CN110242254B - Coal bed gas mining method - Google Patents

Coal bed gas mining method Download PDF

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CN110242254B
CN110242254B CN201810971547.4A CN201810971547A CN110242254B CN 110242254 B CN110242254 B CN 110242254B CN 201810971547 A CN201810971547 A CN 201810971547A CN 110242254 B CN110242254 B CN 110242254B
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reservoir
horizontal
coal bed
well
wellbore
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CN110242254A (en
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王国玲
杨陆武
郭卫东
崔玉环
严开峰
史红玲
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Beijing Orion Energy Technology Development Co ltd
China United Coalbed Methane Corp Ltd
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Beijing Orion Energy Technology Development Co ltd
China United Coalbed Methane Corp Ltd
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    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/006Production of coal-bed methane

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  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

The invention discloses a coal bed gas exploitation method, which can simultaneously open a plurality of adjacent reservoirs, realize the communication between a main well bore and the horizontal sections and the branch well sections of the plurality of reservoirs, and the plurality of adjacent reservoirs play a synergistic effect, effectively increase the permeability of the lower reservoir by utilizing the permeability increasing effect of the upper reservoir, and release the productivity to the maximum extent. The coal bed gas mining method provided by the scheme not only ensures the productivity, but also does not need to additionally construct another well, thereby reducing the coal bed gas mining cost of the multilayer reservoir to a certain extent.

