欧利坨子地区沙三下亚段火山岩成岩作用及孔隙演化

DIAGENESIS AND PORE EVOLUTION OF LOWER Es3 VOLCANIC ROCKS IN OULITUOZI REGION

欧利坨子地区沙三下亚段火山岩类型以火山碎屑岩为主 ,次为玄武岩及粗面岩。在把火山岩在埋藏过程中发生的物理及化学变化纳入成岩作用范畴的前提下 ,研究了成岩作用特征、演化及储集空间的演化。认为在不同沉积时期古地温梯度值的不同 ,成岩作用阶段所对应的深度也随之而改变 ,厚层火山岩从沙一段末期至今主要处于早成岩B期 ,而下部火山岩则从东营组沉积期以后一直处于晚成岩阶段。受其影响厚层火山岩中储集空间以裂缝原生孔隙或裂缝混合孔隙为主 ,储集空间总体保存较差 ,在有机质的作用下 ,局部可保存较好 ;下部火山岩中则以裂缝次生孔隙为主 ,由于溶蚀作用 ,储集空间得以较好保存 ,因而在研究区较深埋藏条件下的火山岩中仍具有较好的成藏条件。

The volcanic rocks of the Lower Es3 in Oulituozi region are mainly volcaniclastic rock,basalt and trachyte.The volcanic rock diagenesis and reservoir space evelution are studied.It is considered that,different deposition stages have different paleo geothermal gradients,and different diagenetic stages correspond to different depths.Thick volcanic rocks from Sha 1 mumber to present are in the early diagenetic B stage;the reservoir spaces are generally fissure primary porosity and fissure compound porosity,and are poorly preserved;the volcanic rocks in the lower part are mainly well developed fissure secondarfy porosity.