低界面张力黏弹流体驱油效果评价及微观驱油机理

特低渗油藏储层物性差、层间非均质性强,注水开发过程中普遍存在含水率上升快,产量递减严重等问题,为进一步改善特低渗透油藏水驱开发效果,开展了低界面张力黏弹流体驱油研究。采用岩心驱油实验评价低界面张力黏弹流体驱油效果,并利用微观可视模拟技术研究低界面张力黏弹流体微观驱油机理。结果表明,岩心单管和双管驱油实验水驱结束,转注低界面张力黏弹流体后,采收率分别提高了7.47%、23.14%;低界面张力黏弹流体的注入可对驱油剖面进行有效调整,增加原油动用程度;水驱后剩余油主要以簇状、孤岛状、膜状、盲端状以及柱状5种形式存在,簇状剩余油所在比例最大;低界面张力黏弹流体可通过增黏、屏蔽暂堵、乳化以及岩石表面润湿性改变等多种作用机制协同,将水驱后剩余油以“塞流式”或乳化分散形成小油滴被夹带渗流运移产出,具有较好的流度控制和洗油能力,在特低渗油藏开发中具有优异的潜在应用前景。

Evaluation of Oil Displacement Effect and Microscopic Oil Displacement Mechanism of Viscoelastic Fluid With Low Interfacial Tension

The ultra-low permeability reservoir has poor physical property and strong interlayer heterogeneity. In the process of waterflooding, there are many problems such as rapid increase of water content and serious decrease of production. In order to further improve the development effect of ultra-low permeability reservoir, low-interfacial tension viscoelastic fluid flooding is carried out. The oil displacement effect of viscoelastic fluid with low interfacial tension was evaluated by core oil displacement experiment, and the microscopic oil displacement mechanism of viscoelastic fluid with low interfacial tension was studied by microscopic visual simulation technology. The results show that the oil recovery of ultra-low permeability core is increased by 7.47% and 23.14% after injection of low interfacial tension viscoelastic fluid. The microscopic visualization oil displacement experiment is consistent with the core oil displacement experiment. The injection of viscoelastic fluid with low interfacial tension can effectively adjust the oil displacement profile and increase the degree of oil production. The remaining oil generated in the model after water flooding mainly exists in five forms: cluster, island, film, blind end and column, and the proportion of cluster remaining oil is the largest. Low interfacial tension by viscoelastic fluid viscous, shielding temporary plugging, emulsification and rock surface wettability change wait for a variety of mechanisms together, the remaining oil after water flooding to "slug flow" or emulsifying dispersion form small oil droplets by placing seepage migration output, has good mobility and wash oil control ability, in a low permeability reservoir development has excellent potential application prospect.