WO2016101680A1 - 地下气化固井方法、井结构 - Google Patents

地下气化固井方法、井结构 Download PDF

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Publication number
WO2016101680A1
WO2016101680A1 PCT/CN2015/091874 CN2015091874W WO2016101680A1 WO 2016101680 A1 WO2016101680 A1 WO 2016101680A1 CN 2015091874 W CN2015091874 W CN 2015091874W WO 2016101680 A1 WO2016101680 A1 WO 2016101680A1
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Prior art keywords
cementing
casing
well
coal seam
flexible sleeve
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PCT/CN2015/091874
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English (en)
French (fr)
Inventor
陈�峰
潘霞
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新奥气化采煤有限公司
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Publication of WO2016101680A1 publication Critical patent/WO2016101680A1/zh

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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
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/20—Flexible or articulated drilling pipes, e.g. flexible or articulated rods, pipes or cables
    • 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
    • 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
    • E21B43/295—Gasification of minerals, e.g. for producing mixtures of combustible gases

Definitions

  • the invention relates to the field of underground coal gasification, in particular to an underground gasification cementing method and a well structure.
  • the formation above the coal seam is more susceptible to cracking due to the need to inject gasification agent into the underground coal seam, generate a large amount of thermal energy to burn the coal seam around the coal seam, and leave a huge burning zone due to coal seam combustion.
  • Collapse which in turn causes stress changes in the stratum, and the cementing casing in the stratum is damaged or fractured due to changes in formation stress. This phenomenon is more prominent in the failure of cementing casings in underground gasification.
  • the formation where cracking and collapse occurs is called the water-conducting fracture zone.
  • the fall zone part of the rock layer completely covered by the overlying rock mass caused by the mining face after mining is called the fall zone.
  • a large number of layers, separation layers and fracture gaps or fracture zones developed above the caving zone are called fissure zones, and the caving zones and fracture zones are collectively referred to as water-conducting fracture zones.
  • Patent CN101158272 discloses an oil well shearing sleeve anti-break telescopic tube, which mainly uses a sleeve coupling on an inner tube and is connected with an upper sleeve, the inner tube is placed in the outer tube, and the outer tube and the inner tube are A seal ring and a spring are installed in the middle, and a pin is mounted on the upper portion, the lower end of the outer tube is coupled with the lower joint, and the lower joint is coupled to the downhole pipe.
  • the inner tube of the telescopic tube is detached and slides for a certain distance to prevent the casing from breaking, and the oil well can still maintain safe production.
  • the above patents are for the displacement of the formation. The casing fracture caused by (non-up and down direction shifting) is ineffective.
  • an aspect of the present invention provides an underground gasification cementing method, in which a cementing casing setting step is performed during the construction of a well that is introduced into the coal seam from the ground or after the completion of the construction: The casing is stopped until the bottom end of the cementing casing enters a set depth of the coal seam, and the cementing casing is connected to the well wall of the well; wherein the cementing casing includes at least a flexible flexible casing, which is expandable and contractible The bottom end of the flexible sleeve constitutes the bottom end of the cementing casing, and the length of the retractable flexible casing is greater than or equal to the sum of the maximum height of the water guiding fracture zone above the coal seam and the set depth.
  • the ground is drilled down and drilled below the set depth; in the cementing casing setting step: by injecting cementing into the gap between the well and the cementing casing The material is cemented to connect the cementing casing to the wellbore; the well continues to be drilled until it is drilled to a predetermined location in the coal seam.
  • the cementing casing further includes a petroleum casing, the top end of which is coupled to the bottom end of the oil casing.
  • the length of the telescopic flexible sleeve is greater than the sum of the maximum height of the water-conducting fracture zone and the set depth, and the difference from the sum is less than or equal to 15 meters.
  • the set depth is equal to 1/5 - 1/3 of the thickness of the coal seam.
  • the telescopic flexible sleeve is a bellows.
  • the bellows has any or any combination of the following characteristics: a, the bellows is a metal bellows or a composite corrugated pipe; b, the compressive strength of the bellows is greater than or equal to 20 MPa; c, the bellows is a heat resistant temperature It is above 350 °C.
  • the inclination of the coal seam is in the range of 0°-54° or 55°-85°.
  • Another aspect of the invention provides a well structure comprising: a well that opens into the coal seam from the ground, and a cementing casing connected to the well wall of the well; the cementing casing includes a retractable flexible casing, which is telescopic The bottom end of the flexible sleeve is located at a set depth in the coal seam, and the length of the retractable flexible sleeve is greater than or equal to the sum of the maximum height of the water-conducting fracture zone above the coal seam and the set depth.
  • the cementing casing further comprises a petroleum casing; the bottom end of the oil casing is flexible and retractable The top end of the sleeve is connected.
  • the length of the telescopic flexible sleeve is greater than the sum of the maximum height of the water-conducting fracture zone and the set depth, and the difference from the sum is less than or equal to 15 meters.
  • the underground gasification cementing method of the present invention is to lower the cementing casing into the well during the construction process of the well passing through the ground into the coal seam, or after the completion of the construction, until the bottom end of the cementing casing enters the coal seam set depth After the stop, the cementing casing is connected to the well wall of the well.
  • the cementing casing comprises at least a bellows, the bottom end of the bellows constitutes a bottom end of the cementing casing, and the length of the bellows is greater than or equal to a sum of a maximum height of the water guiding fracture zone above the coal seam and a set depth So that the bellows cover the water-conducting fracture zone.
  • the retractable flexible sleeve 31 is calculated using the maximum height of the water-conducting fracture belt, so that it is sufficient for the actually produced water-conducting fracture belt to be covered by the flexible flexible sleeve, thereby enabling water-conducting Regardless of the direction in which the formation within the fracture zone is displaced, the retractable flexible casing can move with the well wall to which it is attached so that no fracture occurs.
  • the present invention can prevent the fracture of the cementing casing caused by the displacement of the formation above the coal seam in various directions. For example, if the formation is displaced up and down (longitudinal), the telescoping flexible sleeve can follow the formation movement in a telescopic manner. As another example, if the formation is left and right (lateral) displaced, the telescoping flexible sleeve can follow the formation movement in a curved manner. Alternatively, when the above two directions of displacement occur simultaneously, the telescopic flexible sleeve can simultaneously follow the formation movement in a telescopic or curved manner. In summary, the present invention further avoids the inability of the well to be used normally due to the fracture of the cementing casing, and the resulting reduction in the underground gasification effect or the failure of the underground gasification.
  • the present invention can prevent the fracture of the cementing casing caused by the displacement of the formation above the coal seam in various directions. For example, if the formation is displaced up and down (longitudinal), the telescoping flexible sleeve can follow the formation movement in a telescopic manner. As another example, if the formation is left and right (lateral) displaced, the telescoping flexible sleeve can follow the formation movement in a curved manner. Alternatively, when the above two directions of displacement occur simultaneously, the telescopic flexible sleeve can simultaneously follow the formation movement in a telescopic or curved manner. In summary, the present invention further avoids the inability of the well to be used normally due to the fracture of the cementing casing, and the resulting reduction in the underground gasification effect or the failure of the underground gasification.
