(176f) Developing Novel Technologies for Produced Water Management

Produced water (PW) is a significant challenge in oil and gas operations. Globally, on average, for every volume of oil produced, three volumes of water are produced. The complexity of produced water makes handling a real challenge. Produced water typically comprises various hydrocarbons, production chemicals such as scale and corrosion inhibitors, biocides, demulsifiers, and H₂S scavengers. Discharging untreated produced water to the sea poses several significant environmental risks. For these reasons, new technologies are needed. At the Danish Offshore Technology Centre (DOTC), we have designed a multi-dimensional program with a focus on reducing the environmental impact of hydrocarbon extraction in the North Sea. Reducing environmental impact requires dedicated sensing technologies coupled with control algorithms. Therefore, various sensing and monitoring technologies are being developed.

In this work, we present an overview of novel technologies being developed at DOTC to address specific produced water management challenges in the North Sea. First, we discuss the development of a fast, low-cost, and user-friendly capillary electrophoresis (CE) technology to quantify toxic chemicals in the produced water. Monitoring is crucial in any reduction of the discharge and understanding the concentrations of toxic chemicals in the water phase is critical to quantifying the environmental impact factor. We show that low concentrations (ppm-level) of a commercial biocide can be detected in both de-ionized water and complex brine systems.

Next, we discuss the development of metal-organic framework (MOF) based biomimetic oxygen scavengers. The complete removal of oxygen reduces the occurrence of corrosion in the injection wells and significantly reduces the need for oxygen-scavenging chemicals. Metal-organic frameworks are a class of hybrid materials prepared via the self-assembly of inorganic nodes connected by organic linker molecules. This results in extended network solids with a high internal surface area and porosity. This combined with their high tailorability makes them excellent materials for sorption-based processes. We are developing a new metal-organic framework incorporating cobalt complexes in the structure. By doing so, molecular oxygen can be chemically bound via an electron transfer process between cobalt sites and oxygen. This yields a material with very high O₂ to N₂ selectivity, exceeding what is possible using traditional, physisorption-based sorbents. In addition, the process is reversible, and oxygen can be removed by temperature or vacuum swing. The line-of-sight is to replace chemical scavengers with adsorption towers on the platform.

Finally, we present the development of a novel MOF-based BTEX (benzene, toluene, ethylbenzene, and xylenes) sensor. The sensor is based on a MOF-functionalized fiber probe. First, the MOF selectively bind, and extracts dissolved BTEX from produced water, resulting in a local enrichment of the target analytes. Secondly, the interaction will be probed using Raman spectroscopy, a technique capable of producing unique fingerprint spectra and resolution of complex mixtures. Thus, the sensor will be capable of distinguishing individual BTEX components with high sensitivity. The line-of-sight is developing a fiber probe that allows online and or remote sensing.

The technologies being developed at DOTC provide new solutions that can lead to a significant reduction in the environmental impact of produced water management. These results have direct applications in other wastewater management applications.