Description

Coal bed gas mining method
Technical Field
The invention relates to the technical field of energy exploitation, in particular to a coal bed methane exploitation method.
Background
The coal bed gas is hydrocarbon gas which is stored in a coal bed, takes methane as a main component, is mainly adsorbed on the surface of coal matrix particles, is partially dissociated in coal pores or dissolved in coal bed water, is an associated mineral resource of coal, and belongs to unconventional natural gas. Coal bed gas is a clean high-quality energy and chemical raw material which rises internationally in nearly one and two decades.
The ground well drilling exploitation of coal bed gas is to open a horizontal well from the ground, the horizontal section of the horizontal well enters the unexplored coal bed, the coal bed gas in the coal bed is desorbed by means of water drainage and pressure reduction, and the desorbed coal bed gas flows to the ground through a shaft. The horizontal well increases the contact area between a shaft and a reservoir, particularly the multi-branch horizontal well communicates reservoir fractures, is the most effective coal bed gas exploitation mode, has high gas production rate, long gas production time and high methane content, and can support large-scale commercial utilization. However, the well track of the horizontal well passes through a target horizon, the influence range is limited, only the coal bed gas of the target horizon can be exploited, and the coal bed gas resources of the reservoir stratum adjacent to the target horizon are not used, so that another well needs to be additionally constructed to effectively exploit the multi-layer reservoir stratum, and the coal bed gas exploitation cost of the multi-layer reservoir stratum is high.
Therefore, how to reduce the coal bed methane production cost of the multilayer reservoir becomes a technical problem to be solved urgently by the technical personnel in the field.
Disclosure of Invention
In view of this, the invention provides a coal bed gas exploitation method to reduce the coal bed gas exploitation cost of a multi-layer system reservoir.
In order to achieve the purpose, the invention provides the following technical scheme:
a coal bed gas mining method is suitable for the condition that the distance between adjacent reservoirs is larger than 10m, and comprises the following steps:
step 1) opening a horizontal well, wherein the horizontal well sequentially passes through a plurality of reservoir beds from top to bottom, and is landed on the reservoir bed with the lowest horizontal height;
step 2) controlling the curvature of a well hole to adjust the well hole track of the horizontal well so that the horizontal well sequentially drills a plurality of reservoirs from bottom to top;
step 3) arranging a sieve tube in a main borehole of the horizontal well, wherein the lower end of the sieve tube is higher than the reservoir with the lowest level;
and 4) sequentially drilling the horizontal section and the branch well section of each reservoir from top to bottom.
Preferably, in the coal bed gas mining method, the length of the slope stabilizing section of the horizontal well is 30-50 m.
Preferably, in the coal bed gas production method, the wellbore curvature in the step 2) is less than 6 °/30 m.
Preferably, in the method for exploiting coal bed methane, the step 4) is to establish a new geosteering model according to the wellbore trajectory data of the horizontal well in the step 2) to drill the horizontal section and the branch section of each reservoir.
Preferably, in the coal bed gas production method, the sieve tube is a PE sieve tube.
Preferably, in the coal bed gas mining method, the sieve tube is a glass fiber reinforced plastic sieve tube.
Preferably, in the coal bed gas mining method, the sieve tube is a PVC sieve tube.
Preferably, in the method for exploiting coal bed methane, in the step 3), the upper end of the screen pipe is connected with a technical casing, and the connection length of the screen pipe to the technical casing is 10-20 m.
According to the technical scheme, the coal bed gas exploitation method provided by the invention can simultaneously open a plurality of adjacent reservoirs, realizes the communication between a main well bore and the horizontal sections and the branch well sections of the plurality of reservoirs, enables the plurality of adjacent reservoirs to exert a synergistic effect, effectively increases the permeability of the lower reservoir by utilizing the permeability increasing effect of the upper reservoir, and releases the productivity to the maximum extent. The coal bed gas mining method provided by the scheme not only ensures the productivity, but also does not need to additionally construct another well, thereby reducing the coal bed gas mining cost of the multilayer reservoir to a certain extent.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of a method for producing coalbed methane according to an embodiment of the present invention;
fig. 2 is a three-dimensional projection view of a stereoscopic horizontal well provided by the embodiment of the invention.
Detailed Description
The invention discloses a coal bed gas mining method, which aims to reduce the coal bed gas mining cost of a multilayer reservoir stratum.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 and 2, fig. 1 is a flow chart of a coal bed methane mining method according to an embodiment of the present invention; fig. 2 is a three-dimensional projection view of a stereoscopic horizontal well provided by the embodiment of the invention.
The invention discloses a coal bed gas mining method, which is suitable for the condition that the distance between adjacent reservoirs is more than 10 m. When the underground friction resistance is low, the space between adjacent reservoirs needs to be larger than 50m by the coal bed gas exploitation method provided by the scheme, and when the underground friction resistance is high, the coal bed gas exploitation method provided by the scheme is suitable for the condition that the space between adjacent reservoirs is 10-50 m.
The coal bed gas mining method provided by the scheme comprises the following steps:
step 1) opening a horizontal well, wherein the horizontal well sequentially passes through a plurality of reservoirs from top to bottom, the horizontal well firstly passes through the reservoir with the highest horizontal height and finally lands on the reservoir with the lowest horizontal height, namely the horizontal well sequentially passes through all the reservoirs of the multi-layer system reservoir;
step 2) controlling the wellbore curvature to adjust the wellbore trajectory of the horizontal well so that a shaft of the horizontal well sequentially drills into a plurality of reservoirs from bottom to top, wherein the wellbore curvature is set according to the positions of adjacent reservoirs, the wellbore curvature is controlled so that the wellbore trajectory gradually enters a reservoir with the second lowest horizontal height from the reservoir with the second lowest horizontal height, the wellbore curvature is controlled so that the wellbore trajectory gradually enters a reservoir with the third lowest horizontal height from the reservoir with the second lowest horizontal height, and the like, the wellbore finally enters the reservoir with the highest horizontal height, and the step 2) realizes the communication between the plurality of reservoirs of the multi-layer reservoir and a main wellbore of the horizontal well;
