Controlling Factors for Reservoirs Distribution of the Putaohua Oil Layer in the Saozhao Sag

Types of found reservoirs and its distribution characteristics of Putaohua oil layer in the Sanzhao Sag were analyzed. The controlling factors of hydrocarbon distribution were investigated. Sanzhao Sag is Sag-wide oil-bearing, but its distribution of oil and water is extremely complicated. The reservoir types are mainly fault block reservoirs, low amplitude structure reservoirs, fault-lithologic reservoirs and lithologic reservoirs. The distribution of reservoirs is mainly controlled by three geological factors: first, long-term inherited nose-like structure is predominant direction of petroleum migration; it induced oil and gas migration at a critical period of hydrocarbon accumulation and formed oil-gas accumulation area. Second, fault across main-line of hydrocarbon migration and high angle skew plug off hydrocarbon, and its side adjacent to Sag is a large number of hydrocarbon accumulation areas. Third, multi-fault region can easily form a fault (-lithological) reservoir accumulation area in the slope of sag.