Influencing parameters of recharge efficiency and well types optimization in middle-deep sandstone geothermal reservoir

ABSTRACTRecharge efficiency is of importance to ensure the sustainable utilization of geothermal resources. However, there are still challenges for reinjection work of porous sandstone in North China. The present work aims at optimizing reinjection parameters and well types based on the high recharge efficiency, and it was studied by establishing a numerical model of geothermal production-reinjection and designing an indoor reinjection experiment. It is observed that the effects of skin coefficient, daily reinjection amount, well diameter, well inclination angle, and water layer thickness ratio on the recharge efficiency are decreased in turn. In order to ensure the high efficiency of reinjection work, the mode of two reinjectors and one producer should be selected, preferentially considering around 60° directional well or horizontal well. The skin coefficient should be controlled about 1, the well diameter is greater than 81/2 in, the daily reinjection amount is greater than 2320 m3, and the water layer thickness ratio is about 1:3. The present results can provide helpful references for optimal selection of reinjection parameters and well types of Sandstone Geothermal Reservoir.KEYWORDS: Sandstone geothermal reservoirrecharge efficiencyinfluencing parametersreinjection wellskin coefficient Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was jointly supported by the Study on the mechanism and protection technology of sand erosion from middle and shallow geothermal wellbore, Changzhou Social Development Fund [CE20205053], the State key Research and development program: Unconsolidated sandstone thermal reservoir protection and efficiency drilling and completion technology and materials [2019YFB1504201].Notes on contributorsYixin ZhangYixin Zhang, is a master's degree from Changzhou University. The main research direction is geothermal resources development.Song DengSong Deng, is a professor at Changzhou University. His research interests are geothermal resources development, oil and gas well engineering.Dingkun LingDingkun Ling, is a master's degree from Changzhou University. The main research direction is geothermal resources development.Lei WangLei Wang, received his Ph. D. degree from China University of Petroleum (Being). Currently he works at Sinopec Research Institute of Petroleum Engineering, Beijing. The main research direction is geothermal energy development.Haoping PengHaoping Peng, is a professor at Changzhou University. His research interests are geothermal resources development, oil and gas well engineering.Huijun ZhaoHuijun Zhao, is a professor at Changzhou University. His research interests are geothermal resources development, oil and gas well engineering.Nianyong ZhouNianyong Zhou, is an associate professor at Changzhou University. His research interests are geothermal resources development, oil and gas well engineering.Yun LeiYun Lei, is an associate professor at Changzhou University. His research interests are geothermal resources development, oil and gas well engineering.Meng CuiMeng Cui, received his Ph. D. degree from China University of Petroleum (Being). Currently he works at CNPC Engineering Technology Research and Development Company Limited, Beijing. The main research direction is geothermal well engineering.