CN111021959A - Well drilling method for preventing water accumulation in goaf - Google Patents
Well drilling method for preventing water accumulation in goaf Download PDFInfo
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- CN111021959A CN111021959A CN201911323353.4A CN201911323353A CN111021959A CN 111021959 A CN111021959 A CN 111021959A CN 201911323353 A CN201911323353 A CN 201911323353A CN 111021959 A CN111021959 A CN 111021959A
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- 238000005553 drilling Methods 0.000 title claims abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 17
- 238000009825 accumulation Methods 0.000 title claims abstract description 15
- 239000003245 coal Substances 0.000 claims abstract description 17
- 238000005065 mining Methods 0.000 claims abstract description 15
- 239000004568 cement Substances 0.000 claims abstract description 10
- 239000002002 slurry Substances 0.000 claims abstract description 5
- 238000010276 construction Methods 0.000 claims abstract description 4
- 238000000605 extraction Methods 0.000 claims description 8
- 238000007789 sealing Methods 0.000 claims description 3
- 239000011435 rock Substances 0.000 abstract description 4
- 230000008439 repair process Effects 0.000 abstract description 2
- 238000012360 testing method Methods 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 235000009781 Myrtillocactus geometrizans Nutrition 0.000 description 2
- 240000009125 Myrtillocactus geometrizans Species 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
- 230000009466 transformation Effects 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
- E21B7/00—Special methods or apparatus for drilling
- E21B7/20—Driving or forcing casings or pipes into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes
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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
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
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- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Earth Drilling (AREA)
Abstract
The invention belongs to the technical field of coal bed gas, and particularly relates to a drilling method for preventing water accumulation in a goaf. The invention aims to solve the problem that the existing well body structure mainly has the problem that a large amount of stratum water gushes out from an aquifer in an open hole area and enters a goaf, so that wall rocks in a well are leached and filtered. The method comprises the following specific steps: (1) drawing a water-bearing stratum well-connecting section according to the surrounding hydrogeological condition, and estimating the position of the water-bearing stratum of the ground mining empty well; (2) drilling construction; firstly, drilling a 425mm drill bit to 10m below a decomposed zone of bedrock, putting a 377mm surface casing for well cementation, and raising cement to the ground; drilling a 311mm drill bit to 10m below the last aquifer at the upper part of the goaf, putting a 273mm technical casing pipe for well cementation, and raising the cement to the ground; and (3) drilling a 10m final hole on the bottom plate of the coal seam goaf by using a drill bit with three openings of 241.5mm, or drilling a final hole at the position of complete slurry (wind) leakage, and completing the well by using the open hole. The invention greatly reduces the accidents of well collapse, well blockage and well flooding, thereby reducing the well repair cost caused by the accidents.
Description
Technical Field
The invention belongs to the technical field of coal bed gas, and particularly relates to a drilling method for preventing water accumulation in a goaf.
Background
The original ground mining empty well adopts a two-open hole well body structure, namely a 311mm drill bit, after drilling to a bedrock weathering zone, a 244.5mm surface casing is put in for well cementation, cement returns to the ground, and a well mouth is established; and drilling a 215.9mm drill bit through the goaf or completing the well by an open hole at the position with serious slurry (wind) leakage. The well body structure mainly has the vicious circle that a great amount of stratum water can be gushed out from an aquifer in an open hole area to enter a goaf, so that wall rocks in a well are leached and filtered, and two situations can occur, (1) leaching for a long time and the phenomenon of well blockage due to collapse of partial rock strata can occur under the action of the gravity of water, and the situation can be solved by using air to drill and dredge through a workover team, but the symptoms are treated but not treated, and the inner wall of the rock strata can be damaged, so that the workover cycle is more and more frequent; (2) the water-bearing stratum is filled with the shaft of the mining empty well for a long time, the coal bed gas migration channel is sealed up due to the water seal phenomenon, the water is drained by adopting a large-lift submersible pump generally under the condition, the water seal phenomenon cannot be eradicated by the method, and meanwhile, the shaft easily enters air to generate potential risk of gas combustion explosion. The well body structure adaptability analysis shows that the gas extraction requirement of the ground mining empty well is difficult to guarantee in a double open hole completion mode.
Disclosure of Invention
The invention provides a drilling method for preventing water accumulation in a goaf to solve the problems.
The invention adopts the following technical scheme: a drilling method for preventing water accumulation in a goaf comprises the following specific steps:
(1) before the structure design of the well body of the ground mining empty well, drawing a water-bearing stratum well connection section according to the surrounding hydrogeological condition, and estimating the position of the water-bearing stratum of the ground mining empty well according to the water-bearing stratum well connection section; the well body structure design scheme is supported by data;
(2) drilling construction;
drilling a 425mm drill bit to 10m below a weathering zone of the bedrock to form a drilled hole, putting a 377mm surface casing for well cementation, and raising the cement to the ground;
drilling a second-opening 311mm drill bit to 10m below the lowest aquifer at the upper part of the goaf to form a second-opening drill hole, putting a 273mm technical casing pipe for well cementation to ensure that the aquifer is completely blocked, returning the cement to the ground, and starting the third-opening drilling after the second-opening well cementation waits for 48 hours;
and (3) drilling a 10m final hole on the bottom plate of the coal seam goaf by using a drill bit with three openings of 241.5mm, or drilling a final hole at the position of complete slurry (wind) leakage, and completing the well by using the open hole.
