东濮凹陷胡古2气藏成藏条件分析

Forming condition analysis of Hugu 2 gas reservoir in Dongpu Depression

 李继东 许书堂 杨玉娥 柯明文 赵强

 中国石化中原油田分公司勘探开发研究院，河南 郑州 450000

 Research Institute of Exploration and Development, Zhongyuan Oilfield Company, SINOPEC, Zhengzhou 450000, China

 文中在胡古2气藏油气成因识别的基础上，分析了气藏成藏条件，建立了油气成藏模式，指出了有利的勘探方向。研究认为，胡古2气藏油气主要来自上古生界煤系源岩，是自生自储煤成气藏。其自身煤系烃源岩处于生烃高峰期内，为气藏提供了充足的资源保证；上古生界石千峰组及石盒子组储层发育，储层物性较好，有效储层较厚，为气藏提供了有效的储集空间；石千峰组上段、中生界底部及上石盒子组上段泥岩稳定发育，为气藏提供了良好的盖层条件；该气藏圈闭类型为反向断块圈闭，形成于沙三上沉积前，西倾反向断层起到了很好的封堵作用，后期发育的石家集断层及长垣断层没有对圈闭形成破坏。该区油气大规模运移期在东营期，构造与油气的生成运移具有较好的时空配置关系，油气也得到了很好的保存。上古生界烃源岩镜质体反射率大于1.5%的区域是寻找上古生界自生自储油气藏的有利区带，该区带中具有一定构造背景的洼中隆起是有利的钻探目标。

 On the basis of recognizing hydrocarbon genesis of Hugu 2 gas reservoir, this paper has analyzed the reservoir forming conditions, built up an accumulation model and pointed out favorable exploration direction. The study shows that Hugu 2 is a self-generated and self-stored coal bed gas reservoir from upper Paleozoic coal-bearing source rock which is at hydrocarbon generation peak and provides abundant resource for gas reservoir. Shiqianfeng Formation and Shihezi Formation of upper Paleozoic developed well with good physical property. Thick effective reservoir provides effective reservoir space for gas accumulation. Upper Shiqianfeng Formation, bottom Mesozoic and upper interval of upper Shihezi Formation developed stable mudstone, which forms good cap rock for gas. Trap type of the gas reservoir is antithetic fault block trap, formed before upper Es3 sedimentation. West dipping antithetic fault works well as plugging. Shijiaji Fault and Changyuan Fault developing during later period caused no destroy to the trap. Mass migration of hydrocarbon occurred in Dongying stage. Structure has good spatial-temporal relationship with generation and migration of hydrocarbon which is accordingly preserved as well. The area with Ro of upper Paleozoic source rock greater than 1.5% is the favorable zone for seeking self-generated and self-stored reservoir and the uplift with certain tectonic setting in this zone is the profitable target for drilling.

10.6056/dkyqt201504009