Orderly coexistence and accumulation models of conventional and unconventional hydrocarbons in Lower Permian Fengcheng Formation, Mahu sag, Junggar Basin

ZHI Dongming,TANG Yong,HE Wenjun,GUO Xuguang,ZHENG Menglin,HUANG Liliang

Table 2 Key elements of accumulation models of different resource types in the Fengcheng Formation, Mahu sag, Junggar Basin.

Accumulation model Source- storage relationship Petroleum types Reservoir lithology Reservoir space Migration characteristics Accumulation dynamics Phase state Facies types Typical well Integrated source-reservoir Interbedded structure Shale oil Dolomitic, mudstone, dolomite Micro-fracture, interlayer fracture, micro-nano pore No migration Pressure difference diffusion Adsorption state Semi-deep- deep lake MY1 Thin interbedded layers, with single layer thickness smaller than 1 m Dolomitic, argillaceous siltstone, tuffite Micro-fracture, interlayer fracture, micro-nano pore Primary migration+ self-generation Pressure difference diffusion Free state, adsorption state Shore-shallow lake-semi- deep lake, fan delta front Source-reservoir in close contact Thick interbedded layers, with single layer thickness larger than 1m Tight oil Dolomitic, argillaceous, tuffaceous siltstone-fine sandstone Micro-fracture, matrix pore Primary migration+ self-generation Pressure difference diffusion buoyancy Free state, adsorption state Fan delta front, fan delta external front MH28, MH26 Lateral contact Dolomitic, tuffaceous sandstone Matrix pore, micro-fracture Secondary migration Pressure difference Free state Fan delta internal front MH33 Separated Source-reservoir No contact Conventional oil Sandy- conglomerate, volcanic rock Matrix pore, micro-fracture Secondary migration Buoyancy Free state Alluvial fan, fan delta plain BQ1, X72