恩平凹陷珠海组储层的孔隙度演化模型

Application of porosity evolution model to reservoir assessment of Zhuhai Formation in Enping Sag

珠海组是珠江口盆地恩平凹陷油气勘探的重要目标。运用普通薄片、铸体薄片、扫描电镜、X衍射、毛细管压力曲线等资料,对恩平凹陷珠海组的孔隙结构和成岩演化特征进行了分析,揭示了储层物性特征的主控因素。珠海组储层物性受控于沉积相,与岩石的粒度明显相关。压实作用是引起孔喉变小的主要成岩作用,而溶蚀作用产生的次生孔隙仅引起珠海组上部的孔隙度明显增加,对珠海组下部储层影响不大。根据成岩作用与孔隙度演化的关系,并结合埋藏史和地热史,建立了珠海组成岩序列与孔隙度演化模型。利用该模型,从沉积相与成岩相的叠加效应等角度对珠海组的物性特征进行了评价。

Zhuhai Formation is an important prospecting object in Enping Sag of Pearl River Mouth Basin. The pore structure and diagenesis of Zhuhai Formation were studied by means of normal thin sections, cast thin sections, SEM analysis, X ray diffractions and mercury injection curves. The main factors controlling the reservoir properties were found out. The quality of the reservoirs of Zhuhai Formation was controlled by the sedimentary facies and related with the grain size. The decrease of porosity was mainly caused by the compaction. The secondary pores caused by the acid fluid corrosion resulted in the porosity increase of the upper part of Zhuhai Formation and had few effects on the reservoirs of the lower part of Zhuhai Formation. The porosity evolution model of Zhuhai Formation was finally constructed on the basis of burial and temperature histories and the relationship between diagenesis and porosity. The reservoir quality of different sedimentary and diagenetie facies was evaluated using the model.