CN109209327B - Active drainage gas production method for high-water-yield coal bed gas well group of communication fault - Google Patents
Active drainage gas production method for high-water-yield coal bed gas well group of communication fault Download PDFInfo
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- CN109209327B CN109209327B CN201811186914.6A CN201811186914A CN109209327B CN 109209327 B CN109209327 B CN 109209327B CN 201811186914 A CN201811186914 A CN 201811186914A CN 109209327 B CN109209327 B CN 109209327B
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- 239000003245 coal Substances 0.000 title claims abstract description 83
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 76
- 238000004891 communication Methods 0.000 title claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 64
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000008398 formation water Substances 0.000 claims abstract description 8
- 235000019738 Limestone Nutrition 0.000 claims description 18
- 239000006028 limestone Substances 0.000 claims description 18
- 238000005553 drilling Methods 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 239000002349 well water Substances 0.000 claims description 2
- 238000003795 desorption Methods 0.000 abstract description 4
- 239000011435 rock Substances 0.000 abstract description 4
- 230000004888 barrier function Effects 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 47
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 12
- 230000001965 increasing effect Effects 0.000 description 4
- 238000005065 mining Methods 0.000 description 4
- 230000005465 channeling Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000002817 coal dust Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 235000020681 well water Nutrition 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/006—Production of coal-bed methane
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- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
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Abstract
The invention discloses a method for actively draining and producing gas from a high-yield coal bed gas well group of a communication fault, which comprises the steps of firstly providing the well group, wherein the well group comprises a drainage well and a production well, the drainage well is arranged on a hydraulic fracture channel communicated with the fault, then, the drainage well is utilized for draining water, other wells in the well group are used as the production wells for producing gas, and the pressure potential at the bottom of the drainage well is ensured to be always lower than the pressure potential at the bottom of the production well, which is equivalent to that a water-resisting barrier is arranged on a hydraulic fracture, so that formation water in a water layer is produced from the drainage well so as not to invade a production area in the deep part of a coal bed gas reservoir. The invention can prevent stratum water from invading into the production area in the deep part of the coal bed, so that the coal bed gas absorbed in the coal rock is continuously subjected to pressure reduction and desorption, thereby improving the gas production rate of the coal bed gas production well group.
Description
Technical Field
The invention relates to a drainage and mining method for a large amount of water produced by a coal-bed gas well group after a hydraulic fracture communication fault, in particular to a drainage and mining method for a coal-bed gas well group, which is characterized in that the fault is communicated with a top plate or a bottom plate limestone water layer, and a large amount of stratum water invades a coal bed to cause a large amount of water to be produced by the coal-bed gas well. The method can prevent the stratum water from invading the deep part of the coal bed, so that the coal bed gas absorbed in the coal rock can be subjected to continuous depressurization desorption, and the yield of the coal bed gas well is improved.
Background
Coal bed gas exists in coal beds mainly in an adsorption state, and is generally extracted by reducing pressure. China has abundant coal resources, and the reserve of coal bed gas resources in coal beds is huge. The coal bed gas is used as a clean unconventional natural gas resource, and has attractive prospect for exploration and development. In recent years, China vigorously develops coal bed gas resources in Shanxi, Shaanxi, Xinjiang, Guizhou, Sichuan, Henan and other provinces and obtains better development effect, but with the progress of mining, some problems in production are exposed, wherein the problems are prominent that coal beds are communicated with water layers, the water yield is large, and a reservoir layer cannot be continuously depressurized. The faults generally exist in the stratum, the faults cut the coal bed and water layers on a top plate or a bottom plate, and after the faults are subjected to pressure channeling in the hydraulic fracturing process, the coal bed is communicated with the water layers, so that a large amount of stratum water can continuously enter the coal bed, the pressure of the coal bed can not be reduced to be lower than the critical desorption pressure, and the coal bed gas adsorbed in the coal rock can not be desorbed.
In general, a coalbed methane well group is developed by using a cluster well group, and directional wells are distributed according to a plum blossom shape or a square shape and other well patterns. For dense coal seams, hydraulic fracturing is required. When the fracturing well is close to the fault, the fault is easy to be pressed and crossed, the hydraulic fracture communication fault is caused, then the formation water in the water layer can enter the coal bed along the fault, and the coal bed cannot be exploited in a depressurization mode.
