裂缝闭合规律及其渗流特征研究

发布时间：2018-08-11 11:35

【摘要】：近年来,随着油气田勘探开发的不断深入,裂缝性油气藏的勘探开发在我国有着越来越重要的战略地位。新探明的复杂裂缝性油气藏储量在总的油气资源探明储量的比例不断增加,产量也逐年增长。但高效的开发该裂缝性油气藏却十分困难,因为在裂缝性储层开采过程中,虽然开采前期产能较高,但开采一段时间后,大部分气井产量迅速降低。而其主要原因是:裂缝性储层中的油气被大量采出,裂缝系统内流体压力迅速下降,造成裂缝开度减小,裂缝渗透性也因此而减小。另外,储层裂缝一旦在作用力下发生闭合将不易恢复,即使后期采取注气等措施以恢复地层压力,裂缝的渗流能力也将变得很弱。这将会导致基质岩石中大量的残余油气无法开采,从而将使得该区块油气采收率低。为此,针对裂缝性油气藏这一生产问题,本文以石油工程、石油地质、岩石力学以及渗流理论等学科为基础,通过实验研究和计算机数值模拟,对储层裂缝表面形态特征规律、在不同作用力下的裂缝闭合规律及裂缝内流体渗流特征进行了系统研究,主要完成了以下几个方面的内容:①结合西部地区A区块储层裂缝,系统描述了裂缝的基本特征,包含裂缝分类方法、储层裂缝表征参数、裂缝识别方法以及影响储层裂缝发育的因素;②对裂缝的闭合规律及其裂缝内流体渗流特征进行了理论和实验研究,得出了不同围压下裂缝渗透率和裂缝开度的动态变化规律;③通过储层裂缝闭合实验与仿真模拟相结合,验证了裂缝闭合三个阶段的应力分布、速度场、压力场的变化规律;④基于真实裂缝空间渗流的影响因素,仿真模拟得出了真实裂缝粗糙度和裂缝宽度等对裂缝渗流的影响;⑤在结合室内试验与数值模拟裂缝闭合规律及渗流特征的基础上,探讨了生产过程中井底裂缝的闭合规律以及裂缝闭合对裂缝性油气藏开发效果的影响。这对进一步深入认识裂缝闭合机理及其渗流规律,确定裂缝性油气藏的开发方式和开采速度,准确评价裂缝性油气储层产能变化规律,提高该裂缝性气藏生产能力和油气采收率都具有非常重要的指导意义和实践价值,并能为类似裂缝性油气藏提供参考价值。
[Abstract]:In recent years, with the deepening of exploration and development of oil and gas fields, the exploration and development of fractured reservoirs has more and more important strategic position in China. The proportion of proved reserves of complex fractured reservoirs in the total proved reserves of oil and gas resources is increasing, and the output is increasing year by year. But it is very difficult to develop the fractured reservoir efficiently, because in the process of producing fractured reservoir, although the early production capacity is high, the production of most gas wells decreases rapidly after a period of production. The main reason is that the oil and gas in the fractured reservoir are produced in large quantities, the fluid pressure in the fracture system decreases rapidly, resulting in the decrease of fracture opening and fracture permeability. In addition, once the reservoir fracture is closed under the action force, it will not be easy to recover, even if the gas injection is taken to restore the formation pressure in the later stage, the seepage ability of the fracture will become very weak. This will result in a large amount of residual oil and gas in the matrix rock can not be exploited, which will make the block oil and gas recovery low. Therefore, aiming at the production problem of fractured oil and gas reservoir, based on petroleum engineering, petroleum geology, rock mechanics and percolation theory, and through experimental research and computer numerical simulation, the characteristics of fracture surface morphology in reservoir are studied in this paper. The fracture closure law and fluid percolation characteristics in fractures under different forces are systematically studied. The following contents are mainly completed: 1) combining with the reservoir fractures in block A of the western region, the basic characteristics of fractures are described systematically. Including fracture classification method, reservoir fracture characterization parameters, fracture identification method and factors affecting the development of reservoir fractures, this paper makes theoretical and experimental research on the fracture closure law and the fluid seepage characteristics in the fracture, including the fracture classification method, the reservoir fracture characterization parameters, the fracture identification method and the factors affecting the development of the reservoir fractures. The dynamic variation law of fracture permeability and fracture opening under different confining pressure is obtained. Through the combination of reservoir fracture closure experiment and simulation, the variation law of stress distribution, velocity field and pressure field in three stages of fracture closure are verified. (4) based on the influencing factors of real fracture space seepage, the influence of real crack roughness and crack width on fracture seepage is obtained by simulation. 5 based on the combination of laboratory test and numerical simulation, the fracture closure law and seepage characteristics are obtained. The law of bottom hole fracture closure and the effect of fracture closure on fractured oil and gas reservoir development are discussed in this paper. This is helpful to further understand the mechanism of fracture closure and its percolation law, to determine the development mode and production speed of fractured reservoirs, and to evaluate accurately the law of productivity change of fractured oil and gas reservoirs. It is of great significance and practical value to improve the production capacity and oil and gas recovery of the fractured gas reservoir and to provide reference value for similar fractured reservoirs.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE312

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