Challenge: Produced water from oil/gas exploration and production
Oil and gas exploration and production (from conventional and unconventional resources) invariably generate a saline waste water stream, known as produced water (PW) that needs sustainable management through beneficial reuse and/or pre-treatment for safe disposal. As the volume of PW to that of produced oil/gas can reach several fold, with salinities reaching several fold that of seawater, there remain a number of fundamental challenges facing the petroleum production industry. In the U.S.A., the volume of PW is significantly greater than the volume of water that could be used beneficially (i.e., for recycling by the industry itself or used outside the oil field). This is particularly the case with the Permian Development Region where the increase in high salinity PW volumes is occurring concurrently with the growing number of seismic events, creating mounting constraints on subsurface disposal. The key challenges with recycle/reuse of PW may be summarised as:
Difficult to characterise PW quality partly due to diagenetic mineralisation in high salinity PW, causing changes in the salinity matrix and hence interference with analytical measurements.
High salinity of PW beyond existing treatment methods.
Technical challenges with desalination of high salinity PW using existing methods (including thermal distillation approaches) for large-scale application which translate to technical liability and product water reuse risks. Additionally, apart from low capacity, the generated highly concentrated reject brine has shown to face difficulties with consistent injection into saline water discharge (SWD) wells due to the diagenetic crystallisation phenomenon. As discharge to surface water is not an option in most cases, there is an immediate need for application of appropriate technologies to manage such high salinity produced waters for reuse/recycle through the recovery of commercial grade minerals/metals for safe reuse/recycle.
The need of enabling technologies for beneficial use of highly saline PW, or reject bittern from thermal distillation approaches, is overwhelming, not only for industry to adopt in accordance with market dynamics but also supporting the governments to update regulatory regime for sustainable and safe disposal of PW from Oil/gas exploration and production industry.