CN104196453A - Coalbed methane development well - Google Patents
Coalbed methane development well Download PDFInfo
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- CN104196453A CN104196453A CN201410437180.XA CN201410437180A CN104196453A CN 104196453 A CN104196453 A CN 104196453A CN 201410437180 A CN201410437180 A CN 201410437180A CN 104196453 A CN104196453 A CN 104196453A
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Abstract
The invention provides a coalbed methane development well. The coalbed methane development well comprises an engineering well, a first directional well, a second directional well, a first horizontal well and a second horizontal well, wherein the extension directions of the two directional wells are different, the separation distance between the wellhead of each directional well and the engineering well is 9 cm to 12 cm, the wellhead of the first directional well, the wellhead of the second directional well and the wellhead of the engineering well are all located in a same well field, the first directional well and the second directional well are communicated with the engineering well underground, the first horizontal well is communicated with the first directional well and the engineering well, and the second horizontal well is communicated with the second directional well and the engineering well. According to the coalbed methane development well, the repeated engineering of independent horizontal well drilling in multi-layer coal is reduced, land is saved, and cost is reduced.
Description
Technical field
The present invention relates to coal-bed gas exploitation field, be specifically related to a kind of cbm development well.
Background technology
Existing cbm development well type is generally pressure break straight well and horizontal well.Pressure break straight well because Area of a well is little, the difficult control of fracturing fracture, take up an area many, need lower steel sleeve, destroy Seam Roof And Floor colliery is affected to the shortcomings such as large, replaced by horizontal well gradually.
Horizontal well is generally divided into " U " type horizontal well and " pinniform " multi-branched horizontal well.Mining straight well and the engineering well distance of " U " type horizontal well, horizontal well is beaten toward coal seam downdip direction, is communicated with after having bored horizontal segment with mining straight well again, and horizontal segment generally only has one; The mining straight well of " pinniform " multi-branched horizontal well and engineering well near distance, horizontal well is beaten toward coal seam updip direction, after being first communicated with mining straight well, bores coal seam horizontal segment again, has multiple horizontal branch." U " type horizontal well to landform require high, in the bad region of orographic condition, be difficult to wide-scale adoption.In addition, this horizontal well only has a horizontal branch, and Area of a well is little, and for the coal bed gas field of the certain area of exploitation, drilling well is more, thereby can cause overall drilling cost to rise.
" pinniform " multi-branched horizontal well is generally made up of 1 mouthful of mining straight well and 1 mouthful of engineering well, and two mouthfuls of well locations are in two different well sites, and wellhead ground is apart from general 200～300m." pinniform " multi-branched horizontal well is owing to being by two mouthfuls of well constructions that are positioned at two different well sites, and the distance and bearing in these two well sites is also had to certain requirement, so this well type is also relatively high to the requirement of landform, in the bad region of orographic condition, be difficult to wide-scale adoption.
In sum, in prior art, there is following problem: be difficult to, in the situation that orographic condition is bad, multi-branched horizontal well is set.
Summary of the invention
The invention provides a kind of cbm development well, be difficult to, in the situation that orographic condition is bad, multi-branched horizontal well is set to solve prior art.
For this reason, the present invention proposes a kind of cbm development well, and described cbm development well comprises:
An engineering well;
The first directional well and the second directional well, the bearing of trend difference of two directional wells, the spacing of the well head of each directional well and the well head of described engineering well is 9m to 12m;
Well head, the well head of the second directional well and the well head of described engineering well of described the first directional well are all arranged in same well site, and described the first directional well and the second directional well are communicated with underground with described engineering well respectively;
The first horizontal well, is communicated with described the first directional well and described engineering well;
The second horizontal well, is communicated with described the second directional well and described engineering well.
Further, described well site is of a size of length and is less than or equal to 80 meters, and width is less than or equal to 50 meters.
Further, the spacing of the well head of each directional well and the well head of described engineering well is 10m.
Further, the horizontal movement of each directional well is 280 to 300 meters.
Further, described the first horizontal well comprises two horizontal segments, and two horizontal segments stretch into respectively neighbouring coal seam.
Further, each horizontal segment all has multiple masters and props up.
