Scoring Method for Polymer Screening in Chemical EOR Application

Abstract

Chemical Enhanced Oil Recovery (EOR) is one of the major methods by injecting selected chemicals to implemented reservoir. Types of commonly chemical are surfactant, polymer, alkaline. These chemicals are considerably used to enhance the oil displacement and volumetric efficiency through an extensive investigation into the applicability of EOR technology. In this research, polymer screening was conducted to select the best polymer in combination with a surfactant (Surfactant – Polymer/SP)
formulation. The aim of this combined technique is to find the great potential to improve the remaining oil in L field and at high temperature of 107°C. salinity of brine L field was investigated at around 20,000 ppm. There are 4 stages in this polymer screening; pre-screening, pre-scoring, continues screening, and final scoring. Pre-screening consists of rheology, filtration test, screen factor, and thermal stability. Pre-scoring was conducted based on the result of pre-screening test. Continues screening consists of injectivity test, static adsorption, and dynamic adsorption test. Final scoring was performed after the result of continues screening. The experiment shows 6 polymer which were analyzed in the first stage: P1, P2, P3, P4, P5, and P6. The rheology of 6 polymers showed the viscosity decreased as the increasing shear rate were applied. In compatibility test, P2 were observed turbid over the time period of aging. Filtration ratio value for each of 6 polymers were performed <1.2. The screen factor test was measured with relatively range of 30 – 80. However, P6 had the highest screen factor value. The result of thermal stability test presented P1 had < 5% loss of polymer viscosity during 3 months aging. The second step of pre-scoring showed P1, P2, and P4 had passed to the next stage in continues screening with the highest value of 86.75%, 72.75%, and 74.5%. Furthermore, the injectivity test presented the resistance residual factor (RRF) of P1, P2, and P4 performed high adsorption value. However, the result of dynamic adsorption test presented P1 with the lowest value of 117 µg/g. The final scoring showed P1 was performed excellent result of 95% and thus to be preferred polymer for SP formulation.