Study On Mechanism Of Shale Gas Reservoir In Niutitang Formation,Guizhou Province

With the development of society,people's demand for energy is more and more serious,fossil energy such as oil,coal and other resources are limited,the use of environmental pollution is more serious and non-renewable.Shale gas is a kind of unconventional oil and gas resources,which is rich in reserves in China.The shale of Guizhou Niutitang Formation is widely distributed,the thickness is high,the abundance of organic matter is high and the thermal maturity is good,which is the potential area of shale gas exploration and development The At present,there are few studies on the reservoir mechanism of shale gas in this area,which seriously restricts its exploration and development.Therefore,it is very important to study the shale gas reservoir mechanism of Niuotongtang Formation in Guizhou.In this paper,the black shale of the Cambrian Niututang Formation in Zunyi,Guizhou,northeastern China,and the northwest Guizhou Province were studied.The samples were collected on the basis of data collection and analysis.The samples were collected,and the samples were tested and analyzed.The characteristics of the black shale distribution,tectonic characteristics and sedimentary environment of the Niutitang Formation in the study area were summarized.The characteristics of the gas conditions and the characteristics of the reservoir space were studied systematically.Black shale preservation conditions and high nitrogen content.research shows:(1)Guizhou is well developed.According to the shale formation and tectonic characteristics,Guizhou Province is divided into five organic shale development areas.The thickness of the Niuyutang Formation and the thickness of the organic matter are controlled by the distribution.The sedimentary environment is transferred from the continental margin of the continental shelf to the continental deepwater sediments.From west to east,the overall sedimentary environment is shown as: shallow trough facies ? deep-water continental shelf facies ? slope facies ? basin facies.The tectonic unit is the Yangtze platform and the South China fold belt.(2)The organic matter abundance of the black shale in the study area is high,and the original organic carbon content is 3.28% ~7.5%,with an average of 4.97%.The organic carbon values in the study area and its adjacent areas were between 5.0% and 6.5%.Organic matter abundance is higher.The reflectivity(Ro)of black shale vitrinite in Niutitang Formation of Lower Cambrian is 0.692%~3.112%,The average is 2.072%,the thermal evolution degree is too high.In the Lower Cambrian Niutitang Formation of the study area,organic matter is derived from low-grade aquatic organisms such as algae.(3)The black shale of the Niuotongtang Formation in Guizhou is dominated by quartz and clay minerals.The secondary minerals are pyrite,dolomite,potassium,albite and calcite.Shale internal organic matter rich,organic matter porosity development of a large number of development of feldspar dissolution hole,calcite dissolved holes,pyrite intergranular pores,casting holes,intergranular pores,structural fissures and shrinkage cracks.The specific surface area and pore volume of shale are very large.The organic matter nanometer pore is the main contributor of the specific surface area and pore volume of shale pores.The isothermal adsorption line has the characteristics of type ? isothermal adsorption line,and the adsorption and desorption curves have H2-type lag Ring,there are a lot of shale inside the "ink bottle" type of pores.The porosity of the shale is poor,and the pore in the shale is dominated by micropores.(4)The black shale of the Niututang Formation in Guizhou has experienced the tectonic movement of Indosinian,Yanshan and Soochow at different periods,which has caused the shale reservoir to be destroyed and developed a lot of cracks.Through the analysis of the typical shale gas wells,it is found that the calcite filling cracks in the Niutitang Formation are generally developed,and the hydrothermal deposits and inclusions are analyzed.It is believed that the nitrogen may be related to the late magmatic hydrothermal activity.