Further, described each horizontal segment is respectively provided with three masters and props up, and each master props up drilling depth 800-1000m, middle Zhu Zhi Shang Daliangge branch, and each drilling depth 400-500m of branch, the spacing of each branch is 300m.
Further, the master of described each horizontal segment props up the continuous plastics screen casing that is lowered to diameter 50mm with branch.
Further, the pressure release area of described the first horizontal well and the second horizontal well is not overlapping.
Further, the distance in described adjacent coal seam is 3 to 5 meters, after described two horizontal segments are all drilled to, just starts any horizontal segment mining step-down.
The present invention adopts the well head of two directional wells and an engineering well is all arranged in same well site, from the well head of an engineering well at two directional wells of underground connection, and bore the horizontal well of two different directions by this project well, and the coal bed gas that can be exploited two horizontal wells by two directional wells.Because the well head of above-mentioned two directional wells and an engineering well is all arranged in same well site, so, overcome prior art and be difficult to, in the situation that orographic condition is bad, the difficulty of multi-branched horizontal well is set.The present invention has reduced the repetition engineering of the independent horizontal well drilling of multilayer coal, has saved soil, has reduced cost.
And then, after the first horizontal well of the present invention and the second horizontal well UNICOM directional well, each horizontal well can drill adjacent multilayer coal (being for example two-layer coal) simultaneously, can develop the resource of adjacent multilayer coal simultaneously, has greatly improved the utilization rate of individual well down-hole resource.
Brief description of the drawings
Fig. 1 is the structural representation of the main apparent direction of the cbm development well of the embodiment of the present invention;
Fig. 2 is the structural representation of overlooking direction of the first horizontal segment of the first horizontal well of embodiments of the invention;
Fig. 3 is the first horizontal well of embodiments of the invention and the structural representation of overlooking direction of the second horizontal well.
Drawing reference numeral explanation:
The master that the master that the master that the master that the master of well head 31 engineering wells of well head 30 engineering wells of well head 20 second directional wells of 1 first directional well 2 second directional well 3 engineering well 4 first horizontal well 5 second horizontal well 9 ground 10 first directional wells props up 32 engineering wells props up 41 horizontal segment 42 horizontal segment 51 horizontal segment 52 horizontal segment 411 horizontal segments props up 412 horizontal segments props up 413 horizontal segments props up
Detailed description of the invention
Understand for technical characterictic of the present invention, object and effect being had more clearly, now contrast brief description of the drawings the present invention.
As shown in Figure 1, the present invention is in same well site, the well head 30 of an engineering well and the well head of two directional wells are set, be respectively the well head 10 of the first directional well and the well head 20 of the second directional well, the spacing of the well head of each directional well and the well head of described engineering well is 9m to 12m, be for example 10m, directional well is producing well, for exploiting coal bed methane.
With respect to engineering well, directional well and straight well all use as mining well, also identical on bore and setting of casing, difference be wellbore trajectory and with the distance of engineering well on, directional well is oblique, straight well is straight, on ground 9, the about 10m of well head distance of directional well and engineering well, straight well and engineering well distance 200～300m, engineering well drilling well site area is generally 50 × 80m, mining straight well well site area is generally 30 × 30m, due to engineering well and mining straight well distance 200～300m, so be conventionally placed on two independent well sites, be placed on the words in a well site, or land area is excessive, expense is too high, or ground condition does not just allow, or cannot levy so large-arealy.The present invention adopts the supporting setting of directional well and engineering well, can make directional well and engineering well in same well site, has saved soil, has reduced cost.
The present invention bores 2 mouthfuls of directional wells in a well site to different directions, the horizontal movement of each directional well is 280 to 300 meters, for engineering well and being communicated with of directional well have been flowed out sufficient space, for example, the horizontal movement of directional well is about 290m, and engineering well is after roof lands, apart from the about 100m of coal seam connectivity points, engineering well three is communicated with the first directional well after opening, and starts to bore the first horizontal well 4 after being communicated with successfully.Detailed process is: at one deck coal borer the first horizontal segment 41, return to before connectivity points after having bored one deck coal, attempt carrying out being communicated with for 2 times at another layer of coal, bore the horizontal segment of this one deck coal after being communicated with successfully, i.e. the second horizontal segment 42 again.Each horizontal segment all has multiple masters and props up, to realize larger control area.Adopt the present invention, the distance of the first horizontal segment and the second horizontal segment can closely reach 3 to 5 meters, or is 1 to 2 meter, can be also 8 meters, more than 10 meters or 10 meters.Exploit two spacing and be the adjacent coal seam of 3 to 5 meters, can realize the exploitation in two adjacent nearlyer coal seams, be not subject to the pressure disturbances in adjacent coal seam, also improved in addition production efficiency and resource utilization.
