Numerical simulation of influence of reservoir characteristics on heating process of enhanced geothermal system of horizontal well multi fractures

Abstract

The horizontal well multi-fracture development technology, which is well-developed in the oil and gas industry, can significantly improve the economics of enhanced geothermal systems (EGS). In this paper, a three-dimensional horizontal-well multi-fracture physical model is established for EGS. The performances of EGS under different reservoir characteristics of well spacing and fracture spacing are analyzed by CFX simulation, and the influence mechanism of different reservoir characteristics on the heat recovery process of the EGS reservoir is revealed. The results show that: ①The fracture spacing is the key factor affecting the operating life and mining rate of EGS engineering. Under the same water injection flow, the larger the fracture spacing, the smaller the possibility of forming thermal permeability, the longer the system operation life, but the lower the reservoir recovery rate. The smaller the fracture spacing, the higher the thermal permeability, the shorter the system life, and the higher the reservoir recovery.②The well spacing has a significant effect on the fluid velocity in the fracture. As the well spacing increases, the temperature of the flow-producing fluid increases continuously during the same mining time, and the life of the system also increases. The increase in well spacing also means that the reservoir volume becomes large, so there is more geothermal energy for exploitation and longer life for the system for operating. The research can provide theoretical guidance for the construction of EGS reservoirs and provide theoretical preparation for the commercial exploitation of geothermal energy.

Keywords

• reservoir characteristics
• enhanced geothermal system
• horizontal well
• numerical simulation
• fracture
• heating process