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CN-121993137-A - L-shaped enhanced geothermal exploitation system

CN121993137ACN 121993137 ACN121993137 ACN 121993137ACN-121993137-A

Abstract

The invention relates to the field of geothermal exploitation, in particular to an L-shaped enhanced geothermal exploitation system. The geothermal energy exploitation system mainly solves the problem that the running flow and the heat extraction efficiency are low due to the influence of the size of a buried pipe and the heat resistance of cement and a sleeve. The L-shaped enhanced geothermal exploitation system comprises a water injection well (10), wherein a sand prevention screen (17) of the water injection well is arranged at the lower end of the water injection well (10), the depth of the sand prevention screen (17) of the water injection well is located in a fracture stratum (8), the L-shaped enhanced geothermal exploitation system further comprises a water production well (9), the water production well (9) comprises a well cementation section, an open hole annular section (5) and a horizontal well section, the open hole annular section (5) is located in the fracture stratum (8), and the horizontal well section is located in a high-temperature dry-hot rock reservoir (6). The L-shaped enhanced geothermal exploitation system is not influenced by the size of a buried pipe and the heat resistance of cement and a sleeve, improves the running flow and the heat extraction efficiency, and provides an economically feasible route for the development of geothermal resources of dry hot rock.

Inventors

  • WANG LI
  • YANG YI
  • ZOU CHANGYUN
  • TIAN YULU
  • NIU ZONGTAO
  • Tao Xuejian
  • HAN XIANGZHE
  • ZHENG XIAOQING
  • ZHANG ZHENHUA
  • SONG TAO
  • CHEN SHAOYUN
  • MA XIAOWEI
  • YU CHENGLONG
  • BAI XIAOJIE

Assignees

  • 大庆钻探工程有限公司
  • 中国石油天然气集团有限公司

Dates

Publication Date
20260508
Application Date
20241031

Claims (10)

  1. 1. The L-shaped enhanced geothermal exploitation system comprises a water injection well (10) and is characterized in that a sand prevention screen (17) of the water injection well is arranged at the lower end of the water injection well (10), the depth of the sand prevention screen (17) of the water injection well is located in a fracture stratum (8), the L-shaped enhanced geothermal exploitation system further comprises a water production well (9), the water production well (9) comprises a well cementation section, an open hole annular section (5) and a horizontal well section, the open hole annular section (5) is located in the fracture stratum (8), and the horizontal well section is located in a high-temperature dry-hot rock reservoir (6).
  2. 2. The L-shaped enhanced geothermal exploitation system according to claim 1, wherein the wellhead of the water injection well (10) is connected with a water injection pump (14), the water injection pump (14) is connected with a water collecting device (16), and the water collecting device (16) is internally provided with water at low temperature.
  3. 3. An L-enhanced geothermal exploitation system according to claim 1, wherein the wellhead of the well (9) is connected to a heat exchange means (13).
  4. 4. The L-shaped enhanced geothermal exploitation system according to claim 3, wherein a cyclone sand remover (11) and a filter (12) are arranged between the water extraction well (9) and the heat exchange device (13).
  5. 5. An enhanced L-geothermal exploitation system according to claim 3, wherein the heat exchanger (13) is connected to the water collector (16) by a pipeline.
  6. 6. The L-shaped enhanced geothermal exploitation system according to claim 1, wherein the straight well section of the water producing well (9) is provided with a well cementing tool (3), the well cementing tool (3) is positioned at the upper part of the fracture stratum (8), and a packer (4) is arranged at the lower part of the well cementing tool (3).
  7. 7. The L-shaped enhanced geothermal exploitation system according to claim 6 is characterized in that a heat preservation sleeve (1) is arranged inside the water production well (9), well cementation cement (2) is arranged outside the heat preservation sleeve (1) above the well cementation tool (3), and a sand prevention screen pipe (7) is connected to the heat preservation sleeve (1) at the end part of the horizontal section.
  8. 8. An L-enhanced geothermal exploitation system according to claim 1, wherein the fracture formation (8) is a natural fracture formation or an artificial fracture formation.
  9. 9. The L-type enhanced geothermal exploitation system according to any one of claims 1 to 8, wherein the low-temperature water in the water collecting device (16) is injected into the fractured stratum (8) from the water injection well (10) through the water injection pump (14), the low-temperature water is recharged to the open hole annulus (5) of the water production well (9) through the fracture, enters the horizontal well section along the annulus of the water production well (9), becomes high-temperature water after being heated by the high Wen Ganre rock reservoir (6), and enters the thermal insulation sleeve (1) through the sand control screen (7) and is upwards exploited out of the wellhead.
  10. 10. The L-shaped enhanced geothermal exploitation system according to claim 9, wherein the high-temperature water at the well head is subjected to heat exchange through a heat exchange device (13), becomes low-temperature water, and is recharged through the water injection well (10) after being treated.

