注气油藏原油性质变化规律研究
发布时间：2018-10-18 17:17
【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。
[Abstract]:The fractured and cavernous carbonate reservoirs in Tahe Oilfield are characterized by large caverns, dissolution pores and fractures as the main reservoir space, with strong heterogeneity and coexistence of various flow modes. Exploration and development is a world-class problem. Due to the high degree of formation water mineralization and the high reservoir temperature in Tahe Oilfield, all the technologies that have been successfully used in polymer flooding, ASP flooding, microbial method, thermal oil recovery and so on have been successfully used in sandstone reservoirs. Neither of them can be directly used in fractured and cavernous carbonate reservoirs in Tahe Oilfield. The development of reservoir cracks increases the risk of the application of high-cost chemical method. Gas injection is an effective method to improve oil recovery. Applying it to fractured reservoirs can not only maintain formation pressure, but also improve oil recovery effectively. The statistical data of field gas injection test show that the factors affecting gas injection effect include reservoir characteristics, fluid physical properties and dynamic parameters. Different characteristics of reservoirs have different requirements for gas injection mode and gas injection source. Based on the investigation of the present situation and development trend of gas injection enhanced oil recovery technology at home and abroad, this paper studies the reservoir characteristics and the formation crude oil properties and phase state before gas injection. Based on the analysis of the mechanism of enhanced recovery by injecting different types of gases, nitrogen and hydrocarbon gases were selected as the injection gas source of Tahe Oilfield for experimental study. Through laboratory experiments, the influence of different gases on the high pressure physical properties of formation fluid is clarified, and the variation law of formation fluid properties under different gas injection conditions is grasped, and the corresponding solutions are put forward. The experiment of gas injection and oil displacement was carried out in the laboratory simulation of fracture-cavity reservoir after water flooding, and the feasibility of gas injection to improve oil recovery was analyzed. The experimental results show that gas flooding after water flooding in fracture-cavity reservoir can further improve oil recovery. The results show that after gas injection, the volume coefficient of crude oil increases, the coefficient of expansion increases, the viscosity decreases and the density decreases. At the same gas injection pressure, the dissolved amount of natural gas is much higher than the dissolved amount of nitrogen gas, but at the same injection rate, the change of crude oil properties is similar. From the point of view of gas source and cost, the gas source of nitrogen is abundant, the cost is lower, and the later treatment is easier. Because the difference of gravity and viscosity between gas and oil is great, it is easier to form gravity differentiation with crude oil to achieve the purpose of replacing oil, so nitrogen is a kind of gas source with certain advantages when gas injection is used to improve oil recovery. The results also show that nitrogen injection will increase the saturation pressure of crude oil, decrease the volume coefficient and expansion coefficient of crude oil, and increase the viscosity of crude oil.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE357.7
本文编号：2279830
[Abstract]:The fractured and cavernous carbonate reservoirs in Tahe Oilfield are characterized by large caverns, dissolution pores and fractures as the main reservoir space, with strong heterogeneity and coexistence of various flow modes. Exploration and development is a world-class problem. Due to the high degree of formation water mineralization and the high reservoir temperature in Tahe Oilfield, all the technologies that have been successfully used in polymer flooding, ASP flooding, microbial method, thermal oil recovery and so on have been successfully used in sandstone reservoirs. Neither of them can be directly used in fractured and cavernous carbonate reservoirs in Tahe Oilfield. The development of reservoir cracks increases the risk of the application of high-cost chemical method. Gas injection is an effective method to improve oil recovery. Applying it to fractured reservoirs can not only maintain formation pressure, but also improve oil recovery effectively. The statistical data of field gas injection test show that the factors affecting gas injection effect include reservoir characteristics, fluid physical properties and dynamic parameters. Different characteristics of reservoirs have different requirements for gas injection mode and gas injection source. Based on the investigation of the present situation and development trend of gas injection enhanced oil recovery technology at home and abroad, this paper studies the reservoir characteristics and the formation crude oil properties and phase state before gas injection. Based on the analysis of the mechanism of enhanced recovery by injecting different types of gases, nitrogen and hydrocarbon gases were selected as the injection gas source of Tahe Oilfield for experimental study. Through laboratory experiments, the influence of different gases on the high pressure physical properties of formation fluid is clarified, and the variation law of formation fluid properties under different gas injection conditions is grasped, and the corresponding solutions are put forward. The experiment of gas injection and oil displacement was carried out in the laboratory simulation of fracture-cavity reservoir after water flooding, and the feasibility of gas injection to improve oil recovery was analyzed. The experimental results show that gas flooding after water flooding in fracture-cavity reservoir can further improve oil recovery. The results show that after gas injection, the volume coefficient of crude oil increases, the coefficient of expansion increases, the viscosity decreases and the density decreases. At the same gas injection pressure, the dissolved amount of natural gas is much higher than the dissolved amount of nitrogen gas, but at the same injection rate, the change of crude oil properties is similar. From the point of view of gas source and cost, the gas source of nitrogen is abundant, the cost is lower, and the later treatment is easier. Because the difference of gravity and viscosity between gas and oil is great, it is easier to form gravity differentiation with crude oil to achieve the purpose of replacing oil, so nitrogen is a kind of gas source with certain advantages when gas injection is used to improve oil recovery. The results also show that nitrogen injection will increase the saturation pressure of crude oil, decrease the volume coefficient and expansion coefficient of crude oil, and increase the viscosity of crude oil.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE357.7
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