成岩作用控制下低渗透砂岩润湿性演化过程及机制——以渤海湾盆地东营凹陷为例  

Evolutionary process of the wettability of low-permeability sandstone reservoirs under the control of diagenesis and its mechanism:A case study of the Dongying Sag,Bohai Bay Basin

作　　者：王鑫 曾溅辉[1,2] 贾昆昆 王伟庆 李博 安丛 赵文 WANG Xin;ZENG Jianhui;JIA Kunkun;WANG Weiqing;LI Bo;AN Cong;ZHAO Wen(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting,Beijing 102249,China;Exploration and Development Research Institute,Shengli Oilfield Branch Company,SINOPEC,Dongying,Shandong 257029,China;Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]油气资源与探测国家重点实验室,北京102249 [3]中国石化胜利油田分公司勘探开发研究院,山东东营257029 [4]中国石油勘探开发研究院,北京100083

出　　处：《石油与天然气地质》2023年第5期1308-1320,共13页Oil & Gas Geology

基　　金：国家自然科学基金项目(41972147)。

摘　　要：润湿性对低渗透砂岩中流体的渗流能力具有关键的控制作用。在成岩演化过程中,低渗透砂岩储层流体性质、矿物类型及成分变化频繁,导致润湿性演化机制尚不明确,严重制约了低渗透油气成藏机理的研究工作。以渤海湾盆地东营凹陷古近系沙河街组四段上亚段为例,基于地质资料分析,采用铸体薄片观察、X射线衍射矿物组分分析、基于核磁共振技术的高温高压Amott法润湿性实验和高温高压固-油-水接触角实验,系统分析成岩作用对低渗透砂岩储层润湿性的控制作用。研究结果表明:复杂多样的成岩作用导致不同成岩阶段发育的主要孔隙类型存在差异。在早成岩A期、B期及中成岩A1期、A2期和B期的这5个成岩阶段,低渗透砂岩储层发育的主要孔隙类型依次为压实残余孔、长石溶蚀粒内孔-碳酸盐溶蚀粒间孔、石英边缘溶蚀孔、长石溶蚀粒内孔-碳酸盐溶蚀粒间孔和裂缝。随着成岩演化的进行,压实残余孔、石英边缘溶蚀孔和长石溶蚀粒内孔亲水性变强,而方解石溶蚀粒间孔亲油性变强,白云石溶蚀粒间孔由水润湿变为中性润湿。同时,不同成岩阶段发育的主要孔隙类型及其表面润湿特性决定了低渗透砂岩整体的润湿性。在成岩过程中低渗透砂岩润湿性主要表现为水润湿的特性,在从早到晚的5个成岩阶段依次为强亲水性、弱亲水性、亲水性、中性和亲水性。最后,建立了成岩作用控制下砂岩储层润湿性演化模式,对指导低渗透砂岩储层的甜点预测具有重要意义。Wettability plays a critical role in dictating the fluid percolation within low-permeability sandstone reservoirs.However,the wettability evolutionary mechanisms remain ambiguous given the frequent changes in the fluid properties and mineral types and compositions in these reservoirs throughout diagenesis.This opacity severely hampers the research on the mechanisms of hydrocarbon accumulation in the reservoirs.This study centers on the upper submember of the 4th member of the Paleogene Shahejie Formation in the Dongying Sag,Bohai Bay Basin.Based on the analysis of geological data,we undertake a systematical analysis of diagenesis' s controlling effects on the wettability of lowpermeability sandstone reservoirs through observation of casting thin sections and the X-ray diffraction analysis of mineral compositions,Amott wettability tests using nuclear magnetic resonance(NMR) equipment,and experiments of contact angles in a solid-oil-water system,both under high temperature and pressure.The results highlight distinct major pore types across various diagenetic states attributable to complex diagenesis.Specifically,the early diagenetic stages A and B evidenced the major pore types of residual pores by compaction and both intragranular pores from feldspar dissolution and intergranular pores from carbonate dissolution,respectively,while middle diagenetic stages A1,A2,and B witnessed the presence of dissolution pores at quartz edge,both intragranular pores from feldspar dissolution and intergranular pores from carbonate dissolution,and fractures,respectively as major pore types.As diagenesis advanced,residual pores by compaction,dissolution pores at quartz edge,and intragranular pores from feldspar dissolution grew increasingly hydrophilic.Furthermore,intergranular pores from calcite dissolution trended toward lipophilicity,while intergranular pores from dolomite dissolution evolved from water wetting to intermediate wetting.The overall wettability of the low-permeability sandstone reservoirs is governed by the major por

关 键 词：润湿性 成岩作用 滩坝砂 深层油藏 低渗透砂岩 东营凹陷 渤海湾盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]