area is controlled to enter the drainage operation.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention arranges the horizontal wells at intervals according to the inclination direction of the coal seam, and makes the hydraulic fractures generated by the horizontal wells develop along the inclination direction of the coal seam. That is, the hydraulic fractures in the high-steep coal seam are affected by the formation stress and expand in the vertical wellbore direction in the coal seam. At this time, the coal seam transformation volume is the largest, and the gas production process of the high-steep coal seam is affected by gravity. The gas migrates upward and the water migrates downward, resulting in the gas production law of the high-steep coal seam, thereby achieving the maximum degree of coal seam transformation and improving the high-steep coal seam gas production capacity.

[0028] 2. The drainage and production control method designed in the present invention can reduce the frequency of replacement of drainage pipes and reduce the drainage cost of high-steep coal seams. Moreover, combined with the layout of horizontal wells, it can maximize the release of high-steep coalbed methane production capacity, extend the stable production period, increase production capacity, ensure the stability of the production system, and enhance the comprehensive development effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0030] Figure 1 This is a schematic diagram of the well pattern arrangement structure for high-steep coal seam development provided by the present invention;

[0031] Figure 2 yes Figure 1 A top view of

[0032] Figure 3 This is a flow chart of the main steps of the drainage and production control method for production using the well pattern layout structure for high-steep coal seam development provided by the present invention;

[0033] Figure 4 It is a detailed flowchart of step S2.

[0034] List of reference numerals:

[0035] 1. Integrated well platform; 2. Horizontal well. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the systems or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing those components. Unless otherwise stated, these terms have no special meanings and should not be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "installed," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0039] The present invention relates to the technical field of coalbed methane development, and in particular to a well pattern layout structure and drainage control method for high-steep coal seam development. The purpose is to address the problem of frequent replacement of drainage pipes during production in existing high-steep coal seams, which not only reduces production time and increases operating costs, but also leads to poor drainage effects due to the discontinuous drainage system, affecting overall production. Furthermore, high-steep coalbed methane is generally developed using directional wells constructed along the coal seam's inclination. The corresponding buried depths of reservoir sections vary greatly, making it easy for different sections in the same well to be at different production stages, further increasing the difficulty of drainage and reducing production efficiency. To this end, the present invention provides a well network layout structure for the development of high-steep coal seams, including an integrated well platform and a horizontal well group. The integrated well platform includes multiple wellheads concentrated in the same area of ​​the high-steep coal seam area. The horizontal well group includes at least three horizontal wells arranged at intervals along the inclination direction of the coal seam. The horizontal sections of the horizontal wells are arranged along the direction of the coal seam, and the hydraulic fractures generated by the horizontal wells develop in the coal seam along the inclination direction of the coal seam. Each horizontal well is matched with a wellhead. The present invention provides a drainage and production control method for production using the well network layout structure for the development of high-steep coal seams, including the following steps: during production, obtaining the wellhead pressure, liquid production and gas production of each horizontal well in real time; according to the wellhead pressure, liquid production and gas production corresponding to the horizontal wells in the upper area, the lower area and the middle area, controlling the first drainage pipe string corresponding to the horizontal well in the upper area, the first gas production pipe string corresponding to the horizontal well in the lower area, and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal well in the middle area to enter the drainage operation, and the horizontal wells in the lower area enter the drainage operation before the upper area, and the horizontal wells in the upper area enter the drainage operation before the middle area. The use of drainage and production control methods can reduce the frequency of replacement of drainage pipes and reduce the drainage cost of high-steep coal seams. Moreover, combined with the layout of horizontal wells, it can maximize the release of high-steep coalbed methane production capacity, increase production capacity, ensure the stability of the production system, and improve the overall development effect.

[0040] Below, the well pattern arrangement structure and drainage control method for high-steep coal seam development provided by the embodiments of the present invention are described in detail with reference to the accompanying drawings.

[0041] See Figure 1-2 The present invention provides a well pattern arrangement structure for developing high-steep coal seams, including an integrated well platform and a horizontal well group. The integrated well platform includes a plurality of wellheads centrally arranged in the same area of ​​the high-steep coal seam. The horizontal well group includes at least three horizontal wells spaced apart along the inclination direction of the coal seam. The horizontal sections of the horizontal wells are arranged along the strike of the coal seam. Figure 1 As shown in Figure 2, the hydraulic fractures generated by the horizontal well develop along the inclination direction of the coal seam, as shown in Figure 2. Figure 1 The line segment perpendicular to the horizontal wells in the figure matches a wellhead for each horizontal well.

