Abstract:

Structural traps in Subei basin consist mainly of faulted noses and blocks. According to their origin or having resulted from extension and wrench movements, the structural traps in the basin can be divided into four types,including: typeⅠ,group of faulted noses and blocks that occur in the sag and on its slope one; typeⅡ,faulted blocks developed on both sides of major faults; type Ⅲ, faulted noses and blocks developed on the shearing and transforming position of major faults;and type Ⅳ, complicated faulted blocks that occur between fault-terrace belts. By analyzing the genetic types of structural traps and characteristics of oil sources and pathways of oil migration and accumulation, the reservoiring patterns can be divided into three major types and six subtypes,,i.e (1) primary and secondary reservoirs (subtype a and b) formed mainly typeⅠtraps;(2) subtypes c,d and e reservoirs formed in typeⅡand type Ⅲ traps and migrated either through faults or reservoir rocks;(3) subtype f reservoirs formed in type Ⅳtraps.Presently,the gas and oil reservoirs found in Gaoyou and Jinhu sags in Subei basin are mainly of subtype a and b, which distributed on the slope areas of the sags;secondly are subtype c reservoirs that distributed on both sides of major faults.Besides,there are also some subtype f reservoirs developed within the fault terrace belt in Gaoyou sag.

Key words: structural traps, reservoiring patterns, faulted noses and blocks, Subei basin