  • FIG. 1 is a schematic view of an underground gasification cementing method according to an embodiment of the present invention
  • FIG. 2 is a schematic view of another underground gasification cementing method according to an embodiment of the present invention.
  • an embodiment of the underground gasification cementing method of the present invention is provided in the present embodiment for gasification of underground coal seams.
  • the following cementing casing 3 setting step is performed: lowering the cementing casing 3 into the well 2 until solid The bottom end of the well casing 3 enters the set depth of the coal seam 1 and then stops, and the cementing casing 3 is connected to the well wall of the well 2.
  • the cementing casing 3 comprises at least a telescopic flexible sleeve 31, the bottom end of the retractable flexible sleeve 31 constitutes the bottom end of the cementing sleeve 3, and the length of the telescopic flexible sleeve 31 is greater than or equal to The sum of the maximum height of the water guiding fracture zone 4 above the coal seam 1 and the set depth.
  • the length of the retractable flexible sleeve 31 is used in the calculation.
  • the maximum height of the fracture zone is sufficient to cause the actually produced water-conducting fracture zone 4 to be covered by the flexible flexible sleeve 31, so that the formation within the water-conducting fracture zone 4 is displaced in any direction, and is scalable
  • the flexible sleeves 31 are all movable along with the well wall to which they are connected, so that A break has occurred. That is, the present invention can prevent the fracture of the cementing casing 3 caused by the displacement of the formation above the coal seam 1 in various directions.
  • the telescoping flexible sleeve 31 can follow the formation movement in a telescopic manner.
  • the ground layer 1 is displaced left and right (laterally)
  • the telescopic flexible sleeve 31 can follow the formation movement in a curved manner.
  • the telescopic flexible sleeve 31 can simultaneously follow the formation movement in a telescopic or curved manner.
  • the present invention further avoids the inability of the well to be used normally due to the fracture of the cementing casing 3, and the resulting reduction in the underground gasification effect or the failure of the underground gasification.
  • the coal seam 1 is located in the coal field of Inner Mongolia.
  • the underground coal gasification furnace is used to establish a coal-free gasification underground coal gasification furnace. .
  • the basic geological information includes at least: the compressive strength of the rock layer above the coal seam, the dip angle of the coal seam, and the number of layers of coal. Also, for coal seams with inclination angles in the range of 0°-54° (see the coal seam in Figure 1), the basic geological information also includes the cumulative thickness of the coal seam, and for coal seams with inclination angles in the range of 55°-85° ( Referring to the coal seam in Figure 2, the basic geological information also includes the thickness of the coal seam and the small height of the coal mining face.
  • the roof rock of coal seam 1 is argillaceous sandstone, and further up is clay rock layer, sandy aquifer, shale layer, shallow soil layer and surface.
  • the compressive strength of argillaceous sandstone is between 25 and 35 MPa.
  • the coal seam 1 is a horizontal coal seam (ie, the coal seam has an inclination of 0°), and the coal seam 1 is a single coal seam.
  • the buried depth is 350 meters, and the thickness of the coal seam 1 is 7 meters.
  • this table 1 is quoted from the "mine hydrogeology regulations" (test) issued by the Ministry of Coal Industry.
  • M cumulative thickness, m; n - coal layered layer; m - coal seam thickness, m; h - working face small stage vertical height, m.
  • the maximum height of the water-conducting fracture zone, the gently inclined and inclined coal seam refers to the normal height from the top surface of the coal seam; for the steeply inclined coal seam, it refers to the vertical height from the upper limit of mining.
  • the rock compressive strength is the saturated uniaxial ultimate strength.
  • the thickness of the single layer of coal can be completely vaporized, that is, the cumulative thickness of the coal seam 1 is 7 meters, the number of coal layered layers is 1, and the compressive strength is between 25 and 35 MPa.
  • the maximum height of the water-conducting fracture zone 4 calculated by this formula is 103.7 meters.
  • the temperature in the combustion zone ie: goaf
  • the heat effect on the stratum above the goaf is much more obvious than that in the well mining, which will accelerate Development of the water guiding fracture zone 4.
  • the underground gasification ash and vermiculite remain in the underground space to play a certain filling role.
  • the above thermal action is offset by the filling action. Therefore, at this time, the length of the retractable flexible sleeve 31 is equal to the sum of the maximum height of the water guiding fracture belt and the set depth H.
  • the length of the retractable flexible sleeve 31 is increased by a maximum of 15 meters, based on the sum of the maximum height of the water-conducting fracture zone and the set depth H. That is, the length of the retractable flexible sleeve 31 of the present invention may be equal to the sum of the maximum height of the water-conducting fracture zone and the set depth H, or may be greater than the maximum height of the water-conducting fracture zone and the set depth H, depending on the actual situation.
  • the sum and the difference from this sum are less than or equal to 15 meters.
  • “increase of up to 15 meters” can be understood as the increased margin of the height of the water-conducting fracture zone on the basis of its maximum height after the development of the water-conducting fracture zone is accelerated.
  • the set depth H is the depth at which the bottom end of the retractable flexible sleeve 31 is located in the coal seam.
  • the value of the set depth H is selected by a person skilled in the art according to actual needs to meet the requirement that the flexible flexible sleeve 31 can support the well wall when the coal seam is burned.
  • the set depth is equal to 1/5-1/3 of the thickness of the coal seam, and the thickness of the coal seam of the present embodiment is 7 meters, so the set depth is in the range of 7/5-7/3 meters.
  • the set depth H is selected to be equal to 2 meters.
  • the length of the telescopic flexible sleeve 31 is equal to the sum of the maximum height (103.7 meters) of the water guiding fracture zone 4 and the set depth H (2 meters), that is, 105.7 meters.
  • the retractable flexible sleeve may be a bellows or formed by connecting the bellows and the flexible tube to each other. That is, in the case where the retractable flexible sleeve is entirely a bellows, the bellows is simultaneously adapted to the longitudinal displacement and lateral displacement of the coal seam; in the case where the retractable flexible sleeve includes the bellows and the flexible tube, the corrugation
  • the tube provides flexibility for the flexible sleeve to accommodate longitudinal displacement of the coal seam, while the bellows and flexible tube simultaneously accommodate lateral displacement of the coal seam.
  • the retractable flexible sleeve can be constructed of any material and structure known to those skilled in the art that is scalable and bendable.
  • the telescopic flexible sleeve 31 is a bellows, and further the bellows is a metal bellows having a compressive strength equal to 40 MPa and a heat resistant temperature of 350 °C.
  • the bellows may also be a composite corrugated pipe, for example, an aluminum foil corrugated pipe made of a plurality of materials such as glass fiber and aluminum foil in the prior art, or a steel strip reinforced spiral steel-plastic composite corrugated corrugated pipe.
  • Tube Etc., and the compressive strength of the bellows may also be other values of 40 MPa in the range of greater than or equal to 20 MPa, and the heat resistant temperature of the bellows may also be a temperature value greater than 350 °C.
  • retractable flexible sleeve 31 that is capable of functioning as a cementing force and that moves together when the surrounding formation is displaced in all directions can be used in the present invention.
  • the retractable flexible sleeve 31 is a bellows, and is further preferably a metal bellows or a composite bellows.
  • the retractable flexible sleeve 31 has a compressive strength greater than or equal to 20 MPa and a heat resistant temperature greater than or equal to 350 °C.
