Numerical investigations on the performance analysis of multiple fracturing horizontal wells in enhanced geothermal system

Abstract

The development of geothermal energy through enhanced geothermal systems (EGS) often encounters challenges such as fluid short-circuiting, water loss, and insufficient connectivity. This study presents a time-dependent seepage and heat exchange model for the formation–wellbore–fluid system during the heat extraction process. Taking the Fenton Hill HDR project as a case study, this paper investigates the influence of formation characteristics, wellbore design, and injected fluid properties on heat transfer efficiency. Furthermore, a multi-well EGS utilizing multiple fracturing horizontal wells (MFHW) is proposed, and its production temperature is compared with two types of double-well EGS. The findings reveal that within the horizontal segment of the double-well EGS, an optimal output of 3.4 MW can be achieved at an injection rate of 30 kg/s. Additionally, the extraction temperature shows a positive correlation with factors such as heat production and electrical power generation. In the MFHW project, optimizing heat production potential can be accomplished by increasing the number of perforation fractures, enhancing artificial fracture spacing, improving the perforation angle, extending the horizontal segment, reducing well diameter, and employing a longer vertical heat insulation pipe with lower thermal conductivity. Finally, a comparative analysis of various development models indicates that two-injection-one-production multi-well EGS model exhibits superior performance, with its heat production being twice as efficient as that of one-injection-one-production double-well EGS model.