Performance analysis of pinnate horizontal well in enhanced geothermal system

The well layout is crucial for improving the utilization of hot dry rock geothermal resources. In present work, a three-dimensional enhanced geothermal system (EGS) with pinnate horizontal well is proposed. Furthermore, the effect of pinnate horizontal well structure on the heat extraction performance of present EGS is numerically investigated. For scCO2-based EGS and water-based EGS, the stable heat extraction state and a competitive heat production can be obtained by present EGS. Compared with the conventional EGS with doublet system, the production temperature and the total heat production of EGS with pinnate horizontal well increase by 21.54 K and 21.4 %, respectively. The heat extraction performance of EGS with pinnate horizontal well is positively correlated with the main well bore number and length. In comparison, the branch well structure and number have less effect on the heat extraction performance. Consequently, main wellbore number with 3 or main wellbore length with 300 m can be taken as criterion for the design of the main wellbore. Besides, the branch well with staggered pattern, inclination angel of 60 degrees and the number of 4, is proved to be the optimum arrangement.

Automated summary

In this study, a three-dimensional enhanced geothermal system (EGS) with pinnate horizontal well structure is proposed to improve the heat extraction performance. Numerical investigations show that the production temperature and total heat production of EGS with pinnate horizontal well increase significantly compared to conventional EGS with a doublet system. Design parameters such as main well bore number and length are positively correlated with heat extraction performance.