During water flooding of heterogeneous oil reservoirs, early breakthrough of water can occur and lead to poor volumetric sweep efficiency. Macro-emulsions with oil droplets dispersed in a continuous water phase [oil-in-water (o/w) emulsions], have the potential to block high-permeability zones in these reservoirs, and thereby improve the volumetric sweep by diverting the water flow from high-permeability layers toward lower-permeability layers. In the present work, the potential for produced water with dispersed oil to block sandstone rocks (with permeability of 150-2000 mD) was investigated. Different o/w emulsions with similar oil concentrations as in the produced water were prepared using synthetic oil and crude oil. Water-soluble surfactant was dissolved in synthetic formation water and homogenized with oil using a high-shear rate mixer at different speeds and mixing times. The prepared emulsions were injected into sandstone cores. A Coulter Counter Multisizer was used to measure the droplet size distributions in the injected emulsions and the produced effluent. The droplet size distributions in the emulsions and the pore throat size distributions in rock were compared. The flooding experiments demonstrated that injection of emulsions can significantly reduce the permeability, and depending on the initial permeability of the rock the permeability reduction was up to 47%. Emulsion has the potential to accelerate and improve oil production and reduce the water cut at low-cost investment. Further work is required to qualify this method for field applications.

中文翻译：

---

注水分散油中乳状液以提高油藏注水过程中的体积清扫效率

在非均质油藏注水期间，水可能会提前渗透并导致较差的体积波及效率。具有分散在连续水相中的油滴的大乳液[水包油（o / w）乳液]，有可能阻塞这些油藏中的高渗透率区域，从而通过转移水流来改善体积扫描从高渗透率层到低渗透率层。在目前的工作中，研究了含分散油的采出水阻塞砂岩（渗透率为150-2000 mD）的潜力。使用合成油和原油制备了具有与采出水中相似的油浓度的不同o / w乳液。将水溶性表面活性剂溶解在合成地层水中，并使用高剪切速率混合器以不同的速度和混合时间与油进行均质化。将制备好的乳液注入砂岩岩心中。使用Coulter Counter Multisizer测量注入的乳液和产生的流出物中的液滴尺寸分布。比较了乳液中的液滴尺寸分布和岩石中的孔喉尺寸分布。驱油实验表明，注入乳液可以显着降低渗透率，根据岩石的初始渗透率，渗透率降低可达47％。乳剂具有以低成本投资加速和改善石油生产并减少含水率的潜力。需要进一步的工作才能使这种方法适用于现场应用。