敏感性普通稠油水驱油藏化学降黏实践

Practice of Chemical Viscosity Reduction in Water Flooding for Sensitive Conventional Heavy Oil Reservoirs

针对金8块强水敏普通稠油油藏水驱采收率低、蒸汽吞吐注汽困难的问题,开展了化学降黏研究,并选取2个井组进行矿场先导试验,通过室内研究和矿场实践证实了该技术的可行性。研究表明:多孔介质中原油、降黏剂、固相模型相互作用发生原油乳化分散、岩石润湿性改变、液滴变形和架桥封堵3项作用,从而实现降低原油表观黏度、剥离原油及扩大波及体积的作用。水驱后注入0.3倍孔隙体积降黏剂溶液,水驱残余油被分散乳化,由不可动油变成可动油重新流动,含水下降,采收率提高了7.29个百分点。采用数值模拟方法对试验井组进行设计,在目前反九点水驱井网上,先注入单一化学降黏溶液,当含水超过75%时添加泡沫进行降黏复合驱,化学剂段塞注入量应为0.4倍孔隙体积。对比试验井组注水和化学降黏开发1 a的指标,化学降黏具有减缓含水上升速度、提高采油速度、增加驱替见效期、提高储层吸水能力和提升开发经济效益等优势。该成果对同类油藏具有重要借鉴意义。

In response to the problems of low recovery rate of water flooding and steam injection difficulty in steam stimulation in the strongly water-sensitive conventional heavy oil reservoirs in Block Jin8,the chemical viscosity reduction,mine pilot test were conducted in two well groups,and the feasibility of this technology was verified by laboratory research and mine practice.The study shows that the interaction among crude oil,viscosity reducer and solid-phase model in porous media resulted in three effects:crude oil emulsification and dispersion,rock wettability change,and droplet deformation,bridging and blocking,thus reducing the apparent viscosity of crude oil,stripping the crude oil and expanding the swept volume.After water flooding,the remaining oil was dispersed and emulsified by injecting 0.3 times pore volume of viscosity reducer solution,and the immovable oil was changed into movable oil and flowed again,which decreased the water cut and improved the recovery efficiency by 7.29 percentage points.The test well clusters were designed with reservrir simulation technology.In the current inverted nine-spot water flooding well pattern,a single chemical viscosity-reducing solution was injected first;when the water content exceeded 75%,foam was added for viscosity-reducing compound flooding,and the volume of chemical agent injected into the slug should be 0.4 times the pore volume.Comparing the indicators of the test well cluster with water injection and chemical viscosity reduction for 1 year,chemical viscosity reduction has five advantages:slowing down the rise of water content,improving oil recovery rate,increasing the effective period of displacement,enhancing the water absorption capacity of the reservoir,and promoting the economic benefits of development.There is much for reference of the achievement of the study to similar reservoirs.