辽中凹陷JZ20-A构造油气成藏特征

Characteristics of hydrocarbon accumulation in JZ20-A structure in Liaozhong Sag

李建平 郭永华 周东红

Li Jianping Guo Yonghua Zhou Donghong

辽中凹陷分布有4套烃源岩,东营组二段下亚段、东营组三段、沙河街组一段与沙河街组三段,除东营组二段下亚段多处于未-低熟阶段外均为有效烃源岩。辽中凹陷北洼 和自身的沙河街组三段烃源岩为JZ20-A油气田的主要供油区和油气来源。沙河街组三段烃源岩生烃潜力大,有机质丰度和成熟度较高。通过JZ20-A井主要产层段的包裹体分析,确定了JZ20-A油气田的油气成藏期次,建立了JZ20-A油气田的油气成藏模式。研究结果表明,包裹体均一温度分布于120~140 ℃。油气的主要充注期在距今5 Ma以来明化镇组沉积末期,在东营组沉积时期(约27 Ma)也有少量的油气充注。JZ20-A各油气藏充注程度高,包裹体值(含油流体包裹体丰度指标)均大于5%。油气成藏表现为接力供烃,高压泥岩双重封堵,油气叠层式成藏的特征。

The lower 2 member and 3 member of the Dongying Formation, the 1 and 3 member of the Shahejie Formation are four source rocks in Liaozhong Sag.The latter three are active source rocks,but the lower 2 member of the Dongying Formation is immature to lowly mature.The 3 member of the Shahejie Formation in the northern subsag of the Liaozhong Sag is the main source rocks for the JZ20-A oilfield.The source rocks in the 3 member of the Shahejie Formation are of high organic content and maturity,thus have great potential for hydrocarbon generation.By analyzing the inclusion of the major pay zones in the well JZ20-A,we performed the timing of the hydrocarbon generation and established the hydrocarbon accumulation model in the JZ20-A oilfield.The results indicate that the homogenization temperature of the inclusion is 120-140 ℃. The hydrocarbon charging mainly occurred at 5 Ma ago when the Minghuazhen Formtion was deposited.Hydrocarbon charging also happened at 27 Ma ago when the Dongying Formation deposited.All the reservoirs of JZ20-A oilfield are high in hydrocarbon abundance.The value of the inclusion is above 5%.The characteristics of the hydrocarbon accumulation are relay-type multiple stage hydrocarbon charging,over-pressured shale sealing on both sides and oil/gas accumulation in superimposed multiple layers.

10.11743/ogg20120203