An Overview of in-situ Development Technology of Oil Shale with Near and Sub-critical Water

Abstract

Abstract With unconventional oil and gas reservoirs gradually becoming the global oil and gas hotspot resources, the development and research of unconventional reservoirs has also been paid more and more attention by researchers. Among them, oil shale has enormous reserves in the world and plays an important role in unconventional resources. The development of oil shale can be divided into surface distillation and in-situ development. The purpose of this paper is to systematically summarize and evaluate the application of critical water in the development of oil shale. This paper also tries to find out whether there is more study on its application in order to realize industrial production of oil shale by critical water extraction. At present, researchers in China have done a lot of researches about near and sub-critical water development on oil shale, especially teachers and graduates of Jilin University. In the past two decades, researchers have made rapid progress in extracting organic matter from oil shale by using sub-critical water and near critical water. Sub-critical water refers to water whose temperature is lower than 374 °C and pressure is between 14 and 22.1 MPa, while near-critical water refers to water whose temperature is between 150 and 374 °C while the pressure is between 0.4 and 22.1 MPa. Water in these two states has superior mass transfer performance, acid-base catalytic function and lower dielectric constant than normal water. Of course, the biggest advantages of sub-critical water and near-critical water are non-toxic and inexpensive, which is of great significance to environmental protection in the process of oil shale development. In order to study the feasibility of in-situ extraction of shale oil from near-critical water and sub-critical water for field application, a comprehensive survey was conducted.