泡沫协同注气重力驱提高采收率实验

Experiment of enhanced oil recovery of foam coordinated gas assisted gravity drainage

针对泡沫协同注气重力驱(GAGD)提高采收率效果及机理认识不清的问题,通过三维物理模拟岩心驱替实验,研究泡沫与注气重力驱的协同增油效果;采用大尺寸微观模型开展微观驱替实验,分析油、气、泡沫间的驱替关系与驱油机制。从宏、微观角度,全面揭示泡沫与GAGD组合驱的驱油潜力。结果表明:泡沫与GAGD组合驱替方式可以有效解决GAGD气窜后产油量急剧下降的问题,组合驱岩心实验采收率高达59.4%,远高于GAGD岩心实验采收率(44.9%);气体突破后注泡沫时机越早,泡沫与GAGD组合驱的驱替效果越好;注入泡沫量越多,泡沫与GAGD组合驱效果越好,但这种增幅作用会随着注入量的增多逐渐减小;泡沫与GAGD组合驱的微观驱油机制表现为泡沫封堵主要流动通道,而非主流通道内的泡沫“遇油消泡”,泡沫在孔隙中会残留表面活性剂溶液,形成气-表面活性剂-油模式下的多重驱替方式,将GAGD扩大波及体积的作用与表面活性剂提高驱油效率的作用相结合,协同增效,极大地提高了原油采收率。研究成果为泡沫协同注气重力驱的技术优化与矿场实践提供了依据。

Aiming at the problem of unclear understanding of effect and mechanism of foam coordinated gas assisted gravity drainage(GAGD)to enhance oil recovery,3D physical simulation of core flooding experiment is performed to study synergistic oil production increasing effect of foam and GAGD.Microscopic displacement experiment is car-ried out using large-scale microscopic model to analyze displacement relationship among oil,gas and foam and dis-placement mechanism.Displacement potential of combined foam-GAGD flooding is comprehensively revealed from macro and micro perspective.The results show that combined flooding of foam and GAGD can effectively solve the problem of rapid oil production decline after GAGD gas channeling.Combined flooding recovery is 59.4%,much higher than GAGD recovery of 44.9%in core experiment.The earlier the foam is injected after gas breakthrough,the better the foam-GAGD displacement effect is.The more amount of foam is injected,the better the foam-GAGD is,but increment gradually decreases with the increase of injection amount.Microscopic displacement mechanism of combined foam-GAGD flooding is represented by foam plugging the main flow channels,while foam in non-main flow channels is“defoamed in contact with oil”,with surfactant solution retended in pores,forming a multiple dis-placement mode of gas-surfactant-oil.Combining GAGD expanding swept volume with surfactant improving dis-placement efficiency synergistically increases efficiency,significantly enhancing oil recovery.The research pro-vides basis for technical optimization and field practice of foam coordinated gas assisted gravity drainage.