Advanced Media Filtration for Efficient Produced Water Reinjection

Abstract Produced water volumes are increasing globally due to the extended operation of mature oil fields. At the same time, operators have the requirement to maintain well pressure to ensure oil production. Produced water can be used for this purpose, thus converting the commodity from a waste product to a valuable resource. For this reason, National and International Oil Companies are continuously evaluating the latest technologies to reuse the produced water for reinjection efficiently and minimize the use of other sources of water such as aquifer water or treated seawater. Traditional tertiary treatment technologies such as nutshell filter (NSF) have long been the only option available, together with cartridge filters, to meet the increasingly challenging applications to treat the water suitable for injection for pressure maintenance or into disposal wells. However, NSFs have a narrow operating window, so they often struggle to perform adequately under varying inlet conditions and as a result, they do not meet the required outlet specifications. Operators are looking for a more-resilient advanced media solution to outperform currently available NSF media and fill this technological gap. The evaluation of advanced media includes understanding the impact of impurities concentrations and properties such as total suspended solids (TSS), and oil in water (OIW). Water recovery and the impact of high TSS and oil incursions are also important parameters to consider when deploying new technologies at full scale. Large-scale advanced media pilot study, with flow rates of up to 75,000 BWPD, were performed in the Middle East and North Africa region. The objective was to conduct a sensitivity analysis, measure performance, identify the operating window, and optimize the time between media backwashes such that the treated water could be used for water injection at the well side complying with tight water injection specifications. Achieving the required particle cut size, OIW and TSS concentration is key to avoid plugging of the injection wells. The pilot study evaluated the impact of these relevant produced water properties by performing regular sampling. These data, together with monitoring of the backwash frequency, were used to evaluate the performance and operating window of the advanced media. During the pilot study, which was executed at different sites, over 18 million bbl of produced water were treated, and more than 23,000 bbl of oil were recovered and reprocessed within each facility. Furthermore, no well stimulation was required at the injector wells because of the high-quality output from the mobile treatment equipment during the 18-month pilot study.