川东北元坝地区须家河组第三段天然气富集主控因素

Main controlling factors of natural gas accumulation in the third member of Xujiahe Formation in Yuanba area,northeast Sichuan Basin,China

通过对川东北元坝地区上三叠统须家河组第三段石油地质特征、天然气成藏条件的综合研究,探讨了天然气富集主要控制因素。基于2000余件次分析测试资料、43口井岩性录井资料以及700余张岩石薄片、14口井岩心观测、9口井成像测井等资料,对须家河组第三段的气源条件、砂体展布、储层特征以及天然气藏的保存条件进行分析,明确了优质烃源岩、源储叠置、“甜点”储层及良好的保存条件是控制天然气富集的主要因素。认为优质烃源岩是天然气富集的基础、多套砂砾岩储层与烃源岩垂向叠置利于天然气近源成藏、“甜点”储层是天然气富集的关键、良好的保存条件是天然气成藏的保障。

Based on more than 2000 analytical test data,43 lithologic logging data,700 rock thin sections observations,14 core observations and 9 imaging logging data,combined with the comprehensive study of petroleum geological characteristics and gas accumulation conditions,the gas source conditions,sand body distribution,reservoir characteristics and preservation conditions of the third member of Xujiahe Formation in Yuanba area,northeast Sichuan Basin are analyzed.The research results lead to the recognition that the main factors controlling natural gas enrichment in the third member of Xujiahe Formation are high quality source rock,source-reservoir superposition,“sweet spot”reservoir and good preservation conditions.Of the controlling factors,the high quality source rock is the basis of natural gas accumulation,the vertical superposition of multiple sets of glutenite reservoir and source rock is beneficial to near source gas accumulation,the“sweet spot”reservoir is the key to natural gas accumulation,and good preservation conditions are the guarantee of natural gas accumulation.