中国北方典型（特）低渗透砂岩油藏储层裂缝研究

【作者】 张莉；

【导师】 曲志浩； 岳乐平；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2001， 博士

【摘要】 中国含油气盆地按照构造体系可以分为伸展型盆地、稳定型盆地、挤压型盆地等几种类型。裂缝的成因类型、分布形式以及地质特征与不同构造体系的盆地类型有关。本论文选择中国东部、中部和西部不同含油气盆地中的头台油田、朝阳沟油田、肇州油田、榆树林油田、哈南油田、川口油田、安塞油田及鄯善油田等典型的（特）低渗透砂岩油藏，系统研究了伸展型、稳定型、挤压型盆地裂缝的成因机制、发育特征及分布规律，初步建立了不同构造体系类型盆地的裂缝地质模型，并对不同低渗透砂岩油藏储集层进行了分类，最后探讨了不同类型盆地裂缝在注水开发中的作用。 松辽盆地为伸展型盆地，但经历了明显的反转期，盆地具拉伸和挤压双重特征。伸展构造期主要形成一组近南北向的拉张破裂裂缝和两组斜交共轭剪裂缝。反转构造期主要形成北东、北西向两组共轭剪裂缝和一组近东西向的横张裂缝，随着背斜的弯曲，在核部可能会形成一些少量的张裂缝。三肇地区的构造裂缝主要是在反转构造期形成，其分布受褶皱控制，断层也有一定的控制作用。在现今地应力场作用下注水开发中以东西方向窜水为特征。二连盆地为伸展型盆地，主要发育与伸展断层有关的裂缝。裂缝方向与伸展断层走向基本一致，主要为NNE方向裂缝，其分布受伸展断层的控制。注水开发中显示出明显的断裂导水。 中部稳定区块选择陕甘宁盆地中部川口油田和安塞油田作为研究对象，该区褶皱与断裂构造相对不发育，但在地应力作用下，坚硬脆性岩石仍然可以发生破裂形成裂缝。盆地范围内分布近EW向区域裂缝，其分布主要与沉积微相有关。 吐哈盆地主要发育与褶皱作用有关的裂缝，这与西部挤压型的区域构造特征相符合。裂缝分布受褶皱构造的控制，裂缝发育部位为构造高部位及构造曲率较大的部位。 为了研究不同盆地裂缝在注水开发中的作用，进行了微观砂岩模型水驱油实验，比较了东、中和西部含油气盆地中不同裂缝系统的水驱油特征。开启裂缝系统，一般水驱油方式为裂缝驱油及裂缝一部分基质孔隙驱油，对于微裂缝系统，主要水驱油方式为裂缝—基质孔隙驱油及孔隙驱油，充填裂缝系统则为孔隙驱油方式。 按照裂缝发育特征、发育程度及其对储集层渗流的影响，将中国含油气盆地（特）低渗透砂岩油藏储集层分为裂缝型（包括孔隙—裂缝型储集层和裂缝—孔隙型储集层）和（含裂缝）孔隙型。不同介质类型在注水开发中具有不同的渗流特性。对于孔隙—裂缝型储层，实际上渗流过程主要为单一渗流通道体系—裂缝中的流动，即表现为似 张莉：中国北方典型（特）低渗透砂岩油藏储层裂缝研究（西北大学博士论文）单一介质型储层的渗流特征。对于裂缝—孔隙型储层，属于双重介质型储层；注水开发可以分为两个过程，即裂缝多相渗流阶段和裂缝中水置换油阶段。对于孔隙型储层，开发过程中的油水流动在孔隙中进行。中国东部、西部含油气盆地储层的渗流类型主要为似单一裂缝介质型和双重介质型，中部含油气盆地储层的渗流类型可以表现为裂缝HL隙型和孔隙型。 东部、西部大部分和中部部分裂缝发育的（特）低渗透区块，构成裂缝型油藏，。可以采用超前注水、周期性注水、控讳注水强度、不等距井网等措施改善开发效果。孔隙型油藏在注水开发中可以遵循一般（特）低渗透砂岩油藏开发的原则，但经过压裂的孔隙型油藏，仍应注意裂缝对注水开发的影响。更多还原

【Abstract】 The development tendency of Chinese oil industiy indicates that the large-scale oilfields with good physical properties are fewer and fewer. Hence the exploration and development of low-permeability oilfields are increasingly exerting attention. Since 1990s in China, the ratios of reserves of low-permeability reservoirs to total proven reserves are higher and higher. At present, the reserves of low-permeability reservoirs reach more than 70%. As a result, low- permeability oilfields are thought to be the main bases in Chinese petroleum indusUy. With the development of low-permeability oilfields, it is found that fractures play important roles in waterflooding. On the one hand, natural fractures may increase the permeability of reservoirs, link up pores and improve the production of oil wells, which is profitable to reservoirs. On the other hand, fractures will increase the heterogeneity of reservoirs, result in the water channeling along fractures in the waterflooding and as a result play a negative role in the developmenL In a word, fractures not only decide waterflooding effects, but also control layer division and pattern arrangement. Hence, the study of fractures has been attached more and more attention and it is of significance to get a deeper understanding and study. Chinese petroliferous basins can be classified structurally as extensional, stable and compressional basins. The purpose of the thesis is to develop the different fracture geologic models for different basins. Many typical low-permeability sandstone reservoirs such as Toutai, Yushulin, Chaoyanggou, Hanan, Shanshan, Changqing and Chuankou oilfleld are selected to study the characteristics of fractures. In the Songliao basin, fractures are fanned through the two stages - the extensional and reversal stage. Two or three fracture orientation sets could develop during the early extensional stage. One set is the SN extension fracture and the others are shear fractures. Mineral cement is vety typical in these fracture sets. NE and NW shear fracture sets and EW extension fracture set are found to develop in the late reversal stage, which are controlled by folds. The Erlian Basin is an extensional basin and fractures are considered to be related to extension faults. The fractures extend along the direction of faults, that is NNE fracture set. The fracture nets play a very important role in the exploration and development of the Hanan oilfield. iii 2 In the middle stable basin, although folds and faults are few, fractures can be formed in the brittle rocks. The fracture types are the EW regional fractures, which were formed during Yanslian periods and the NE fractures formed during Xishan periods. The fracture distribution and density are related to lithology and rock thickness. Fractures related to folds are developed in the western compressional basin Sandstone micro-model experiment technique is used and the water-oil displacement experiment is done to simulate the conditions of reservoir flowing. Low-permeability sandstone reservoirs can be divided mainly into two types according to the characteristics, density and the effect of fractures on reservoirs. These two types are fractured sandstone reservoirs (including porous-fractured reservoirs and fractured-porous reservoirs) and porous reservoirs. Different types have different flowing characters duri更多还原