松辽盆地南部大情字井油田青二段低渗透储层成因

Genesis of Eq_2 Low Permeability Reservoir in Daqingzijing Oilfield in Southern Songliao Basin

低渗透储层是地层岩性油气藏最重要的特征之一,明确其成因是大情字井油田青二段油藏制定合理开发方案的依据之一。从沉积环境和成岩作用两方面对低渗透储层的形成进行了分析:大情字井油田青二段储层岩性为三角洲前缘沉积的粉细砂岩和粉砂岩,沉积物粒度细和泥质含量高是形成低渗透储层的基础;储层整体上处于中成岩A期阶段,碳酸盐胶结物的多期胶结是形成致密储层的关键因素。胶结作用使大量连通的原生孔隙转变成渗透性极差的微孔隙,加剧了低渗透储层的形成和演化。

Low permeability reservoir was one of the most significant characteristics of lithologic reservoirs.To clarify its genesis mechanism was one of the bases for setting up a rational oil development program in Eq2 Reservoir of Daqingzijing Oilfield.From both sedimentary environment and diagenesis aspects,the genesis mechanism of low permeability reservoirs was analyzed.The Eq2 reservoir of Daqingzijing Oilfield is fine-grained sandstone and siltstone of delta front.The fine grain size and high clay content are the bases of forming low permeability reservoirs.Moreover,the reservoir is in A period of middle diagenetic stage,of which the carbonate cement presents multiple phases cementation.The cementation turns a large number of primary communicating pores into micropores with poor permeability,it exacerbates the formation and evolution of low-permeability reservoirs.