【作者】 胡振华；

【导师】 汪伟英； 汪庆；

【作者基本信息】 长江大学 ， 石油与天然气工程， 2015， 硕士

【摘要】 塔河油田缝洞型碳酸盐岩油藏以大型溶洞、溶蚀孔洞及裂缝为主要储集空间,其非均质性极强,且多种流动方式共存,勘探开发属于世界级难题。由于塔河油田油藏地层水矿化度高及油藏温度高,使得所有已成功用于砂岩油藏的聚合物驱、三元复合驱、微生物法、热力采油等提高采收率技术,均不能直接用于塔河油田缝洞型碳酸盐岩油藏。储集体裂缝发育,更增添了高成本化学法应用的风险性。注气是一种有效的提高原油采收率的方法,将其应用于裂缝性油藏,不仅可以维持地层压力,还可以有效提高采收率。矿场注气试验统计数据表明,影响注气效果的因素包括油藏特征、流体物性和动态参数三方面。不同特点的油藏对注气方式和注气气源有不同的要求。本论文在对国内外注气提高采收率技术现状及发展趋势调研的基础上,通过对缝洞型油藏储层特征和注气前地层原油性质及相态的研究,综合注入不同类型气体提高采收率机理的分析,确定采用氮气和烃类气体作为塔河油田注入气源进行实验研究。通过室内实验研究,明确了不同气体对地层流体高压物性特征的影响,掌握了不同注气条件下,地层流体性质变化规律,提出相应的解决方案。在室内模拟缝洞油藏注水后进行注气驱油实验,分析注气驱油提高采收率的可行性,实验结果表明,缝洞油藏水驱之后进行气驱可以进一步的提高原油采收率。研究结果表明：注气后原油体积系数增大,膨胀系数升高,粘度下降,密度降低。在相同注气压力下,天然气溶解量远高于氮气溶解量；但相同注气量时,原油性质变化幅度相近；从气源和成本的角度考虑,氮气的气源丰富,成本较低,后期处理较容易,由于气油重力差和粘度差的差异较大,更容易与原油形成重力分异现象从而达到替油的目的,因此对于缝洞型油藏注气替油提高采收率时氮气是一种具有一定优势的气源。研究结果还显示,注入氮气含氧将导致原油饱和压力增大,体积系数和原油膨胀系数均有所降低,原油粘度上升,对注气提高采收率不利,同时也会给生产带来安全隐患。更多还原

【Abstract】 The fracture-pore carbonate reservoir is characterized by network reservoir,with cavity as the main accumulating space and fracture as the connection channel. Tahe Oilfield is of strong heterogeneous carbonate reservoir, various flow way co-exist, and exploration and development is very difficult. Because of the high salinity of formation water and high temperature of the reservoir, the methods such as polymer flooding, three element composite, microbial method, thermal recovery and EOR technology which have been successfully used in sandstone reservoir, can’t be directly used for cave type carbonate reservoir in Tahe oilfield seam. The development of reservoir fracture leads to the high risk of using chemical method.Gas injection is an effective method for enhancing oil recovery. It not only can maintain the formation pressure, but also can effectively improve the recovery rate for the gas injection process in a fractured reservoir. Mine gas injection test statistics show that there are three factors including reservoir characteristics, fluid properties and dynamic parameters affect gas injection results. The different characteristics of the reservoir have different requirements for gas injection and gas source. This thesis focuses on the domestic and foreign gas injection to enhanced oil recovery based on the present situation and development tendency of research, through the research on cave type reservoir characteristics and gas injection before the formation oil properties and phase behavior of different types of gas injection,the comprehensive analysis of improving oil recovery mechanism,identified as the Tahe oil field gas injection was applied to study nitrogen and hydrocarbon gas. Through laboratory experiments, we know the effects of different gases on the characteristics of formation fluid pressure. And in the different gas injection conditions, we know the change rule of fluid properties. What’s more, we put forward the corresponding solutions. After water injection for fractured reservoir, we do gas injection simulation experiment in the indoor. Firstly, we have an analysis of the feasibility of gas injection for enhancing oil recovery. Secondly, compared with the gas injection flooding development methods, in order to improve the recovery rate of provide the basis for scheme selection.The results show that volume coefficient of crude oil increases, the expansion coefficient increased, the viscosity decreased, the density decreased after gas injection. At the same gas injection pressure, gas solubility is much higher than the amount of nitrogen dissolved. When they are the same injection rate, the range-ability of oil property was similar. In Consideration of the source and cost, nitrogen has the rich sources and low cost. What’s more, it is easy for post-processing. In immiscible flooding or gravity function mechanism flooding, Nitrogen for crude oil light component extraction ability is lower than that of the natural gas. So Nitrogen has advantages for gas injection in a fractured reservoir. Due to gravity difference and viscosity difference, it is easier to form gravity differentiation phenomenon so as to achieve the purpose of oil displacement. The results also show that if nitrogen injection has oxygen, it will lead that oil saturation pressure rise, volume coefficient and expansion coefficient of the crude oil was decreased, the viscosity of the crude oil rise. It is bad for gas injection, and it will bring hidden dangers in the production.更多还原