A kind of job practices that improves ground coal bed gas extraction effect
Technical field
The invention belongs to the coal-bed gas exploitation technical field, be specifically related to a kind of job practices that improves ground coal bed gas extraction effect.
Background technology
At present the main mode of production coal bed gas has: the ground peupendicular hole, the pinniform horizontal well is set in the coal seam, and near-end butt joint horizontal well begins the branch well hole of constructing after crossing the cave, and far-end butt joint horizontal well begins the branch well hole of constructing after crossing the cave.
Find after deliberation, the ground peupendicular hole is low because of coal seam brill encountering rate, the extraction effect of coal bed gas is not as horizontal well to a certain extent, and horizontal well is because there is the internal resistance of flowing in the horizontal segment pit shaft, horizontal segment is long more, and internal resistance is big more, and the flowing pressure along end direction in the horizontal wellbore increases, the pressure drop of horizontal segment end is little than well head, causes the output of horizontal segment end to reduce.Therefore to make horizontal well economic benefit maximum, just have the reasonable levels segment length, thereby influenced the maximization of drilling depth.
When horizontal well is in the stratum of different occurrences, the stratum for example has a down dip, horizontal well can be because wellbore trace be descending, its terminal position is lower than horizontal segment starting point, cause terminal strata pressure big than the strata pressure at horizontal segment starting point place, therefore to separate pressure reduction big than horizontal segment starting point place on the ground of horizontal segment end, causes the output of horizontal segment end to reduce.Although and the terminal resistance of the horizontal segment on the updip stratum stratum that has a down dip relatively is less relatively, but still be subjected to the influence of terminal resistance, influence gas output.Therefore horizontal segment is longer, and pressure differential is bigger, and the poor efficiency horizontal segment just may be long more.
Traditional near-end butt joint horizontal well just begins the branch well hole of constructing after the cave of crossing vertical cave well, horizontal segment before the cave influences gas production because of the branch well hole of not constructing, and present far-end butt shaft is generally after the coal seam horizontal segment through 300~500m creeps into, carrying out the cave is communicated with, implement the Multilateral Wells job engineering after crossing the cave, coal seam section before the cave branch well hole of also not constructing, the horizontal segment drilling depth is less before the cave, and in certain control range under the equal conditions, the output of coal bed gas is to become certain linear with drilling depth, does not therefore reach the maximization of coal seam reservoirs drilling depth.
At present containing the coal measure strata exploiting coal bed methane of multilayer coal, one group of horizontal butt shaft is a horizontal well of construction and a cave well in same coal seam only.If need in the multilayer coal seam, also will build the needs of more well site with regard to needing the coal bed gas in the many groups of the construction horizontal wells different coal by exploiting coal bed methane, can not realize the maximizing the benefits of input and output with satisfied construction and extraction.
In sum, under equal geological conditions, existing coal bed gas extraction technology exists that methane output is little, his the producing cost height of constructing, construction and extraction land occupation are many, shortcomings such as long construction period.
Summary of the invention
Technical problem solved by the invention provides a kind of job practices that can shorten construction period, reduction operating expenses, minimizing construction extraction land used, improve ground coal bed gas extraction effect.
For solving above-mentioned technical problem, the technical scheme that the present invention takes:
A kind of job practices that improves ground coal bed gas extraction effect, realize by following steps:
(1), construction vertical cave well, this cave well is made the cave and is lowered to glass reinforced plastic sleeve in each the coal seam section that needs the extraction coal bed gas, with realize the horizontal well far-end with it smoothly butt joint guarantee that again cave, coal seam section can not cave in after butt joint;
(2), constructing is used to realize the horizontal well peupendicular hole section and the darkest inferior division inclination section and the inferior division master horizontal hole of buried depth of far-end butt joint, is lowered to protective casing on roof top; Continue to creep into along the coal seam after the construction landing enters horizontal segment, at far-end with after dock in the peupendicular hole cave, continuation horizontal branch well before main horizontal hole and the inferior division cave before coal seam, forward position construction inferior division cave, crossing the cave has constructed before the inferior division cave before the main horizontal hole and inferior division cave after the horizontal branch well, return to horizontal branch well behind near the posterior inferior division cave of constructing again the well rear end, cave, whenever finish a Multilateral Wells Duan Jun and replace into solid free completion fluid;
(3), after the construction of inferior division well is finished, be lowered to the recoverable whipstock at top set kickoff point (KOP) place, the sidetracking construction master of top set horizontal hole, after the orientation construction, dock with the peupendicular hole cave section in the superjacent, and continue before coal seam, forward position construction top set cave horizontal branch well before the main horizontal hole and top set cave, finish before the top set cave before the main horizontal hole and top set cave after the horizontal branch well, return behind the cave horizontal branch well behind the construction top set cave, according to the corresponding numbers of branches of peupendicular hole cave quantity construction, every construction is finished a Multilateral Wells Duan Jun and is replaced into solid free completion fluid;
(4), the construction finish topmost branch well after, take out the recoverable whipstock respectively, with the lower curved section of each the main horizontal hole in the horizontal well, window a little to seeing the cementing concrete shutoff of coal point from sidetracking;
(5), vertical down-hole, cave bores well-flushing, removes to be communicated with landwaste and the sediment that construction produces, equipment, land drainage step-down extraction coal bed gas are adopted by the row of installation.