[0042] Specifically, there are two horizontal well groups, and the horizontal sections of the horizontal wells in the two horizontal well groups are in opposite directions. Figure 1-2 As shown. In addition, the horizontal section lengths of the horizontal wells in the two horizontal well groups can be the same or different. Multiple wellheads are concentrated in the same area, which reduces the distance between the wellheads and facilitates the staff to check and repair all wellheads within a close range, making the operation more convenient. The area where the integrated well platform is concentrated is flexibly selected according to the actual situation on site. For example, Figure 1 As shown, it is distributed in the middle part of the high and steep coal seam area.

[0043] More specifically, according to the gas and water distribution law of the high-steep coal seam, the high-steep coal seam is divided into an upper area, a middle area and a lower area along the inclination direction of the coal seam. The upper area, the middle area and the lower area all contain at least one horizontal well in the horizontal well group. This ensures that horizontal wells are set in the upper, middle and lower areas. Regarding the spacing between horizontal wells, this application does not make specific restrictions, but predicts the gas production, liquid production and bottom hole pressure of wells at different locations based on the numerical simulation software of the coalbed methane layer, and uses these data as a reference for the design of the horizontal well spacing. The upper area, the middle area and the lower area all contain at least one horizontal well in each horizontal well group.

[0044] In the above embodiment, the present application distributes the setting positions of horizontal wells at intervals according to the inclination direction of the coal seam, arranges the horizontal sections along the direction of the coal seam, and develops the hydraulic fractures generated by the horizontal wells along the inclination direction of the coal seam, that is, utilizes the expansion law of the fracturing cracks in the high-steep coal seam and the gas production law of the high-steep coalbed methane production process affected by gravity, so as to achieve the maximum degree of coal seam transformation and improve the production capacity of high-steep coalbed methane.

[0045] In one embodiment, the horizontal wells in the lower area are installed with a first drainage pipe string with a large displacement function during production. The first drainage pipe string is a large displacement drainage pipe string with a large drainage capacity and is mainly responsible for drainage. Affected by the downward supply of free water contained in the upper coal seam under the action of gravity, the gas field is flooded or has high water content throughout the development process. A large displacement drainage pipe string is used to achieve drainage and pressure reduction of the entire reservoir of the high-steep coal seam, and alleviate the impact of the large amount of water in the middle and upper horizontal wells on gas production. The drainage volume of the drainage pipe string is determined according to parameters such as the type of drainage pump, the size of the pipe string, and the depth of the drainage pump. This is a known prior art to those skilled in the art. The selection of the type of drainage pipe string is determined according to the predicted liquid production and bottom hole pressure. The higher the liquid production and bottom hole pressure, the greater the drainage volume of the selected drainage pipe string.

[0046] In one embodiment, a first gas production string is installed in the horizontal wells in the upper region during production. This first gas production string is a self-flowing gas production string. During coalbed methane production, gas and water flow in the coal seam due to differences in density. Since gas has a lower density and tends to flow toward higher structural areas, more gas accumulates in the upper region. A self-flowing gas production string is used for gas production.

[0047] In one embodiment, horizontal wells in the central region are equipped with a corresponding second drainage string or second production string during production, depending on gas and liquid production. The drainage volume of the second drainage string is less than that of the first drainage string. The central area of ​​a steep coal seam is affected by the gas-water differentiation of the upper coal seam. Initially, drainage is used for gas production, while later, gas production is primarily responsible. Depending on the initial water and gas volumes, the production string is replaced based on production dynamics. High gas production is replaced with the second production string, while high water production is replaced with the second drainage string.

[0048] For another embodiment, see Figure 3 The present invention also provides a method for controlling production by utilizing the well pattern arrangement structure for high-steep coal seam development described in the above embodiment, comprising the following steps:

[0049] S1, during production, real-time acquisition of wellhead pressure, liquid production, and gas production for each horizontal well;

[0050] S2, according to the wellhead pressure, liquid production and gas production corresponding to the horizontal wells in the upper area, the lower area and the middle area, control the first drainage pipe string corresponding to the horizontal wells in the upper area, the first gas production pipe string corresponding to the horizontal wells in the lower area and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal wells in the middle area to enter the drainage operation, and the horizontal wells in the lower area enter the drainage operation before the upper area, and the horizontal wells in the upper area enter the drainage operation before the middle area.

[0051] It should be noted that since there may be more than one horizontal well in the upper, middle and lower areas, the decision on whether to start the drainage operation will be based on the wellhead pressure, liquid production and gas production corresponding to each horizontal well in each area; that is, the drainage operation between each horizontal well is judged separately, and the horizontal well in the same area that meets the drainage conditions first will enter the drainage operation first.

