临清坳陷东部断裂系统与上古生界煤成气成藏

Fault system and accumulation of Upper Palaeozoic coal-derived gas in eastern Linqing depression

为提高临清坳陷东部的油气勘探效率,以构造解析理论和含油气系统理论为指导,采用定量和定性相结合的方法分析了研究区断裂特征、发育演化,并结合油气成藏要素和成藏条件分析了其对上古生界煤成气成藏的影响。结果表明:平面上断层按走向可分为NE向(或NNE向)和NW向(或近EW向)两组;包括正断层和逆断层两种类型,正断层自基底到盖层中均有发育,而逆断层仅发育在侏罗系以下的地层当中,具有基底卷入的特征;断裂活动时期断裂可作为运移通道,对于油气的垂向运移和调整起着控制作用;剧烈的构造活动形成了多种与断层相关的构造类圈闭,圈闭形成时间与油气生成时期匹配良好;综合成藏条件的研究结果认为临清坳陷东部上古生界煤成气主要存在4种成藏模式。临清坳陷东部断层具有多期发育的特征,并控制着上古生界煤成气成藏,勘探重点为新生代断陷区,以晚期成藏为主要勘探类型。

In order to improve the oil-gas exploration efficiency of eastern Linqing depression,this paper,on the basis of theories of tectonic analysis and petroleum system,analyzed the fault characteristics and developing evolution in the use of quantitative and qualitative methods,and studied the influence of oil-gas accumulation elements and conditions on the coal-derived gas accumulation of Upper Palaeozoic.The results show that： according to the strike,the faults can be divided into two groups,namely strike NE（or NNE） and NW（or EW）;there are two kinds of fault,namely normal faults and reverse faults;normal faults develop in the place from basement to cap rock,while reverse faults only develop in the stratum under the Jurassic,and have the characteristics of basement involved;active faults become the migrating pathway of oil-gas,and played an important role in controlling oil-gas migration and adjustment in the vertical direction.Because of strong tectonic movements in the history,many tectonic traps related to the faults had been formed.The time of trap formation matched well with the hydrocarbon generation stage.By the comprehensive analysis of accumulation conditions,four coal-derived gas accumulation models have been presented in eastern Lingqing depression.The faults are characterized by multi-phase development,and control the accumulation of Upper Palaeozoic coal-derived gas in eastern Linqing depression.The exploration of coal-derived gas should focus on the Cenozoic fault depression,and regard the late period accumulation as the main exploration reservoir type.