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Reasonable Viscosity Ratio of Polymer/Surfactant Combination System in High Condensation and High Viscosity and High Salt and Homogeneous Reservoir: Take the Kongnan Reservoir of Dagang Oilfiled as Research Object
Zhang Jie, Yang Huaijun, Cao Weijia, Su Xin, Lu Xiangguo
In recent years, with the growth of oil consumption and the reduce of new proved reserves, the development of high viscosity oil reservoir was paid more and more attention. As Kongnan block of Dagang oilfield has characteristics of hypercoagulability, high viscosity and high salinity, core flow experimental apparatus and core displacement experiment apparatus were used to study the effect of oil displacement efficiency of polymer/surfactant combination system, and analyze the mechanism of the relationship between recovery growth and core permeability. The results showed that, for the weak heterogeneous reservoir, with the increase of core permeability, the resistance coefficient and residual resistance coefficient of the polymer/surfactant combination system were decreased. With the increase of viscosity ratio (μsp/μo) and core permeability, the oil recovery increased, but the increase rate decreased. With the increasing of the core permeability, the size of the rock increased, while the inaccessible pore volume decreased. So the adaptability of the reservoir and the polymer/surfactant combination system was affected by the average permeability, and then the effect of the polymer flooding of the polymer/surfactant combination system flooding was influenced. Comprehensively considering technical and economic effects,the reasonable viscosity ratio (μsp/μo) in polymer flooding should be about 0.5~1.0.
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