The Low-Tension Polymer Flood Approach to Cost-Effective Chemical EOR

Abstract

ABSTRACT The Low Tension Polymer Flood approach addresses the two EOR problems of cost and control. Coinjection of low concentration surfactant and a biopolymer, followed by a further mobility control buffer, leads to much reduced overall chemical consumption, even in relatively high clay content rock. Though the optimum chemical injection period is more prolonged, the oil recovery timescale is not unduly prolonged. The LTPF process moves chemical flooding surfactant a long way toward being a simple, low-level waterflood additive process, attractive for field operations. It uses surfactant-polymer interactions as an advantage rather than coping with them as a problem. The chemical system described is based on a scleroglucan biopolymer (500 – 750 ppm) plus surfactant mixture (3000 ppm total surfactant). No cosolvent is used. This system was developed specifically for use with high salinity injection water (seawater) in a high temperature reservoir. The essential phase behavior description is given, together with other physical parameters and detailed coreflood performance. Finally, we discuss the computer simulation approach used to predict reservoir performance and the results obtained.