致密砂岩凝析气藏油气水多相渗流规律研究

发布时间：2018-06-25 09:04

本文选题：致密砂岩凝析气藏 + 启动压力　；参考：《北京科技大学》2015年博士论文

【摘要】：拥有较大资源储量的致密砂岩凝析气藏,是非常规油气藏的重要组成部分,相关研究也已经受到重视。目前,针对致密砂岩凝析气藏研究的文献报道还较少,该类气藏由于存在相态变化,而且目前对该储层中多相渗流机理的认识还不清楚,成为了该类气藏高效开发的瓶颈。针对以上问题,本文选取吐哈油田两个致密砂岩凝析气藏为研究对象,拟以实验为主要手段,结合理论分析,系统研究影响流体渗流的储层渗透性伤害、应力敏感性、启动压力特征、多相渗流特征等关键问题,以期揭示储层中油气水多相复杂渗流规律,为致密砂岩凝析气田的开发提供理论和实验基础。本文从储层岩性和微观结构研究入手,通过渗流实验进一步研究了致密砂岩凝析气藏流体渗流对储层渗透性的影响,从液锁效应、井筒积液伤害和储层敏感性三方面揭示了储层渗透性的伤害机理。研究结果表明：储层为灰色中-巨粗砂岩,孔隙为粒内溶蚀孔、剩余粒间孔及微裂缝,喉道极其细小,液锁效应是由液相吸附作用引起的,液相过早析出和反凝析液污染近井储层都会加剧液锁效应。在储层特性研究基础上,通过自行设计实验流程和方法分别开展了致密凝析气储层的启动压力实验和气液渗流特征研究,揭示了启动压力的产生机理,认为吸附边界层是产生启动压力的内在原因,所设计的“非稳态动用-压力平衡法”测定启动压力,避免了以往方法测试误差大的缺点,模拟真实气藏所测得启动压力具有实际意义。将稳态法相渗实验引入到致密凝析气藏的气液渗流特征测试中,研究了两相和三相相渗特征,全面揭示了该类储层多相渗流规律。所测得两相渗流曲线除包含共渗区外还存在气和液的单相渗流区,反映了真实气藏变相态渗流全过程,避免了非稳态法只能测得两相共渗区的不足。油气水三相渗流中油相、气相的相对渗透率均是油气水三相饱和度的函数,而水相的仅仅是其自身饱和度的函数。在上述研究的基础上,还开展了储层真实岩心开采动态物理模拟实验,认为所研究气藏的采收率范围中等。最后结合致密砂岩凝析气储层的特点,建立了致密砂岩凝析气藏油气水三相渗流数学模型和产能计算方法。从室内物理模拟提升到理论模型和产能的研究,并将产能计算方法模拟结果与现场产量进行对比,进一步表明了该计算方法的合理性,并且对于油田现场具有一定的指导意义。
[Abstract]:Dense sandstone condensate gas reservoir with large reserves is an important part of unconventional reservoir. At present, there are few reports on the study of condensate gas reservoirs in dense sandstone. Due to the existence of phase behavior changes and the unclear understanding of the mechanism of multiphase percolation in this reservoir, this kind of gas reservoir has become the bottleneck of the efficient development of this kind of gas reservoir. In view of the above problems, this paper selects two tight sandstone condensate gas reservoirs in Tuha Oilfield as the research object, taking the experiment as the main means, combining with the theoretical analysis, systematically studies the permeability damage and stress sensitivity of the reservoir that affect the fluid percolation. The key problems such as start-up pressure characteristics and multiphase percolation characteristics are discussed in order to reveal the complex percolation law of oil, gas and water in reservoir and to provide theoretical and experimental basis for the development of condensate gas field in tight sandstone. Based on the study of reservoir lithology and microstructure, the effect of fluid seepage on reservoir permeability in tight sandstone condensate gas reservoir is further studied by seepage experiments, and the effect of liquid lock on reservoir permeability is also discussed in this paper. The damage mechanism of reservoir permeability is revealed in three aspects: wellbore fluid damage and reservoir sensitivity. The results show that the reservoir is gray medium to giant coarse sandstone, the pore is inner dissolution pore, the remaining intergranular pore and micro fracture, the throat is extremely small, and the liquid lock effect is caused by liquid phase adsorption. Early precipitation of liquid phase and contamination of near-well reservoir by reverse condensate will aggravate liquid locking effect. Based on the study of reservoir characteristics, the start-up pressure experiments and gas-liquid percolation characteristics of dense condensate gas reservoirs are carried out by designing the experimental flow and method, respectively, and the mechanism of start-up pressure is revealed. It is considered that the adsorption boundary layer is the internal cause of starting pressure. The unsteady-state production-pressure balance method is designed to measure the starting pressure, which avoids the shortcoming of large error in the previous methods. It is of practical significance to simulate the start-up pressure measured by real gas reservoir. The steady-state phase permeability experiment is introduced into the gas-liquid percolation characteristic test of dense condensate gas reservoir. The two-phase and three-phase permeability characteristics are studied, and the multi-phase percolation law of this kind of reservoir is fully revealed. The measured two-phase percolation curve contains gas and liquid single phase percolation zone, which reflects the whole process of real gas reservoir percolation, and avoids the deficiency that the unsteady state method can only measure the two-phase percolation zone. The relative permeability of the oil phase and the gas phase is the function of the three phase saturation of oil, gas and water, while the water phase is only the function of its own saturation. On the basis of the above research, the dynamic physical simulation experiment of reservoir real core production is carried out, and it is considered that the range of recovery factor of the studied gas reservoir is middle. Finally, combined with the characteristics of tight sandstone condensate gas reservoir, the mathematical model and productivity calculation method of oil-gas-water three-phase percolation in tight sandstone condensate gas reservoir are established. From indoor physical simulation to theoretical model and productivity research, the simulation results of productivity calculation method and field production are compared, which further shows that the calculation method is reasonable and has certain guiding significance for oilfield field.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE312

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