Recent Oil and Gas discoveries provide an increasing outlook of gas fields containing CO2 content between 10 mol % to as high as 70 mol % CO2. The gas needs to be treated for managing CO2 emission and to fulfil treated gas specification for sales gas or for LNG production. The increasing amount of CO2 content in newly discovered gas fields requires smart designs to minimize CAPEX/OPEX while adhering to emissions requirements. Amines and membranes are commercially available technologies for CO2 removal. However, membranes alone can only do bulk CO2 removal and cannot achieve low CO2 specifications (certainly not deep CO2 for LNG specifications). So membranes will often need an amine unit meeting the CO2 specification as a polishing step.
For this paper, a case study based on amine technology will be discussed. The gas contains high CO2 (~20 mol %) which will feed a LNG plant downstream. The treated gas specification is the typical required LNG specification of 50 ppm. Amine technology is a well-proven process for CO2 removal and capable of meeting these stringent specifications, but comes with high CAPEX and OPEX at these increased levels of CO2. In this study a smart design, which involves a pioneering approach, was undertaken which enables reduction of OPEX by 30 %, and capturing a CAPEX gain of 24 % against a conventional amine design.