深部细粒碎屑岩储层成岩作用研究——以苏北盆地张家垛油田阜三段为例

毗邻烃源岩的细粒储层,由于其岩石结构、组分及沉积环境的特殊性,成岩作用表现出一定差异。本文以张家垛油田阜三段细粒碎屑岩储层为例,通过铸体薄片、X射线衍射、扫描电镜等相关分析,研究其成岩作用的特殊性。研究结果表明:(1)细粒储层的成分成熟度和结构成熟度较高,常被泥岩包裹,在压实作用中若存在欠压实,粒间孔可以被很好地保留下来;(2)细粒储层形成时水动力较弱,杂基含量高导致微孔较多;(3)大量的粘土矿物使孔隙比表面增加,抑制了后期硅质和碳酸盐胶结物的析出;(4)比表面的增加减缓了孔隙流体的对流速率和扩散速率,不利于次生孔隙的形成,粒度越细,次生孔隙越不发育。细粒碎屑岩储层有别于常规储层,对其特殊的成岩作用进行研究具有重要的理论价值和实际意义。

Diagenesis of the deep-seated fine-grained clastic reservoirs: An example from the 3rd member of the Funing Formation in the Zhangjiaduo Oil Field,Subei Basin

Currently much attention is given to the fine-grained clastic reservoirs with the exploration and development of dense oil and shale gas. The diagenesis of the deep-seated fine-grained clastic reservoirs from the 3rd member of the Funing Formation in the Zhangjiaduo Oil Field is dealt with in this paper on the basis of cast section examination,X-ray diffraction analysis and SEM. The results of research are outlined as follows. (1)The intergranular pores can be well preserved when the disequilibrium compaction took place,and the fine-grained clastic reservoirs with relatively higher compositional maturity and textural maturity are commonly sealed by mudstones;(2)Abundant micropores are caused by higher contents of matrix due to weakly hydrodynamic conditions during the deposition of the fine-grained clastic reservoirs;(3)The occurrence of abundant clay minerals leads to the increase of specific surface of the pores and the decrease of the precipitation of siliceous and carbonate cements;(4)The increase of specific surface of the pores slows down the convective velocity and diffusive velocity of pore fluids,and may be unfavourable for the formation of the secondary pores. The study of the diagenesis of the fine-grained clastic reservoirs in this paper is of both theoretical and practical values.