[0052] In the present application, the drainage and production control method further includes: if the liquid production of the horizontal wells in the central area is greater than the first liquid production threshold, a second drainage pipe string is installed in the horizontal wells in the central area.

[0053] The production and drainage control method further includes: if the gas production of the horizontal wells in the central area is greater than a first gas production threshold, installing a second gas production string in the horizontal wells in the central area.

[0054] In one embodiment, see Figure 4 Step S2 of “selectively controlling the first drainage pipe string corresponding to the horizontal wells in the upper area, the first gas production pipe string corresponding to the horizontal wells in the lower area, and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal wells in the middle area to enter the drainage operation based on the wellhead pressures, liquid production rates, and gas production rates corresponding to the horizontal wells in the upper area, the lower area, and the middle area” specifically includes:

[0055] S21, determining whether the wellhead pressure value corresponding to the horizontal well in the lower area currently obtained is less than the wellhead pressure value obtained last time and whether the liquid production value is less than the liquid production value obtained last time;

[0056] S22, if the current wellhead pressure value is less than the wellhead pressure value obtained last time and the liquid production value is less than the liquid production value obtained last time, obtain the wellhead pressure difference between the current wellhead pressure value and the last wellhead pressure value and obtain the liquid production difference between the current liquid production value and the last liquid production value;

[0057] S23, if the wellhead pressure difference is less than the preset pressure difference, and the liquid production difference is less than the preset liquid production difference, controlling the first drainage pipe string corresponding to the horizontal well in the lower area to enter the drainage operation;

[0058] S24, when all the first drainage pipe strings in the lower area are activated, determining the difference between the wellhead pressure value of the horizontal well in the upper area and the first pressure threshold, and the difference between the gas production and the second gas production threshold;

[0059] S25, if the wellhead pressure value corresponding to the horizontal well in the upper region is greater than the first pressure threshold and the gas production is greater than the second gas production threshold, control the gas flow production string corresponding to the horizontal well in the upper region to enter the drainage operation;

[0060] S26, when all first gas production strings in the upper area are activated, determining the difference between the wellhead pressure value of the horizontal well in the middle area and the second pressure threshold, and the difference between the gas production and the third gas production threshold;

[0061] S27, if the wellhead pressure value corresponding to the horizontal well in the central area is greater than the second pressure threshold and the gas production is greater than the third gas production threshold, the second gas production string or the second drainage string corresponding to the horizontal well in the central area is controlled to enter the drainage operation.

[0062] Before executing step S24, it is necessary to determine whether all horizontal wells in the lower area have entered the drainage operation. If all horizontal wells have entered the drainage operation, the judgment operation of step S24 is executed again. Before executing step S26, it is necessary to determine whether all horizontal wells in the upper area have entered the drainage operation. If all horizontal wells have entered the drainage operation, the judgment operation of step S26 is executed again.

[0063] In the above embodiment, the drainage of the horizontal wells in the lower area is put into operation the earliest in the same well area, the drainage of the horizontal wells in the upper area is put into operation after the drainage of the lower area in the same well area, and the drainage operation of the horizontal wells in the middle area is put into operation the latest in the same well area. Through this drainage control, the workload of replacing production pipes in the high-steep coal seam area can be reduced by about 2 / 3, thereby achieving the functions of reducing the replacement frequency of drainage pipes and reducing the drainage cost of high-steep coal seams. Moreover, combined with the arrangement of horizontal wells, the release of high-steep coalbed methane production capacity can be maximized, the stable production period can be extended, the production capacity can be increased, the stability of the production system can be guaranteed, and the comprehensive development effect can be improved.

