A midstream facility in Northeast British Columbia is located within one of Canada's most sour conventional gas fields.The facility processes gas from wells with H2S as high as 40 wt%,containing extremely high amounts of other contaminants including mercaptans,elemental sulphur and CO2.Located at the heart of this field is a multi-towered amine system utilizing Shell's patented Sulfinol-D,which consists of a blend of Diisopropanolamine(DIPA),Sulfolane and water.The solution is used to sweeten a typical inlet gas of 165 mmscfd containing 12% H2S,10% CO2,>200 ppm COS and>150 ppm mercaptans. Over the past 30 years,the Sulfinol-D solution has experienced elevated degradation rates,requiring multiple investigations to help battle the amine degradation.Mitigation steps from these investigations have included [1] the replacement of the reboiler bundle to reduce thermal degradation,[2] the installation of horizontal coalescing filters to reduce inlet contamination and [3] on-site vacuum distillation to reduce heat stable salts and DIPA-Ox.Degradation rates have typically been controlled at 5-6 lbs/mmscf through these initiatives. In 2017,through to 2019,degradation rates began to unexpectantly climb.At their peak,rates in excess of 20-23 lbs/mmscf were observed,well beyond typical Sulfinol-D degradation rates of 2-3 lbs/mmscf.During this time degradation was controlled primarily by bleed and feed; a very expensive solution resulting in the facility replacing roughly 80% of their inventory per year. This paper follows the steps taken to reduce the amine degradation from 23 lb/mmscf to 2 lb/mmscf over a one-year period from November 2019 to October 2020.It will highlight the inlet feed upgrades completed during the 2019 turnaround and will evaluate the overall effectiveness of all other amine degradation control measures put in place.This will include an evaluation of the reduction in the overall amine degradation rate and will specifically break down the amine degradation mechanism(CO2,O2 and sulphur)observed during each stage of the program.
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