孝（泉）—新（场）—合（兴场）地区须家河组砂岩储层中粘土矿物研究

【作者】 孙治雷；

【导师】 黄思静；

【作者基本信息】 成都理工大学 ， 矿物学、矿床学、岩石学， 2006， 硕士

【摘要】 运用X射线衍射(XRD)、扫描电子显微镜(SEM)、偏光显微镜、电子探针分析等手段，对川西坳陷中段孝(泉)—新(场)—合(兴场)地区须家河段主要砂岩储层(须2、须4段)中的粘土矿物进行了综合分析。研究结果表明，富岩屑贫长石的总体岩石类型特征是决定该区自生粘土矿物成岩作用的物质基础；孝-新-合地区须家河组主要储层砂岩中可识别的粘土矿物主要有伊利石、绿泥石与高岭石三种，其中，伊利石、绿泥石是该区含量最多的矿物，二者含量上的此消彼长控制了须2、须4段粘土矿物纵向上分布规律的整个趋势；自生粘土矿物是孝—新—合地区主要砂岩储层中含量仅次于碳酸盐的胶结物，纵向上，自生绿泥石集中分布在须2段，高岭石仅出现在须4段顶部，而由于研究区面积过于狭小，次级构造带不是控制其平面分布的重要因素；晚三叠世海、陆相沉积环境的转换、古气候、古环境是控制该区陆源(异源)粘土矿物类型组合与分布规律的重要因素，但由于埋深已达到5000m以上，陆源粘土矿物均经过复杂成岩作用的改造，在利用其现今特征来对以上各方面进行解译时，需持谨慎态度。 须2段以颗粒包膜形式普遍赋存的自生绿泥石在成岩早期沉淀，其物质来源主要为中基性火山岩岩屑、铁镁暗色矿物的水化分解以及先驱粘土矿物的交代转化作用，该段赋存的绿泥石后期有继续生长的现象，其再生长所需物质来源可能是下伏地层中具海相色彩的富镁流体，流体运移通道是须2段下部较为发达的裂缝系统。绿泥石的颗粒包膜在一定程度上从物理方面抵制了压实作用，从化学角度抑制了自生石英的成核生长，使某些层位原生粒间孔隙得到较好的保存；自生高岭石在渗透率相对较高、侧向连通性较好的须4段顶部集中出现，其形成受包括煤系地层酸性水、相邻泥岩压释水、有机酸在内的多种酸性流体联合作用有关，碎屑长石等铝硅酸盐的溶解是形成自生高岭石的物质基础。该区自生高岭石含量与次生孔隙之间表现出良好的相关性表明，它至少是长石溶解和次生孔隙发育带的指示矿物；具有最高含量粘土矿物伊利石堵塞了该区须家河主要砂岩储层的孔隙，其最常见的孔隙搭桥式产状将大量的孔隙和孔隙喉道切割成微细的束缚孔隙，大大降低了储层的渗透率。更多还原

【Abstract】 The clay minerals samples of reservoir sandstones that collected from Xujiahe Formation II and IV in the Xiao(quan)-Xin(chang)-He(xingchang) Area of the middle section of Western Sichuan Sag are analysed with the help of X-ray Difrraction(XRD)、Scanning electron microscope(SEM)、Thin-section analysis、 Electronic probe microscopy (EPM) and so on; The experiments prove that the reservoir sandstones of the area have a characteristic of more abundant lithic fragments whereas are short of feldspars ,which are the material resources of the clay minerals diagenesis there. Three main clay mierals can be identified in Xujiahe Foramation reservoir sandstones in this area, they are illite ,chlorite and kaolinite. Among them ,the content of illite is at the utmost and chlorite has the secondary content. The waning and waxing of the main clay minerals(illite and chlorite) nearly represent the whole clay distribution pattern character in the Xujiahe Foramation II and IV vertically ; The authigenic clay minerals has the second place in content in the reservoir sandstones ,with the authigenic carbonate mineral has the first place in content., The authigenic chlorite appears mainly in Xujiahe Foramation II however , the authigenic kaolinite appears in the upper Xujiahe Foramation IV vertically. Because of the narrowness of the target area ,the sub-tectonic belts in the area have not play the important role of the distribution pattern horizontally; The type assemblages and distributing characteristics of the terrigenous (heterogenous) clay minerals are controlled by the transfer of marine and terrestrial facies, palaeoclimate and palaeoenvironment, however, we must have the prudential attitude in the deciphering work on the above aspects because of the violent alteration in the diagenesis stages in the case of the buried depth in target formations have already reached 5000m.The authigenic chlorite in Xujiahe Foramation II that exists prevalently in grain-coatings(or pore-linings) mainly precipitated during early diagenesis stage and the dominating material resources of chlorite are the prehydration and decompound of neutral and basic volcanic rock fragment(VRF), dark-colored ferromagnesian and the metasomatic replacement of the precursory clay minerals.The authigenic chlorite existing in this member(Xujiahe Foramation II) has revegetation, the potential main material resources are the Mg-rich flow in the underlying strata that has full-bodied marine characteristic ,the transfer passages are probably the abundant fissure system更多还原