Numerical simulation of electricity generation potential from fractured granite reservoir through a single horizontal well at Yangbajing geothermal field

Abstract

Development of deep high-temperature heat reservoir at Yangbajing geothermal field has very important significance for capacity expanding and sustaining of the ground power plant. The geological exploration found that there is a fractured granite heat reservoir with an average temperature of 248 °C at depth of 950∼1350 m in well ZK4001 in the north of the geothermal field. In this work, a simplified conceptual model of the 950∼1350 m reservoir is established based on all the existing geological data, and the electricity generation potential from this fractured granite reservoir by geothermal water mining through a single horizontal well is numerically simulated. The results indicate that the single horizontal well system attains an electric power of 3.23∼3.48 MW and an energy efficiency of about 50.00∼17.16 during 20 years under reference conditions. The main parameters that affect the heat extraction and electricity generation are reservoir porosity, permeability and water production rate. Higher porosity or higher permeability or higher water production rate will be favorable for improving the electricity generation performance, under the precondition of not arousing vaporization and precipitation in the liquid water saturated reservoir.