东濮凹陷柳屯环洼深层油气藏成藏条件分析

ANALYZING THE CONDITIONS OF FORMING DEEP-SEATED OIL/GAS RESERVOIRS AROUND LIUTUN SAG IN DONGPU DEPRESSION

柳屯洼陷是东濮凹陷的第二大生油洼陷 ,洼陷的西侧、东侧分别是西部断阶带和中央隆起带主力油气区。 2 0 0 0年以来 ,H96等 4口探井均获得突破 ,发现了H96断块区沙三段高温高压凝析油气藏。该区油气藏与东濮凹陷主体常温常压油气区相比 ,是一套相对独立的高温高压成藏封闭体系 ,油气藏特点为 :高温、高压、低密度、低粘度 ,明显不同于相邻的断阶带和隆起带。该油气藏纵向发育的沙三2 盐岩和侧向发育的沙三4 盐岩与断裂的有机配合组成该区沙三段高压封闭系统。异常高压形成期、异常高孔隙发育期和烃源岩油气生成期三者有机配合 ,是该区形成高温高压油气富集区的重要条件。

Liutun Sag is the second-largest source sag in Dongpu Depression.The west fault bench zone and central uplift zone are on the west and east of this sag respectively and they are the major oil-and gas-bearing areas.Since 2000,four exploration wells,such as well H96,etc,have been successful and the Es 3 high temperature and high pressure condensate reservoir has been found out at H96 fault block.As compared with the principal normal temperature and normal pressure oil/gas reservoirs in Dongpu Depression,the condensate reservoir is located in a relatively independent sealing reservoiring system and is possessed of these characters as high temperature,high pressure,low density and low viscosity,which is obviously different from the reservoirs in the neighboring fault bench zone and uplift zone.The formation of the Es 3 high pressure sealing system at H96 fault block resulted from a reasonable matching of the vertically developing Es 3 2 salt layers and laterally developing Es 3 4 salt layers with the faults.A perfect coordination of the three,as abnormal high pressure forming period,abnormal high pore developing period and hydrocarbon generating period was the important condition of forming oil/gas enrichment area with high temperature and high pressure at the fault block.