Reservoir Studies Of The Cambrian Loushanguan Group In The Jinshayankong Area Of The South Sichuan Basin

The large-scale dolomite developed by the Cambrian Loushanguan Group in the southern Sichuan Basin is one of the most important reservoirs in the region,and it has certain exploration potential.This paper takes the Jinshayankong area as the basic research object,and the Cambrian Loushanguan Group as the research target layer.Based on the detailed sampling work and data collation indoor,and through X-ray diffraction,trace elements and other analytical testing methods,the following understanding is obtained:?1?In the study area,the Loushanguan group has a strong mixed effect.It is a restricted platform On the whole.It can classify 5 sedimentary subfacies.including tidal flat,lagoon,plate,bars in platform and the edge of the tidal flat.The first section of the Loushanguan Group is dominated by the tidal flat subfacies,and the second section is dominated by the bars and the lagoon subfacies.?2?The total thickness of the Cambrian Loushanguan Group is close to 1 km in the jinshayankong area.The rock types are dominated by granular dolomite and crystalline dolomite.The types of reservoir space are mainly intergranular dissolved pores and intercrystalline dissolved pores,followed by cracks and karst caves.The porosity distribution is 0.61%¹0.82%,and the average porosity is 3.04%.the permeability is 0.01⁹.26×10^-3?m²,and the average permeability is 1.06×10^-3?m².It shows the characteristics of low porosity and low permeability.?3?The diagenesis of the reservoir of the Loushanguan group is mainly composed of cementation filling,compaction,dolomitization,dissolution,rupture and recrystallization.Cementation filling is the most important diagenesis that causes the reservoir properties to deteriorate.It experienced the dissolution and burial corrosion in the quasi-synchronous period.It is analyzed by geochemical means that there are at least three different types of dolomitization fluids,which correspond to shallow burial period,deep burial period and uplift burial period.The dolomite formed by the precipitation of dolomitized fluids with different properties under different diagenetic environments shows completely different cathodoluminescence characteristics and trace element distribution characteristics.?4?According to the comprehensive analysis,the sedimentary facies,reservoir diagenesis and tectonic movement jointly control the development of the Dolomite reservoirs of the Cambrian Loushanguan Group.The sedimentary facies belt distribution is the foundation,and the high-energy phase zone particle beach is the most favorable part of the primary pore development.Diagenesis is the key,and complex late diagenetic alterations control the evolution of reservoir pores.The tectonic movement constitutes a good diagenetic fluid migration channel,which can promote the later dissolution.