In order to solve the above problems, there are two main methods for solving the problems: one is to block water, although the method can block a water outlet channel, the blocking direction is difficult to control, so that a coal bed can be blocked while a water layer is blocked, and a coal bed gas well cannot produce gas; another method is to drain water, and drain the water after the water flows into the coal bed gas shaft, so that the coal bed gas and the water flow out simultaneously, but the method is passive drainage and has low efficiency.
The Chinese patent publication numbers are: CN 102926732A, provides a method for opening and releasing a well for coal bed gas of a coal bed with high water content on the top plate, which is to arrange a water pumping well at the center of a well pattern to drain the high water content limestone in the top plate of the coal bed so as to reduce the pressure of the top plate limestone. The method can obtain a good effect aiming at the limestone stratum with relatively small water content, and if the water body of the limestone water layer is large, the difficulty of water drainage and pressure reduction is large, and the cost is high.
Disclosure of Invention
The invention aims to provide a drainage and gas production method for a communication fault coalbed methane well group, which is used for actively draining water and draining water before stratum water invades a coalbed production area, has high efficiency and can greatly improve the yield of coalbed methane wells.
The technical scheme adopted by the invention is as follows: a method for actively draining and producing gas from a high-yield coal bed gas well group communicating with a fault comprises the steps of firstly providing a well group, wherein the well group comprises a drainage well and a production well, the drainage well is arranged on a hydraulic fracture channel communicated with the fault, then, the drainage well is utilized for draining water, other wells in the well group are used as the production wells for producing gas, the bottom hole pressure potential of the drainage well is ensured to be always lower than the bottom hole pressure potential of the production well, and stratum water in a water layer is produced from the drainage well of the coal bed so as not to invade into a production area in the deep part of the gas reservoir.
In the above, the drilling completion positions of the drainage well and the production well are both sandy mudstones at the lower part of the coal seam, and a water-containing limestone layer exists at the upper part or the lower part of the coal seam.
In the above, the water layer is a water-containing limestone layer at the upper part or the lower part of the coal seam.
In the above, considering that the water volume of the drainage well is large and coal dust may be produced, a centrifugal pump or a screw pump is generally selected for drainage.
In the above, in order to keep the formation pressure potential of the drainage well region lower than that of the production well region, the drainage well and the production well are required to be provided with underground pressure gauges, and the bottom pressure is monitored in real time in the production process.
The method mainly aims at solving the problem that stratum water in limestone invades a coal bed through a fault and the coal bed gas cannot be desorbed because the stratum water is blown into the fault in the hydraulic fracturing process of the coal bed gas well, and adopts a drainage well distributed on a hydraulic fracture channel to drain and reduce pressure before the stratum water does not flow into a stratum of a production well area, so that the stratum of the hydraulic fracture channel area forms a low-pressure area, and other production well areas far away from the fault form a high-pressure area.
The invention has the beneficial effects that:
a drainage well is distributed on a hydraulic fracture channel communicated with the fault, so that formation water coming from the fault is directly discharged from the drainage well, the formation water is prevented from invading a production area in the deep part of a coal bed, the coal bed gas can be smoothly subjected to depressurization and desorption, and the gas yield of a coal bed gas production well group is improved.
Drawings
FIG. 1 is a schematic cross-sectional view of a drainage and gas production scheme of a coalbed methane well group according to the present invention (with the water layer located at the upper portion of the coal seam), wherein the arrows indicate the flow direction of formation water.
Fig. 2 is a schematic cross-sectional view of a drainage and gas production scheme of a coal-bed gas well group according to the invention (a water layer is positioned at the lower part of a coal bed), wherein an arrow indicates the flowing direction of formation water.
FIG. 3 is a schematic plan view of a drainage and gas production scheme for a coalbed methane well group according to the present invention, with arrows indicating the direction of fluid flow.
In the figure: 1-fault; 2-a drainage well; 3-a production well; 4-aqueous limestone layer; 5-hydraulic fracture; 6-sandy mudstone; 7-coal seam.
