Maximum tolerance for water content at various stages of a natuna production

Abstract

Though the Natuna field in offshore Indonesia contains natural gas resources, its CO2 content exceeds 70%. While existing technologies can handle the separation challenges, the question of CO2 transport and storage will still remain due to the lack of aquifer storage sites with sufficient sealing integrity in this part of South Asia. Substantial occurrences of natural gas hydrates have been discovered in offshore Indonesia roughly 700 miles from Natuna, making the pipeline transport economically feasible. This work aimed to assess the risk of hydrate formation during this transport as evaluated by two different approaches: traditional method based on water dew-point versus evaluation accounting for alternative routes of hydrate formation. The hydrate risk analysis was also conducted for produced natural gas at transport conditions. We have investigated the case study involving using the separated CO2 for simultaneous safe long-term storage of CO2 and release of methane for in situ hydrates located at the North Makassar Basin in offshore Indonesia. Utilization of CO2 will require additive gases to increase gas permeability and reduce the blocking of sediments by new CO2-dominated hydrate. This analysis was conducted for variable content of nitrogen and H2S. We have concluded that the water dew-point-based method appears to severely underestimate the risk of hydrate formation; the maximum water concentration it allows in gas will be larger by a factor of eighteen than the one permitted by approaches that used water adsorption on hematite (rust) as the criterion.