Hydrocarbon accumulation in the upper submember of the 4th member of the Shahejie Formation in the Gubei depression, Zhanhua, Shandong

The Gubei depression lies in the eastern part of the Zhanhua region, Shandong, where two oil-gas plays are recognized for the upper submember of the 4th member of the Shahejie Formation in the Gubei depression in the light of the examination of the source rocks, reservoir rocks and cap rocks and hydrocarbon accumulation. Furthermore, three models for hydrocarbon accumulation are contructed, including the endogenetic lateral accumulation and migration, endogenetic vertical accumulation and migration, and mixed types of accumulation and migration models. The key factors for hydrocarbon accumulation include the structural traps, unconformities and faults. Under the abnormally high pressures, the hydrocarbons may migrate along the faults and unconformities, and constitute the stereoscopic networks together with the skeletal sandstones,which cause the steep slopes, low uplifts and ramps to be favourable for the hydrocarbon accumulation and migration.