摘要
随着国内外花岗岩油气藏的不断发现,花岗岩风化壳储层越来越受到人们的关注。前人已对花岗岩风化壳的地质特征及储层特征做了许多基础研究工作,但针对花岗岩风化壳形成和演化过程的研究比较薄弱,对花岗岩风化壳改造-保存作用的研究也比较少。针对花岗岩风化壳储层的形成机理和分布规律等难题,通过开展花岗岩风化壳储层的井孔岩心观察、岩石薄片分析、野外露头踏勘、测井曲线特征分析及地震反射特征综合解释等工作,系统探索了花岗岩风化壳储层形成、改造和保存的动力学机制,并取得以下主要认识:(1)提出了花岗岩风化壳的"双层结构"动态成因模式,认为风化壳储层是由顶部残积层或溶蚀层与底部崩解层2个层段构成,溶蚀层和残积层作为同一层段,实为崩解层顶面在不同演化阶段的产物。在风化壳演化早期,崩解层开始发育为溶蚀层,出现溶蚀层-崩解层"双层结构";在风化壳演化中期,溶蚀层演变为残积层,形成残积层-崩解层"双层结构";在风化壳演化晚期,仅保留崩解层。(2)指出花岗岩风化壳储层在形成的同时,经历了构造掀斜、断裂破坏、水流冲蚀等改造作用,并认为后期地层覆盖的保存作用对花岗岩风化壳至关重要,后期地层覆盖越早,对花岗岩风化壳储层的保存越有利。(3)认为不同高程、不同坡度和不同构造带上的风化壳类型存在巨大差异,在构造顶部只发育崩解层,在构造高部位的边缘区发育残积层,在构造中—低部位发育溶蚀层。崩解层广泛分布。(4)阐明了花岗岩风化壳的有利储层勘探方向,认为在构造中—低部位保存下来的溶蚀层发育带是最有利的储层发育区带。花岗岩风化壳"双层结构"动态成因模式的提出以及风化壳储层的形成-改造-保存机理对其他相关盆地花岗岩风化壳储层的地质成因及油气勘探具有重要的借鉴意义。
With the continuous discovery of granite reservoirs at home and abroad,granitic weathering crust reservoir have attracted more and more attention.Predecessors have done a lot of basic researches on the geological characteristics and reservoir features of granitic weathering crust.However,there is less research on the formation and evolution process of granitic weathering crust,as well as its transformation and preservation.Aiming at the problems about the formation mechanism and distribution regularity of granitic weathering crust reservoirs,based on the borehole core observation,rock thin section analysis,field outcrop survey,logging curve analysis and comprehensive seismic reflection interpretation on granitic weathering crust reservoirs,this paper systematically explores the dynamic mechanism of the formation,transformation and preservation of granitic weathering crust reservoirs,and obtains the following main understandings.(1)This paper proposes the dynamic genetic pattern of the"double-decker texture"of granitic weathering crust.It is considered that the weathering crust reservoir is composed of two layers,the top eluvium or dissolution layer and the bottom disintegration layer.As the same interval,the dissolution layer and the eluvium are actually the products of the top surface of the disintegration layer in different stages of evolution.In the early evolution of the weathering crust,the disintegration layer began to develop into a dissolution layer,and a double-decker texture with dissolution layer and disintegration layer appeared;in the middle-stage evolution of the weathering crust,the dissolution layer evolved into an eluvium,forming a double-decker texture with eluvium and disintegration layer.In the late evolution of the weathering crust,only the disintegration layer was preserved.(2)It is pointed out that the granitic weathering crust reservoir has undergone structural tilting,fracture destruction,fluvial abrasion and other transformation effects when it is formed,and it is believed that the preservation effect brought by the later stratigraphic coverage is crucial to the granite weathering crust.The earlier the later stratigraphic coverage occurs,the better it is for the preservation of granitic weathering crust reservoirs.(3)It is believed that there is a huge difference in the types of weathering crust on different elevations,different slopes and different structural belts.Only disintegration layers are developed at the top of the structure,eluvia are developed in the marginal areas of the high structural part,and dissolution layers are developed in middle-low structural parts.The disintegration layer is widely distributed.(4)This paper clarifies the exploration direction for the favorable reservoirs of granitic weathering crust,and believes that the development zone of dissolution layer preserved in the structural middle-lower parts are the most favorable development zones of reservoirs.The proposed dynamic genetic model of the double-decker texture of granitic weathering crust and the formation-transformation-preservation mechanism of weathering crust reservoirs have important reference significance for understanding the geological origin and exploiting hydrocarbon resources in granitic weathering crust reservoirs in other related basins.
作者
刘震
朱茂林
刘惠民
李晓珂
梁裳恣
巩建强
张鹏飞
Liu Zhen;Zhu Maolin;Liu Huimin;Li Xiaoke;Liang Shangzi;Gong Jianqiang;Zhang Pengfei(State Key Laboratory of Petroleum Resources and Prospecting,Beijing 102249,China;School of Geosciences,China University of Petroleum,Beijing 102249,China;Sinopec Shengli Oilfield Company,Shandong Dongying 257001,China;Department of Geology,Northwest University,Shaanxi Xi'an 710069,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Geological Research Institute,Sinopec Shengli Oilfield Company,Shandong Dongying 257015,China)
出处
《石油学报》
EI
CAS
CSCD
北大核心
2021年第2期163-175,共13页
Acta Petrolei Sinica
基金
国家科技重大专项“岩性地层油气藏成藏动力、临界条件与分布模式”(2011ZX05001-001-07)资助。
关键词
花岗岩
风化壳储层
动态成因模式
分布模式
东营凹陷
granite
weathering crust reservoir
dynamic genetic model
distribution model
Dongying sag