(511f) Selective Removal of Ethane and Natural Gas Liquids at the Well Pad Via Electrogenerative Processing

Maasoomeh Jafari¹, Samgopiraj Velraj¹, and Jason Trembly¹

1. Institute for Sustainable Energy and the Environment, Department of Chemical and Biomolecular Engineering, Ohio University, 350 W. State Street, Athens, Ohio 45701, USA

The U.S. has seen tremendous growth of natural gas liquids (NGLs) supply over recent years, due to the development of unconventional resources. The majority of the new NGL capacity comes from natural gas producing plays (Utica and Marcellus shale) and associated gas from tight oil production (Eagle Ford and Bakken shale). Ethane, the key component of NGLs, is costly and energy intensive to recover from natural gas as cryogenic (turbo-expansion) processing is required. Further ethane storage, handling, and transportation are expensive.

Ethane oversupply has caused the gap between U.S ethane conversion capacity and production. The ethane recovery from NGLs has imposed an additional cost on gas processors. Therefore, the natural gas processors reject ethane to the gas pipeline system to eliminate the recovery cost. However, this technique can not completely manage the ethane overabundance as the gas condensation may occur through transportation under operating pressure. Although the NGLs export is another management technique, most of NGLs plants are far from the coasts.

Cost-effective modular gas separation technologies which may be implemented at the well head are desired. Current cryogenic gas separation technologies will not be cost-effective at individual well head gas throughputs and are not well suited for down scaling. Furthermore, modular methodologies which directly convert NGLs (especially ethane) into more value-added intermediates or materials (such as chemicals or fuels), without need for prior separation, would be the most advantageous as such technologies would reduce flaring of associated gas from oil wells and alleviate mid-stream gas separation bottlenecks.

To address this issue, Ohio University (OHIO) is developing a modular electrogenerative oxidative dehydrogenation (e-ODH) process, which directly converts NGLs at the well head into fungible fuels, electrical power, and pipeline-quality natural gas. In this process, ethane and other NGLs contained in the well head gas are selectively converted into ethylene (alkenes) and byproduct electrical power using a solid oxide fuel cell (SOFC) module, followed by upgrading of the alkenes into gasoline range hydrocarbons and pipeline-quality natural gas in an oligomerization reactor. Advantages offered by this e-ODH process include the following: 1) Modular operation with lower capital and operating costs; 2) Selective conversion of NGLs contained in well head gas; 3) Production of gasoline range hydrocarbons, pipeline-quality natural gas, and electrical power as products; and 4) Utilizes existing SOFC and oligomerization reactor technology minimizing commercial adoption and market entry risk.

To further develop the e-ODH technology, OHIO has been developing Aspen Plus simulations and focusing on the development of high temperature electro catalysts with high ethylene selectivity. Aspen Plus simulation efforts to date have shown the e-ODH process potentially offers well pad operators a novel methodology to convert ethane and associated NGL components into value-added chemicals and byproduct power with an attractive return. This presentation will discuss results from OHIO’s e-ODH Aspen Plus simulation and catalyst development efforts including material characterization and electrochemical performance.