Beyond Conventional Water Injection: A Novel LIBS-Based Design Framework for Sustainable Engineered Water to Rejuvenate Mature Oil Fields.

Produced water (PW) is ineluctable in a mature field, but a key resource for pressure maintenance. Gradual pressure depletion and the diminishing returns from conventional waterflooding (CWF) have compelled the "X" field toward other alternatives. The study focuses on the design and optimization of Sustainable Engineered Water (SEW) as an injection fluid to arrest pressure decline and boost recovery with resources available near the injection facilities. Salinity evaluation of PW, borewell water (BW), and river water (RW) judged that a combination of 70% PW and 30% BW is optimum, with an average salinity of 4988 ppm. Concurrently, laser-induced breakdown spectroscopy (LIBS) was used for characterizing SEW, which enabled a qualitative, quick estimation of the multivalent ions governing the interactions at the rock/brine interface, including multicomponent ion exchange (MIE). A combination of 30% RW and 70% PW has a salinity of 5362 ppm with evidence of divalent ions from LIBS, and the need for construction of a connecting pipeline has screened out the feasibility of RW. Contact angle measurement shows that the selected combination can alter the wettability toward a more water-wet state. Henceforward, 70% PW and 30% BW were considered as SEW with reasonably less divalent ions aiding MIE. Conclusively, the feasibility of the SEW was assessed through a core-flooding experiment under the reservoir pressure and temperature conditions, wherein an increment of 16.05% oil recovery was observed.