Abstract:Underground in-situ conversion is an inevitable trend of industrialized development of oil shale， and the autothermic pyrolysis in-situ conversion process （ATS） is a compound and efficient heating method to realize underground in-situ conversion of oil shale. In order to investigate the influence of different high-temperature carrier gases in the preheating stage on the effect of autogenous thermal in-situ conversion of oil shale， this paper took the oil shale in Fuyu area of Jilin， China， as an example， and injected four high-temperature gases， namely， nitrogen， air， steam， and carbon dioxide， into the preheating stage to conduct numerical simulation analysis， and compared the differences in the final oil and gas yields and the energy recovery rates. Taking the high-temperature nitrogen injection group as the control group in the preheating stage， the results showed that the time needed to complete the extraction by injecting high-temperature air， steam and carbon dioxide was reduced by 22%， 39% and 12%， respectively， and the maximum energy recovery rate was increased by 55%， 86% and 23%， respectively， and the total oil production was reduced by 5%， increased by 18% and reduced by 11%. From the perspectives of mining completion time， energy recovery rate and total oil production， steam injection preheating had the best effect. Therefore， a comprehensive comparison showed that the autogenous thermal extraction method of steam injection preheating could effectively increase the oil production， reduce the time required for extraction， and improve the energy utilization rate.

Abstract:China has abundant oil shale which is a potential oil and gas resource and important strategic resource to ensure national energy security. In-situ exploitation is the development trend of the oil shale industry. Through a systematic data collection and investigation， the development process of oil shale in-situ exploitation technology is summarized. The main technical characteristics and development status of four kinds of heating technologies， including conduction heating， convection heating， radiation heating and reaction heating technologies， and five kinds of reservoir reconstruction technologies， including hydraulic fracturing， underground blasting， freezing wall， grouting curtain and gas injection barrier underground space sealing technologies， are further analyzed. According to the characteristics of China’s oil shale resources， three key technologies that must be broken through and adopted for the in-situ exploitation of oil shale are proposed. The first is the high-efficiency heating technology with multiple heating， high efficiency downhole heater and catalytic efficiency as the core. The second is the horizontal well steering drilling technology with rotary steering drilling and precise distance measurement guiding for dual well as the keys. And the third is the composite reservoir reconstruction technology with CO2 dry fracturing， acid fracturing and gas injection barrier underground space sealing technologies. It is hope that this work could provide some reference for the in-situ exploitation technology of oil shale in China.