[0064] It should be noted that this application does not make any specific restrictions on the specific values ​​of the first gas production threshold, the second gas production threshold, the third gas production threshold, the first pressure threshold, the second pressure threshold, the preset pressure difference, and the preset liquid production difference, and they are flexibly set according to actual conditions.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the protection scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for controlling the development and drainage of high-steep coal seams, characterized in that: The method for regulating and controlling the development and drainage of high-steep coal seams is based on a well pattern arrangement structure for the development of high-steep coal seams. The well pattern arrangement structure for the development of high-steep coal seams includes an integrated well platform and a horizontal well group. The integrated well platform includes a plurality of wellheads centrally arranged in the same area of ​​the high-steep coal seam region. The horizontal well group includes at least three horizontal wells spaced apart along the inclination direction of the coal seam. The horizontal sections of the horizontal wells are arranged along the direction of the coal seam, and the hydraulic fractures generated by the horizontal wells develop in the coal seam along the inclination direction of the coal seam. Each of the horizontal wells is matched with a wellhead, and the high-steep coal seam region is divided into a plurality of wellheads according to the gas and water distribution law of the high-steep coal seam. The coal seam is divided into an upper area, a middle area, and a lower area along the inclination direction. Each of the upper area, the middle area, and the lower area includes at least one horizontal well in the horizontal well group. The horizontal wells in the lower area are installed with a first drainage pipe string during production. The horizontal wells in the upper area are installed with a first gas production pipe string during production. The first gas production pipe string is a self-flowing gas production pipe string. The horizontal wells in the middle area are installed with a corresponding second drainage pipe string or a second gas production pipe string according to the gas production and liquid production during production. The drainage volume of the second drainage pipe string is less than that of the first drainage pipe string. The drainage and production control method comprises the following steps: During production, the wellhead pressure, liquid production and gas production of each horizontal well are obtained in real time; According to the wellhead pressures, liquid production rates, and gas production rates corresponding to the horizontal wells in the upper, lower, and middle regions, the first drainage pipe string corresponding to the horizontal wells in the upper region, the first gas production pipe string corresponding to the horizontal wells in the lower region, and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal wells in the middle region are controlled to enter drainage operations, and the horizontal wells in the lower region enter the drainage operations before the upper region, and the horizontal wells in the upper region enter the drainage operations before the middle region; The step of "selectively controlling the first drainage pipe string corresponding to the horizontal wells in the upper area, the first gas production pipe string corresponding to the horizontal wells in the lower area, and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal wells in the middle area to enter drainage operations based on the wellhead pressures, liquid production rates, and gas production rates corresponding to the horizontal wells in the upper area, the lower area, and the middle area" specifically includes: Determine whether the wellhead pressure value corresponding to the horizontal well in the lower area currently obtained is less than the wellhead pressure value obtained last time and whether the liquid production value is less than the liquid production value obtained last time; If the current wellhead pressure value is less than the wellhead pressure value obtained last time and the liquid production value is less than the liquid production value obtained last time, then obtaining the wellhead pressure difference between the current wellhead pressure value and the last wellhead pressure value and obtaining the liquid production difference between the current liquid production value and the last liquid production value; If the wellhead pressure difference is less than the preset pressure difference, and the liquid production difference is less than the preset liquid production difference, the first drainage pipe string corresponding to the horizontal well in the lower area is controlled to enter the drainage operation.

2. The method for controlling the development and drainage of high-steep coal seams according to claim 1, characterized in that: There are two horizontal well groups, and the horizontal sections of the horizontal wells in the two horizontal well groups are in opposite directions.

3. The method for controlling the development and drainage of high-steep coal seams according to claim 1, characterized in that: The drainage and production control method further includes: If the liquid production of the horizontal wells in the middle area is greater than the first liquid production threshold, a second drainage string is installed in the horizontal wells in the middle area; or If the gas production of the horizontal wells in the middle area is greater than the first gas production threshold, a second gas production string is installed in the horizontal wells in the middle area.

4. The method for controlling the development and drainage of a high-steep coal seam according to claim 1 or 3, characterized in that: The step of "selectively controlling the first drainage pipe string corresponding to the horizontal wells in the upper area, the first gas production pipe string corresponding to the horizontal wells in the lower area, and the second drainage pipe string or the second gas production pipe string corresponding to the horizontal wells in the middle area to enter drainage operations based on the wellhead pressures, liquid production rates, and gas production rates corresponding to the horizontal wells in the upper area, the lower area, and the middle area" further specifically includes: When all first drainage pipe strings in the lower area are activated, determining the difference between the wellhead pressure value of the horizontal well in the upper area and the first pressure threshold value, and the difference between the gas production and the second gas production threshold value; If the wellhead pressure value corresponding to the horizontal well in the upper area is greater than the first pressure threshold and the gas production is greater than the second gas production threshold, the gas flow production string corresponding to the horizontal well in the upper area is controlled to enter the drainage operation; When the first gas production string in the upper area is started, determining the difference between the wellhead pressure value of the horizontal well in the middle area and the second pressure threshold, and the difference between the gas production volume and the third gas production threshold; If the wellhead pressure value corresponding to the horizontal well in the central area is greater than the second pressure threshold and the gas production is greater than the third gas production threshold, the second gas production string or the second drainage string corresponding to the horizontal well in the central area is controlled to enter the drainage operation.

Images