Detailed Description
The embodiments of the present invention will be further explained with reference to fig. 1, fig. 2 and fig. 3:
the first embodiment is as follows:
referring to fig. 1 and 3, the active drainage gas production method of a high-yield coal bed gas well group for communication faults, provided by the invention, comprises the steps of firstly providing a well group, wherein the well group comprises a drainage well 2 and a production well 3, drilling completion positions of the drainage well 2 and the production well 3 are both sandy shale 6 at the bottom of a coal bed 7, a water-bearing limestone 4 is positioned at the upper part of the coal bed 7, the drainage well 2 and the production well 3 are both provided with downhole pressure gauges, the drainage well 2 is arranged on a channel of a hydraulic fracture 5 communicated with the fault 1, the fault 1 penetrates through the water-bearing limestone 4, the sandy shale 6 and the coal bed 7, then drainage is carried out by using the drainage well 2, the drainage well 2 adopts a centrifugal pump or a screw pump for drainage, other wells in the well group are used as the production well 3 for gas production, and the bottom hole pressures of the drainage well 2 and the production well 3 are controlled by adjusting a drainage rate and a gas, guarantee all the time that the shaft bottom pressure potential of drainage well 2 is less than 3 shaft bottom pressure potentials of production well in the production process, make the regional stratum of drainage well 2 be low pressure potential region, the regional stratum of production well 3 is high pressure potential region, thereby make the stratum water in the water layer produce from appointed drainage well 2 and do not invade the production area in 7 deep in coal seams, ensure that coal seam 7 can effectively step down, let the coal bed gas that adsorbs in the coal petrography continuously desorb.
Example two:
referring to fig. 2 and 3, the active drainage gas production method of a high-yield coal bed gas well group for communication faults, provided by the invention, is to firstly provide a well group, wherein the well group comprises a drainage well 2 and a production well 3, drilling completion positions of the drainage well 2 and the production well 3 are both a sandy shale layer 6 at the bottom of a coal bed 7, a water-bearing limestone layer 4 is positioned at the lower part of the coal bed 7, the drainage well 2 and the production well 3 are both provided with downhole pressure gauges, the drainage well 2 is arranged on a channel of a hydraulic fracture 5 communicated with the fault 1, the fault 1 penetrates through the sandy shale layer 6, the coal bed 7 and the water-bearing limestone layer 4, then drainage is carried out by using the drainage well 2, the drainage well 2 adopts a centrifugal pump or a screw pump for drainage, other wells in the well group are used as the production well 3 for gas production, bottom hole pressures of the drainage well 2 and the production well 3 are controlled by adjusting drainage rate and gas production rate, guarantee all the time that the shaft bottom pressure potential of drainage well 2 is less than 3 shaft bottom pressure potentials of production well in the production process, make the regional stratum of drainage well 2 be low pressure potential region, the regional stratum of production well 3 is high pressure potential region, thereby make the stratum water in the water layer produce from appointed drainage well 2 and do not invade the production area in 7 deep in coal seams, ensure that coal seam 7 can effectively step down, let the coal bed gas that adsorbs in the coal petrography continuously desorb.
Application example:
in the Sichuan south China, the coal bed gas mining horizon is a two-fold system Longtan group No. 2, No. 3, No. 7 and No. 8 coal bed, the lower part of the Longtan group is an Emei mountain basalt group and a Maokou group, the Emei mountain basalt group is a grayish green basalt, the Maokou group is a huge thick layer limestone, and the water-rich property is very strong; the upper part of the quan group is a three-fold system of flying fairy and the flying fairy group is mudstone or silty mudstone. And (4) the development of a regional internal fault layer. The X well group in the region is in plum blossom distribution with 4 directional wells (X-1, X-2, X-3 and X-4 wells respectively) combined, and is positioned at the fault FyNear, fault FyCutting a coal bed of a Longtan group, basalt of a basalt group of Emei mountain and limestone of a Maokang group, and pressing and channeling faults in an X-1 well in a well group in a fracturing process to cause the limestone of the Maokang group to be communicated with the coal bed of the Longtan group. In the initial production, the X-1 well is pumped by a tubular pump at 22m per day3The displacement of/d is used for drainage, but the bottom hole pressure cannot be reduced. The bottom hole pressure of the production wells X-2, X-3 and X-4 in the well group can be slowly reduced after drainage, but the water yield is continuously increased, and the average gas yield of a single well is increased to 1300m3The tubular pump after/d can not meet the drainage requirement, and the gas production rate of the production well is reduced. Then, the embodiment of the invention is adopted to replace the electric submersible centrifugal pump for the X-1 well, and the large discharge capacity (the water yield is 60 m) is adopted3And/d) performing active forced drainage, and always keeping the bottom pressure of the X-1 well lower than that of the production wells X-2, X-3 and X-4. After a period of drainage and production, the average gas production rate of the production wells X-2, X-3 and X-4 is gradually increased to 4600m3D, and the average single well water production of the 3 production wells is reduced to 7m3And d. The yield increasing effect is obvious.
