Well bore structure for changing abandoned coal-bed gas well into empty well

Abstract

The utility model discloses a drilling well bore structure for changing a waste coal-bed gas well into an empty well, the well bore structure is composed of a main branch and a plurality of branches, the main branch is formed by reshaping and repairing an original ground waste coal-bed gas well through a sleeve, the plurality of branches are formed by windowing sidetrack drilling on the main branch, the adjacent branches are sealed and separated by bridge plugs, and the bridge plugs are connected with the main branch. A guide device is arranged at a windowing side drilling point of each branch, the bridge plug is a fishable bridge plug, each branch can fish each bridge plug after drilling to form a tree-shaped goaf ground extraction well, the lower part of each branch is communicated with a closed goaf space, and the ground extraction of gas in a plurality of closed goaf spaces can be realized. According to the well drilling well bore structure, through sidetrack drilling and directional drilling, gas of working faces of a plurality of goaf areas can be extracted through waste coal-bed gas wells in the later period, a tree-shaped goaf area ground extraction well can be formed at low cost and high efficiency, and the gas extraction effect of the goaf areas of a coal mine can be improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a goaf gas control technical field, especially to a kind of drilling well wellbore structure of abandoned coalbed gas well change goaf well. BACKGROUND

[0002] Goaf gas extraction technology can reduce gas concentration to the greatest extent, ensure coal mine safety production, and is conducive to reducing air pollution.Common gas extraction technologies include ground drilling extraction, high extraction roadway mining and high-level drilling mining.The main methods of goaf gas extraction by ground drilling method include extraction by mining well and extraction by goaf well, and suitable pre-extraction well can be transformed or special drilling well is constructed.The method of transforming mining well and goaf well by ground pre-extraction drilling well is tried in China, and the wellbore structure formed has a short service range, limited extraction range, and the extraction is difficult to guarantee in later period, so the extraction effect is not ideal. UTILITY MODEL CONTENT

[0003] The utility model aims at providing a kind of drilling well wellbore structure of abandoned coalbed gas well change goaf well, to realize the control of goaf underground gas, ensure underground safety production, and fully utilize abandoned coalbed gas well in goaf.

[0004] The technical scheme adopted by the utility model is: a kind of drilling well wellbore structure of abandoned coalbed gas well change goaf well, the wellbore structure is composed of one main branch and multiple branches, the main branch is formed by repairing the original ground abandoned coalbed gas well by casing shaping, and multiple branches are formed by windowing sidetracking on the main branch, bridge plug is used for sealing between adjacent branches, a whipstock is arranged at the windowing sidetracking point of each branch, the bridge plug is a retrievable bridge plug, each bridge plug can be fished after drilling each branch, forming tree-shaped goaf ground extraction well, the lower part of the main branch and each branch is connected with a closed goaf space, and gas in multiple closed goaf spaces can be extracted on the ground.

[0005] Further, the distance between adjacent windowing build-up points is more than 20m.

[0006] Further, the first bridge plug is located more than 100m above the goaf roof.

[0007] Further, the branch includes build-up section and stable inclination section, the maximum build-up rate of build-up section is 8° / 30m, and the maximum inclination of stable inclination section is 70°.

[0008] Further, the branch includes build-up section and stable inclination section.

[0009] Further, the inner diameter of the main branch is 124.26mm, φ116 sidetracking whipstock is arranged at the build-up point of the windowing sidetracking point of each branch, and the diameter of branch drilling hole is 114mm.

[0010] The drilling well body structure of the abandoned coal bed gas well converted into a goaf well can realize gas extraction from multiple goaf working faces of the abandoned coal bed gas well in the later period, can realize low-cost and high-efficiency formation of a tree-shaped goaf surface extraction well, and can improve the goaf gas extraction effect of the coal mine.

