歧口凹陷沙河街组火山岩成岩作用及对储集性能的控制

根据岩心观察资料,利用偏光显微镜、扫描电镜等对歧口凹陷沙河街组火山岩的成岩作用进行了详细地研究,把成岩作用类型分为早期和晚期两个阶段、13种成岩作用类型。根据成岩作用阶段划分依据,结合盆地埋藏-热演化史和烃类充注史等资料,将歧口凹陷沙河街组火成岩成岩作用阶段划分为早期和晚期两个阶段。火成岩共发生了3期溶蚀作用、2期构造作用、2期油气充注作用,以及绿泥石、硅质、碳酸盐等胶结作用。主要成岩序列为溶蚀作用Ⅰ→构造作用Ⅰ→栉壳状绿泥石→细纤维状绿泥石→硅质Ⅰ→较粗纤维状绿泥石→烃类充注Ⅰ→硅质充填Ⅱ→亮晶方解石Ⅰ→构造作用Ⅱ→溶蚀作用Ⅱ→烃类充注Ⅱ→亮晶方解石Ⅱ→铁方解石→硅质充填Ⅲ→溶蚀作用Ⅲ。成岩作用对储集性能的控制具有改善和破坏的双重作用,对储集性能具有改善作用的成岩作用类型有挥发分逸出作用、熔蚀作用、冷凝收缩作用、脱玻化作用、机械压实破裂作用、风化淋滤溶蚀作用、次生溶蚀作用。对储集性能具有破坏作用的成岩作用类型有熔结作用、充填作用、机械压实压溶作用、胶结作用。

Diagenesis of Volcanic Rocks in Shahejie Formation of Qikou Depression and Its Control over Reservoir Performance

Based on the micro-examination of core observation data by means of polarization microscope and scanning electron microscope,the authors systematically studied the diagenesis of Shahejie Formation vocalic rocks in Qikou depression,and divided the diagenesis system of volcanic rocks into early diagenetic phase and late diagenetic phase as well as thirteen diagenetic types.According to the evidence of diagenetic division stages in combination with the data of basin burial-thermal evolution history and hydrocarbon charging history,the early diagenetic stage and the late diagenetic stage were recognized in Shahejie Formation of Qikou depression.The diagenesis of volcanic rocks has undergone three stages of dissolution,two stages of tectonism,two stages of hydrocarbon charging and chlorite cementation,siliceous cementation and carbonate cementation.The main diagenetic sequences are dissolution Ⅰ→structure movement Ⅰ→pectinate texture chlorite→fine fibrous chlorite →silicic Ⅰ→coarse fibrous chlorite→hydrocarbon charging→silicic filling Ⅱ →sparry calcite Ⅰ →tectonismⅡ →dissolution Ⅱ →hydrocarbon charging Ⅱ →sparry calcite Ⅱ →ferrocalcite→silicic filling Ⅲ →dissolution Ⅲ.Studies indicate that diagenesis has played dual functions of improving and destroying on the reservoir physical property.The diageneses which are constructive to the reservoirs are mainly volatile and escaping action,dissolution,condensation and contraction,diversification,mechanical compaction,weathering-leaching dissolution,and corrosion.The diageneses which are destructive to the reservoirs are mainly clinkering action and filing action,mechanical compaction and pressure solution,and cementation.