  • the ground is drilled down and drilled below the set depth H in the coal seam. That is, in the present embodiment, the ground is drilled down until the bottom of the well enters a portion below 2 meters in the coal seam. This step is the establishment step of well 2 and the complete establishment of well 2 has not been completed.
  • the cementing casing 3 employed in the present embodiment includes a petroleum casing 32 and a retractable flexible casing 31.
  • the oil jacket 32 and the retractable flexible sleeve 31 are joined together by means well known to those skilled in the art (e.g., welding, threaded connections, flange connections, etc.). Specifically, referring to the orientation in FIG.
  • the cementing casing 3 is placed in a top-to-bottom direction with the direction of the ground pointing to the coal seam in a top-to-bottom direction, and the cementing casing 3 has a relatively disposed top end and
  • the oil sleeve 32 has oppositely disposed top ends and bottom ends
  • the retractable flexible sleeve 31 has oppositely disposed top and bottom ends, and among all of the "top and bottom ends", the top end is located above the bottom end, ie The direction from the top to the bottom is the top to bottom direction.
  • the top end of the retractable flexible sleeve 31 is connected to the bottom end of the oil casing 32, and the bottom end of the retractable flexible sleeve 31 constitutes a solid.
  • the top end of the oil casing 32 constitutes the top end of the cementing casing 3.
  • Step 1 Lower the cementing casing 3 into the well 2 until the bottom end of the cementing casing 3 (the bottom end of the telescopic flexible casing 31) enters the set depth H in the coal seam 1 and stops. That is, the end face of the bottom end of the cementing casing 3 (the bottom end of the telescopic flexible sleeve 31) is located at the set depth H in the coal seam 1.
  • the flexible sleeve 31 which is telescopic has a pipe section of 2 meters long located in the coal seam 1.
  • Step 2 cementing by injecting cementing material into the gap between the well 2 and the cementing casing 3,
  • the cementing casing 3 is connected to the well wall.
  • cement slurry ie, cementing material
  • the cementing casing 3 is connected to the well wall.
  • the cement slurry flows through the inside of the cementing casing 3 until it flows to the bottom of the well, and flows upward from the annulus between the well wall and the outer peripheral wall of the cementing casing 3, when the well The annulus between the wall and the outer peripheral wall of the cementing casing 3 is filled with the cement slurry and the injection of the cement slurry is stopped. After the cement slurry is solidified, it fixedly connects the cementing casing 3 to the well wall of the well 2.
  • the above is only a brief description of the slurrying and cementing. The method of the slurrying and cementing used in this embodiment is well known to those skilled in the art and will not be described in detail.
  • cementing material is not limited to cement slurries and may include other materials known to those skilled in the art.
  • cementing may also be performed by other cementing methods, and is not limited to the above-described slurrying.
  • the well 2 is continuously drilled until it is drilled to a predetermined position in the coal seam 1, which in the present embodiment is the bottom plate of the coal seam 1.
  • the predetermined position is determined according to actual needs. For example, after the well 2 is fully established, it is used as an underground gasification intake or outflow well, so the position of the gasification passage provided in the coal seam is determined according to the need to determine the bottom of the intake or outflow well. The location, in turn, determines the location of the well bottom of the well 2. The position of the bottom of the well 2 is the above-mentioned "predetermined position".
  • the cementing casing setting step is performed during the establishment of the well 2, and the slurry is cemented by means of the establishment of the well 2.
  • the cementing casing setting step may be performed after the well 2 is completely established, and other methods known to those skilled in the art may be selected according to actual conditions to cement the casing 3 and the well 2 The well wall is connected.
  • the well is cleaned and/or the well wall below the retractable flexible casing 31 is simply supported.
  • the retractable flexible sleeve is calculated by presetting the position at which the bottom end of the retractable flexible sleeve 31 projects into the coal seam 1, and according to the maximum height of the water guiding fracture belt and the position in the coal seam 1 described above.
  • the length of the tube 31 enables the retractable flexible sleeve 31 to be covered immediately after being connected to the well wall Cover the range of water-conducting fracture zones where the formation may be displaced. Thereby, the advantageous effects already mentioned above are guaranteed.
  • This embodiment gasifies the coal seam in Ningxia.
  • the coal seam is a steeply inclined coal seam 1.
  • the inclination of the coal seam 1 is between 60° and 65°, and the coal seam 1 is buried at a depth of 460 meters.
  • the coal seam 1 is sandwiched by three thin layers of crucibles, and the thickness of the coal seam 1 is 12 meters.
  • the roof rock layer of coal seam 1 is sandy shale, the compressive strength is about 30Mpa (less than 40Mpa), and the roof rock layer is further covered with cement rock, shale, limestone, basalt, shallow loess and surface.
  • the coal seam 1 containing thin crucibles can be completely vaporized, and the coal seam 1 is divided into 4 layers with three layers of sandwiching, and the underground gasification channel is arranged along the inclined direction of the coal seam 1
  • the coal working face has a vertical height h of up to 26 meters.
  • the maximum height of the water-conducting fracture zone 4 is calculated to be 103.9 meters.
  • the combustion zone ie: goaf
  • the length of the flexible flexible sleeve 31 is equal to the sum of the maximum height of the water guiding fracture zone and the set depth H. , increase the increment of 13 meters.
  • the length of the telescopic flexible sleeve 31 is 118.9 meters (the maximum height of the water-conducting fracture belt 4 is 103.9 meters, the set depth is 2 meters and the increment is 13 meters).
  • the telescopic flexible sleeve 31 is a metal bellows having a compressive strength equal to 40 MPa and capable of withstanding a temperature of 350 °C.
  • the starting point for the set depth H can be selected at any point above the upper surface of the coal seam to which the cementing casing is connected.
  • the distance between the highest point and the lowest point of the upper surface of the coal seam to which the cementing casing is connected is not large, the calculation starting point of any one of the two points as the set depth H does not affect the implementation of the method. And the realization of beneficial effects.
  • the retractable flexible sleeve in the cementing casing of the present invention can effectively follow the formation in each The displacement in one direction has a more significant beneficial effect on the coal seam having a certain inclination angle (inclination greater than 0) with respect to the prior art.
  • FIG. 1 Another aspect of the invention also provides a well structure, wherein Figures 1 and 2 simultaneously show two embodiments of the well structure of the present invention, respectively.
  • the well structure shown in FIG. 1 includes a well 2 that is introduced into the coal seam 1 from the ground, and a cementing casing 3 that is connected to the well wall of the well 2.
  • the cementing casing 3 comprises a retractable flexible sleeve 31, the bottom end of the retractable flexible sleeve 31 is located at a set depth H in the coal seam 1, and the length of the telescopic flexible sleeve 31 is greater than or equal to The sum of the maximum height of the water guiding fracture zone 4 above the coal seam 1 and the set depth H.
  • the length of the flexible sleeve 31 is sufficient for the water-conducting fracture belt 4 to be covered by the flexible flexible sleeve 31, so that the formation within the water-conducting fracture zone 4 is displaced in any direction, and the flexible sleeve is retractable.
  • Each of the 31 can move with the well wall to which it is attached so that no breakage occurs.
