Studies On The Fluid Inclusions In Shitouzhai Paleo-oil Reservoirs Guizhou

It is clear that a very significant oil and gas evidence in the region of southwest Guizhou,and has good prospects for oil and gas exploration.This paper,systematically studies the forming conditions,dating of hudrocarbon emplacement in the GuiZhou shitouzhai ancient reservoirs by means of fluid inclusion.Its results showed that:(1)The fluid inclusions of the target paleo-oil reservoir vary in the size and shape. Among the inclusions type of the reservoirs,aqueous inclusions,liquid-vapor aqueous inclusions,CH₄ inclusions and CH₄-H₂O inclusions occupy first place,liquid hudrocarbon inclusions come second.(2)Shitouzhai reefs of ancient limestone reservoir,gas-liquid water inclusions homogenization temperature varies mainly from 90 to 160℃.Salinity generally below 5 wt NaCl%,pressure is between 42×10⁵ and 235×10⁵.According to microscopic laser Raman spectroscopy analytic results,the composition of the ancient reservoir hydrocarbon inclusions is maining CH₄.(3)The calcite,formed by dissolved pore and fracture filling in the permian reef paleo-oil reservoirs,was divided into three epochs:In the first epoch,(the homogenous temperature varies from 77 to 84℃)it is dominated by aqueous inclusions and liquid-vapor aqueous inclusions,appears organic inclusions accidentally;in the second epoch,(the homogenous temperature varies from 91 to 103℃)it mainly contains liquid phase C₂H₆ inclusions,and next gas phase CH₄ inclusions,bitumen inclusions and liquid-vapor aqueous inclusions;in the third epoch, (the homogenous temperature varies from 117 to 155℃)it contains a lot of gas phase organic inclusions(with about 93%-96%CH₄ and 4%-7%CO₂).As the temperature increases,maturity of organic matter increased,and the components of inclusions from liquid hydrocarbon mainly to the gaseous hydrocarbons gradually.There are thre epochs hydrocarbon infilling,itd times were 235～237.5 Ma,230～232.5 Ma and 227.5～185 Ma.respectively The Sm-Nd isotopic age of the third epoch calcite is 182(21)Ma,in accord with the above results.