Lacustrine Shale Oil in China & Differential enrichment mechanism of organic matter under reduction conditions in freshwater and saline lakes

Séminaire de Dr Xinping Liang de l’Institut pour l’Energie de l’Université Pekin

Lacustrine shale oil in China

Abstract

This article presents the latest state of exploration and development of continental shale oil in the main basins of China, summarizes its main theoretical considerations and key technologies for exploration and development, analyzes its main challenges in theory and technology, and suggests prospects for exploration and development of continental shale oil in China. It is believed that shale oil of medium and high maturity is a key area for the breakthrough of production in China, this will play an important role in China’s stable oil production in the future. The efficient development of medium and low maturity shale oil resources can be significantly improved and lead to serious changes in oil production only after new breakthroughs are made in the theory and technology of shale deposits. 

Keywords: continental shale oil; exploration and development; challenges and measures

Differential enrichment mechanism of organic matter under reduction conditions in freshwater and saline lakes

Abstract

There are different mechanisms of reduction water column for the formation and preservation of organic matter during the depositional period of the continental lake basin. Therefore, determining the nature of the water column and its influencing factors is the key factor for differential enrichment of organic matter. In this study, by analyzing the TOC, mineral types, iron speciation, elements and isotopes characteristics of typical freshwater and saline lake organic-rich shales, the water column of synsedimentary environment of different lake shale deposits was compared. Our results show that the organic-rich shale of the Chang 7 Member (Ch7) of Yanchang Formation in the Ordos Basin and the Lucaogou Formation (P2l) in the Jimsar Sag of Junggar Basin in freshwater-saline environments have an intensity of sulfate reduction (BSR) (SRI < 1.375), the shales of Fengcheng Formation (P2f) in saline lake of the Mahu Sag in Junggar Basin have strong BSR (SRI > 1.375). This indicates that in ferruginous conditions the organic matter consumed by BSR is lower than the preserved organic matter, resulting a higher TOC content; in euxinic conditions caused by excessive volcanic activity or the input of hydrothermal fluids, a large amount of organic matter was degraded and consumed, causing more iron oxides (and other iron-containing minerals) dissolve gradually to form pyrite, reducing the TOC content. This study not only enabled to understand the shale oil enrichment, but also proposed a better theoretical and practical model for hydrocarbon accumulation in shale formations, to guide future shale oil exploration efforts.

Keywords: organic-rich shale; ferruginous conditions; euxinic environment; differential enrichment of organic matter; freshwater and saline lakes