准噶尔盆地西北缘二叠系碎屑岩储层成岩相与成岩演化研究

西北缘克百地区二叠系砂砾岩储层是准噶尔盆地最重要的油藏储集岩之一。运用偏光显微镜在对碎屑岩储层的成岩作用、自生矿物及孔隙特征详细观察的基础上,结合扫描电镜、孔渗测试及测井、录井资料的分析,对该区二叠系砂砾岩储层的岩石类型和成岩作用进行了研究,指出压实作用、胶结作用、溶蚀作用是影响该类储层物性的主要成岩作用。在此基础上,结合成岩作用和成岩阶段的研究,划分出了7个成岩相:1)高成熟强溶蚀相,2)高成熟强胶结相,3)高成熟中胶结中溶蚀相,4)高成熟弱压实相,5)高成熟强压实相,6)低成熟弱压实相,7)低成熟强压实相,并对各个成岩相的形成条件、成岩特征、成岩环境、成岩演化序列和成岩模式进行了归纳和总结,对不同成岩相的砂砾岩储集性能进行了分析,阐述了优良储层发育的主要成岩相带及沉积相带。

内蒙古红岭铅锌-多金属矿床二叠系火山碎屑岩中硫化物压力影的发现及成矿意义

内蒙古东部的黄岗-甘珠尔庙锡、铜多金属成矿带中发育多个与燕山期岩浆活动有关的富铜的锡多金属矿床,如大井子、安乐、毛登和敖脑达坝等,矿床的主要围岩为二叠系的页岩和板岩,但对二叠系地层与成矿的关系目前仍存在不同认识。本文以红岭铅锌-多金属矿床为研究对象,通过详细的野外地质调研、显微岩矿相、SEM/EDS、硫化物的原位微区元素和同位素分析等,对矿区二叠系黑色板岩及其中的硫化物压力影进行了详细工作。结果表明,红岭矿床主要赋矿围岩为二叠系黑色板岩和大理岩,其中黑色板岩的原岩为晶屑凝灰岩,碎屑以石英、钾长石晶屑为主,并可见少量浆屑和锆石、磷灰石、铬铁尖晶石等晶屑,胶结物主要由黑云母、石英和钾长石组成。岩石经历了明显的轴向为NE向的褶皱变形,其中构造片理发育,走向与区域构造线方向一致。黑色板岩中顺岩石层理可见压力影构造,其核部由磁黄铁矿、黄铜矿、闪锌矿组成,影子矿物主要为石英和绿泥石。压力影中影子矿物的延伸方向与岩石片理方向一致,为NE向,可被成矿期的热液脉体穿切,表明其核部矿物形成与地层同期,为同生成因,并经历了成岩后的挤压变形。压力影中硫化物的原位硫同位素组成(-0.33‰~+1.75‰)与前人获得的矿石中硫化物的S同位素组成一致,表明其可能为成矿提供了部分S和Cu等成矿物质。这一认识不仅对理解区内富铜多金属矿床的成矿物质来源提供了重要依据,同时对指导区域找矿具有指导意义。

Application of seismic facies and attributes analysis on the identification of Permian igneous rock

Seismic facies and attributes analysis techniques are introduced.The geological characteristics of some oil fields in western China are used in conjunction with drilling results and logging data to identify the lithology,intrusion periods,and distribution range of the Permian igneous rocks in this area.The lithologic classification,the vertical and horizontal distribution,and the intrusion periods of igneous rock were deduced through this study.Combining seismic facies and attributes analysis based on optimization can describe the igneous rock in detail.This is an efficient way to identify lithology and intrusion periods.Using geological data and GR-DT logging cross-plots the Permian igneous rock from TP to TT was divided into three periods.The lithology of the first period is tuff and clasolite with a thickness ranging from 18 to 80 ms.The second is basalt with a thickness ranging from 0 to 20 ms.The third is tuff and clasolite and dacite whose thickness ranges from 60 to 80 ms.These results can help understand the clasolite trap with low amplitude and the lithologic trap of the Carboniferous and Silurian.They can also guide further oil and/or gas exploration.