  • the present invention can prevent the fracture of the cementing casing 3 caused by the displacement of the formation above the coal seam 1 in various directions. For example, if the formation is displaced up and down (longitudinal), the telescoping flexible sleeve 31 can follow the formation movement in a telescopic manner. For another example, if the ground layer is displaced left and right (laterally), the telescopic flexible sleeve 31 can follow the formation movement in a curved manner. Alternatively, when the above two directions of displacement occur simultaneously, the telescopic flexible sleeve 31 can simultaneously follow the formation movement in a telescopic or curved manner. In summary, the present invention further avoids the inability of the well to be used normally due to the fracture of the cementing casing 3, and the resulting reduction in the underground gasification effect or the failure of the underground gasification.
  • the cementing casing 3 further includes a petroleum casing 32.
  • the bottom end of the oil cannula 32 is coupled to the top end of the retractable flexible sleeve 31.
  • the length of the retractable flexible sleeve 31 is equal to the sum of the maximum height of the water guiding fracture zone 4 and the set depth.
  • the set depth H is equal to 2 meters.
  • the length of the retractable flexible sleeve 31 is equal to the sum of the maximum height (103.7 meters) of the water guiding fracture zone 4 and the set depth H (2 meters), that is, 105.7 meters.
  • the retractable flexible sleeve 31 is a metal bellows having a compressive strength equal to 40 MPa and a heat resistant temperature of 350 °C.
  • the above-mentioned well 2 cementing casing (including the retractable flexible casing, the oil casing and their connection manner) and the connection mode of the well 2 and the cementing casing 3 and other Described in relation to well 2 and cementing casing
  • the features are consistent with those described in the above-described underground gasification cementing method described based on FIG. 1, and therefore will not be described again.
  • the well structure shown in FIG. 2 includes a well 2 that is introduced into the coal seam 1 from the ground, and a cementing casing 3 that is connected to the well wall of the well 2.
  • the cementing casing 3 comprises a retractable flexible sleeve 31, the bottom end of the retractable flexible sleeve 31 is located at a set depth H in the coal seam 1, and the length of the telescopic flexible sleeve 31 is greater than or equal to The sum of the maximum height of the water guiding fracture zone 4 above the coal seam 1 and the set depth H.
  • the cementing casing 3 further includes a petroleum casing 32.
  • the bottom end of the oil cannula 32 is coupled to the top end of the retractable flexible sleeve 31.
  • the length of the retractable flexible sleeve 31 is equal to the sum of the maximum height of the water guiding fracture zone 4 and the set depth.
  • the set depth H is equal to 2 meters.
  • the length of the retractable flexible sleeve 31 is equal to the maximum height of the water-conducting fracture zone 4 (103.9 meters), the set depth H (2 meters) and the sum of 13 meters, that is, 105.7 meters.
  • the retractable flexible sleeve 31 is a metal bellows having a compressive strength equal to 40 MPa and a heat resistant temperature of 350 °C.
  • cementing casing including the retractable flexible casing, the oil casing and their connection manner
