陕北富县延长组特低孔渗砂岩储层控制因素分析

研究表明 ,陕北富县延长组总体为特低孔渗砂岩储层。沉积岩石粒度普遍较细 ,是导致岩石储集性较差的先天地质因素 ;岩石中“抗压实性”较差的长石、岩屑等软碎屑颗粒含量高 ,加之延长组砂岩又历经了较长的埋藏期 ,因此强烈的压实作用是形成特低孔渗储层的又一主要原因 ;较强的胶结作用 ,尤其是晚期碳酸盐胶结作用 ,对延长组特低孔渗砂岩储层的形成也有着重要影响 ;晚期溶蚀作用不充分且持续时间不长 ,对储层没能发挥明显的改造作用 ,这也是形成特低孔渗砂岩储层的一个重要因素

FACTORS CONTROLLING THE VERY LOW-POROSITY AND-PERMEABILITY SANDSTONE RESERVOIR OF THE YANCHANG FORMATION IN FUXIAN AREA, NORTH SHAANXI

The Upper Triassic Yanchang Formation in the Fuxian area is totally a very low porosity and permeability sandstone reservoir. The general fine grainsize of sedimentary rock is the inborn factor that resulted in the very low porosity and permeability. The strong compaction resulted from a long burial period and high content flexible grains such as feldspar and lithic fragment is the second main factor that caused the very low porosity and permeability. The strong cementation, especially the late carbonate cementation also seriously influenced the reservoir characteristic of the Yanchang Formation .The late dissolution is not so thorough and long as not to improve the porosity and permeability of the Yanchang Formation obviously.