step 3), placing a screen pipe in a main well hole of the horizontal well, wherein the lower end of the screen pipe is higher than the reservoir with the lowest horizontal height, the screen pipe is used for supporting the main well hole above the reservoir with the lowest horizontal height, and preferably, the screen pipe is placed into the main well hole through a releasing tool;
and 4) sequentially drilling the horizontal section and the branch well section of each reservoir from top to bottom, specifically, firstly drilling the horizontal section and the branch well section of the reservoir with the highest horizontal height, then drilling the horizontal section and the branch well section of the reservoir with the second highest horizontal height, then drilling the horizontal section and the branch well section of the reservoir with the third highest horizontal height, and so on, and finally drilling the horizontal section and the branch well section of the reservoir with the lowest horizontal height, and in the step 4), drilling the horizontal section and the branch well section horizontally or parallelly along each reservoir, wherein the contact area of the horizontal well and the corresponding reservoir is increased by the aid of the horizontal section and the branch well section, so that the coal bed gas exploitation efficiency and the exploitation amount are guaranteed.
The coal bed gas exploitation method provided by the scheme can be used for simultaneously opening a plurality of adjacent reservoirs, the well track of the horizontal well penetrates through the plurality of reservoirs of the multi-layer system reservoir, one main well is communicated with the horizontal sections and the branch well sections of the plurality of reservoirs, the plurality of adjacent reservoirs play a synergistic effect, the permeability of the lower reservoir is effectively increased by utilizing the permeability increasing effect of the upper reservoir, and the capacity is released to the maximum extent. The coal bed gas mining method provided by the scheme not only ensures the productivity, but also does not need to additionally construct another well, thereby reducing the coal bed gas mining cost of the multilayer reservoir to a certain extent.
The horizontal well comprises a straight well section, a deflecting section and a horizontal section, preferably, a self-stabilizing deflecting section is provided with a shaft communicated with a plurality of reservoirs, namely, the self-stabilizing deflecting section starts to control the curvature of the well hole to adjust the track of the well hole, the curvature of the well hole is set along with the position of a target reservoir, and the target reservoir is the next reservoir to be drilled.
When a horizontal section and a branch well section are formed in a target reservoir, the construction capacity of a drilling machine and an underground guiding tool needs to be considered, preset footage is completed, the number of the branch well sections to be formed in the target reservoir and the footage number are determined according to the resource condition of the target reservoir, and more branch well sections and longer footage numbers can be arranged under the condition that the resource condition of the target reservoir is good.
In order to further optimize the technical scheme, the length of the steady slope section of the horizontal well is 30-50m so as to deal with uncertainty of reservoir burial depth.
The curvature of the borehole in the step 2) is less than 6 degrees/30 m.
And 4) specifically, establishing a new geosteering model according to the well track data of the horizontal well in the step 2) to drill the horizontal section and the branch well section of each reservoir so as to improve the drilling rate of the reservoir.
The sieve tube in this scheme adopts the non-metal sieve tube, and preferred sieve tube is PE (polyethylene) sieve tube, glass steel (FRP) sieve tube or PVC (polyvinyl chloride) sieve tube.
The glass fiber reinforced plastic sieve tube is light and hard in weight, non-conductive, stable in performance, high in mechanical strength, less in recycling and corrosion resistant.
The PE sieve tube has strong impact resistance and wear resistance, and can ensure the operation requirement of the sieve tube.
The PVC screen pipe has enough use strength, and can ensure the operation requirement of the screen pipe.
In the step 3), the upper end of the screen pipe is connected with the technical casing, and the connection length of the screen pipe to the technical casing is 10-20m so as to ensure the connection strength of the screen pipe to the technical casing.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A coal bed gas mining method is suitable for the condition that the distance between adjacent reservoirs is larger than 10m, and is characterized by comprising the following steps:
step 1) opening a horizontal well, wherein the horizontal well sequentially passes through a plurality of reservoir beds from top to bottom, and is landed on the reservoir bed with the lowest horizontal height;
step 2) controlling the wellbore curvature to adjust the wellbore trajectory of the horizontal well so that the horizontal well sequentially drills into the plurality of reservoirs from bottom to top, wherein the wellbore curvature is set according to the positions of adjacent reservoirs, the wellbore curvature is controlled so that the wellbore trajectory gradually enters a reservoir with the second lowest horizontal height from the reservoir with the second lowest horizontal height, the wellbore curvature is controlled so that the wellbore trajectory gradually enters a reservoir with the third lowest horizontal height from the reservoir with the second lowest horizontal height, and the like, the wellbore finally enters the reservoir with the highest horizontal height, and the step 2) realizes the communication between the plurality of reservoirs of the multi-layer reservoir and the main wellbore of the horizontal well;
step 3) arranging a sieve tube in a main borehole of the horizontal well, wherein the lower end of the sieve tube is higher than the reservoir with the lowest level;
and 4) sequentially drilling the horizontal section and the branch well section of each reservoir from top to bottom.
2. The coal bed methane mining method according to claim 1, wherein the steady slope section length of the horizontal well is 30-50 m.
3. A coal seam gas mining method according to claim 1, characterized in that the wellbore curvature in step 2) is less than 6 °/30 m.
4. The method for exploiting coal bed methane according to claim 1, wherein the step 4) comprises drilling the horizontal section and the branch section of each reservoir by establishing a new geosteering model according to the borehole trajectory data of the horizontal well in the step 2).
5. The method of claim 1, wherein the screen is a PE screen.
6. The method of claim 1, wherein the screen is a glass reinforced plastic screen.
7. The method of claim 1, wherein the screen is a PVC screen.
8. The method for exploiting coal bed methane according to claim 1, wherein in the step 3), the upper end of the screen pipe is connected with a technical casing, and the connection length of the screen pipe to the technical casing is 10-20 m.
CN201810971547.4A 2018-08-24 2018-08-24 Coal bed gas mining method Active CN110242254B (en)

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CN111706302B (en) * 2020-08-21 2020-12-11 北京英泰科技术服务有限公司 Integrated process method for short-target front-distance horizontal well of coal-bed gas well

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