  • connection mode of the well 2 and the cementing casing 3 and other The features described in relation to the well 2 and the cementing casing are identical to those described in the above-described underground gasification cementing method described with reference to Fig. 2, and therefore will not be described again.
  • the bottom end of the retractable flexible sleeve can be connected with other sleeves to achieve the required support requirements for the well wall.
  • the cementing casing in the underground gasification cementing method and well structure of the present invention is not limited to the above description, but is also optionally composed only of a retractable flexible sleeve.
  • the above only describes the case where the coal seam inclination angle is in the range of 0°-54° or in the range of 55°-85°.
  • the coal seam inclination angle is in the range of 54°-55°, it can be respectively in the range of 0°-54°.
  • the formula is used to calculate the maximum height of the water-conducting fracture zone, and then the maximum calculated height of the two is used as the maximum height of the water-conducting fracture zone of the coal seam.

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Abstract

公开了一种地下气化固井方法，该方法中，向井中下放固井套管（3），直至固井套管（3）的底端进入煤层（1）设定深度（H）后停止，并将固井套管（3）与井（2）的井壁连接；固井套管（3）至少包括可伸缩的柔性套管（31），柔性套管（31）的底端构成固井套管（3）的底端，并且柔性套管（31）的上端位于煤层上方最大的导水裂隙带（4）以上。另外，公开了一种井结构，该井结构包括由地面通入煤层（1）的井（2）以及连接于井壁的固井套管（3），固井套管（3）包括可伸缩的柔性套管（31），柔性套管（31）的底端位于煤层中的设定深度（H）处，并且柔性套管（31）的上端位于煤层上方最大的导水裂隙带（4）以上。

Description

地下气化固井方法、井结构
本申请要求于2014年12月24日向中国专利局提交的、申请号为201410820229.X、发明名称为“地下气化固井方法、井结构”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及煤炭地下气化领域，尤其涉及一种地下气化固井方法以及一种井结构。
背景技术
在地下气化、油田开发、煤层气开采中，由于固井套管下放操作不当、地应力变化、井下恶劣环境腐蚀等原因造成固井套管损毁、腐蚀、断裂等失效现象的发生。其中，由于对目标层位进行注水压裂、打压增隙、加热、采空等操作，使得目标层以上地层充液蹩压而上升或者失去支撑而下陷，造成固井套管被挤压变形，甚至断裂，使得钻井不能正常使用。在煤炭地下气化中，由于需要向地下煤层注入气化剂、煤层燃烧气化产生大量热能加热煤层周围岩层、因煤层燃烧留下巨大的燃空区等因素，使得煤层以上地层更加容易开裂、塌陷，进而造成该段地层的应力变化，处在该段地层的固井套管因地层应力变化而损毁或断裂，这种现象在地下气化的固井套管失效中显得更为突出。其中，发生开裂和塌陷的地层称为导水裂隙带。具体言之，工作面回采后引起的煤层上覆岩体完全垮落的部分岩层称为冒落带。冒落带之上大量出现的切层、离层和断裂隙或裂隙发育带称为裂隙带，冒落带和裂隙带合称导水裂隙带。
专利CN101158272公开了一种油井剪切式套管防断伸缩管，主要是采用在内管上联接套管接箍，且与上部套管联接，内管置于外管中，在外管与内管中间安装有密封环和弹簧，并在上部装有销钉，外管下端与下接头联接，下接头联接井下管道。当地层上升时，伸缩管内管脱离，滑动一段距离，能防止套管断裂，油井仍然能保持安全生产。但是，上述专利对于因地层错动 (非上下方向的错动)而引起的套管断裂是没有效果的。
发明内容
本发明的目的在于提供一种地下气化固井方法和一种井结构，其可防止因煤层上方的地层在各个方向上的错动而引起的固井套管的断裂。
为实现上述目的，本发明一方面提供一种地下气化固井方法，在由地面通入煤层的井的构建过程中、或构建完毕后，执行如下固井套管设置步骤：向井中下放固井套管，直至固井套管的底端进入煤层设定深度后停止，并将固井套管与井的井壁连接；其中，固井套管至少包括可伸缩的柔性套管，可伸缩的柔性套管的底端构成固井套管的底端，并且可伸缩的柔性套管的长度大于或等于煤层上方的导水裂隙带的最大高度与设定深度的和值。
根据本发明，在执行固井套管设置步骤之前，由地面向下钻井并钻至设定深度的下方；在固井套管设置步骤中：通过向井和固井套管之间缝隙注入固井材料进行固井，以将固井套管与井壁连接；继续对井进行钻进直至其钻至煤层中的预定位置。
根据本发明，固井套管还包括石油套管，可伸缩的柔性套管的顶端与石油套管的底端连接。
根据本发明，可伸缩的柔性套管的长度大于导水裂隙带的最大高度与设定深度的和值，并与和值的差值小于或等于15米。
根据本发明，设定深度等于煤层厚度的1/5-1/3。
根据本发明，可伸缩的柔性套管为波纹管。
根据本发明，波纹管具有如下任一或任意组合特征：a、波纹管为金属波纹管或复合材料波纹管；b、波纹管的抗压强度大于或等于20MPa；c、波纹管为耐热温度为350℃以上。
根据本发明，煤层的倾角位于0°-54°或55°-85°的范围内。
本发明的另一方面提供一种井结构，包括：由地面通入煤层的井、以及连接于井的井壁的固井套管；固井套管包括可伸缩的柔性套管，可伸缩的柔性套管的底端位于煤层中的设定深度处，并且可伸缩的柔性套管的长度大于或等于煤层上方的导水裂隙带的最大高度与设定深度的和值。
根据本发明，固井套管还包括石油套管；石油套管的底端与可伸缩的柔 性套管的顶端连接。
根据本发明，可伸缩的柔性套管的长度大于导水裂隙带的最大高度与设定深度的和值，并与和值的差值小于或等于15米。
相比于现有技术，本发明的有益效果在于：
本发明的地下气化固井方法，是在由地面通入煤层的井的构建过程中、或构建完毕后，向井中下放固井套管，直至固井套管的底端进入煤层设定深度后停止，并将固井套管与井的井壁连接。其中，固井套管至少包括波纹管，波纹管的底端构成固井套管的底端，并且波纹管的长度大于或等于煤层上方的导水裂隙带的最大高度与设定深度的和值，以使波纹管覆盖导水裂隙带。由此，煤层燃烧形成燃空区后，由于导水裂隙带中形成了导水断层，在导水断层中有地下水通过，造成该区域岩层稳定性下降，容易形成地层错动，由于可伸缩的柔性套管可伸缩的柔性套管31的长度在计算中使用的是导水裂隙带的最大高度，故其足以使得实际产生的导水裂隙带被可伸缩的柔性套管覆盖，进而使得导水裂隙带范围内的地层无论是在何方向上发生错动，可伸缩的柔性套管均能够随着与其连接的井壁一起运动，从而不会发生断裂。即本发明可防止因煤层上方的地层在各个方向上的错动而引起的固井套管的断裂。例如，若地层发生上下(纵向)错动，则可伸缩的柔性套管能够以伸缩的方式跟随地层运动。又例如，若地层发生左右(横向)错动，则可伸缩的柔性套管能够以弯曲的方式跟随地层运动。或者，同时发生上述两种方向的错动时，可伸缩的柔性套管能够同时以伸缩或弯曲的方式跟随地层运动。综上，本发明进而避免了因固井套管断裂而导致的井不能正常地使用，以及由此导致的地下气化效果的降低或者地下气化的失败。