For example, as shown in Figure 2, the horizontal segment of every layer of coal has three main, for example, the master that the first horizontal segment 41 has a horizontal segment props up 411, the master of horizontal segment prop up 412 and the master of horizontal segment prop up 413, each master props up drilling depth 800-1000m, above make a call to two subbranches for middle main, the drilling depth 400-500m of branch, the spacing of each branch is 300m, each horizontal segment makes the control area of every layer of coal be about 0.9 square kilometre, and the control gross area of two horizontal segments is about 1.8 square kilometres.In order to prevent stopping up seepage channel after horizontal hole coal seam from collapsing, be lowered to the continuous plastics screen casing of diameter 50mm at horizontal segment.
Bore after the first horizontal well 4, at engineering well inclination section cementing plug, cut off, extract sleeve pipe at sizing collar place, then the engineering well inclination section of sidetracking the second horizontal well 5, landing, setting of casing, three are opened, are communicated with the second directional well and according to the process of two horizontal segments of the first Horizontal Well Drilling, the horizontal segment 51 and the horizontal segment 52 that bore the two-layer coal of the second horizontal well 5, be finally lowered to screen casing, completion.For the simple integrally-built relation that embodies cbm development well, in Fig. 1, only illustrate the relation of engineering well and directional well, the handshaking procedures of engineering well and two horizontal wells is not shown.
On a well site, only have like this three well heads, be respectively the well head of two directional wells and the well head of an engineering well.Engineering well is propped up and is connected two directional wells by the master of two different engineering wells, and each directional well connects a horizontal well, and just there are 2 horizontal wells in each like this well site.Each horizontal well has two horizontal segments, and two horizontal segments form up and down to be arranged.Like this, in a well site, two horizontal well drilling depth 16000m altogether, two horizontal well control area 2 × 1.8=3.6 square kilometre.So, adopt cbm development well of the present invention, the one, can develop the resource of adjacent multilayer coal simultaneously, greatly improve the utilization rate of individual well down-hole resource; The 2nd, reduce the repetition engineering of the independent horizontal well drilling of multilayer coal, save soil, reduce cost; The 3rd, multilayer coal is developed simultaneously, has avoided the interference to the exploitation of adjacent coal seam of Pressure Drop that independent exploitation one deck causes.
Further, described well site is of a size of length and is less than or equal to 80 meters, and width is less than or equal to 50 meters.Be that the present invention adopts an engineering well drilling well site, can control multiple coal seams of above-mentioned area, greatly improved the utilization rate of individual well down-hole resource.
Further, Fig. 3 be the first horizontal well of embodiments of the invention and the second horizontal well overlook direction projection structural representation, as Fig. 3, the pressure release area of described the first horizontal well 4 and the second horizontal well 5 is not overlapping, in other words, the horizontal projection of the first horizontal well and the second horizontal well is not overlapping, does not interact ensureing between the first horizontal well and the second horizontal well.
Adopt the present invention, the distance of the first horizontal segment and the second horizontal segment can closely reach 3 to 5 meters, after described two horizontal segments are all drilled to, just starts any horizontal segment mining step-down.In other words, can exploit two spacing and be the adjacent coal seam of 3 to 5 meters, can fully realize the exploitation in two adjacent nearlyer coal seams, improve production efficiency.
And two coal seams of prior art exploitation are first to build a horizontal well to exploit, exploit behind this coal seam, exploit other one deck coal and just need bore again water horizontal well (section), and then exploit.When drilling well, the pressure in coal seam is the reset pressure on stratum, the exploitation of coal bed gas need to be carried out drainage and step-down to coal seam, the methane being adsorbed on like this in coal seam just can discharge in desorb, after mining a period of time, the pressure in coal seam will be more much lower than original formation pressure, and also can produce pressure drop affects near stratum mining coal seam, near if coal seam drilling horizontal well that at this moment will be mining coal seam, the pressure in the coal seam of boring will be lower, will increase the weight of the lose returns in drilling process, cause the generation of complex accident.So there is problem of pressure drop in two adjacent coal seams of prior art exploitation, causes the second layer coal of close together not exploit.
