【作者】 王明献；

【导师】 陈景山； 沈昭国； 焦方正；

【作者基本信息】 西南石油学院 ， 矿产普查与勘探， 2005， 博士

【摘要】 根据钻井、岩心、测井以及露头剖面等资料的综合精细分析,在陕西省富县地区上三叠统延长组第6段中识别出三角洲、湖泊和湖底扇三种沉积相。其中的砂体成因类型主要包括水下分流河道、河口坝、远砂坝、水下决口扇、水下天然堤、前缘席状砂、湖底重力流水道、远源浊积、浅湖漫流席状砂、砂质滩坝等砂体。它们发育于富县三角洲的高速生长时期,是控制本区长6段储集砂体发育与分布的先天性地质因素。通过高分辨率层序地层学的详细研究,将本区长6段划分为3个中期基准面旋回,每个中期基准面旋回由4～6个短期基准面旋回叠加组成。根据储集砂体的发育和时空分布主要受不同级次基准面升降旋回控制这一事实,提出以不同级次湖泛面沉积的泥质隔层为边界的储集砂体划分方案,据此将本区长6段储集砂体划分为3个砂组。以砂组为作图单位,分别展示了本区3个砂组的地层厚度、砂岩厚度以及沉积相的平面展布特征。通过岩心描述、薄片鉴定和化验测试资料的分析,本区长6段储集砂体主要由中砂岩、细砂岩和粉砂岩组成,属于长石砂岩和岩屑质长石砂岩类型,经历了压实、胶结、交代等破坏性成岩作用以及导致孔隙度增加的溶蚀作用,现今处于晚成岩阶段A期—B期。砂体的储集空间类型以次生孔隙为主,孔隙度分布于1.7%～16.3%,主要分布在7%～12%之间,渗透率变化于0.01～19.6×10^-3μm²,属于低孔低渗储层类型。从宏观和微观的角度阐明了储层的非均质性特征,指出储层的平面非均质性主要受沉积环境和沉积相的控制,四种不同类型的层内非均质性则与微相类型、沉积序列、成岩改造等有关。将孔隙演化与成岩演化有机结合起来,恢复了砂体的原始孔隙度为37%左右,经过压实、胶结、溶蚀等成岩变化,到白垩纪中、晚期油气充注时孔隙度降低为14%左右,后因原油降解生成沥青充填部分孔隙,导致孔隙度减小到现今的9%左右,并探讨了砂体的“四史”配置关系。采用三阶段的建模策略,运用地质原型模型和随机模拟方法,分别建立了长6段砂体的地层构造格架模型、三维沉积相模型和三维储层参数模型。运用模糊评判方法,对储集砂体进行分类评价,指出本区长6段不发育Ⅰ类好砂体,Ⅱ类较好砂体仅在局部零星发育,广泛发育的是Ⅲ类一般砂体。更多还原

【Abstract】 According to the comprehensive detailed analysis of data such as core, drilling, logging and outcrop section, three kinds of sedimentary facies, namely, delta, lake and sublacustrine fan, are recognized in the Chang 6 Member, Upper Triassic, Fuxian area. The genetic types of their sandbodies mainly include subaqueous distributary channel, river mouth bar, distal bar, subaqueous crevasse splay and levee, deltaic front sand sheet, sublacustrine gravity-flow channel, distal turbidite, and sand sheet and sandy shoal and bar in shallow lake. Developing in the rapid growing period of delta in Fuxian area, those facies are the inborn geological factors controlled the development and distribution of the reservoir sandbodies in the Chang 6 Member of this area. Through detailed study of high-resolution sequence stratigraphy, the Chang 6 Member of this area can be divided into three medium-term base-level cycle, while each medium-term base-level cycle is made up of four to six short-term base-level cycle. From the fact that development and space-time distribution of the reservoir sandbodies are mainly controlled by fluctuation of base-level cycle of different grades, the reservoir sandbodies division solution having muddy barriers deposited by flooding surface of different grades as the boundary is brought forward. On the basis of this solution, the Chang 6 Member of this area can be divided into three sand-suites. Using the sand-suites as the unit for mapping, it shows areal distribution of the stratum thickness, sandstone thickness and sedimentary facies of the three sand suites. According to the information of core description, slice identification, chemical examination and testing, reservoir bodies of the Chang 6 Member are comprised of medium-and fine-grained sandstone and siltstone, which belongs to arkose and lithic arkose, and are in the term A-B of late diagenetic stage after experiencing those destructive diagenesis such as compaction, cementation and replacement, and corrosion which causes increasing of porosity. The reservoir space of the sandbodies is dominated by secondary pore. Its. porosity ranges in 1.70%~16.30%, mainly in7%~12%, and permeability differs within 0.01—19.6 X10’3 u m2, and belongs to the kind of reservoir bed with lower porosity and lower permeability. The inhomogeneous characteristic of reservoir is illustrated macroscopieally and microscopically. It is indicated that plane inhomogeniety of reservoir beds is mainly controlled by the depositional environment and sedimentary fades, and four types of intrabed inhomogeniety are related to microfacies, depositional sequence and diagenetic reworking. Combining pore evolution with diagenetic evolution organically, the primary porosity of the sandbodies is recovered to 37%, and decreased to around 14% when oil and gas infilled in middle and late Cretaceous after experiencing diagenetic change such as compaction, cementation and corrosion. Later, due to degradation of oil into bitumen causing partial porosity filled up, the porosity currently redused to about 9%. With application of the model-building strategy of three stages and the metfaed of geologic model and random simulation, 3D model of stratigraphy-structure framwork, sedimentary fades, and reservoir parameter are established respectively for sandbodies of the Chang 6 Member. With the application of fuzzy judge methodology, a classification evaluation to the reservoir sandbodies is made, pointing out that Type I sandbody does not develop in this area, Type II sandbody is in scattered distribution, and Type HI sandbody is of abroad distribution.更多还原