Description

L-shaped enhanced geothermal exploitation system Technical Field The invention relates to the field of geothermal exploitation, in particular to an L-shaped enhanced geothermal exploitation system. Background Geothermal drilling technology is still the only means of geothermal resource exploration and development at present, geothermal wells are divided into single well systems and multi-well systems according to the number of wellbores, and open-loop systems and closed-loop systems according to whether heat exchange fluid in the wellbores enters into stratum. The most widely used technology at present is to adopt and irrigate the well, namely the open loop system of multi-well, its advantage lies in getting the thermal efficiency high, with low costs, the disadvantage lies in only being applicable to the geothermal resource of water fever type, the common buried depth is shallower, the exit temperature is lower. The multi-well closed-loop system is represented by a U-shaped well geothermal development technology, has the advantages of 'no water from heat extraction', and has the disadvantages of complex construction process and high cost. The single well closed loop system is a system with relatively lowest construction cost in all geothermal wells, but the lower heat extraction efficiency restricts the development scale of the system, and in order to solve the problem, an L-shaped geothermal well technology is formed, namely, a horizontal branch is added to the bottom of a well on the basis of the original single well closed circulation, a horizontal well is drilled, a well is cased into a well, a well is cemented and completed, an insulating inner pipe is put into the well, an annular space is filled, the inner pipe is adopted, the length and the area of a long horizontal section are increased, the reinforced heat exchange of the horizontal section is enhanced, the reciprocating circulation high-efficiency heat extraction is realized, and compared with the straight well closed type, the length of the horizontal section is increased to prolong the heat exchange well section, but the L-shaped geothermal well technology is limited by the size of a buried pipe and the heat-insulating effect of cement and the casing, and the running flow and the heat extraction efficiency are lower. Disclosure of Invention In order to overcome the defect that the running flow and the heat extraction efficiency are low due to the influence of the size of a buried pipe and the heat-resistant effect of cement and a sleeve in the conventional geothermal exploitation system, the invention provides an L-shaped enhanced geothermal exploitation system, which is not influenced by the size of the buried pipe and the heat-resistant effect of cement and the sleeve, improves the running flow and the heat extraction efficiency and provides an economic and feasible route for the development of geothermal resources of dry hot rock. The L-shaped enhanced geothermal exploitation system comprises a water injection well, wherein the lower end of the water injection well is provided with a water injection well sand prevention screen, the depth of the water injection well sand prevention screen is positioned in a fracture stratum, and the L-shaped enhanced geothermal exploitation system further comprises a water production well, wherein the water production well comprises a well cementation section, an open hole annular section and a horizontal well section, the open hole annular section is positioned in the fracture stratum, and the horizontal well section is positioned in a high-temperature dry-hot rock reservoir. Further, the wellhead of the water injection well is connected with a water injection pump, the water injection pump is connected with a water collecting device, and the water collecting device is internally provided with warm water. Furthermore, the wellhead of the water extraction well is connected with a heat exchange device. Furthermore, a rotational flow sand remover and a filter are arranged between the water collecting well and the heat exchange device. Further, the heat exchange device is connected with the water collecting device through a pipeline. Furthermore, a well cementing tool is arranged at the straight well section of the water production well, the well cementing tool is positioned at the upper part of a fracture stratum, and a packer is arranged at the lower part of the well cementing tool. Further, the inside of the water collecting well is provided with a heat-insulating sleeve, well cementation cement is arranged outside the heat-insulating sleeve above the well cementation tool, and a sand prevention screen pipe is connected to the heat-insulating sleeve at the end part of the horizontal section. Further, the fracture formation is a natural fracture formation or an artificial fracture formation. Further, low-temperature water in the water collecting device is injected into a crack stratum from a water injection w