Observing the wellhead pressure of the ground mining empty well, and if the coal bed gas concentration is greater than the extraction requirement (generally greater than 40% and above) and the trial extraction can be continuously operated, selecting a three-opening well body structure for the ground mining empty well; if the negative pressure of the ground goaf is airless due to poor sealing of the goaf or other reasons, a 193mm casing is put in for well cementation, and then four-hole drilling is continuously carried out.
And drilling a fourth 171.3mm drill bit to the final hole of the lower group of the preset coal seams, and setting a 139mm casing for well cementation and completion.
Different from the prior art, the invention at least comprises the following beneficial effects:
1. well collapse, well plugging and well flooding accidents are greatly reduced, and therefore well repair cost caused by the accidents is reduced.
2. The well body structure is more stable, thereby greatly improving the productivity and yield of the single well.
3. When the phenomenon of no gas exists in the underground negative pressure, the well can be continuously drilled to the coal final hole of the lower group through the goaf on the basis of the well body structure, and the scrapping of the drilled well is avoided.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
FIG. 1 is a schematic diagram of a well bore structure of a drilling method for preventing water accumulation in a gob according to the present invention.
In the figure: 1. 377mm surface casing, 2 mm and 273mm technical casing, 3mm and 193mm casing, 4 mm lower coal seam, 5mm and 139mm casing, 6 mm and quarto drill holes, 7mm and three-opening drill holes, 8 mm aquifer, 9mm and two-opening drill holes, 10 mm and one-opening drill holes, 11mm ground, 12 mm goaf.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
A drilling method for preventing water accumulation in a goaf comprises the following specific steps:
(1) before the structure design of the well body of the ground mining empty well, drawing a water-bearing stratum well connection section through the surrounding hydrogeological conditions, and estimating the position of the water-bearing stratum of the ground mining empty well according to the water-bearing stratum well connection section;
(2) drilling construction;
drilling a 425mm drill bit to 10m below a weathering zone of the bedrock to form a drilled hole, putting a 377mm surface casing for well cementation, and raising the cement to the ground;
drilling a second-opening 311mm drill bit to 10m below the lowest aquifer at the upper part of the goaf to form a second-opening drill hole, putting a 273mm technical casing pipe for well cementation to ensure that the aquifer is completely blocked, returning the cement to the ground, and starting the third-opening drilling after the second-opening well cementation waits for 48 hours;
and (3) drilling a 10m final hole on the bottom plate of the coal seam goaf by using a drill bit with three openings of 241.5mm, or drilling a final hole at the position of complete slurry (wind) leakage, and completing the well by using the open hole.
Observing the wellhead pressure of the ground mining empty well, and if the coal bed gas concentration is greater than the extraction requirement (generally greater than 40% and above) and the trial extraction can be continuously operated, selecting a three-opening well body structure for the ground mining empty well; if the negative pressure of the ground goaf is airless due to poor sealing of the goaf or other reasons, a 193mm casing is put in for well cementation, and then four-hole drilling is continuously carried out.
And drilling a fourth 171.3mm drill bit to the final hole of the lower group of the preset coal seams, and setting a 139mm casing for well cementation and completion.
Experimental data
The invention is further illustrated by taking 2 empty wells near the Panzhuang zone of blue flame corporation as an example.
In the last two years, the blue flame company carries out the well body structure transformation of 5 goafs in a coal mine goaf of a Panzhuang block, wherein a first test well and a second test well are in the same goaf range, the linear distance is about 200m, no large structural change exists in the middle, the stratum development is stable, no interference exists in other goafs when the goafs are close to the first test well, and therefore the first test well and the second test well have certain contrast.
In the first test, gas in the goaf is extracted by adopting a well body structure of a two-opening open hole completion mode, the pressure at the well head is stable during gas production, and gas is not produced after 66d of well plugging; after 150 days, the pressure of the drifting is recovered, and the operation time is only 13d when the second well plugging is carried out at 163 d; recovering the pressure after completing the well dredging on the 172 th day, and stopping the well for the third time on the 182 th day, wherein the running time is 10 d; within 200 days 3 well plugging accidents occurred consecutively. The second test well is a three-opening well body structure of a casing sealed aquifer reconstructed according to the method, the pressure of the well head is stable in the 200d well completion, and the pressure of the well head is reduced at 158d, so that the operation frequency of extraction equipment is improved, and the second test well has no secondary production accident at present and is stable in operation. And carrying out labor accumulation and production 159781m in the first test well 200d, and carrying out labor accumulation and production 317638m in the second test well 200 d.
