Produced Water Management for Sustainable Reinjection––Bench Scale Tests to Remove and Destroy KHI

Dolphin Energy Limited’s (DEL) production scheme is based on a wet transport of well effluents from offshore platforms (DOL-1 and DOL-2) to the onshore treatment plant. At the onshore receiving facilities, sour gas is routed to gas sweetening, condensate is stabilized and treated and produced sour water is routed to water treatment units. Since the plant startup in 2006, non-chemically contaminated waste water is used for irrigation after treatment. Produced waste water and chemically contaminated waste water are re-injected into a deep reservoir without any major treatment further to H2S stripping, oil skimming, pH control and multi-media filtration. However, local authorities have expressed their concerns about the quality of water injected and the potential risk of long term injectivity loss. Indeed, as sealines need to be protected all year round against corrosion using a Corrosion Inhibitor (CI) and hydrate formation during winter by using Kinetic Hydrate Inhibitor (KHI), produced water recovered onshore is chemically contaminated with polymer based chemicals. As KHI could damage the reservoir, it has to be removed from produced water prior to reinjection. However, no technology was clearly available and referenced for this application. Dolphin Energy launched numerous bench scale tests with a third party laboratory to identify the best treatment scheme to remove KHI. The paper will first explain the overall strategy put in place to identify applicable processes. Then, it will describe the laboratory tests on produced water for KHI removal and destruction. Eventually, results will be presented and compared in order to conclude with applicable treatment schemes that would remove and destroy KHI from produced water for sustainable reinjection.