The present invention is for the exploitation in adjacent coal seam, before mining step-down, just the horizontal well two-layer coal (section) has all bored, form two horizontal segments and exploit later again, can not produce previous mining affects the phenomenon that posterior horizontal segment creeps into, so just can not produce the problems referred to above.
The foregoing is only the schematic detailed description of the invention of the present invention, not in order to limit scope of the present invention.For each ingredient of the present invention can mutually combine under the condition of not conflicting, any those skilled in the art, not departing from equivalent variations and the amendment done under the prerequisite of design of the present invention and principle, all should belong to the scope of protection of the invention.
Claims (10)
1. a cbm development well, is characterized in that, described cbm development well comprises:
An engineering well;
The first directional well and the second directional well, the bearing of trend difference of two directional wells, the spacing of the well head of each directional well and the well head of described engineering well is 9m to 12m;
Well head, the well head of the second directional well and the well head of described engineering well of described the first directional well are all arranged in same well site, and described the first directional well and the second directional well are communicated with underground with described engineering well respectively;
The first horizontal well, is communicated with described the first directional well and described engineering well;
The second horizontal well, is communicated with described the second directional well and described engineering well.
2. cbm development well as claimed in claim 1, is characterized in that, described well site is of a size of length and is less than or equal to 80 meters, and width is less than or equal to 50 meters.
3. cbm development well as claimed in claim 1, is characterized in that, the spacing of the well head of each directional well and the well head of described engineering well is 10m.
4. cbm development well as claimed in claim 1, is characterized in that, the horizontal movement of each directional well is 280 to 300 meters.
5. cbm development well as claimed in claim 1, is characterized in that, described the first horizontal well comprises two horizontal segments, and two horizontal segments stretch into respectively neighbouring coal seam.
6. cbm development well as claimed in claim 5, is characterized in that, each horizontal segment all has multiple masters and props up.
7. cbm development well as claimed in claim 6, is characterized in that, each horizontal segment is respectively provided with three masters and props up, and each master props up drilling depth 800-1000m, middle Zhu Zhi Shang Daliangge branch, and each drilling depth 400-500m of branch, the spacing of each branch is 300m.
8. cbm development well as claimed in claim 7, is characterized in that, the master of each horizontal segment props up the continuous plastics screen casing that is lowered to diameter 50mm with branch.
9. cbm development well as claimed in claim 1, is characterized in that, the pressure release area of described the first horizontal well and the second horizontal well is not overlapping.
10. cbm development well as claimed in claim 5, is characterized in that, the distance in described adjacent coal seam is 3 to 5 meters, after described two horizontal segments are all drilled to, just starts any horizontal segment mining step-down.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410437180.XA CN104196453B (en) | 2014-08-29 | 2014-08-29 | Coalbed methane development well |
| HK15100645.2A HK1200200A1 (en) | 2014-08-29 | 2015-01-20 | Coalbed gas development well |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410437180.XA CN104196453B (en) | 2014-08-29 | 2014-08-29 | Coalbed methane development well |
Publications (2)
| Publication Number | Publication Date |
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| CN104196453A true CN104196453A (en) | 2014-12-10 |
