Literature review of implemented polymer field projects

Abstract

Polymer flooding is a mature enhanced oil recovery (EOR) technology applied in field projects as early as the late 1950s. There exists extensive amount of experience, know-how and learning related to field implementation of polymer with respect to logistics, engineering design, reservoir properties and monitoring & surveillance in the literature. The aims of this paper are twofold. It is firstly to compile an up-to-date data base for implemented pilot/field polymer injection projects reported in the literature over the last 50 years. Based on the compiled data qualitative information and statistics are presented regarding differences between projects being classified as technical successes compared to the discouraging cases reported. Secondly, to assure that that planning and implementation of upcoming polymer projects can leverage on the large amount of experience and lessons learned built up in the industry over the years. 40 of the reported polymer projects were classified as successes and 6 were assessed discouraging. 46 projects have been performed in the U.S.A. (64 %) followed by 6 in Canada and P.R. China (8 %), 4 in Germany (5.6 %), etc. 66 projects were implemented onshore and only 6 offshore. HPAM was used as polymer in 92 % of the cases and the rest were using biopolymer (1 projects used a hydrophobic associative polymer). Data analysis reveals that 4 of the discouraging projects experienced significant drop in injectivity during the flood. The projects using emulsion-based synthetic polymers had more challenges related to injectivity compared to the cases using the powder type synthetic polymers. 3 of the discouraging cases injected only 17 % pore volume (PV) compared to 34 % PV slug size for the successful projects. Average permeability in the successful projects was 563 mD vs. only 112 mD in the discouraging cases. The success rate for projects implementing polymer injection in secondary mode was higher than when injecting polymer in tertiary mode. No major differences could be identified between successful and discouraging projects with respect to polymer concentration, resistance factor, residual resistance factor, polymer retention, well spacing, formation temperature and oil viscosity. The number of challenges and issues observed in the production wells due to polymer breakthrough and production was in general low and mostly related to increased tendency for corrosion and formation of emulsions in the production system.