Research

Turning a Hazard into Sustainable Revenue Streams: H2S Valorization in Offshore Oil and Gas Productions through Process Intensification

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Abstract

The grand challenges of the 21st century lie squarely at the interplay of water, energy, and food— the so-called water-energy-food nexus. Add climate change into the mix, and the challenges become more challenging. Aggressive measures to decarbonize the energy market are necessary to tackle the threat of climate change. However, due to the ever-increasing global population, energy requirements are expected to increase 50% by 2030. While ensuring that we protect the natural environment, it is also important to provide energy security. This calls for an energy supply that is consistent, reliable, sufficient, and affordable. Natural gas has arguably the least carbon footprint among fossil energy resources (carbon dioxide emission of burning natural gas is approximately half that of coal). While natural gas cannot be viewed as the permanent solution to energy security, it plays a vital role as the bridge fuel in the transition to a low-carbon economy. Hydrogen sulfide (H2S) is a major hazardous by-product in oil and gas production as well as many bio-based manufacturing processes, such as anaerobic digestion. Desulfurization of sour gas is essential prior to transportation or further processing due to its extremely toxic, acidic, and corrosive nature. Several offshore oil and gas production platforms are suffering from elevated levels of H2S in recent years, and the production facilities are not designed for such high levels of H2S. Currently, H2S is removed using a non-regenerative scavenging process. The scavenger reacts with H2S and produces less acidic, water-soluble compounds in an irreversible reaction. Although the current process is rather established, it comes with significant challenges. Such challenges include high OPEX due to excessive amounts of the scavenger used in offshore productions, environmental concerns coming from the increasing levels of H2S and increased mass of discharged spent scavenger, and fouling issues creating blockages in several downstream unit operations, such as wastewater treatment facilities. For these reasons, design and development of more sustainable approaches that can fulfil the H2S content threshold limit requirements and that can eliminate the disadvantages of the current non-regenerative H2S-scavenging process are deemed necessary, specifically from an economic point of view. This work focuses on the design and techno-economic analysis of an intensified process that can be installed on an offshore platform to simultaneously remove and convert H2S from produced natural gas to value-added product(s) to generate new revenue streams. The added benefits of this new process are that it allows for the efficient recovery of resources by turning the hazard, H2S, into an opportunity. The proposed process is therefore well suited for the application of intensification concepts, integrating reaction and separation into a single unit.