Dissolution in He 8 Sandstones, Sulige Gasfield, Ordos Basin: Origin, Distribution, and Effect on Reservoir Properties

摘要

Dissolution plays a dominant controlling role on reservoir properties in delta sandstone of the Permian He 8 Formation, Sulige gasfield. Dissolution forms intergranular dissolved pore and intragranular dissolved pore. Areas with high percentages of dissolved pores occur along delta-plain distributary channel and delta-front underwater distributary channel deposits. Due to dissolution, the porosity increased to 10-17% with permeability as high as 10md. Wells drilled through He 8 sandstones have high daily gas production of 4～6×10~4m~3/d.