Abstract
The impetus for waste minimization and water recycling within the oil and gas industry comes from increasingly stringent environmental regulations and deteriorating water supplies. The most challenging part in terms of the design of a water recycling system is minimizing the capital and operating costs while meeting water quality requirements. A recent development in selective functionalization of ion exchange resins enhances the chances of developing an economically feasible process for the selective treatment of produced water.
A case study is presented wherein produced water containing high concentrations of calcium, magnesium (hardness), barium, strontium, iron (scale) and boron (crosslinking agent) was treated with three different chelating resins. Dynamic column studies were conducted on all three chelating resins and breakthrough curves were determined for different cations. It was observed that iminodiacetic acid based resin selectively decreases the hardness of water; sulphonic acid based resin decreases the concentration of iron, barium, and strontium; while N-methylglucamine based resin selectively adsorbed the boron.
Analysis of water was conducted using Inductively Coupled Plasma Spectroscopy (ICP) and Ion Chromatography (IC) instruments. The calcium and magnesium ions adsorbed on the column were eluted by allowing 1mol/L hydrochloric acid to pass through the column. Recycling of adsorption and elution was found to be satisfactory. Dynamic adsorption operations showed that adsorption had significant effect on selectivity of cations, and low flow rate enhanced said adsorption.
This case study could be helpful for designing selective adsorbents for removal of scale forming cations, hardness favoring cations, and boron from produced/waste water in an economically feasible process. This work will provide a basis for further evaluations of field applications of resin filters for oilfield produced waters.
