Prospects of power generation from the deep fractured geothermal reservoir using a novel vertical well system in the Yangbajing geothermal field, China

Abstract

Deep geological exploration via well ZK4001 indicated that there exist high-temperature fractured geothermal reservoirs at the depth of 950–1350 m in the Yangbajing geothermal field. The detected reservoir temperature reached approximately 248 °C, showing a huge production potential. In this work, a novel geothermal production system using vertical wells was designed to investigate the power generation potential from the deep fractured geothermal reservoir at this site. A large well field with multiple wells arranged in a five-spot configuration was proposed to maximize the commercial scale electricity generation. The optimal mass flow rate was 17 kg/s for the single geothermal production unit. And a total of 24 single units could be reached using 8 production wells and 8 injection wells. The results showed the production temperature within the range of 240–248 °C, only reduced by 3.3% in 30 years lifetime. The total installed capacity of the proposed geothermal power system reached 66.0 MW. The levelized cost of electricity (LCOE) was estimated at 15 $/MWh, which was significantly cheaper than the electricity price of Tibet in 2019. Furthermore, the operation of this power system could reduce greenhouse gas (GHG) emissions with the maximum value of 20.3 Mt by replacing the same installed capacity of fossil fuel plant over a 30-year production period. This work provides important references for the sustainable power generation and future capacity expansion in the Yangbajing geothermal field.