Abstract
Nowadays, a growing interest is shown for CO2 rich natural gas fields. Especially South East Asia, Australia and South America are regions where the exploitation of such gas fields is investigated.
A wide range of proven technologies for CO2 removal exists, from the traditional amine units, membrane systems including one or multiple stages, to newly developed cryogenic technologies and combinations of the above. These technologies need to be adapted and optimized providing technically and commercially viable solutions to gas field operating companies for the conditioning of such a low caloric natural gas.
This paper presents the results of a study comparing the most promising natural gas conditioning technologies considering various process parameters like CO2 and hydrocarbon feed content, plant capacity, treated gas specification, hydrocarbon recovery requirement and the potential CO2 valorization application (e.g. enhanced oil recovery (EOR)). Air Liquide Global E&C Solutions has a unique position in performing such a technology comparison as a technology provider for all bricks. Inhouse and commercial tools were used in order to optimize each technology brick independently as well as to intregrate the bricks together.
Various process schemes have been studied for natural gas feedstocks containing up to 60 vol% CO2. This paper comprises general process description of the conventional amine and membrane setups as well as more information about the innovative cryogenic solution proposed herein. The total costs of ownership for the different processes have been evaluated taking into account capital and operational expenditures as well as the hydrocarbon recovery of the applied processes.
Although the optimum solution strongly depends on the specific project's parameters, some general trends and conclusions can be derived from the results of the study: the combination of membranes with cryogenics is the most suitable solution in case of high CO2 containing feed stocks and if the CO2 product is used for EOR applications, means a pure CO2 product delivered at high pressure. Amine wash and hybrids of amine wash and membrane seem to be favorable at low to medium CO2 containing feed stocks and if the CO2 product shall be supplied at low pressure to battery limits. Beyond that, the paper also comprises conclusions and recommendations taking into account the other project and process parameters and their respective operating ranges.