CN111894528A - Coal measure stratum multi-gas combined mining and capacity replacing method - Google Patents
Coal measure stratum multi-gas combined mining and capacity replacing method Download PDFInfo
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- CN111894528A CN111894528A CN202010899508.5A CN202010899508A CN111894528A CN 111894528 A CN111894528 A CN 111894528A CN 202010899508 A CN202010899508 A CN 202010899508A CN 111894528 A CN111894528 A CN 111894528A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/14—Obtaining from a multiple-zone well
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
- E21B43/305—Specific pattern of wells, e.g. optimizing the spacing of wells comprising at least one inclined or horizontal well
Abstract
The invention discloses a coal measure stratum multi-gas co-production and capacity take-over method, which comprises the following steps: step 1, selecting a relatively-developed block of a coal bed and a compact sandstone layer in a coal-based stratum, and drilling a U-shaped well in the block, wherein the horizontal section of the U-shaped well is in an inclined state, and the horizontal section penetrates through a plurality of reservoirs; step 2, performing joint production on a plurality of reservoirs penetrated by the horizontal well section through fracturing, wherein the vertical well section with a high construction position produces gas, and the vertical well section with a low construction position drains water and powder and gives consideration to gas production; step 3, after the gas production rate of the horizontal well section is reduced, a packer is adopted to seal the vertical well section and the horizontal section, and gas production is carried out on the sandstone layer by utilizing the two vertical well sections of the U-shaped well; and 4, performing commingling production on all reservoirs after the gas production rate in the step 3 is reduced. The method provided by the invention solves the problem that the pressure of the coal seam produced water, the high-pressure reservoir and the low-pressure reservoir is not matched, reduces the interference of coal seam powder production, and realizes the capacity replacement of coal-based gas development.
Description
Technical Field
The invention relates to the technical field of coal-based gas mining, in particular to a coal-based stratum multi-gas co-mining and capacity replacing method.
Background
China has abundant coal resources, a large amount of coal resources have abundant coal-series unconventional natural gas, and coal bed gas, dense gas and even shale gas in coal-series strata have wide development prospects. Coal bed gas, dense gas and shale gas are often developed as a single gas reservoir type for a long time in China, so that the single well yield is low. Because the coal bed, the compact sandstone layer and the shale are alternately superposed and distributed in the coal-based stratum, and meanwhile, in most of the stratum, the sandstone layers or the coal beds which are not communicated with each other are also arranged above the alternately superposed and distributed layers of the coal bed, the compact sandstone layer and the shale, if different types of gas reservoirs in the stratum are combined for mining, the single-well yield can be improved, the drilling cost is saved, and the large-scale industrial development of the coal-based gas is realized. Because the shale gas development difficulty is large and the cost is high, the multi-gas co-production of coal-series strata at home and abroad mainly takes the co-production of coal bed gas and dense gas, and the shale gas development is considered in the co-production process.
At present, coal-based gas combined mining at home and abroad mainly takes a vertical well combined mining mode and a horizontal well multi-section fracturing combined mining mode as main modes. The vertical well commingling production is that a plurality of reservoir beds which are vertically overlapped and distributed are connected in series by a shaft for commingling production; the horizontal well commingling mode is characterized in that a plurality of reservoirs which are overlapped at a short distance are communicated through a fracturing fracture. The vertical well has simple technology and lower cost, and the structure of the tubular column is relatively convenient to adjust. The drilling difficulty of the horizontal well or the multi-branch horizontal well is relatively high, the cost is high, and the commingled production development effect is good. Patent CN107246254A discloses a coal-series gas U-shaped well drilling and developing method, wherein a horizontal well section of a U-shaped well is combined with a fracturing fracture to carry out co-production on adjacent coal-series gas.
Aiming at various current commingled mining development modes, different commingled mining modes cannot effectively use the whole coal-series stratum or the problem of stratum replacement in the production process is not considered during the commingled mining development. The vertical well has simple technology and lower cost, the tubular column structure is relatively convenient to adjust, but the exploitation effect is poor, and more wells and ground well sites are needed for a unit area development block. The drilling difficulty of the horizontal well or the multi-branch horizontal well is relatively high, but the commingled mining development effect is good, mainly the multi-section fracturing mode mining of the horizontal well is taken as a main mode, and the problem of stratum take-over is not considered. And the capacity is decreased more quickly when the conventional gas reservoir is exploited, so that the production zone replacement is realized during the commingled exploitation development, the service life of a gas well is prolonged, and the development efficiency of the whole coal-series gas reservoir is improved. If the fracturing exploitation is carried out on the whole well section by adopting the U-shaped well, the problems are as follows: 1. the pressure mismatch causes the high-pressure layer to inhibit the low-pressure layer, and the low-pressure reservoir is damaged; 2. the coal bed gas has large water yield, has large influence on other reservoirs, and simultaneously produces powder to damage other strata.
