The Characteristics Of The Mineral Components And Its Controls On The Organic-rich Gas Shale

In this paper,the author take middle and upper Permian marine organic-rich shale as the research object.Combining the macro and micro method,analyzed the characteristics of the shale's organic geochemical&physical properties and mineral components.This paper discussed the features of the geochemical,physical properties,mineral components of organic-rich,high siliceous shale of the Permian Gufeng and Dalong Formation in Lower Yangtze Region.Analyzed the controls of the gas-bearing property in Organic-rich Shale.The facies of Permian strata of this study area was the deep-water basin and shallow shelf.Also in some parts of the study area was developed in platform marginal.During the research Deep water basin and continental basin are beneficial to the growth of dark siliceous shale.The Gufeng Formation and the Dalong Formation in this study area have high content of organic carbon(TOC).But TOC of the samples from different era have the obvious difference which average is 5%.The kerogen type of Dalong formation is mainly ?1 but Gufeng formation is mainly ?2.Gufeng formation and Dalong formation are generally in a mature or post-mature stage,among which Ro of Dalong formation is 0.66 to 0.72%,Gufeng formation Ro high thermal evolution degree is 0.77?2.67%.It's absolutely to know that Gufeng formation has a high thermal evolution degree.The permain strata of this study has the high brittleness mineral content and low porosity.the quartz content of Gufeng formation is 65%and Dalong formation is 38%,the porosity of Dalong formation is 3.30%and Dalong formation is 4.32%.According to the investigation data in Gufeng and Dalong formation,we can see that both of them have high abundance of organic matter,moderatily degree of thermal evolution which could form shale gas reservoir of hydrocarbon generation.The high brittleness mineral content in siliceous shale and micro-fractures develop benefit to the later fracture operation and exploitation of shale gas.In this paper by analyzing the data from isothermal adsorption experiment,we found that the total organic carbon content has a highly correlation coefficient which reached 0.98 with saturated adsorption gas shale content.Based on this,it's easy to know that the organic carbon content is one of the main control factors of containing gas of the shale.From the experiment solution,we know that when organic carbon content is more than 5%,the saturated adsorption gas concentration is usually more than 1.42 m3/t.The organic carbon content and quartz mineral content have a certain positive correlationship according to the experiment.It infers that the increase of quartz mineral of siliceous shale leads to the increase of saturated adsorption gas.But clay mineral can't be found an abvious correlationship with shale hydrocarbon content.So that the shale hydrocarbon content mainly controlled by the organic carbon content,porosity and different mineral content.The rare earth element geochemistry of the test data from samples in Chaohu and Jingxian shows that the Ce element performs a slightly negative abnormity which means the biogenic deposit.By using the microscopic,foraminifera and radiolarian fossils can be seen usually.The siliceous shale which is rich of organic matter in south of anhui formed mainly with the biogenic deposit,by the geochemical element test data and the microscopic petrology characteristics.The hot water sedimentary is also an influenced factor.The homology of the silicon and kerogen is an important factor to the high siliceous shale which is rich in organic matter.