【作者】 张彪；

【导师】 宁正福；

【作者基本信息】 中国石油大学(北京) ， 油气田开发工程， 2020， 硕士

【摘要】 致密油气资源勘探研究表明,我国致密油气资源分布广泛,储量丰富。本论文针对常用的致密储层开采技术所带来的高粘度压裂液污染储层,封堵渗流通道,以及环境污染等问题,提出了一种清洁无污染致密油开采新技术—EEOR(Electrical Enhanced Oil Recovery)。本论文从理论研究和实验研究两方面入手,深入分析研究EEOR技术的可行性,从而对致密油现场开发有一定的指导意义。首先从微观尺度入手,采用单一毛细管模型模拟多孔介质中一条渗流通道,通过求解Poisson-Boltzman方程得到电荷密度和电势的解析表达式,然后与NavierStokes方程结合得到单一毛细管中的电渗流流速表达式以及无因次表观粘度表达式。其次分析研究了宏观尺度下多孔介质中的电动学现象,利用分形理论,用一束不规则的毛管束模型来表征多孔介质,结合单一毛细管的电动学理论推导出多孔介质中电渗效应和电粘效应解析表达式。最后,以长-7地层天然露头岩心为实验对象进行室内物理模拟实验,结合前述章节的理论知识,分析直流电场提高致密砂岩驱替效率的效果,在实验过程中,主要考虑的影响因素为电势梯度,驱替液浓度,驱替方式,以及原油粘度。实验结果表明:存在最佳电势梯度和驱替液浓度(在本实验范围内分别为10V,0.7mol/L),使得致密砂岩驱替效率达到最大值,与不加电相比,驱油效率提高50%;在连续驱和同时加电驱驱替方式下,驱油效率均高于不加电下的常规水驱的驱油效率,此外同时加电驱驱替方式下的产油速度要高于连续驱替方式下的产油速度,从采收率提高效果看,低浓度下使用同时加电驱效果好,高浓度下使用连续加电驱效果好。通过以上研究表明,直流电场对改善致密储层物性,降低流动阻力,提高采收率有着较好的应用效果。更多还原

【Abstract】 The resources exploration research shows that tight oil and gas resources in China are widely distributed and rich in reserves.Due to the problems of high-viscosity fracturing fluid contaminated reservoirs,blocking percolation channels,and environmental pollution caused by commonly used tight reservoir production technologies,this paper proposes a new clean and unpolluted tight oil exploration technology-EEOR(Electrical Enhanced Oil Recovery).This thesis starts from the theoretical and experimental researches,and profoundly analyzes the feasibility of EEOR technology which has sort of guiding significance for the field development of tight oil.Firstly,in the micro-scale,a single capillary model is used to simulate a percolation channel in a porous medium.An analytical expression of the charge density and electric potential is obtained by solving the Poisson-Boltzman equation,and then combined with the Navier-Stokes equation to obtain the electroosmotic flow velocity expression in a single capillary expression and dimensionless apparent viscosity expression.Secondly,the electrokinetic phenomenon in porous media at the macro-scale is analyzed.By using fractal theory,a bundle of irregular capillary model is used to characterize the porous media.The electrokinetic theories in single-capillary theories are used to derive the analytic expression of electroosmotic effect and electro-viscous effect.Finally,the outcrop cores of the Chang-7 formation are used as the experimental object for indoor physical simulation experiments,and the theoretical knowledge of the previous chapter is used to analyze the effect of the DC electric field to improve the displacement efficiency of tight sandstone.During the experiment,the main influencing factor are electric potential gradient,displacement fluid concentration,displacement method,and crude oil viscosity.The experimental results show that there is an optimal potential gradient and displacement fluid concentration(10V,0.7mol/L respectively in the scope of this experiment),which makes the displacement efficiency of tight sandstone reach the maximum value,and compared with regular water displacement,displacement efficiency is increased by 50%;Under the conditions of sequential flooding and simultaneous flooding,the oil displacement efficiency are higher than that of conventional water flooding without applied DC.In addition,the oil production rate under the simultaneous flooding is higher than that of sequential flooding.In view of the effect of enhanced oil recovery,the effect of simultaneous flooding at low concentration is good,and the effect of sequential flooding at high concentration is good.The above research shows that the DC electric field has a good application effect on improving the physical properties of tight reservoirs,reducing flow resistance,and improving oil recovery.更多还原