东濮凹陷桥口地区油气藏形成期次研究

Research on formation stages of hydrocarbon reservoirs in Qiaokou area of Dongpu sag

东濮凹陷桥口构造不同区块第三系油气藏形成期差异较大 ,总体上层位越新成藏时期越晚 ,层位越老成藏时期越早。应用储集层自生伊利石测年、饱和压力及流体包裹体均一温度等方法 ,综合分析认为 ,桥口地区油气藏形成主要分为两大阶段 :第一阶段距今时间约 18.4～ 3 0 .4Ma ,相当于东营组沉积期末—馆陶组沉积早期 ,是最主要的油气藏形成期 ,其中距今 17～ 2 7Ma为剥蚀期 ,压力减小有利于天然气成藏 ,气藏的绝大部分形成于该阶段 ;第二阶段为距今 2Ma以来 ,相当于第四纪至现今 ,已形成的气藏发生调整 ,同时二次生成的天然气继续注入。

On the basis of applying K Ar dating of illite, saturation pressure and homogenization temperatures of fluid inclusion, formation stages of hydrocarbon reservoirs in Qiaokou area are studied. The result shows that there are three main formation stages of hydrocarbon reservoirs in Qiaokou area. The first stage is about 30.4 18.4Ma, which is corresponding to sedimentary period of Dongying Formation-Lower Guantao Formation, which is the main formation time of hydrocarbon reservoirs . In the second stage, the great majority of formation ages of hydrocarbon reservoirs distributes in the denudation period from 27Ma to17Ma. The pressure decrease in the denudation period is helpful to formation of hydrocarbon reservoirs. In the third stage, formation time of gas reservoirs is from 2Ma to now, corresponding to Quaternary to now. On one hand, the gas reservoirs formed in the first stage is adjusted; on the other hand, it is second formation process of natural gas reservoirs. Formation time of hydrocarbon reservoirs is different in different tectonic units of Qiaokou structure. In general, characteristics of the formation time is as follows: the newer of layer, the later of formation time; the older of layer, the earlier of the formation time.