Disclosure of Invention
In view of the above technical problems, the present invention provides a method for coal-based formation multi-gas co-production and capacity take-over in view of the defects of the prior art.
The invention adopts the following technical scheme:
a coal measure stratum multi-gas combined mining and capacity replacing method comprises the following steps:
and 4, performing commingling production on all reservoirs after the gas production rate in the step 3 is reduced.
In one embodiment of the present invention, in the step 2, the following operations are specifically performed: and performing multi-reservoir commingling production on the horizontal well section in a multi-section fracturing mode.
In one embodiment of the present invention, in the step 3, the following operations are specifically performed: and (3) sealing the straight well section and the horizontal well section by adopting a packer, perforating and fracturing the compact sandstone layer of the straight well section, and then performing commingled production by utilizing the straight well section.
One embodiment of the present invention is that the specific operation of step 4 is as follows: and taking out the packer, performing combined production on the coal bed gas and the compact sandstone layer, draining and producing gas by the vertical well connected with the low structural position of the horizontal well section, and producing gas by the vertical well connected with the high structural position of the horizontal well section.
One embodiment of the present invention is that the specific operation of step 4 is as follows: when the gas production of the sandstone layer is reduced or the working fluid level of the coal bed is lower than that of the upper sandstone layer, taking out the packer of the vertical well section at the low construction position, setting an annular space between the oil production pipe and the shaft, and producing gas and draining water by using the vertical well section at the low construction position and producing gas by using the vertical well section at the high construction position; and when the height of the coal bed working fluid level is lower than that of the upper sandstone layer, all the packers are taken out, and the whole commingled production is carried out.
The invention has the beneficial effects that:
(1) according to the invention, the horizontal well section and the straight well section of the U-shaped well are used for production, the mining modes of the straight well and the horizontal well are combined, the mining range of the whole coal-series stratum is wider in the vertical direction, the three-dimensional development of the coal-series stratum is realized, the well field area is saved, and the production cost is reduced.
(2) According to the invention, the coal measure stratum is exploited by combining the development advantages of the vertical well and the horizontal well with different well body parts of the U-shaped well, so that the exploitation mode is lower in cost for exploiting the same number of reservoirs in the coal measure stratum than that of the single vertical well and the single horizontal well, and the drilling and development costs can be saved.
(3) The capacity replacing mode provided by the invention can prolong the stable production time of the gas well and the service life of the gas well. The new capacity replacing mode avoids the interlayer interference during the multi-layer joint mining and improves the joint mining efficiency. Meanwhile, the problem that the pressure of the coal seam water production reservoir, the high pressure reservoir and the low pressure reservoir is not matched is solved, and the interference of coal seam powder production is reduced.
(4) The invention forms a set of rolling development mode that the mining horizon is from deep to shallow, the development mode is from easy to difficult, and the combined mining gas production rate is from high to low. The high-efficiency joint mining method mainly takes the mining of dense gas and coal bed gas, gives consideration to the mining of shale gas and realizes the replacement of a producing zone in space and time.
Drawings
FIG. 1 is a block diagram of a specific implementation of the present invention;
FIG. 2 is a schematic view of step 2 of example 1;
FIG. 3 is a schematic view of step 3 of example 1;
FIG. 4 is a schematic view of step 4 of example 1;
FIG. 5 is a schematic view of the structure of a straight well section in the low formation position in step 4 of example 1;
FIG. 6 is a schematic view of step 4 of example 2;
FIG. 7 is a schematic structural view of a straight well section of a high formation location in step 4 of example 2;
FIG. 8 is a schematic structural view of a straight well section in the low formation position in step 4 of example 2;
in the figure, 1 is a compact sandstone layer, 2 is a coal layer, 3 is a shale layer, 4 is a fracturing fracture, 5 is a U-shaped well, 6 is a packer, 7 is an oil production pipe, 8 is a shaft, 9 is an oil pumping unit,
and 61 is annular packing.
Detailed Description
The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.
In the invention, the vertical well section at the low construction position is a vertical well section connected with the low construction position of the horizontal well section, and the vertical well section at the high construction position is a vertical well section connected with the high construction position of the horizontal well section.
