束鹿凹陷中南部古近系致密砾岩成因类型及储层评价

发布时间：2018-03-18 20:44

本文选题：岩石类型　切入点：碳酸盐岩　出处：《中国地质大学(北京)》2016年博士论文　论文类型：学位论文

【摘要】：致密油气作为非常规油气的重要组成部分,具有广阔的勘探前景。束鹿凹陷位于渤海湾盆地冀中坳陷的西南部,在古近系沙河街组三段下部沉积时期发育了大套以碳酸盐岩碎屑为主的、具低孔低渗特征的角砾岩,近年来成为华北油田致密油气勘探的重要目标。本文综合地震、测井、岩心、薄片及分析测试等资料,对束鹿凹陷砾岩的沉积特征和储层特征进行了研究,建立了沉积模式,探讨了有利储层发育的控制因素,并提出了致密砾岩储层的评价方法。将内源砾石纳入岩性分类方案,依据支撑类型和颗粒来源将砾岩分为颗粒支撑陆源砾岩、颗粒支撑混源砾岩、杂基支撑陆源砾岩、杂基支撑混源砾岩和颗粒支撑内源砾岩五种。陆源砾石的母岩是来自古生代的碳酸盐岩,内源砾石与陆源砾石类似,具有明显的砾石边界,但易变形,具有软沉积物变形的特征,形状不规则,被拉长或者压扁呈长条状或次圆状,可能形成于古近系碎屑流侵蚀下伏软沉积物并携带向前搬运的过程中。根据砾岩的沉积构造及展布特征等,从成因上将砾岩分为两大类,一类是冲积扇与湖泊作用形成的扇三角洲砾岩,一类是地震作用形成的滑塌扇砾岩。扇三角洲平原和前缘的辫状河道,岩性既有杂基支撑陆源砾岩又有颗粒支撑陆源砾岩,见砾石的近叠瓦状排列或者低角度定向排列,正粒序和反粒序都比较发育。地震诱发的滑塌扇内扇主水道发育巨厚的颗粒支撑陆源砾岩,中扇辫状水道形成的砾岩岩石类型比较复杂,这些砾岩与盆内广泛分布的典型震积岩伴生。震积岩主要标志有软沉积物液化变形(液化脉、液化水压构造、底辟构造、液化卷曲变形、负载和球枕构造、环形层和沉陷构造)和脆性变形(微同沉积断裂)。该区碳酸盐角砾岩储层具有低孔低渗-致密的特征,孔隙度主要集中在0.4%~6%之间,渗透率为(0.04~40)×10-3μm2,局部裂缝发育的地方渗透性好,总体属于裂缝-孔隙型。储集空间包括粒内孔(石英等颗粒的溶解孔,晶粒白云岩的晶间孔和晶间溶孔)、粒间孔、裂缝(构造缝、贴粒缝、收缩缝、砾内缝)以及有机质孔隙。储层的物性主要受砾石成分、岩相、成因类型、成岩作用、构造作用以及有机质控制。针对致密砾岩的沉积和储层特征,建立了“砾石成分-岩相-砾岩成因-裂缝-成岩作用-有机质”六位一体的评价方法,指出了致密砾岩有利储层的分布区域。
[Abstract]:As an important part of unconventional oil and gas, dense oil and gas have a broad prospect of exploration. Shoulu sag is located in the southwest of Jizhong depression in Bohai Bay basin. During the lower depositional period of the third member of Shahejie formation, Paleogene, a large set of breccia with the characteristics of low porosity and low permeability was developed, which is mainly carbonate rock clastic. In recent years, it has become an important target of tight oil and gas exploration in North China Oilfield. In this paper, the sedimentary characteristics and reservoir characteristics of conglomerate in Shulu sag are studied, the sedimentary model is established, and the controlling factors of favorable reservoir development are discussed. The evaluation method of dense conglomerate reservoir is put forward. According to the support type and grain source, the conglomerate is divided into three groups: granular support continental conglomerate, granular support mixed conglomerate, complex base supporting continental conglomerate, and complex base supporting continental conglomerate. There are five kinds of mixed conglomerate and endogenetic conglomerate supported by complex base. The parent rock of continental source gravel is carbonate rock from Paleozoic. The endogenous gravel is similar to continental gravel and has obvious gravel boundary, but it is easy to deform. Characterized by deformation of soft sediments, irregular in shape, elongated or compressed in long or subcircular form, It may be formed in the process of soft sediment and carrying forward transport under the erosion of Paleogene clastic flow. According to the sedimentary structure and distribution characteristics of conglomerate, the conglomerate can be divided into two categories from genesis. One is fan delta conglomerate formed by alluvial fan and lacustrine interaction, the other is sliding fan conglomerate formed by earthquake. It can be seen that the near imbricate arrangement or the low angle directional arrangement of the gravel, both the positive grain sequence and the reverse grain sequence are relatively developed. The main channel of the inner fan of the slide fan induced by the earthquake develops extremely thick grains to support the continental conglomerates. The types of conglomerate rock formed in the middle fan braided channel are quite complex, and these conglomerates are associated with typical seismite widely distributed in the basin. The main indicators of seismite are the liquefaction deformation of soft sediments (liquefaction vein, liquefied water pressure structure, diapir structure). Liquefaction curl deformation, load and ball pillow structure, annular layer and subsidence structure) and brittle deformation (micro-synsedimentary fault). The carbonate breccia reservoir in this area is characterized by low porosity and low permeability, with porosity mainly between 0.4% and 6%. The permeability is 0.04 ~ 40 脳 10 ~ (-3) 渭 m ~ (2). The local fracture has good permeability and belongs to the fracture-pore type. The reservoir space includes the intragranular pore (dissolution pore of quartz and other particles), intergranular pore and intergranular dissolved pore of grain dolomite, intergranular pore, fracture (structural fracture, etc.). The physical properties of the reservoir are mainly controlled by gravel composition, lithofacies, genetic type, diagenesis, tectonism and organic matter. The evaluation method of "gravel composition-lithofacies-conglomerate genesis-fracture-diagenesis-organic matter" is established, and the distribution area of compact conglomerate favorable reservoir is pointed out.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P618.13

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