二类油层复习体系流动能力及驱油效果研究

发布时间：2018-10-18 14:53

【摘要】：聚合物/三元复合体系驱油在大庆油田一类油层中已经得到应用并且取得了良好的经济效益。但是随着油田开采年限的不断加长,大部分主力油层已经进入高含水阶段,随着油井含水的增加,原油开采的经济效益越来越差,这就迫切地需求加大对二类或三类油层的开采力度。由于二类油层与主力油层相比具有渗透率低、厚度薄、连通性差的特点,使得传统的驱油方法在二类油层中并不完全适用。因此需要在二类油层条件下进一步研究提高原油采收率的方法。为研究复合驱油体系在二类油层中的流动能力及其驱油效果,在实验研究过程中,以恒压注入为主要实验条件,通过测量不同注入压力与流量的对应关系,开展了同一岩心注入不同粘度聚合物体系实验方法的研究,不同渗透率岩心不同粘度体系渗流规律研究,利用流量-压差法确定了启动压力梯度,分析了渗透率、体系粘度与相同稳定流量对应的注入压力之间的关系。结果表明:注入压力梯度与稳定流量之间呈现近似线性关系。岩心渗透率越低,体系粘度越高,启动压力梯度越大。以实验数据为基础,绘制了不同注入压力梯度下不同粘度聚合物体系的流体流动难易图版。通过开展三元复合体系室内一维渗流实验,分析了不同粘度三元复合体系在不同渗透率岩心中的渗流规律,以及三元复合体系与聚合物溶液渗流规律的差异。研究结果表明:三元复合体系与聚合物在岩心内流动特性相似,这是由于ASP体系流动性质主要由聚合物决定。另外,由于三元复合体系在岩心内存在竞争吸附,减少了聚合物溶液在孔隙表面的吸附,宏观表现为相同压力条件下三元复合体系渗流阻力较低,流量较大。最后,应用三管并联岩心进行驱油实验,研究了不同驱替阶段聚合物及三元复合体系驱油过程中的流量分配率、含水率和采油率变化,评价了渗透率级差对采收率的影响及剩余油分布状况。研究结果表明:聚驱含水率普遍高于三元复合体系含水率,且同一体系渗透率级差增加,含水率下降程度减弱;相同渗透率级别条件下,三元复合体系化学驱采收率都高于聚合物,且同一体系渗透率级差越大,化学驱采收率越低。本文研究结果能够为聚合物及复合驱油体系在二类油层内推广应用奠定理论基础,对于有效开发二类油层具有重要意义。
[Abstract]:Polymer / ASP flooding system has been applied in Daqing oil field and good economic benefits have been obtained. However, as the production life of the oil field continues to grow, most of the main reservoirs have entered the stage of high water cut. With the increase of water cut in oil wells, the economic benefits of crude oil production are getting worse and worse. There is an urgent need to increase the production of two or three types of reservoirs. Due to its low permeability, thin thickness and poor connectivity, the conventional flooding method is not completely applicable in the second class reservoir. Therefore, it is necessary to further study the method of improving oil recovery under the condition of the second class reservoir. In order to study the flow ability of the compound flooding system in the second class reservoir and its displacement effect, in the course of experimental study, the relationship between different injection pressure and flow rate was measured by taking constant pressure injection as the main experimental condition. The experimental method of injecting different viscosity polymer system into the same core and the seepage law of different viscosity system in different permeability core are studied. The starting pressure gradient is determined by using flow-pressure difference method, and the permeability is analyzed. The relationship between the viscosity of the system and the injection pressure corresponding to the same steady flow rate. The results show that there is an approximate linear relationship between the injection pressure gradient and the steady flow rate. The lower the core permeability, the higher the viscosity and the higher the starting pressure gradient. Based on the experimental data, the fluid flow chart of polymer system with different viscosity under different injection pressure gradient was plotted. Through the laboratory one-dimensional seepage experiments of ternary composite system, the seepage law of different viscosity ternary composite system in different permeability rock core and the difference of seepage law between ternary composite system and polymer solution are analyzed. The results show that the flow characteristics of the ternary composite system are similar to those of the polymer in the core because the fluidity of the ASP system is mainly determined by the polymer. In addition, due to the competitive adsorption in the core, the adsorption of polymer solution on the pore surface is reduced. The macroscopical performance is that the seepage resistance of the ternary composite system is lower and the flow rate is larger under the same pressure. Finally, the flow distribution rate, water cut and oil recovery rate of polymer and ternary composite system in different displacement stages were studied by using three parallel core flooding experiments. The influence of permeability differential on oil recovery and the distribution of remaining oil are evaluated. The results show that the water cut of polymer flooding is generally higher than that of ternary composite system, and the permeability difference of the same system increases, and the decrease of water cut is weakened. The chemical flooding recovery of the ternary composite system is higher than that of the polymer, and the greater the permeability difference of the same system, the lower the chemical flooding recovery. The results of this paper can lay a theoretical foundation for the extension and application of polymer and composite flooding system in the second class reservoir, and are of great significance for the effective development of the second class reservoir.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.46

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