According to the drilling method for preventing water accumulation in the goaf, the ground goaf adopts a large-diameter drilling process, the three-opening structure and the large caliber effectively prevent collapse and well plugging of a part of open hole areas, and when the goaf has a negative pressure and gas-free phenomenon, the goaf can be continuously drilled to a lower group of coal beds through the goaf by the well body structure to complete well. The phenomenon that negative pressure is airless due to the fact that the situation that the inner airtightness of the goaf is poor is avoided.
Claims (4)
1. A well drilling method for preventing water accumulation in a goaf is characterized by comprising the following specific steps:
(1) drawing a water-bearing stratum well-connecting section according to the surrounding hydrogeological condition, and estimating the position of the water-bearing stratum of the ground mining empty well;
(2) drilling construction;
drilling a 425mm drill bit to 10m below a weathering zone of the bedrock to form a drilled hole, putting a 377mm surface casing for well cementation, and raising the cement to the ground;
drilling a second-opening 311mm drill bit to 10m below the lowest aquifer at the upper part of the goaf to form a second-opening drill hole, putting a 273mm technical casing pipe for well cementation to ensure that the aquifer is completely blocked, returning the cement to the ground, and starting drilling by the third-opening drill after the cement is solidified;
and (3) drilling a 10m final hole on the bottom plate of the coal seam goaf by using a drill bit with three openings of 241.5mm, or drilling a final hole at the position of complete slurry (wind) leakage, and completing the well by using the open hole.
2. The drilling method for preventing water accumulation in a gob according to claim 1, wherein: after three openings are drilled, observing the pressure of a wellhead of the ground mining empty well, and if the concentration of the coal bed gas is greater than the extraction requirement (generally greater than 40% and above) and the extraction can be continuously operated, selecting a three-opening well body structure for the ground mining empty well; if the negative pressure of the ground goaf is airless due to poor sealing of the goaf or other reasons, a 193mm casing is put in for well cementation, and then four-hole drilling is continuously carried out.
3. The drilling method for preventing water accumulation in a gob according to claim 2, wherein: and drilling a fourth 171.3mm drill bit to the final hole of the lower group of the preset coal seams, and setting a 139mm casing for well cementation and completion.
4. The drilling method for preventing water accumulation in a gob according to claim 1, wherein: the waiting time of the second-opening cementing well is 48 h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911323353.4A CN111021959A (en) | 2019-12-20 | 2019-12-20 | Well drilling method for preventing water accumulation in goaf |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911323353.4A CN111021959A (en) | 2019-12-20 | 2019-12-20 | Well drilling method for preventing water accumulation in goaf |
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| CN111021959A true CN111021959A (en) | 2020-04-17 |
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| CN201911323353.4A Pending CN111021959A (en) | 2019-12-20 | 2019-12-20 | Well drilling method for preventing water accumulation in goaf |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111663918A (en) * | 2020-07-10 | 2020-09-15 | 中勘资源勘探科技股份有限公司 | Coal mining ground grouting process and grouting structure |
| CN112145131A (en) * | 2020-10-12 | 2020-12-29 | 山西晋城无烟煤矿业集团有限责任公司 | Method for extracting coal-bed gas well in inclined coal-bed goaf |
| CN113863895A (en) * | 2021-04-30 | 2021-12-31 | 中国矿业大学 | Well body structure of oil and gas well penetrating through recoverable coal seam and construction method |
| CN114233368A (en) * | 2021-12-28 | 2022-03-25 | 山西晋煤集团技术研究院有限责任公司 | Method for treating harmful gas downward discharge of overlying goaf |
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2019
- 2019-12-20 CN CN201911323353.4A patent/CN111021959A/en active Pending
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111663918A (en) * | 2020-07-10 | 2020-09-15 | 中勘资源勘探科技股份有限公司 | Coal mining ground grouting process and grouting structure |
| CN112145131A (en) * | 2020-10-12 | 2020-12-29 | 山西晋城无烟煤矿业集团有限责任公司 | Method for extracting coal-bed gas well in inclined coal-bed goaf |
| CN113863895A (en) * | 2021-04-30 | 2021-12-31 | 中国矿业大学 | Well body structure of oil and gas well penetrating through recoverable coal seam and construction method |
| CN114233368A (en) * | 2021-12-28 | 2022-03-25 | 山西晋煤集团技术研究院有限责任公司 | Method for treating harmful gas downward discharge of overlying goaf |
| CN114233368B (en) * | 2021-12-28 | 2023-10-13 | 山西晋煤集团技术研究院有限责任公司 | Method for treating harmful gas leakage in overlying goaf |
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Application publication date: 20200417 |