本发明的井结构，包括由地面通入煤层的井以及连接于井的井壁的固井套管。固井套管包括可伸缩的柔性套管，可伸缩的柔性套管的底端位于煤层中的设定深度处，并且可伸缩的柔性套管的长度大于或等于煤层上方的导水裂隙带的最大高度与设定深度的和值，以使波纹管覆盖导水裂隙带。由此，煤层燃烧形成燃空区后，由于导水裂隙带中形成了导水断层，在导水断层中有地下水通过，造成该区域岩层稳定性下降，容易形成地层错动，由于可伸缩的柔性套管31可伸缩的柔性套管的长度在计算中使用的是导水裂隙带的 最大高度，故其足以使得实际产生的导水裂隙带被波纹管覆盖，进而使得导水裂隙带范围内的地层无论是在何方向上发生错动，可伸缩的柔性套管均能够随着与其连接的井壁一起运动，从而不会发生断裂。即本发明可防止因煤层上方的地层在各个方向上的错动而引起的固井套管的断裂。例如，若地层发生上下(纵向)错动，则可伸缩的柔性套管能够以伸缩的方式跟随地层运动。又例如，若地层发生左右(横向)错动，则可伸缩的柔性套管能够以弯曲的方式跟随地层运动。或者，同时发生上述两种方向的错动时，可伸缩的柔性套管能够同时以伸缩或弯曲的方式跟随地层运动。综上，本发明进而避免了因固井套管断裂而导致的井不能正常地使用，以及由此导致的地下气化效果的降低或者地下气化的失败。
附图说明
图1是本发明的实施例的一种地下气化固井方法示意图；
图2是本发明的实施例的另一种地下气化固井方法示意图。
具体实施方式
如下参照附图描述本发明的实施例。
参见图1，在本实施例中提供了本发明的地下气化固井方法的一个实施例，其用于地下煤层的气化。
在本实施例的方法中，在由地面通入煤层1的井2的构建过程中、或构建完毕后，执行如下固井套管3设置步骤：向井2中下放固井套管3，直至固井套管3的底端进入煤层1设定深度后停止，并将固井套管3与井2的井壁连接。其中，固井套管3至少包括可伸缩的柔性套管31，可伸缩的柔性套管31的底端构成固井套管3的底端，并且可伸缩的柔性套管31的长度大于或等于煤层1上方的导水裂隙带4的最大高度与设定深度的和值。
由此，煤层1燃烧形成燃空区后，在煤层1上方的地层发生错动时，即形成导水裂隙带4时，由于可伸缩的柔性套管31的长度在计算中使用的是导水裂隙带的最大高度，故其足以使得实际产生的导水裂隙带4被可伸缩的柔性套管31覆盖，进而使得导水裂隙带4范围内的地层无论是在何方向上发生错动，可伸缩的柔性套管31均能够随着与其连接的井壁一起运动，从而不会 发生断裂。即本发明可防止因煤层1上方的地层在各个方向上的错动而引起的固井套管3的断裂。例如，若地层发生上下(纵向)错动，则可伸缩的柔性套管31能够以伸缩的方式跟随地层运动。又例如，若地层1发生左右(横向)错动，则可伸缩的柔性套管31能够以弯曲的方式跟随地层运动。或者，同时发生上述两种方向的错动时，可伸缩的柔性套管31能够同时以伸缩或弯曲的方式跟随地层运动。综上，本发明进而避免了因固井套管3断裂而导致的井不能正常地使用，以及由此导致的地下气化效果的降低或者地下气化的失败。
具体地，进一步参照图1，在本实施例中，煤层1位于内蒙的煤田中，在本实施例中，在此处借助钻孔建立无井式煤炭地下气化炉进行煤炭地下气化生产煤气。
首先，对该煤层1进行勘探以获取该煤层1的基础地质信息。基础地质信息至少包括：该煤层1以上岩层的抗压强度、煤层倾角、煤分层层数。并且，对于倾角位于0°-54°的范围内的煤层(参见图1中的煤层)，基础地质信息还包括煤层的累计采厚，而对于倾角位于55°-85°的范围内的煤层(参见图2中的煤层)，基础地质信息还包括煤层厚度和采煤工作面小阶段垂高。勘探上述基础地质信息的方法为本领域技术人员公知的，故在此不再详细描述。通过上述勘探，如图1所示，煤层1的顶板岩石为泥质砂岩，再往上为粘土岩层、砂质含水层、页岩层，浅土层、地表等。泥质砂岩的抗压强度在25～35MPa之间。该煤层1为水平煤层(即该煤层的倾角为0°)，且该煤层1为单层煤层。其中，埋深350米，煤层1的厚度在7米。
然后，根据基础地质信息，计算此煤层1在气化后形成燃空区时，可能出现的导水裂隙带4的最大高度。上述计算参见表1。
表1导水裂隙带最大高度的经验公式
Figure PCTCN2015091874-appb-000001
Figure PCTCN2015091874-appb-000002
其中，1、此表1引自煤炭工业部制定的“矿井水文地质规程”(试行)。
2、M—累计采厚，m；n—煤分层层数；m—煤层厚度，m；h—工作面小阶段垂高，m。
3、导水裂隙带最大高度，对缓倾斜和倾斜煤层，系指从煤层顶面算起的法向高度；对于急倾斜煤层，系指从开采上限算起的垂向高度。
4、岩石抗压强度为饱和单轴极限强度。
根据所探勘的基础地质信息，按单层煤厚能够全部气化掉，即煤层1累计采厚为7米，煤分层层数为1，抗压强度在25～35MPa之间。根据上述数值，选择表1中相应的公式(下面所列公式)：
Figure PCTCN2015091874-appb-000003
由该公式计算得到导水裂隙带4的最大高度为103.7米。而考虑到地下气化是在煤层1中进行燃烧气化，燃烧区(即：采空区)温度较高，对采空区以上地层的热作用比井工开采时的要明显很多，会加速导水裂隙带4的发育。而又考虑到地下气化后灰渣和矸石滞留在地下空间起到一定的填充作用， 上述热作用与填充作用相抵消。故此时，可伸缩的柔性套管31的长度等于导水裂隙带的最大高度和设定深度H之和。当然，在其他可选的实施例中，根据该煤层的实际情况，可以考虑地下气化对煤层1以上岩层的热作用、灰渣和矸石滞留地下对采空区起到充填支撑顶板等因素，将可伸缩的柔性套管31的长度在等于导水裂隙带的最大高度和设定深度H之和的基础上，再最多增加15米的增量。即本发明的可伸缩的柔性套管31的长度，根据实际情况，可以等于导水裂隙带的最大高度和设定深度H之和，也可以大于导水裂隙带的最大高度和设定深度H之和并与这个和值的差值小于或等于15米。其中，“最多增加15米的增量”可理解为对于导水裂隙带的发育被加速后，导水裂隙带的高度在其最大高度的基础上的所增加的富裕量。
此外，设定深度H为可伸缩的柔性套管31的底端位于煤层中的深度。该设定深度H的数值，由本领域工作人员根据实际需要选取，以满足可伸缩的柔性套管31能够在煤层燃烧时对井壁起到足够的支撑作用即可。优选地，设定深度等于煤层厚度的1/5-1/3，本实施例的煤层厚度为7米，故设定深度位于7/5-7/3米的范围内。在本实施例中，选择设定深度H等于2米。
综上，在本实施例中，可伸缩的柔性套管31的长度等于导水裂隙带4的最大高度(103.7米)和设定深度H(2米)之和，即为105.7米。
在计算完可伸缩的柔性套管的长度后，根据该长度选择合适的可伸缩的柔性套管。其中，可伸缩的柔性套管可为波纹管、或由波纹管和柔性管彼此连接形成的。即，在可伸缩的柔性套管整体为波纹管的情况下，波纹管同时适应于煤层的纵向错动和横向错动；在可伸缩的柔性套管包括波纹管和柔性管的情况下，波纹管为柔性套管提供了可伸缩性以适应于煤层的纵向错动，而波纹管和柔性管同时适应于煤层的横向错动。当然，本发明不局限于此，可伸缩的柔性套管可由任何本领域技术人员公知的具有可伸缩性和可弯曲性的材料和结构构成。
在本实施例中，可伸缩的柔性套管31为波纹管，并且进一步该波纹管为金属波纹管，其抗压强度等于40MPa，耐热温度为350℃。当然，本发明不局限于此，波纹管还可以为复合材料波纹管，例如现有技术中由玻璃纤维、铝箔等多种材料复合而成的铝箔波纹管、或者钢带增强螺旋钢塑复合波纹管 等，而且波纹管的抗压强度还可以为大于或等于20MPa的范围中的除去40MPa的其他值，波纹管的耐热温度还可以为大于350℃的温度值。
可理解，任何能够起到固井作用并在周围地层发生各个方向错动时随之一起运动的可伸缩的柔性套管31，均能够在本发明中使用。优选地，该可伸缩的柔性套管31为波纹管，并进一步优选为金属波纹管或复合材料波纹管。可伸缩的柔性套管31抗压强度大于或等于20MPa，耐热温度大于或等于350℃。
