RESEARCH ARTICLE


Laboratory Study on EOR in Offshore Oilfields by Variable Concentrations Polymer Flooding



Kaoping Song*, Ning Sun, Yanfu Pi
Institute of Petroleum Engineering, Northeast Petroleum University, Daqing, Heilongjiang Province, 163318, P.R. China


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© 2017 Song et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Northeast Petroleum University, Daqing, Heilongjiang Province, 163318, P.R. China; Tel: +8618345443356; E-mails: skp2001@sina.com, 549518733@qq.com


Abstract

Background:

Polymer flooding is the most commonly applied chemical enhanced-oil-recovery technique in offshore oilfields. However, there are challenges and risks in applying the technology of polymer flooding to offshore heavy oil development.

Objective:

This paper compared the spread law and the displacement effect of different injection modes and validated the feasibility of enhancing oil recovery by variable concentrations polymer flooding.

Method:

Two types of laboratory experiments were designed by using micro etching glass models and heterogeneous artificial cores. Furthermore, in order to determine a better polymer flooding mode, the displacement results, displacement characteristic curves and oil saturation distribution of heterogeneous artificial cores were also compared, respectively.

Results:

The experimental results showed that the recovery of variable concentrations polymer flooding was higher than that of constant concentration polymer flooding, under conditions of same total amount of polymer and similar water flooding recovery. Its sweep efficiency and displacement efficiency were also significantly higher than those of constant concentration polymer flooding. Moreover, variable concentrations polymer flooding had lower peak pressure and was at lower risk for reaching the formation fracture pressure.

Conclusion:

As a consequence, variable concentrations polymer flooding has certain feasibility for heterogeneous reservoir in offshore oilfields, and can improve interlayer heterogeneity to further tapping remaining oil in medium and low permeability layer. Conclusions of this paper can provide reference for the field application of polymer flooding in offshore oilfields.

Keywords: Offshore oilfields, Variable concentrations polymer flooding, Laboratory experiments, Micro etching glass models, Heterogeneous artificial cores.