A breakthrough study by some Saudi Aramco scientists, engineers and environmentalists, supported by the company’s Environmental Protection Department (EPD) regulations, has identified an alternative source of injection water that will help to conserve the Kingdom’s scarce groundwater reserves. In the late 1970s, Saudi Aramco began the process of replacing all low total dissolved solids (TDS) — groundwater being used for waterflood operations with processed seawater from the Qurayyah plant. The company had also been considering the extension of this practice to the few remaining fields that are still using groundwater with much higher TDS. However, today, there is an alternative — secondary treated sewage effluent (TSE). Traditionally, sewage and other waste water are collected from urban areas for safe disposal. This is mainly sanitary wastewater and rain water, while in some instances, the wastewater may contain minimal amounts of industrial waste. These are all collected and transported through the sewer system to the municipality wastewater treatment plants for treatment prior to disposal. Currently, a small portion of the treated effluent is being reused while efforts are ongoing to improve and upgrade the distribution network’s capacity for increased TSE utilization. TSE is considered a valuable source of water given its quality and many potential uses, one of which is irrigation. This is by far the most common application of TSE today, as more than 74 percent of Saudi Aramco’s generated sanitary wastewater from its facilities and communities is being treated and used for irrigation. Maximizing wastewater reuse is one of Saudi Aramco’s Water Conservation Strategy pillars. The drive to enhance water source sustainability and explore use of TSE as an alternative for existing reservoir injection waters aligns with this conservation policy. Saudi Aramco subsequently carried out a study to evaluate the use of TSE from nearby cities such as Riyadh that is currently being disposed and not beneficially reused for water injection at the Nuayyim and Khurais fields. The study is the first corporate assessment with involvement of representatives from various corporate departments, including EPD, Research and Development Center (R&DC), EXPEC ARC, the Facilities Planning Department (FPD), the Southern Area Production Engineering Department (SAPED), the Reservoir Management Department (RMD), the Sea Water Injection Department (SWID) and the Khurais Producing Department (KhPD), which hosted the study. There were four focus areas: supply and reliability of TSE plants; quality and compatibility; environmental policies; and economic feasibility. The study concluded that TSE is an environmentally reliable and compatible alternative to current injection waters used to recover oil (i.e., aquifer water or seawater). Furthermore, the TSE has been found to reduce scale and limit any incompatibility effect to the reservoir formation. Nidal Samad, senior environmental scientist, said that Saudi Aramco’s EPD is playing a major role in implementing the company’s Water Conservation Policy and ensuring that the Kingdom’s water resources are sustainably utilized. “EPD establishes mandates, provides technical support, and monitors for compliance,” he said. “As for this initiative, the use of TSE provides a more sustainable water source than groundwater which EPD, R&DC, and EXPEC ARC have encouraged by working closely with the Khurais Producing Department team to successfully complete this study.” Ali A. Hamed, general supervisor from the South Ghawar Producing Department, who previously acted as the KhPD Engineering superintendent and leader of TSE assessment sub-teams, added, “Such a promising and encouraging finding by the team encourages us to explore in detail the potential for pilot deployment in the future.” Tony Rizk, science specialist at R&DC and member of the TSE quality assessment team, explained, “Groundwater is a precious national asset, and the corporate work that has been carried out has demonstrated that largely wasted TSE can be used to generate wealth and preserve shallow aquifer water for future generations.” EXPEC ARC petroleum engineer Peter Osode acknowledged that “significant flow assurance risk associated with onshore development in a challenging ‘hard-water’ reservoir environment has placed limitations on the use of sulfate-rich injection seawater, and therefore, TSE opens up a new vista of opportunity for reducing fluid compatibility risks and enhancing economic value of our assets.” Ahmed Otaibi, senior engineer from KhPD, who led the reliability and sustainability assessment team, indicated that this initiative serves the national interest in finding wiser ways to use increasing Kingdom’s excess wastewater by the industries. “The study confirms that the TSE has high potential for use as injection water in either new developments or at existing fields of close proximity to TSE plants. It could also have a good potential for use in some reservoir fracturing operations. “There was always a lingering thought about the prospects of utilizing this unused asset — TSE for reservoir injection. This thought has been finally crystallized through a corporate multidisciplinary team that has successfully established a new horizon for our company’s future business operations,” he said.