Lithofacies paleogeographic characteristics of the Middle Cambrian Shayilike Formation, Tarim Basin, NW China

The Shayilike Formation is an important horizon in Cambrian oil and gas exploration in the Tarim Basin, where and the fine-scale delineation of sedimentary facies remains the key factor restricting the breakthrough of oil and gas exploration in this horizon. Based on a large number of core observations and petrography on 230 thin sections, this study has summarized 10 typical lithofacies assemblages in the study area and identified 4 typical seismic facies zone characteristics. Furthermore, the sedimentary facies types and distribution characteristics of the Shayilike Formation were analyzed. The results show that: (1) the Shayilike Formation of middle Cambrian age in the Tarim Basin consists of 6 sedimentary facies, including evaporative platform, limited platform, open platform, platform margin and slope-basin facies, which can be further divided into 7 subfacies and 15 microfacies. (2) Combined with stratigraphic thickness distribution and seismic data, the lithofacies paleogeography map of the Middle Cambrian Shayilike Formation was compiled, and the sedimentary facies model from carbonate platform to slope basin was established. Further study of the lithofacies paleogeography of the Shayilike Formation can clarify the relationship between evaporite cap rocks and intersalt dolomite reservoirs and provide theoretical support for further breakthroughs in the field of intersalt exploration.