| CN104196453B CN104196453B (en) | 2017-02-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410437180.XA Active CN104196453B (en) | 2014-08-29 | 2014-08-29 | Coalbed methane development well |
Country Status (2)
| Country | Link |
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| CN (1) | CN104196453B (en) |
| HK (1) | HK1200200A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104790915A (en) * | 2015-04-22 | 2015-07-22 | 西南石油大学 | Coal bed methane recovery method |
| CN104912479A (en) * | 2015-04-30 | 2015-09-16 | 中煤科工集团西安研究院有限公司 | Method for drilling and completion of horizontal branched well for coal bed gas |
| WO2019062259A1 (en) * | 2017-09-28 | 2019-04-04 | 中国石油天然气股份有限公司 | Method for extracting coalbed methane in low permeability coal seam, and extraction well pattern |
| CN110185418A (en) * | 2019-06-20 | 2019-08-30 | 中联煤层气有限责任公司 | A kind of coal bed methane exploring method of coal seam group |
| CN112377168A (en) * | 2020-11-11 | 2021-02-19 | 中联煤层气有限责任公司 | Coal bed gas multi-branch horizontal well suitable for tectonic coal and drilling method |
| CN112796660A (en) * | 2021-01-25 | 2021-05-14 | 北京大地高科地质勘查有限公司 | Construction method of double-parallel-branch horizontal communication well |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201236690Y (en) * | 2008-07-04 | 2009-05-13 | 兴和鹏能源技术(北京)有限公司 | Multi-branch horizontal well |
| CN102116140A (en) * | 2011-01-25 | 2011-07-06 | 煤炭科学研究总院西安研究院 | Construction method for enhancing extraction effect of ground coal bed gas |
| CN203335054U (en) * | 2013-05-31 | 2013-12-11 | 华北石油管理局 | Multi-branch horizontal well system suitable for coalbed methane of syncline structure |
| US20130340997A1 (en) * | 1998-11-20 | 2013-12-26 | Vitruvian Exploration, Llc | Method and system for accessing subterranean deposits from the surface and tools therefor |
| CN204024473U (en) * | 2014-08-29 | 2014-12-17 | 富地柳林燃气有限公司 | Cbm development well |
-
2014
- 2014-08-29 CN CN201410437180.XA patent/CN104196453B/en active Active
-
2015
- 2015-01-20 HK HK15100645.2A patent/HK1200200A1/en unknown
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130340997A1 (en) * | 1998-11-20 | 2013-12-26 | Vitruvian Exploration, Llc | Method and system for accessing subterranean deposits from the surface and tools therefor |
| CN201236690Y (en) * | 2008-07-04 | 2009-05-13 | 兴和鹏能源技术(北京)有限公司 | Multi-branch horizontal well |
| CN102116140A (en) * | 2011-01-25 | 2011-07-06 | 煤炭科学研究总院西安研究院 | Construction method for enhancing extraction effect of ground coal bed gas |
| CN203335054U (en) * | 2013-05-31 | 2013-12-11 | 华北石油管理局 | Multi-branch horizontal well system suitable for coalbed methane of syncline structure |
| CN204024473U (en) * | 2014-08-29 | 2014-12-17 | 富地柳林燃气有限公司 | Cbm development well |
Non-Patent Citations (1)
| Title |
|---|
| 翟亚锋等: "鱼骨型水平井分支井眼完井技术实施探讨", 《新疆石油天然气》 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104790915A (en) * | 2015-04-22 | 2015-07-22 | 西南石油大学 | Coal bed methane recovery method |
| CN104912479A (en) * | 2015-04-30 | 2015-09-16 | 中煤科工集团西安研究院有限公司 | Method for drilling and completion of horizontal branched well for coal bed gas |
| WO2019062259A1 (en) * | 2017-09-28 | 2019-04-04 | 中国石油天然气股份有限公司 | Method for extracting coalbed methane in low permeability coal seam, and extraction well pattern |
| US10731451B2 (en) | 2017-09-28 | 2020-08-04 | Petrochina Company Limited | Exploitation method and exploitation well pattern for coalbed methane in low-permeability coalbed |
| CN110185418A (en) * | 2019-06-20 | 2019-08-30 | 中联煤层气有限责任公司 | A kind of coal bed methane exploring method of coal seam group |
| CN112377168A (en) * | 2020-11-11 | 2021-02-19 | 中联煤层气有限责任公司 | Coal bed gas multi-branch horizontal well suitable for tectonic coal and drilling method |
| CN112377168B (en) * | 2020-11-11 | 2023-03-10 | 中联煤层气有限责任公司 | Coal bed gas multi-branch horizontal well suitable for tectonic coal and drilling method |
| CN112796660A (en) * | 2021-01-25 | 2021-05-14 | 北京大地高科地质勘查有限公司 | Construction method of double-parallel-branch horizontal communication well |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104196453B (en) | 2017-02-15 |
| HK1200200A1 (en) | 2015-07-31 |
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