Enhanced heat extraction from hot-dry-rock geothermal reservoirs due to interacting secondary thermal cracks. Final report

Technical Report · Sun Apr 01 00:00:00 EST 1979

DOI:https://doi.org/10.2172/5913105· OSTI ID:5913105

Hsu, Y C

How the fluid circulating through the main hydraulic fracture and the thermally-induced secondary, growing, interacting cracks affects the time-varying temperature, deformations, stresses, thermal crack geometry, water flow rates through the main and thermal cracks, reservoir coolant outlet temperature, and reservoir thermal power of the cracked geothermal reservoir is investigated. First, a simplified version of the proposed hot-dry-rock reservoir is considered. A closed-form solution of the rock temperature without thermal crack was found and substituted into SAP-IV computer code to calculate the stresses. These stresses being superposed with earth stresses and fluid pressure were used in conjunction with the fracture mechanics criterion to determine the initiation of secondary thermal crack. After the initiation of secondary thermal crack, the rock temperature was then calculated by a two-dimensional heat conduction program AYER. The detailed procedures for carrying out these steps are listed. Solutions developed are applied to studying the time-varying temperature field, thermal stresses and crack geometry produced, and additional heat power generated in the reservoir. Conclusions were discussed and summarized. (MHR)

• Research Organization: New Mexico Univ., Albuquerque (USA). Dept. of Mechanical Engineering
• OSTI ID: 5913105
• Report Number(s): NMEI-27
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
HOT-DRY-ROCK SYSTEMS
HEAT EXTRACTION
A CODES
COMPUTER CODES
CRACKS
DEFORMATION
FLOW RATE
GEOMETRY
HYDRAULIC FRACTURING
STRESSES
THERMAL STRESSES
COMMINUTION
FRACTURING
GEOTHERMAL SYSTEMS
MATHEMATICS
Geothermal Legacy
150906* - Geothermal Engineering- Reservoir Stimulation & Extraction Technology