Water treatment technology performance for chemical enhanced oil recovery: modeling, simulation and optimization

Abstract

The use of ASP (alkali–surfactant–polymer) slug could be affected by the use of high hardness water, especially when injecting an alkaline agent (Na2CO3). The injection water quality of the TFT field is not adequate for cEOR (chemical enhanced oil recovery), because it contains a high hardness rate up to 160°f (report DC R&D 2019). With a TDS rate varying between 4 and 6 g/l, it could cause a formation of insoluble complexes with alkaline agents, and on the other hand, the decrease in the performances of the injected surfactants and polymers. In this work, a simulation study was carried out in order to identify the most adequate treatment process between NF (nanofiltration) and RO (reverse osmoses). The performance of the 4040 type membrane modules has been tested under different operating conditions of temperature and feed pressure (25°–45°) and (3.1–22 bar), respectively. Several membrane configurations (6:0, 4:2) have been tested to determine their effect on the process’ performance. The results showed that the NF90 4040 presents the best performances toward the requirements of the cEOR. Furthermore, the membrane configuration effects the quality of permeate and recovery rate. The results showed a rejection rate of 90% and 95%, respectively, for the total hardness (Ca2+ and Mg2+) and the sulfate.