| Title | The experimental study on hydraulic fracture propagation in dry hot rock |
|---|---|
| Authors | Baoping Zhang, Zuo Chen, Shihua Liu, Jian Zhou |
| Year | 2023 |
| Conference | World Geothermal Congress |
| Keywords | dry hot rock, hydraulic fracturing, stress difference, fluid viscosity |
| Abstract | As the increase of the demand towards energy as well as the requirement of green energy, we are doing pilot development project of HDR in Qinghai plateau. Up to now several HDR wells have been drilled and hydraulically fractured to increase heat exchange volume between injection and production wells. Among the wells, some interconnected well through the fracture system, but the others interconnection was poor. To understand fracture extension in HDR, a series experiments were done in the laboratory with polyaxial loading system. During the tests cubic granite samples were taken from outcrops in the plateau and gradually heated to 180℃ before actual testing. In the tests, we investigated the effects of stress difference, pumping rate, fluid viscosity, rock texture and natural fractures on the hydraulic fracture propagation. It turns out that stress difference is the dominate element in fracture extension orientation and natural fractures and rock textures do affect fracture extension path when stress difference is minor. In addition, high pumping rate and fluid viscosity would result in the increase of fracture initiation pressure. Low temperature fracturing fluid injection such as fluid nitrogen on fracture complexity need more study. |