Introduction
China’s dependence on foreign crude oil exceeds 70%,posing significant challenges to national energy security. How‐ever, traditional, easily discoverable conventional oil explora‐tion targets are increasingly scarce. As an important strategicreplacement resource, shale oil plays an indispensable role insafeguarding national energy security and has gradually be‐come a hotspot in the oil and gas exploration sector. In recentyears, a significant amount of exploration practices has notedthat the enrichment of shale oil is closely related to the micromigration of hydrocarbons, in addition to the effect of originalin-situ retention (Jarvie, 2012). The micro-migration of shaleoil primarily refers to the short-distance migration of liquid hy‐drocarbons between formations with varying hydrocarbon gen‐eration and accumulation capacities. It is a phenomenon of hy‐drocarbon differential enrichment within the microcosmicsource-reservoir coupling context of the shale system (Hu etal., 2024). Micro-migration reflects the entire process of oilgeneration, expulsion, and accumulation, influencing the multilayer oil-bearing and locally enriched characteristics withinshales. Studying the micro-migration of shale oil is critical fordeepening the understanding of differential enrichment mecha‐nisms in petroleum and promoting the prediction of “sweetspots” in shale reservoirs.Scholars have conducted a substantial amount of researchon the micro-migration within shale systems. For example, Ra‐ji et al. (2015) identified the Kimmeridge shale in the SouthernViking Graben of the North Sea as a mixed shale system con‐taining sand-siltstone bands based on geological and geochemi‐cal analyses. The phenomenon of oil and gas migration and ac‐cumulation at the meter scale within the sandy bands was ob‐served. Hackley et al. (2020) conducted a study on the Wolf‐camp A shale in the Midland Basin using organic petrology,mineralogy, and micro-Fourier transform infrared spectroscopy(μ -FTIR), confirming that the oil within the fine-grained car‐bonate interbeds originated from adjacent silica-rich or calcare‐ous shales with strong hydrocarbon generation potential. Therecurrent meter-scale lithofacies cycles promoted vertical com‐positional differentiation of the oil components. In the study ofthe organic-rich shale from the Qing 1 Member in the Chan‐gling depression, Songliao Basin, meanwhile, Liu et al. (2021)clarified that the organic-rich laminated shale had good hydro‐carbon generation capability. The generated oil underwentmicro-migration to the sandy laminations, where it accumulat‐ed in place. As a result, the light components of the shale oilwithin the sandy laminations were up to 2.65 times higher thanthe heavy components, indicating good fluidity. In general, pre‐vious studies have made substantial progress in understandingthe channels, driving forces, and identification of hydrocarboncomponents involved in the micro-migration of shale oil. Theyhave also preliminarily elucidated that short-distance interlayermigration is a key factor controlling the differences in oilbearing property and mobility in different types of shale. How‐ever, there are still many challenges in revealing the micromigration mechanism of shale oil, especially in tracing micromigration, and quantitatively evaluating the volume of migrat‐ing hydrocarbons and their impact on the enrichment of shaleoil. This perspective aims at providing a systematic review ofmethods for tracing the micro-migration of shale oil, and focus‐ing on issues such as shale oil micro-migrated effects, the influ‐ence of migrated hydrocarbons on the oil-bearing property andshale oil mobility. By doing so, it is hoped to provide new in‐sights into the dynamic differential enrichment of lacustrineshale oil.
Paper Information：
Shang Xu, Jie Wen, Qiyang Gou, Qiqi Li, Bingchang Liu. Research Progress and Significance of Shale Oil Micro-Migration. Journal of Earth Science, 2024. https://doi.org/10.1007/s12583-024-0071-7
