摘要
溶蚀作用是玛湖凹陷黄羊泉地区百口泉组储层孔隙形成的重要成岩事件。砾岩储层泥砂砾混杂,孔隙结构复杂,成岩流体运移模式不明确,溶蚀作用是否提高储层物性取决于溶蚀副产物是否被有效带出。因此,溶蚀作用对砾岩储层物性的影响值得进一步研究。在砾岩储层岩相分类基础上,通过铸体薄片中矿物溶蚀量的精确统计,结合物性、扫描电镜、Quemscan矿物分析、X射线衍射和包裹体等分析测试,系统研究了砾岩储层中溶蚀作用对储层物性的影响。研究表明:溶蚀作用副产物主要为自生石英和自生黏土矿物。第一期石英次生加大主要来源于蒙皂石向伊利石转化,第二期石英次生加大主要来源于石英颗粒的压溶作用;伊利石主要来源于凝灰质溶蚀、高岭石和蒙脱石的转化;促进形成绿泥石所需的Fe^(2+)主要来源于研究区内大量火山岩碎屑。溶蚀作用对不同类型岩相储层物性影响不同。以岩相类型Ⅰ为主的储层含少量矿物溶蚀孔和贴粒缝,溶蚀作用较弱,储层物性低;以岩相类型Ⅱ为主的储层多见凝灰质溶蚀形成的溶蚀孔,孔隙内沉淀大量伊/蒙混层和伊利石,孔隙度分布范围较大,渗透率低,溶蚀作用对此类储层仅进行物质再分配;以岩相类型Ⅲ为主的储层,含大量长石和岩屑溶蚀孔,溶蚀作用对储层物性有一定的提升。
Dissolution is an important diagenetic occurrence in pore formation in the Huangyangquan area of the Baikouquan Formation,Mahu Sag.Conglomerate reservoirs are mixed with mud,sandstone and gravelstone,with complex pore structure and an unclear migration mode of diagenetic fluid.Whether or not dissolution improves the physical properties of reservoirs depends on the effective removal of the dissolution by-products.The influence of dissolution on reservoir physical properties in a conglomerate reservoir was systematically studied using petrographic classification derived from accurate observations of mineral dissolution properties in cast thin sections,combined with physical properties,scanning electron microscopy,Qemscan mineral analysis,X-ray diffraction and inclusion analysis.The results show that the by-products of dissolution were mainly authigenic quartz and autogenous clay minerals.The primary authigenic quartz was mainly from the conversion of smectite to illite.The secondary authigenic quartz was mainly the result of pressure dissolution of quartz particles.The illite is mainly the product of dissolution of tuff and the transformation of kaolinite and smectite.The Fe2+ needed in the formation of chlorite were sourced mainly from the large amount of volcanic debris in the study area.Dissolution has had different effects on reservoirs,depending on their lithofacies type.Dissolution is weak in reservoirs containing mainly lithofacies type Ⅰ,with a small amount of mineral and attached-particle dissolution pores,resulting in low physical properties.Lithofacies type Ⅱcontain some tuffaceous dissolution pores in which large amounts of mixed illite/montmorillonite layers or illite are precipitated.This has produced high porosity but low permeability,since the dissolution process has merely redistributed materials within such reservoirs.Lithofacies type Ⅲ reservoirs contain a large number of dissolution pores in feldspars and debris,improving the reservoir properties considerably.
作者
肖萌
袁选俊
吴松涛
谢宗瑞
王成云
XIAO Meng;YUAN XuanJun;WU SongTao;XIE ZongRui;WANG ChengYun(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;Research Institute of Exploration and Development,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang 834000,China;Research Institute of Exploration and Development,Huabei Oilfield Company,PetroChina,Cangzhou,Hebei 062552,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2023年第3期945-958,共14页
Acta Sedimentologica Sinica
基金
中国博士后科学基金项目(2020M680819)。
关键词
溶蚀作用
物性影响
岩相
砾岩储层
准噶尔盆地
dissolution
physical effects
petrographic facies
conglomerate reservoir
Junggar Basin
