Characteristics of Lower Paleozoic Black Shale Reservoir in Weixin District of Northern Yunnan Province

摘要

The North area of Yunnan Province is one of favorable target areas for prospecting shale gas of marine hydrocarbon reservoirs in South China, with the black rock series developed well at Lower Cambrian Niutitang Formation and Lower Silurain Longmaxi Formation. The black rock series can be classified into seven types of lithofacies, including black shale, siliceous shale, calcarleous shale, silty shale, carbonaceous shale, argillaceous siltstoue and carbonatite. The total content of organic carbon is 0.02% to 9.37%. The organic matter is overmature, with 2.05%～3.62% of Ro and dominated by type II-kerogen. The microporosity is dominated by the micropores, with pore size less than 10nm, secondly is foraminules with pore size ranging from 10nm to 100nm. The shale gas content is low overall, only 0.42 stere per ton average, and variety range is relatively large. Our research shows the content of plagioclase, carbonate and clay inflect the content of shale gas in the area of relieved synclines and less fault.