Reservoir properties and control factors of Permian sands in Sulige gas field,Ordos Basin

Reservoir characteristics of P2h8(the 8th member of Shihezi formation) and P1s1(the 1st member of Shanxi formation) in the Permian system of Sulige gas field,Ordos Basin,have been synthetically studied by using thin section analysis,casting,mercury penetration and SEM etc.The result shows that the reservoir space of P2h8 and P1s1 sandstones in Sulige gas field is primarily secondary pore,then primary pore;the pyroclastics formed during volcanic event mixed in fluvial sandy sediments and provided material basis for later dissolution;the composition and texture of the sandstone were controlled by sedimentary environment.Comprehensive analysis indicates that compaction is the major cause of porosity reduction;cementation has double action on reservoir stimulation;dissolution has greatly improved sandstone porosity and is the key factor of forming high porosity and high permeability reservoir.