H2S Valorization Technologies to Produce Hydrogen from Unconventional Highly Viscous Oil Reservoirs: Moving Forward to the Production of Clean Fuels in Venezuela

Abstract

Abstract The production of clean fuels in Venezuela is currently a great challenge, since the country has huge reserves of hydrocarbons (mainly highly viscous) where acid gases such as hydrogen sulfide (H2S) are generated due to high temperatures involved in the production process (e.g. after the application of thermal processes). H2S represents a considerable risk to human life and the environment, in the same way that it causes corrosion and other flow assurance issues and potential damage to facilities and equipment. The objective of this article is to perform a state-of-the-art review of H2S conversion techniques from hydrocarbon reservoirs in Venezuela that allow the production of hydrogen and low carbon fuels, as wells as less toxic products with greater commercial value. Among the most widely H2S valorization techniques reported in the literature are thermocatalytic splitting, hydrogen sulfide methane reformation (H2SMR), non-thermal plasma, and electrolysis. At present most of these technologies are at research scale to provide good understanding and advancement on their fundamental process mechanisms as well as potential avenues for applications. For the Venezuelan case, thermocatalytic splitting is one of the techniques that has been widely studied from combustion tests, using extra-heavy crudes from the Orinoco Oil Belt and nanoparticle catalysts. Results of the review of this article show that the techniques based on the use of catalysts allow the production of H2 and by-products of commercial value for the petrochemical industry (i.e. carbon disulfide), one of the critical points being the selection of the most suitable catalyst along with temperature control. In the case of Venezuelan unconventional reservoirs, the separation of hydrogen from the reservoir's fluids to the surface conditions, for which membrane absorption techniques are required, as well the management of scales, etc. are some of the important and challenging aspects to take into consideration in the development of the technology at field conditions. This article opens opportunities to produce hydrogen by thermal cracking at reservoir conditions for unconventional highly viscous oil reservoirs. It will highlight important technologies and applications in Venezuela and worldwide; and as such, this work will serve as a guideline for the evaluation of H2S conversion to H2 technologies from lab to potential field implementations.