Advancing Produced Water Injectivity: A Fit-For-Purpose Chemical Approach for Reuse and Disposal

Abstract Oilfield operations generate a significant volume of produced water (PW) containing large amounts of oil carryover, solids, heavy metals, and chemical additives. PW management is crucial for industry to demonstrate social responsibility and ensure the protection of ecosystems and human health. A key challenge in this process is maintaining injectivity into disposal (SWD) or injection wells to prevent excessive pressure buildup and formation damage. In this work, PW samples collected from Salt-water Disposal (SWD) lines were characterized via particle size, turbidity and geochemical analysis. A laboratory workflow based on coreflood was developed to evaluate the injectivity of PW into the reservoir formation. Three chemically distinct additives—a standard iron sulfide dissolver (A), a novel non-corrosive dissolver (B), and a low molecular weight coagulant (C)—were initially tested. Injectivity index and permanent injectivity loss were measured for each treatment scenario. To validate laboratory findings under field-representative conditions, Millipore filtration tests were conducted on real-time produced water samples in the field, including evaluations of two additional formulations (D&E), specifically selected based on lab results for their enhanced ability to address oil carryover and manage suspended solids under variable field conditions. Results show that in the absence of oil carryover, PW injection resulted in 80% injectivity loss mainly due to particle deposition and core face plugging. Treatments with chemicals A and B yielded a more than twofold improvement, reducing permanent injectivity loss to 27% and 29%, respectively. Coagulant C demonstrated exceptional performance when combined with a 25 μm filtration step, reducing injectivity loss to just 2%. In contrast, the presence of oil carryover significantly impaired injectivity, leading to a 95% loss due to larger particle aggregates and increased oil wetting of the core surface. Chemical C, through the formation of insoluble flocs that enmeshed oil droplets and particles, achieved zero injectivity loss when coupled with filtration. Millipore tests further validated the superior performance of chemical treatment strategies, demonstrating improved filtration rates across all evaluated formulations. Following the laboratory success, field trials were conducted in Permian Basin to validate the effectiveness of chemical treatment programs in enhancing both surface water quality and injectivity in saltwater disposal (SWD) wells. The chemical program, implemented across a multi-stage SWD line, resulted in a 69% reduction in total suspended solids and an 88% reduction in oil carryover. Furthermore, a separate trial in a US South Delaware Basin disposal well demonstrated sustained injectivity improvements, as evidenced by consistently low Hall slope values over a 50-day treatment period. These results validate the chemical treatment strategy as a scalable, field-ready solution suitable for produced water reuse and disposal—particularly in water-stressed regions such as the Middle East and North Africa (MENA).