Abstract: Based on the regional structure evolvement and formation character, it is recognized that low dip and small break faults and high shale/stratum value exist in J_2x-K_1q in Wellblock SX11 in Shixi area, which are the mainly geological reasons resulting in close of the faults by developed shale daubing layers of J_2x-K_1q and restricting the hydrocarbon accumulation in SX11 well by migration of the lower oil-gas into higher positions (K_1q) along the conductive faults. Also, such a close may control the migration of the lower oil-gas into K_1q trap at the same wall in SX6 well. The research of fault closure formed by the shale daubing effect can help the researches of oil-gas exploration in studied area and similar areas.

Key words: Shixi oil field, fault clay, shale daubing, replacement pressure, shale/stratum value, oil conducting fault