Kinetic Hydrate Inhibitor Removal by Physical,Chemical and Biological Processes

摘要

Hydrate formation is a major flow assurance issue in the production from oil and gas fields.Kinetic hydrate inhibitors(KHI) act as anti-nucleating agents and delay the formation of gas hydrates.These chemicals are more economical than the thermodynamic inhibitors and are added at a low dosage without disturbing the pipeline flow. Globally,different proprietary KHI compounds are used;one type of KHI was investigated in the present work.Considering that produced water containing KHI may have negative impact on the environment and reservoir permeability,efficient treatment solutions to remove KHI are needed. The objective of the lab tests was to assess KHI removal efficiencies of various physical,chemical and biological treatment methods for KHI removal,including:membrane filtration,ozonation,biotreatment and heated centrifugation.The feed solution for the experiments was prepared by adding 1.5%KHI to a synthetic brine solution.To check the effectiveness of heated centrifugation process,the supernatant was eluted through crushed Sulaiy core for deposition/interaction studies.Two criteria were used to verify the effect on the treated effluent:cloud point and interaction with the crushed core. The key results are: 1Centrifugation of 1.5%KHI solution at 65oC removed 45%of the KHI and proved effective in removing the higher molecular weight KHI polymers. 2The KHI remaining in the supernatant showed no signs of depositing on the crushed Sulaiy core;the supernatant met the key process requirements of cloud point>65°C and<10%retention on Sulaiy core. 3The membrane filtration tests indicate that the KHI removal efficiencies of 99.9%,99.7%&83.3%can be expected for RO,NF&UF membranes,respectively. 4Ozonation is capable of oxidizing 70%of the KHI and biotreatment can remove 50–60%of the COD associated with KHI. To the authors’knowledge,this is the first work reported in the literature regarding KHI removal using some of these processes.The treatment processes have great potential when implemented by the oil&gas industry for environmental and operational sustainability.