CSG water: desalination and the challenge for the CSG industry—developing a holistic CSG brine management solution

Abstract

The management of brine, generated from the desalination of CSG produced water, is a key challenge for the CSG industry. In many cases, the cost and technical challenges relating to the management of brine has a greater impact on the economic and technical feasibility of desalinating CSG produced water than the desalination plant itself. The challenge is to determine the best solution for brine management, given the high salinity of the brine and limited options available for acceptable disposal. This has driven the need for more sustainable options, including using salt recovery processes to recover the salts for beneficial use. Where suitable strata can be identified, brine injection may be considered as a low life-cycle cost solution for brine disposal. CSG brine is particularly high in alkalinity, and as such, brine management options, including acid mine waste neutralisation and recovery of salts (sodium chloride [NaCl] and sodium carbonate [Na2CO3]) are possible. The latter uses selective salt crystallisation, which is generally higher in capital and operating costs, but is offset by the revenue gained from the sale of salt(s). Other brine management options include solar evaporation ponds or zero liquid discharge technology to produce a mixed salt residue that can be disposed through onsite encapsulation or landfill. The feasibility and life-cycle cost of any brine management option depends primarily on the location of CSG sites and the availability of brine management disposal/sale opportunities in reasonable proximity—this is one of the greatest challenges for managing brackish CSG produced water sources, particularly as the CSG sites are in remote inland locations. Further challenges associated with the management of salts recovered include establishing a viable commercial route for the market sale of the salts. This peer-reviewed paper explores technical considerations, challenges and the life-cycle cost of the brine management options. The emerging trends for desalination and brine management in the CSG Industry will also be featured in this paper.