溱潼凹陷北坡阜三段储层方解石化作用及形成机制探讨

Calcilization and Its Formating Mechanism of Reservoir on the Third Member in Fuling Group on the North Slope of Qintong Depression

程晓玲

Cheng Xiaoling

中国石化无锡实验地质研究所

Wuxi Research Institute of Experimental Geology , SINOPEC, Wuxi 214151 , P. R. China

基于溱潼北坡24 口井阜三段岩心砂岩储层铸体薄片及普通薄片的分析,对方解石与储层孔渗的关系、方解石分布规律进行了研究,同时对方解石形成机制进行了探讨。结果表明,方解石化作用是本区的破坏性成岩作用,方解石含量大于10 %时对储层物性有明显的影响,其成岩作用的结果是堵塞孔隙、喉道,使孔隙连通性变差、岩石渗透性降低。方解石含量有西部高于东部,下砂组高于上砂组的规律。方解石分布的不均衡可能与当时的水介质条件、物源、辉绿岩侵入有关。

On the basis of core analysis data of resin pore casts and thin sections of the reservoir rocks on the third member in Fuling group of 24 wells on the north slope of the Qintong basin , the author discusses the relationship between calcites and physical properties of the reservoir rocks ,characteristics of calcite distribution , and formation conditions of calcites. The results demonstrate that calcitic cementations are destroying diagenesis in the field. The reservoir rocks will be obviously influenced when calcites amount are more than 10 percent in the reservoir rocks. The effect of calcilization is to occlude porosity , and decrease throat connection and permeation. Calcitic amount in the western area are more than in the eastern area , the upper reservoirs rocks of the third member in Fuling group more than the lower. It was possible that calcite distribution imbalance were resulted from hydrochemical conditions ,source rocks ,and diabase inrush.