PRODUCED WATER DEOILING: AN 'UNCONVENTIONAL' APPLICATION OF CIVIL WATER TREATMENT METHODS TO OIL GAS OFFSHORE ENVIRONMENTS

摘要

De-oiling processes and operations are crucial with regard to removing oil/condensates residuals from produced water prior reinjection or discharge. Offshore environments often increase the associated issues due to 1) the necessity to meet strict water specifications, 2) the operational criticalities and associated costs, 3) the necessity to improve the performance of existing facilities. This paper discusses the 'unconventional' field application of a de-oiler based on coalescence technology usually applied for 'civil' purposes (i.e. fuel service areas cleaning) to enhance the performance and capacity of the Produced Water Treatment in offshore gas production processes. The main goal of the application was to enhance the separation of residual hydrocarbons from produced waters in order to: 1. Increase the lifetime of carbon filters; 2. Reduce maintenance costs associated to the carbon filters replacement (work force, supply, re-generation, disposal of exhausted carbon); 3. Recover the whole production of liquid hydrocarbon associated to water. Key aspect is the easy operating principle based only on physics that exclude the need of electrically powered facilities. Field test has been conducted in offshore Italy field following continuously both operational parameters and de-oiling performance. Laboratory and field activities, conducted in parallel, have been essential for the deep understanding of results and possible applicative constrains. Results of the test as well as the main observations useful for a widespread application of the technology in existing offshore installations are extensively reported in the paper.