Abstract:

Yancheng Sag is a continental fault-sag situated in Subei-South Yellow Sea Basin.The sag continuously subsided and developed steady,this laid foundation for the deep pool formation;the Funing and Taizhou Formations possessed fovourable hydrocarbon generation abilily,the second member dense sandstone reservoir of the Taizhou Formation was characterized by low porosity and permeability,both of them provided necessary condition for the pool formation.Yancheng natural gas pools have the tendency of gas and water upsidedown,and are characterized by alternate low abnormal pressure and hydrostatic pressure,long well section and low gas production rate.The gas is mainly methane derived from pyrolysis of humic organic matter.The deep faults and fractures act as the passages.The most favourable areas are Nanyang and Xinyang subsags.

Key words: deep basin gas pool, gas-water upside down, dense reservoir, deep fracture, Yancheng Sag