Simulation of thermal breakthrough factors affecting carbonate geothermal-to-well systems

Abstract

Fractures play a pivotal role in carbonate thermal storage systems, serving as primary hydraulic conductivity channels that significantly influence thermal breakthrough times and heat extraction efficiency in geothermal-to-well systems. Their impact is critical for well placement and system life prediction. This paper focuses on a geothermal-to-well system within the carbonate reservoir of the Wumishan formation in the Rongcheng geothermal field, Xiong'an new area. It employs a combination of field tests and numerical simulations to determine the permeability of the reservoir and the evolution of fractures between wells. It also examines the influence of fracture width and roughness coefficient on the seepage and temperature fields under various injection scenarios and predicts thermal breakthrough times for production wells. The results show: Higher permeability is observed near well D16 compared to well D22 within the studied geothermal-to-well systems. Wider fractures between wells result in faster temperature decline in production wells. Lower injection flow rates lead to slower temperature reduction in injection wells. The use of roughness coefficients minimizes temperature variations in production wells. This study not only offers guidance for the development and utilization of the geothermal well system, but also contributes to a deeper understanding of the groundwater seepage and heat transfer process influenced by fractures.

Keywords

• geothermal recharge
• influencing factor
• thermal breakthrough
• seepage field
• temperature field