Laboratory Simulation of Oil/gas Filling into Silurian Asphalt Sandstones and Its Impact on Reservoir Quality in Tazhong Area

Key words: 
• Tarim basin /
• Silurian /
• asphalt sandstone /
• reservoir property /
• simulation experiment

Abstract: Asphalt filling into pore of interparticle and matrix reduced pore space while decreased porosity and permeability during transformation of crude oil into asphalt in Silurian reservoir sandstone in Tazhong area. Impact on reservoir quality of oil/gas filling into reservoir of asphalt sandstones has been studied by means of laboratory simulation. Sandstone with fewer asphalt and lower porosity and permeability at early stage of oil/gas infilling is nonreservoir and oil/gas can not fill in. Sandstone, whose porosity and permeability could be increased at late stage of oil/gas filling when oil with lower viscosity filled into, was effective oil/gas reservoir when more and uniform asphalt filling as well as the low porosity and permeability at early stage of oil/gas infilling. Sandstone, with uniform asphalt filling as well as higher remained porosity at early stage of oil/gas infilling, whose porosity and permeability could be improved as oil with various viscosity filled into. Simulations under laboratory temperature indicate that physical property of crude oil is the key factor for influence of ability of oil/gas refilling into asphalt sandstones. Filling of oil with low viscosity is essential for oil accumulation in Silurian asphalt sandstones. 