深层储集层成岩作用及孔隙度演化定量模型——以东濮凹陷文东油田沙三段储集层为例

Diagenesis of deep sandstone reservoirs and a quantitative model of porosity evolution:Taking the third member of Shahejie Formation in the Wendong Oilfield,Dongpu Sag,as an example

利用普通薄片、铸体薄片、X射线衍射、扫描电镜等资料,分析东濮凹陷文东油田沙三段深层储集层砂岩成岩作用和孔隙演化过程。研究表明,储集层砂岩目前处于晚成岩阶段,储集层发育原生粒间孔隙和长石、岩屑、胶结物等不稳定组分的粒间溶孔、粒内溶孔。储集层物性分布受碳酸盐等的胶结、溶蚀及异常高压带分布的控制。孔隙度参数演化分析表明,储集层初始孔隙度为36.75%,压实过程孔隙度损失率为40.49%,胶结-交代过程孔隙度损失率为37.25%,后期溶蚀、溶解过程孔隙度增加率为17.88%。储集空间中原生孔隙占总孔隙的55.03%,次生孔隙占总孔隙的44.97%。孔隙度计算过程中误差率为0.96%,影响误差的主要因素为颗粒分选系数。

The diagenesis and porosity evolution in the deep 3rd member of Shahejie Formation of the Wendong Oilfield was analyzed using thin-sections,casting thin-sections,X-ray diffractometry,scanning electron micrograph observations,and other data.Sandstone reservoirs are currently at the late diagenetic period.Pores consist of primary pores and the inter-granular dissolved and intra-granular dissolved pores of feldspar,debris and carbonate cements.Physical properties are mainly controlled by carbonate cementation and dissolution,and distribution of abnormally high fluid pressure.The evolution of porosity parameters shows that primary porosity is 36.75%,the porosity loss rate is 40.49% during the process of mechanic compaction,the porosity loss rate is 37.25% during the process of cementation and metasomasis,and the porosity increase rate is 17.88% during the process of dissolution.The proportion of primary porosity is 55.03%,and that of the secondary porosity is 44.97%.The error rate in the quantitative study of porosity is 0.96%,and the main influencing factor of the error rate is sorting coefficient of detrital rock（S0）.