[0011] No matter from the aspects of promoting the remaining resources of closed coal mines, reusing the underground and surface space, eliminating the safety hidden danger of gas overflow in the coal goaf, and promoting the development of mine gas utilization in the low-carbon and environmental protection direction, the gas extraction and utilization mode adopting the technology is worth promoting. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is a front view structural schematic diagram of the utility model;

[0013] Figure 2 It is a top view structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0014] In order to better understand the purpose, structure and function of the utility model, the following will be further described in detail in combination with the drawings.

[0015] As shown in Figure 1 and Figure 2 , a drilling well body structure of an abandoned coal bed gas well converted into a goaf well, the well body structure is composed of one main branch and multiple branches, the main branch is formed by repairing the original surface abandoned coal bed gas well through casing shaping, the inner diameter is 124.26mm, and the multiple branches are formed by windowing sidetracking on the main branch, according to the drilling construction sequence number of the branches, the distance requirement of the windowing build-up points of the adjacent branches is more than 20m.

[0016] Bridge plugs 1 are used for spacing between the adjacent branches, and self-lowering φ114 fishable bridge plugs are respectively lowered from bottom to top, so that circulation is established in the subsequent drilling process, and the first bridge plug 1 is located more than 100m above the goaf roof. A φ116 sidetracking guide is arranged at the build-up point (avoiding the casing coupling) of the windowing sidetracking point of each branch, the diameter of the branch borehole is 114mm, and the lower part of the main branch and each branch is connected with one closed goaf space.

[0017] The branch mainly includes a build-up section and a stable section, and can also include an increasing section and a decreasing section according to the need, the maximum build-up rate of the build-up section can reach 8° / 30m, and the maximum well inclination of the stable section can reach 70°. After the drilling of each branch is completed, each bridge plug 1 and the guide 2 are fished, a tree-shaped goaf surface extraction well is formed, and the gas in the multiple closed goaf spaces can be surface extracted.

[0018] The well structure in the drilling construction process of the gas extraction well for the goaf gas ground extraction is the well structure in the drilling construction process of the gas extraction well for the goaf gas ground extraction, and the original ground coal bed gas well is transformed, so that the tree-shaped well structure is formed in the later well completion, and multiple closed space goafs can be efficiently extracted.

[0019] It can be understood that the utility model is described through some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the utility model. In addition, these features and embodiments can be modified to adapt to specific conditions and materials under the guidance of the utility model without departing from the spirit and scope of the utility model. Therefore, the utility model is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the application belong to the scope protected by the utility model.

Claims

1. A drilling shaft structure for converting abandoned coalbed methane wells into goaf wells, characterized in that, The well structure is composed of a main branch and multiple branches. The main branch is formed by repairing the original surface abandoned coal bed gas well through casing shaping. The multiple branches are formed by window sidetracking on the main branch. Adjacent branches are sealed by bridge plugs. A guide device is arranged at the window sidetracking point of each branch. The bridge plug is a fishable bridge plug. After drilling of each branch, the bridge plug can be fished, forming a tree-shaped goaf surface extraction well. The main branch and the lower part of each branch are connected to a closed goaf space, which can realize surface extraction of gas in multiple closed goaf spaces.

2. The wellbore construction for converting a depleted coalbed gas well to a vacant well according to claim 1, wherein, The distance between the window sidetracking points of adjacent branches is more than 20 m.

3. The wellbore construction for converting a depleted coalbed gas well to a vacant well according to claim 1, wherein, The first bridge plug is located more than 100 m above the goaf roof.

4. The wellbore construction for converting a depleted coalbed gas well to a vacant well according to claim 1, wherein, The branch includes a build-up section and a hold section. The maximum build-up rate of the build-up section is 8° / 30 m, and the maximum inclination of the hold section is 70°.

5. The wellbore construction for converting a depleted coalbed gas well to a vacant well according to claim 4, wherein, The branch includes a build-up section and a drop section.

6. The wellbore structure for converting a depleted coalbed gas well into a mined-out well according to any one of claims 1 to 5, characterized in that, The inner diameter of the main branch is 124.26 mm. A φ116 sidetracking guide device is arranged at the window sidetracking point of each branch. The diameter of the branch borehole is 114 mm.

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