至此，选定了可伸缩的柔性套管31。
此后，由地面向下钻井并钻至煤层中的设定深度H的下方。即，在本实施例中，由地面向下钻井，直至井底进入到煤层中2米处以下的部分。此步骤为井2的建立步骤，并且尚未完成井2的全部建立。
另外，在本实施例中所采用的固井套管3包括石油套管32和可伸缩的柔性套管31。将石油套管32和可伸缩的柔性套管31通过本领域技术人员公知的方式(例如焊接、丝扣连接、法兰盘连接等)连接在一起。具体地，参照图1中的定向，以地面指向煤层的方向为由上至下的方向，将固井套管3沿由上至下的方向放置，固井套管3具有相对设置的顶端和底端，石油套管32具有相对设置的顶端和底端，可伸缩的柔性套管31具有相对设置的顶端和底端，并且上述所有“顶端和底端”中，顶端位于底端的上方，即由顶端指向底端的方向为由上至下的方向。在本实施例中，在固井套管处于上述定位时，可伸缩的柔性套管31的顶端与石油套管32的底端连接，此时可伸缩的柔性套管31的底端即构成固井套管3的底端，石油套管32的顶端即构成固井套管3的顶端。
之后，执行如下固井套管设置步骤。
步骤1：向井2中下放固井套管3，直至固井套管3的底端(即可伸缩的柔性套管31的底端)进入煤层1中设定深度H后停止。即，固井套管3的底端(即可伸缩的柔性套管31的底端)的端面位于煤层1中设定深度H处。换言之，在本实施例中即为可伸缩的柔性套管31具有2米长的管段位于煤层1中。
步骤2：通过向井2和固井套管3之间缝隙注入固井材料进行固井，以 将固井套管3与井壁连接。在本实施例中，向井2中注入水泥浆(即固井材料)进行返浆固井，将固井套管3与井壁连接。可理解，在上述钻井的过程中，井钻至煤层1中设定深度H的下方，而在上述步骤1中将可伸缩的柔性套管31的底端下放至煤层1中设定深度H处，此时可伸缩的柔性套管31的底端距离井底有一段距离。使得在向井2中注入水泥浆时，水泥浆从固井套管3内部流过，直至流至井底，并由井壁和固井套管3的外周壁之间的环隙向上流动，当井壁和固井套管3的外周壁之间的环隙充满水泥浆后停止注入水泥浆。待水泥浆凝固后，其将固井套管3与井2的井壁固定连接。上述仅为返浆固井的简要描述，本实施例所使用的返浆固井的方法是本领域技术人员公知的，故不再进行详细的描述。当然，固井材料不局限于水泥浆，还可包括本领域技术人员公知的其他材料。并且，在其它可选的实施例中，也可通过其它固井方法进行固井，而不局限于上述返浆固井。
至此，固井套管设置步骤完成。
然后，继续对井2进行钻进直至其钻至煤层1中的预定位置，在本实施例中，预定位置为煤层1的底板。当然，本发明不局限于此，在其他可选的实施例中，预定位置根据实际需要确定。例如，该井2在全部建立完毕后，将其作为地下气化的进气井或出气井，故根据需要在煤层中设置的气化通道的位置，来确定进气井或出气井的井底的位置，进而确定井2的井底的位置。该井2的井底的位置即为上述“预定位置”。
至此，井2全部建立完成。
可理解，在本实施例中，固井套管设置步骤是在井2的建立过程中执行的，并且借助于井2的建立进行返浆固井。当然，在其他可选的实施例中，固井套管设置步骤可在井2全部建立完成后执行，并根据实际情况选择其他本领域技术人员公知的方法将固井套管3和井2的井壁连接。
可选地，在井2完全建立完毕后，进行洗井，和/或对位于可伸缩的柔性套管31以下的井壁进行简单支护。
综上，通过预先设定可伸缩的柔性套管31的底端伸入煤层1中的位置、以及根据导水裂隙带的最大高度与上述伸入煤层1中的位置来计算可伸缩的柔性套管31的长度，能够使得可伸缩的柔性套管31在连接于井壁后正好覆 盖可能发生地层错动的导水裂隙带范围。由此，保证了上述已经提及的有益效果。
参照图2，本发明的地下气化固井方法的第二个实施例。与上述图1所示出的实施例的相同之处不再赘述。
本实施例对宁夏的煤层进行气化。经过勘探，该煤层为急倾斜煤层1，该煤层1的倾角在60°～65°之间，煤层1埋深460米，煤层1夹杂三层薄夹矸，煤层1的厚度为12米。煤层1顶板岩层为砂质页岩，抗压强度为30Mpa左右(小于40Mpa)，顶板岩层再往上是含水泥岩、页岩、石灰岩、玄武岩、浅层黄土、地表。在地下气化过程中，含有薄夹矸的煤层1可以完全气化掉，含三层夹矸则将煤层1被分为4层，沿煤层1倾角方向布置地下气化通道时，气化采煤工作面小阶段垂高h可达26米。
综合以上地质信息，根据表1选取导水裂隙带4的最大高度的公式(为如下公式)：
Figure PCTCN2015091874-appb-000004
计算得到导水裂隙带4的最大高度为103.9米，考虑到地下气化是在煤层1中进行燃烧气化，燃烧区(即：采空区)温度较高，对采空区以上地层的热作用比井工开采时的要明显很多，会加速导水裂隙带4的发育，将可伸缩的柔性套管31的长度在等于导水裂隙带的最大高度和设定深度H之和的基础上，增加13米的增量。综上，在本实施例中，可伸缩的柔性套管31的长度为118.9米(导水裂隙带4的最大高度为103.9米、设定深度2米与增量13米之和)。
在可伸缩的柔性套管31的长度确定后，选择合适的可伸缩的柔性套管31。在本实施例中，可伸缩的柔性套管31为金属波纹管，其抗压强度等于40MPa，能承受350℃的温度。
应当指出，由于煤层是倾斜的，设定深度H的计算起点可选择与固井套管相连接的煤层上表面处的任意一点。换言之，由于固井套管相连接的煤层的上表面的最高点和最低点之间相差的距离不大，以二者中任意一点作为设定深度H的计算起点均不会影响本方法的实施和有益效果的实现。
由于本发明的固井套管中的可伸缩的柔性套管能够有效地跟随地层在各 个方向上的错动，故相对于现有技术，对具有一定倾斜角度(倾斜度大于0)的煤层具有更加显著的有益效果。
本发明另一方面还提供了一种井结构，其中，图1和图2同时分别示出了本发明的井结构的两个实施例。
图1所示出的井结构，包括：由地面通入煤层1的井2、以及连接于井2的井壁的固井套管3。其中，固井套管3包括可伸缩的柔性套管31，可伸缩的柔性套管31的底端位于煤层1中的设定深度H处，并且可伸缩的柔性套管31的长度大于或等于煤层1上方的导水裂隙带4的最大高度与设定深度H的和值。
由此，煤层1燃烧形成燃空区后，由于导水裂隙带中形成了导水断层，在导水断层中有地下水通过，造成该区域岩层稳定性下降，容易形成地层错动，由于可伸缩的柔性套管31的长度足以使得导水裂隙带4被可伸缩的柔性套管31覆盖，进而使得导水裂隙带4范围内的地层无论是在何方向上发生错动，可伸缩的柔性套管31均能够随着与其连接的井壁一起运动，从而不会发生断裂。即本发明可防止因煤层1上方的地层在各个方向上的错动而引起的固井套管3的断裂。例如，若地层发生上下(纵向)错动，则可伸缩的柔性套管31能够以伸缩的方式跟随地层运动。又例如，若地层发生左右(横向)错动，则可伸缩的柔性套管31能够以弯曲的方式跟随地层运动。或者，同时发生上述两种方向的错动时，可伸缩的柔性套管31能够同时以伸缩或弯曲的方式跟随地层运动。综上，本发明进而避免了因固井套管3断裂而导致的井不能正常地使用，以及由此导致的地下气化效果的降低或者地下气化的失败。
具体地，在本实施例中，固井套管3还包括石油套管32。石油套管32的底端与可伸缩的柔性套管31的顶端连接。可伸缩的柔性套管31的长度等于导水裂隙带4的最大高度与设定深度的和值。其中，设定深度H等于2米。可伸缩的柔性套管31的长度等于导水裂隙带4的最大高度(103.7米)和设定深度H(2米)之和，即为105.7米。可伸缩的柔性套管31为金属波纹管，抗压强度等于40MPa，耐热温度为350℃。在本实施例中，上述有关井2、固井套管(包括可伸缩的柔性套管、石油套管以及它们的连接方式)和井2与固井套管3的连接方式的特征以及其他未记述的有关井2和固井套管的特 征与在上述基于图1所描述的地下气化固井方法中所记载的特征一致，故不再赘述。
参照图2，本发明的井结构的另一个实施例，
图2所示出的井结构，包括由地面通入煤层1的井2、以及连接于井2的井壁的固井套管3。其中，固井套管3包括可伸缩的柔性套管31，可伸缩的柔性套管31的底端位于煤层1中的设定深度H处，并且可伸缩的柔性套管31的长度大于或等于煤层1上方的导水裂隙带4的最大高度与设定深度H的和值。
