惠民凹陷南坡曲古1井煤成气藏研究

RESEARCH ON WELL QUGU-1 COALFORMED GAS RESERVOIR IN THE SOUTH SLOPE OF HUIMIN SAG

我国渤海湾盆地惠民凹陷南坡在曲古 1井沙二段砂层中发现了工业天然气藏。由于本区构造演化史非常复杂 ,对于该气藏的形成时期及其成藏过程有不同认识。文章通过曲古 1井天然气组成、稳定碳同位素、流体包裹体等分析结果 ,结合二次生气中心、构造发育史、断裂活动等研究成果 ,对曲古 1井天然气成因、来源及成藏过程进行了详细研究。初步认为该井天然气来源于东部二次生气中心石炭—二叠系煤层 ,在东营运动时期聚集成藏 ,主要运移通道是曲堤断裂。该气藏仅有一期成藏过程 ,东营运动之后曲堤断裂活动趋于停滞 ,气源补充枯竭 ,而气藏本身由于扩散等作用而规模不断变小。

A commercial gas reservoir was found out by we ll Qugu-1 in E s 2 sand in the south slope of Huimin Sag in Bohaiwan Basi n in China.There are some different ideas about the gas reservoir formation peri od and process,because the tectonic evolution history in this region is very com plicated.According to the analysis results of the composition and stable carbon isotope of natural gas collected from well Qugu-1 and the fluid inclusions and in combination with the achievements of studying secondary gas generation center ,tectonic evolution history and fault activity,etc.,the genesis,source and accum ulation process of the natural gas of well Qugu-1 are investigated in detail in the paper.It is primarily considered that the gas in the well came from the eas tern secondary gas generation center of Carboniferous-Permian coal measures;Qu ti fault was its major migration channel;and the gas reservoir was formed during Dongying Age only with one reservoir formation process.After Dongying Movement, the activity of Quti fault was trending toward being stagnated,thus causing gas source's being exhausted,and the range of the gas reservoir was uninterruptedly contracting because of diffusion loss,etc.