According to geological data, hydraulic fracturing data, drainage and production data and water chemistry analysis data, the communication relation among a water layer, a fault and a hydraulic fracture is analyzed, and an active drainage method is formulated according to the communication relation, so that formation water in the water layer is produced from a specified drainage well and does not invade a production area in the deep part of a coal bed gas reservoir, the coal bed can be effectively depressurized, and coal bed gas adsorbed in coal rocks is continuously desorbed.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (4)
1. An active drainage gas production method for a high-yield coal bed gas well group communicated with a fault is characterized in that the method comprises the steps of firstly providing the well group, wherein the well group comprises a drainage well and a production well, the drainage well is arranged on a hydraulic fracture channel communicated with the fault, then drainage is carried out by using the drainage well, other wells in the well group are used as the production wells for gas production, the bottom hole pressure potential of the drainage well is ensured to be always lower than that of the production well, and formation water in a water layer is produced from the drainage well so as not to invade a production area in the deep part of a coal bed gas reservoir; and the drainage well and the production well are both provided with underground pressure gauges, and the bottom hole pressure is controlled by adjusting the drainage rate and the gas production rate.
2. The active drainage gas production method of a communication fault water-producing coal bed gas well group according to claim 1, wherein the drilling positions of the drainage well and the production well are all sandy shale formation at the lower part of the coal bed, and water-containing limestone formation exists at the upper part or the lower part of the coal bed.
3. The active drainage gas production method of a communication fault water-producing coal bed gas well group according to claim 1, wherein the water layer is a water-containing limestone layer at the upper part or the lower part of the coal bed.
4. The active drainage gas production method of the communication fault high water production coal bed gas well group according to claim 1, wherein the drainage well is a centrifugal pump or a screw pump.
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| CN113565481A (en) * | 2020-04-28 | 2021-10-29 | 中国石油化工股份有限公司 | Method for exploiting reservoir bodies in fractured zone |
| CN112431578B (en) * | 2020-12-02 | 2022-07-29 | 山西潞安环保能源开发股份有限公司常村煤矿 | Method for extracting mine gas from low-permeability coal seam containing fault |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102086774A (en) * | 2011-01-17 | 2011-06-08 | 中联煤层气国家工程研究中心有限责任公司 | Drainage method of gas in coal bed |
| CN102926732A (en) * | 2012-10-12 | 2013-02-13 | 唐书恒 | Coalbed methane developing and well spacing method for high-water content coal reservoir of head plate |
| CN103628856A (en) * | 2013-12-11 | 2014-03-12 | 中国地质大学（北京） | Water resistance gas production well spacing method for coal-bed gas block highly yielding water |
| RU2556094C1 (en) * | 2014-02-13 | 2015-07-10 | Общество с ограниченной ответственностью "ЛУКОЙЛ-Западная Сибирь" | Oil deposit development method |
| CN107152302A (en) * | 2017-06-29 | 2017-09-12 | 重庆大学 | Cut the uniform permeability-increasing gas pumping method of pressure in a kind of complex geological structure coal seam |
| CN107558963A (en) * | 2017-08-25 | 2018-01-09 | 重庆矿产资源开发有限公司 | A kind of southwest coal bed gas well mining stage production control method |
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| US9418180B2 (en) * | 2010-07-26 | 2016-08-16 | Exxonmobil Upstream Research Company | Method and system for parallel multilevel simulation |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102086774A (en) * | 2011-01-17 | 2011-06-08 | 中联煤层气国家工程研究中心有限责任公司 | Drainage method of gas in coal bed |
| CN102926732A (en) * | 2012-10-12 | 2013-02-13 | 唐书恒 | Coalbed methane developing and well spacing method for high-water content coal reservoir of head plate |
| CN103628856A (en) * | 2013-12-11 | 2014-03-12 | 中国地质大学（北京） | Water resistance gas production well spacing method for coal-bed gas block highly yielding water |
| RU2556094C1 (en) * | 2014-02-13 | 2015-07-10 | Общество с ограниченной ответственностью "ЛУКОЙЛ-Западная Сибирь" | Oil deposit development method |
| CN107152302A (en) * | 2017-06-29 | 2017-09-12 | 重庆大学 | Cut the uniform permeability-increasing gas pumping method of pressure in a kind of complex geological structure coal seam |
| CN107558963A (en) * | 2017-08-25 | 2018-01-09 | 重庆矿产资源开发有限公司 | A kind of southwest coal bed gas well mining stage production control method |
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