Formation Mechanism and Heterogeneity Evaluation of Lacustrine Shale Reservoirs

In the process of conventional oil and gas exploration in the past, organic shale is usually regarded as the source rock, but its role as the reservoir is ignored. It is generally believed that hydrocarbon expulsion and migration occur after organic shale reaches the threshold of hydrocarbon generation, and hydrocarbon accumulation occurs in the overlying sandstone or conglomerate reservoir with good physical properties. With the update of shale oil and gas exploration theory in recent ten years, more and more studies have shown that after organic shale hydrocarbon generation and expulsion, there are still a large number of hydrocarbon retention or near-source rock and accumulation with short-distance migration, and the exploration potential is huge, and it is an important replacement field for global oil and gas exploration. Different from marine organic-rich shales, it is difficult to define the formation mechanism of shale reservoirs because of the complex tectonic background of the provenance area in terrestrial sedimentary basins and the frequent changes of paleohydrology controlled by paleoclimate conditions, thus the heterogeneity is strong. The specific manifestations are as follows: (1) The mineral assemblages of different terrestrial lacustrine basins differ greatly, leading to the formation of different types of shale reservoirs, including fracture type, pure shale type, carbonate type, tuff type, etc., and the pore structure is diverse; (2) Different sedimentary dynamic processes and rapid sedimentary facies change lead to strong heterogeneity in the spatial and temporal distribution of the reservoir, and the source-reservoir marching relationship of oil and gas accumulation is complex.

Dynamic evaluation of shale oil and gas enrichment "sweet spots" through macro to nano-scale characterization techniques is a hot research field supporting global shale oil and gas exploration and development. This topic aims to introduce the lithofacies, diagenetic evolution, formation mechanism and main controlling factors of shale oil and gas reservoir quality in different terrestrial sedimentary basins, and their effects on shale oil and gas enrichment.

We invite researchers to contribute their new work, which will be extended to explore as many aspects as possible in the evaluation of unconventional reservoirs. Potential topics include but are not limited to the following:
• New technological advances for lithofacies identification and characterization;
• Diagenesis between oil/gas, water, and shale;
• Formation mechanism and controlling factors of shale reservoir;
• Heterogeneity evaluation of shale reservoirs;
• Effect of minerals and lithology or lithofacies on shale oil and gas enrichment.