A study on paleogeography of the Early Devonian and potential of hydrocarbon resources in Yanyuan-Ninglang area, southwest of China

In order to explore the potential of oil and gas resources in areas west of the Kangdian Earth'axis, a comprehensive study of the Early Devonian black shale in Yanyuan-Ninglang region is carried out by combining the regional geological survey work with drilling and testing data. The results indicates that:(1) The early Devonian paleogeography of Yanyuan-Ninglang area is mainly controlled by the Kangdian Paleo-land and the activities of the Paleo-Tethys tectonic domain. Littoral tidal flat facies developed in the area close to the Jinhe-Qinghe fault, restricted bay facies appeared in the local area surrounded by the Paleo-uplift and platform, while continental shelf and basin facies developed in the northwest area far from the uplift.(2)In the late early Devonian,the Daguaping Formation developed the black shale, which is relatively stable in distribution and thick (20m to 100m) in the Yangpaixi-Yankou area and generally contains calcium, high contents of organic carbon and brittle minerals and with a moderate thermal evolution. It is an important source rock and favorable shale gas horizon.(3)Black shale develops in a restricted bay environment, and places such as Yangpaixi, Yankou, Maopingzi, are the most favorable areas in the Yanyuan-Ninglang region.