具体地，在本实施例中，固井套管3还包括石油套管32。石油套管32的底端与可伸缩的柔性套管31的顶端连接。可伸缩的柔性套管31的长度等于导水裂隙带4的最大高度与设定深度的和值。其中，设定深度H等于2米。可伸缩的柔性套管31的长度等于导水裂隙带4的最大高度(103.9米)、设定深度H(2米)与增量13米之和，即为105.7米。可伸缩的柔性套管31为金属波纹管，抗压强度等于40MPa，耐热温度为350℃。在本实施例中，上述有关井2、固井套管(包括可伸缩的柔性套管、石油套管以及它们的连接方式)和井2与固井套管3的连接方式的特征以及其他未记述的有关井2和固井套管的特征与在上述基于图2所描述的地下气化固井方法中所记载的特征一致，故不再赘述。
当然，不局限于上述两个实施例，在上述两个实施例的基础上，可伸缩的柔性套管的底端还可连接有其他套管，以实现所需的对井壁的支护要求。
在本发明的地下气化固井方法和井结构中的固井套管，不局限于上述描述，还可选地仅由可伸缩的柔性套管构成。
此外，上述仅描述了煤层倾角在0°-54°范围内或在55°-85°范围内的情况，当煤层倾角在54°-55°范围内时，可以分别按照在0°-54°范围内和在55°-85°范围内选择公式计算导水裂隙带的最大高度，然后采用二者中计算结果较大的作为该煤层的导水裂隙带的最大高度。
以上仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围 之内。

Claims (11)

  1. 一种地下气化固井方法，其特征在于，
    在由地面通入煤层(1)的井(2)的构建过程中、或构建完毕后，执行如下固井套管设置步骤：
    向所述井(2)中下放固井套管(3)，直至所述固井套管(3)的底端进入所述煤层(1)设定深度(H)后停止，并将所述固井套管(3)与所述井(2)的井壁连接；
    其中，所述固井套管(3)至少包括可伸缩的柔性套管(31)，所述可伸缩的柔性套管(31)的底端构成所述固井套管(3)的底端，并且所述可伸缩的柔性套管(31)的长度大于或等于所述煤层(1)上方的导水裂隙带(4)的最大高度(Hf)与所述设定深度(H)的和值。
  2. 根据权利要求1所述的地下气化固井方法，其特征在于，
    在执行所述固井套管设置步骤之前，由地面向下钻井并钻至所述设定深度(H)的下方；
    在所述固井套管设置步骤中：通过向所述井(2)和固井套管(3)之间缝隙注入固井材料进行固井，以将所述固井套管(3)与所述井壁连接；
    继续对所述井(2)进行钻进直至其钻至所述煤层(1)中的预定位置。
  3. 根据权利要求1所述的地下气化固井方法，其特征在于，
    所述固井套管(3)还包括石油套管(32)，所述可伸缩的柔性套管(31)的顶端与石油套管(32)的底端连接。
  4. 根据权利要求1所述的地下气化固井方法，其特征在于，
    所述可伸缩的柔性套管(31)的长度大于所述导水裂隙带(4)的最大高度(Hf)与所述设定深度(H)的和值，并与所述和值的差值小于或等于15米。
  5. 根据权利要求1-4中任一项所述的地下气化固井方法，其特征在于，
    所述设定深度(H)等于煤层厚度的1/5-1/3。
  6. 根据权利要求1-4中任一项所述的地下气化固井方法，其特征在于，
    所述可伸缩的柔性套管(31)为波纹管。
  7. 根据权利要求6所述的地下气化固井方法，其特征在于，
    所述波纹管具有如下任一或任意组合特征：
    a、所述波纹管为金属波纹管或复合材料波纹管；
    b、所述波纹管的抗压强度大于或等于20MPa；
    c、所述波纹管为耐热温度为350℃以上。
  8. 根据权利要求1-4中任一项所述的地下气化固井方法，其特征在于，
    所述煤层(1)的倾角位于0°-54°或55°-85°的范围内。
  9. 一种井结构，包括：
    由地面通入煤层(1)的井(2)、以及连接于所述井(2)的井壁的固井套管(3)；
    其特征在于，
    所述固井套管(3)包括可伸缩的柔性套管(31)，所述可伸缩的柔性套管(31)的底端位于所述煤层(1)中的设定深度(H)处，并且所述可伸缩的柔性套管(31)的长度大于或等于所述煤层(1)上方的导水裂隙带(4)的最大高度(Hf)与所述设定深度(H)的和值。
  10. 根据权利要求9所述的井结构，其特征在于，
    所述固井套管(3)还包括石油套管(32)；
    所述石油套管(32)的底端与所述可伸缩的柔性套管(31)的顶端连接。
  11. 根据权利要求9或10所述的井结构，其特征在于，
    所述可伸缩的柔性套管(31)的长度大于所述导水裂隙带(4)的最大高度(Hf)与所述设定深度(H)的和值，并与所述和值的差值小于或等于15米。
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CN104563874B (zh) * 2014-12-24 2017-03-01 新奥科技发展有限公司 地下气化固井方法、井结构
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1122619A (zh) * 1993-05-03 1996-05-15 德里弗莱克斯公司 加固井的预制件或胎膜管状结构
CN101158272A (zh) * 2007-11-07 2008-04-09 无锡浩安科技发展有限公司 油井剪切式套管防断伸缩管
CN102536135A (zh) * 2010-11-30 2012-07-04 韦特柯格雷公司 波纹管型可调节套管
RU2462576C1 (ru) * 2011-04-12 2012-09-27 Открытое акционерное общество "Татнефть" имени В.Д. Шашина Устройство для удлинения обсадных колонн в скважине
CN104563874A (zh) * 2014-12-24 2015-04-29 新奥气化采煤有限公司 地下气化固井方法、井结构

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101832105A (zh) * 2010-04-28 2010-09-15 李孝勇 超短半径径向水平井的钻井、固井方法及其设备
CN102465693A (zh) * 2010-10-29 2012-05-23 乌兰察布新奥气化采煤技术有限公司 一种煤炭地下气化钻孔井身结构及其构造方法
CN102425394A (zh) * 2011-09-12 2012-04-25 联合石油天然气投资有限公司 一种低压油藏侧钻井固井完井工艺
CN202659194U (zh) * 2012-06-15 2013-01-09 潍坊市宇宏石油机械有限公司 一种新型套管与波纹管组合的井壁修复装置
CN103147716B (zh) * 2013-03-08 2016-06-22 中煤科工集团重庆研究院有限公司 采动区煤层气地面井局部固井方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1122619A (zh) * 1993-05-03 1996-05-15 德里弗莱克斯公司 加固井的预制件或胎膜管状结构
CN101158272A (zh) * 2007-11-07 2008-04-09 无锡浩安科技发展有限公司 油井剪切式套管防断伸缩管
CN102536135A (zh) * 2010-11-30 2012-07-04 韦特柯格雷公司 波纹管型可调节套管
RU2462576C1 (ru) * 2011-04-12 2012-09-27 Открытое акционерное общество "Татнефть" имени В.Д. Шашина Устройство для удлинения обсадных колонн в скважине
CN104563874A (zh) * 2014-12-24 2015-04-29 新奥气化采煤有限公司 地下气化固井方法、井结构

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