Above-mentioned horizontal well comprises horizontal well peupendicular hole section, the master of top set horizontal hole, inferior division master horizontal hole, vertical cave well, main horizontal hole before the top set cave, main horizontal hole before the inferior division cave, one end of the master of top set horizontal hole and inferior division master horizontal hole all is communicated with horizontal well peupendicular hole section, the master of top set horizontal hole all is connected with the corresponding cave of vertical cave well with inferior division master horizontal hole, the master of top set horizontal hole is the horizontal branch well before the front and back of vertical cave well are respectively arranged with the top set cave, horizontal branch well behind the top set cave, inferior division master horizontal hole is the horizontal branch well before the front and back of vertical cave well are respectively arranged with the inferior division cave, horizontal branch well behind the inferior division cave, the master of top set horizontal hole and inferior division master horizontal hole continue to extend to forward the coal seam main horizontal hole of constructing being connected the back with vertical cave well.
Above-mentioned vertical cave well with the top set cave before be installed on glass reinforced plastic sleeve in main horizontal hole docks before the main horizontal hole, inferior division cave the coal seam section.
The above-mentioned master of top set horizontal hole, inferior division master horizontal hole are connected by top set's inclination section, inferior division inclination section respectively with horizontal well peupendicular hole section.
Compared with prior art, the present invention can shorten construction period, reduces construction and producing cost, minimizing construction extraction land used, improve ground coal bed gas extraction effect.
Description of drawings
Fig. 1 is the schematic perspective view of job practices of the present invention;
Fig. 2 is the vertical cut-away schematic view of job practices of the present invention.
1. vertical cave wells among the figure; 2. cave, coal seam section; 3. horizontal well; 4. horizontal well vertical section; 5. inferior division inclination section; 6. inferior division master horizontal hole; 7. main horizontal hole before the inferior division cave; 8. horizontal branch well before the inferior division cave; 9. horizontal branch well behind the inferior division cave; 10. top set's inclination section; 11. the master of top set horizontal hole; 12. main horizontal hole before the top set cave; 13. horizontal branch well before the top set cave; 14. horizontal branch well behind the top set cave; 15. glass reinforced plastic sleeve.
The specific embodiment
The present invention is described in detail below in conjunction with the drawings and specific embodiments.
The present invention realizes by following steps:
(1), construction vertical cave well 1, this cave well is made the cave and is lowered to glass reinforced plastic sleeve 15 in each the coal seam section that needs the extraction coal bed gas, with realize horizontal well 3 far-ends with it smoothly butt joint guarantee that again cave, coal seam section 2 can not cave in after butt joint;
(2), constructing is used to realize the horizontal well peupendicular hole section 4 and the darkest inferior division inclination section 5 and the inferior division master horizontal hole 6 of buried depth of far-end butt joint, is lowered to protective casing on roof top; Continue to creep into along the coal seam after the construction landing enters horizontal segment, at far-end with after dock in the peupendicular hole cave, continuation horizontal branch well 8 before main horizontal hole 7 and the inferior division cave before coal seam, forward position construction inferior division cave, crossing the cave has constructed before the inferior division cave before the main horizontal hole and inferior division cave after the horizontal branch well, return to horizontal branch well 9 behind near the posterior inferior division cave of constructing again the well rear end, cave, whenever finish a Multilateral Wells Duan Jun and replace into solid free completion fluid;
(3), after the construction of inferior division well is finished, be lowered to the recoverable whipstock at top set kickoff point (KOP) place, the sidetracking construction master of top set horizontal hole 11, after the orientation construction, dock with the peupendicular hole cave section 2 in the superjacent, and continue before coal seam, forward position construction top set cave horizontal branch well 13 before the main horizontal hole 12 and top set cave, finish before the top set cave before the main horizontal hole 11 and top set cave after the horizontal branch well 13, return behind the cave horizontal branch well 14 behind the construction top set cave, according to the corresponding numbers of branches of peupendicular hole cave quantity construction, every construction is finished a Multilateral Wells Duan Jun and is replaced into solid free completion fluid;
(4) after topmost branch well is finished in construction, take out the recoverable whipstock respectively,, window a little to seeing the cementing concrete shutoff of coal point from sidetracking with the lower curved section of each the main horizontal hole in the horizontal well;
(5) vertical 1 time brill well-flushing of cave well is removed the landwaste and the sediment that are communicated with the construction generation, and equipment, land drainage step-down extraction coal bed gas are adopted by the row of installation.
Above-mentioned horizontal well 3 comprises horizontal well peupendicular hole section 4, the master of top set horizontal hole 11, inferior division master horizontal hole 6, vertical cave well 1, main horizontal hole 12 before the top set cave, main horizontal hole 7 before the inferior division cave, one end of the master of top set horizontal hole 11 and inferior division master horizontal hole 6 all is communicated with horizontal well peupendicular hole section 4, the master of top set horizontal hole 11 all is connected with the corresponding cave of vertical cave well 1 with inferior division master horizontal hole 6, the master of top set horizontal hole 11 is horizontal branch well 13 before the front and back of vertical cave well 1 are respectively arranged with the top set cave, horizontal branch well 14 behind the top set cave, inferior division master horizontal hole 6 is horizontal branch well 8 before the front and back of vertical cave well 1 are respectively arranged with the inferior division cave, horizontal branch well 9 behind the inferior division cave, the master of top set horizontal hole 11 and inferior division master horizontal hole 6 continue to extend to forward the coal seam main horizontal hole of constructing being connected the back with vertical cave well 1.
Above-mentioned vertical cave well 1 with the top set cave before be installed on glass reinforced plastic sleeve 15 in main horizontal hole 7 docks before the main horizontal hole 12, inferior division cave the coal seam section.
The master of top set horizontal hole 11, inferior division master horizontal hole 6 are connected by top set's inclination section 10, inferior division inclination section 5 respectively with horizontal well peupendicular hole section 4.