SOFTOX FOR STRANDED GAS UTILIZATION

Many of today’s oil producers are forced to flare associated natural gas or shut-in wells because they cannot economically bring the gas to market. Natural gas flaring and venting exposes produc- ers to environmental liabilities, reduces potential revenues, and depreciates assets. Initially, this project will focus on a particularly acute problem for many producers—the co-production (with oil) of sour gas containing more that 1% H2S. In the absence of readily available centralized gas processing facilities or qualified re-injection wells, producers must either flare this sour gas or halt production. While sour gas flaring will be the initial focus, the proposed SoftOx gas-to-liquids conversion process is more broadly applicable for monetizing any natural gas resource that is cur- rently economically stranded, flared, or vented. If successful, the SoftOx process could allow the monetization of over 5 Quads (5 EJ) per year of flared or vented natural gas worldwide, resulting in a reduction of up to 1% of global greenhouse gas emissions. The proposed SoftOx process is a proprietary thermocatalytic process that converts hydrogen sulfide and methane into liquid sulfur-containing hydrocarbon compounds and sweetened hydrogen- rich natural gas. The novelty of this process lies in the use of sulfur for methane oxidation (soft oxidation)—instead of oxygen—allowing it to overcome fundamental challenges with oxygen-based methane conversion to liquids: the thermodynamically favorable conversion of methane to carbon dioxide and the high cost of separating oxygen from air. Moreover, the simplicity of the proposed two-stage thermocatalytic process allows for the economical production of small modular process units that can address the relatively low volumes of flared and vented natural gas ( 10,000 Mcfd) to be economical. This DOE STTR Phase I project will address several key technical challenges remaining to demonstrate an integrated, economical, and robust SoftOx process with high liquid yields. This work will include: (1) integrating an ethylene-to-olefins reactor for higher liquids yields after the softox reactor, (2) integrating a hydrogen sulfide membrane separator and recycle after the ethylene reactor, and (3) demonstrating on an integrated bench-scale system long-term catalyst and system performance. The results of these activities will be used to refine a SoftOx process model to demonstrate the potential for an economic payback of under 2 years at a scale small enough (under 100 Mcfd) to treat wellhead sour gas (> 1% H2S).