Example (A)
Example 1
Referring to fig. 1-5, a coal measure formation multi-gas co-production and capacity take-over method comprises the following steps:
and 4, because the compact sandstone layer 1 has the characteristics of long gas production period, high gas production decreasing speed and the like, after the gas production is carried out on the compact sandstone layer 1 in the step 3, the initial gas production is larger, then the initial gas production is rapidly reduced, after the yield of the compact sandstone layer 1 on the upper part of the stratum is reduced, the packer 9 is taken out, perforation and fracturing are carried out on the coal bed 2, the compact sandstone layer 1 on the upper part of the stratum and the coal bed 2, the sandstone layer 1 and the shale layer 3 which are distributed in a laminated manner on the lower part of the bottom layer, at the moment, the gas production and drainage are carried out by using the straight well section with the low structure position, and the gas production is carried out by using the. Wherein, the vertical shaft section of the low construction position utilizes a pumping unit 9 arranged in an oil production pipe 7 to drain water, and utilizes the annular space between a shaft 8 and the oil production pipe 7 to produce gas.
In the figure, the hollow arrows are the migration direction of gas in the vertical well section, the solid arrows are the migration direction of liquid in the vertical well section, the dotted arrows are the migration direction of gas in the reservoir and the horizontal well section, and the solid arrows are the migration direction of liquid in the reservoir and the horizontal well section.
Example 2
Referring to FIGS. 1-3, 6-8, Steps 1-3 are the same as example 1, with the only difference being step 4: when the coal seam 2 at the upper part of the stratum is positioned below the tight sandstone layer 1, a packer 6 can be arranged between the coal seam 2 and the tight sandstone layer 1, and the specific setting mode is as follows: the vertical well section of the high construction position is provided with a full packer, the vertical well section of the low construction position is provided with an annular packer 61, gas production and drainage are carried out by utilizing the vertical well section of the low construction position at the moment, gas production is carried out by the vertical well section of the high construction position, and after the working fluid level of the coal bed is lower than the sand rock layer at the upper part, all packers are taken out for integral commingled production. Wherein, the vertical shaft section of the low construction position utilizes a pumping unit 9 arranged in an oil production pipe 7 to drain water, and utilizes the annular space between a shaft 8 and the oil production pipe 7 to produce gas.
The present invention has been disclosed in the foregoing in terms of preferred embodiments, but it will be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of the present invention. Further modifications of the invention should also be considered within the scope of the invention without departing from its principles.
Claims (5)
1. A coal measure stratum multi-gas combined mining and capacity replacing method is characterized by comprising the following steps:
step 1, selecting a block with a better coal bed and a better dense sandstone layer in a coal-based stratum, and drilling a U-shaped well in the block, wherein a horizontal well section of the U-shaped well is in an inclined state, and simultaneously the horizontal well section penetrates through a plurality of reservoir layers;
step 2, performing joint production on a plurality of reservoirs penetrated by the horizontal well section through fracturing, wherein the vertical well section with a high construction position produces gas, and the vertical well section with a low construction position drains water and powder and gives consideration to gas production;
step 3, after the gas production rate of the horizontal well section is reduced, sealing the vertical well section and the horizontal well section by using a packer, and performing gas production on the sandstone layer by using two vertical well sections of the U-shaped well;
and 4, performing reservoir commingling after the gas production rate in the step 3 is reduced.
2. The method according to claim 1, wherein the specific operations in step 2 are as follows: and performing multi-reservoir commingling production on the horizontal well section in a multi-section fracturing mode.
3. The method according to claim 1, wherein the specific operations in step 3 are as follows: and (3) sealing the straight well section and the horizontal well section by adopting a packer, perforating and fracturing the compact sandstone layer of the straight well section, and then performing commingled production by utilizing the straight well section.
4. The method according to claim 1, wherein the specific operation of step 4 is as follows: and taking out the packer, performing combined production on the coal bed gas and the compact sandstone layer, draining and producing gas on the straight well section with the low structural position, and producing gas on the straight well section with the high structural position.
5. The method according to claim 1, wherein the specific operation of step 4 is as follows: after the gas production of the sandstone layer is reduced, gas production and drainage of the coal bed are carried out by using two vertical well sections, when the working fluid level of the coal bed is lower than that of the upper sandstone layer, the packer of the vertical well section at the low construction position is taken out, an annular space is arranged between the oil production pipe and the shaft, and gas production and drainage are carried out by using the vertical well section at the low construction position and the vertical well section at the high construction position; and when the height of the coal bed working fluid level is lower than that of the upper sandstone layer, all the packers are taken out, and the whole commingled production is carried out.
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Cited By (2)
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| CN113653470A (en) * | 2021-10-21 | 2021-11-16 | 西南石油大学 | Coal bed in-situ hydrogen production and coal bed gas development integrated method and structure |
| CN114320237A (en) * | 2021-12-20 | 2022-04-12 | 中煤地质集团有限公司 | Novel composite coal gas reservoir coalbed methane multilayer combined mining method |
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