洞-缝-洞介质中水驱油注采规律研究

Law of Water Flooding in Vug-Fracture-Vug Medium

张东 李爱芬 姚军 司志梅

Zhang Dong Li Aifen Yao Jun Si Zhimei

中国石油大学(华东)石油工程学院,山东青岛 266580

School of Petroleum Engineering,China University of Petroleum(Huadong),Qingdao,Shandong,266580,China

为了揭示缝洞型油藏的注采机理,研究了缝洞介质中的水驱油规律。利用有机玻璃制作了一组不同裂缝宽度的洞-缝-洞组合模式物理模型,开展了物理模拟试验,分析了水驱后剩余油分布规律及形成机制,并研究了注入速度、裂缝宽度、毛管力对水驱油采收率、含水率的影响,通过相似理论计算得到了不同溶洞高度对应的临界裂缝宽度。研究发现:水驱后的剩余油主要存在于未波及的单向连通溶洞与裂缝中,表面活性剂溶液驱后的剩余油主要存在于单向连通溶洞的上部;当溶洞内的油水界面到达一定高度产生的压差克服毛管力作用时,水才能进入裂缝底部;注入速度越小、裂缝宽度越大、毛管力越小,模型采收率越高;溶洞高度越高,其对应的临界裂缝宽度越小。研究结果表明,表面活性剂驱可以提高洞-缝-洞型油藏的采收率。

It is important to study the law of water flooding in fractured-vuggy medium to determine the development mechanism of fractured-vuggy reservoir.Based on a typical connecting type of fractures and vugs,a series models with different fracture aperture were made from synthetic glass.Physical simulation experiments were carried out by using those models,and the distribution and origin of residual oil were analyzed.The influences of flow velocity,fracture aperture and capillary force on oil recovery and water cut were studied.The critical fracture aperture in different vug heights was further calculated using similarity criteria.The results indicated that the residual oil after water flooding mainly lay in the not connected bypassed vugs and fractures.The residual oil after surfactant flooding mainly lay in the top of the not connected vugs.When the differential pressure,which was caused by the interface of oil and water rising in the vugs,could overcome the capillary force,water would flow into the bottom of the fracture.The oil recovery of the model increased along with the decreasing of flow velocity,increasing of fracture aperture and decreasing of capillary force.The critical fracture aperture decreased along with the increasing of vug height.The oil recovery of this vug-fracture-vug medium can be effectively enhanced by surfactant flooding.

国家重点基础研究发展计划("973"计划)项目"碳酸盐岩缝洞型油藏开采机理及数值模拟研究"(编号:2011CB201004)、国家科技重大专项"剩余油形成机理及定量分析方法研究"(编号:2011ZX05014-003-006HZ)部分研究成果。

https://doi.org/10.3969/j.issn.1001-0890.2012.04.017