Streamlined Natural Gas Treatment by Membranes Only

Abstract

Offshore gas treatment faces constraints for space and weight limits. This paper will present an innovative concept of using only membranesto remove multiple contaminants, reduce weight, space and cost on offshore installations and becoming an enabler for gas monetization. Membrane separation is a cost effective way to remove CO2 from natural gas. The typical offshore membrane treatment package usually consists of a relatively complex pre-treatment step followed by a simple membrane system to remove CO2. The solution using only membranes for gas treatment consists of: a first stage of poly (ether ether ketone) or PEEK membranes, resistant to the main impurities in natural gas, able to remove H2S, heavy hydrocarbons and water, thus essentially replacing the pre-treatment for offshore CO2 removal membrane packages a second stage of poly-imide membranes with high CO2 / CH4 selectivity for CO2 removal The membrane-only solution can be applied for treatment of large volumes of gas for pipeline specification to remove CO2 and other contaminants. Key benefits are simplicity of operation, compactness of footprint, weight reduction and a reduction in or elimination of adsorbent media replacements. Topside weight and cost reduction can increase gas treatment capacity and flexibility and are an enabler for gas monetization. Due to their resistance to impurities PEEK membranes can also be used to treat flared gas for valorization through gas-to-power applications, thus reducing flaring. For gas-to-power applications, the gas will undergo some basic conditioning (such as hydrocarbons dew point, BTU adjustment, H2S removal) by a compact membrane unit to be used for power generation on the offshore platform.