Produced water is the water that is being extracted from the subsurface during oil and gas production. It originates from water that is trapped in permeable sedimentary rocks within the well bore. It includes water that has been injected into the formation to maintain reservoir pressure and any chemicals added during the production/treatment processes. Disposal of such waste water can be problematic in environmental terms due to high salinity and oil content. Experience to date has shown that re-injecting produced water is an attractive, environmentally-sound solution to water disposal. Since 1975, initiated by 15 countries in western coasts of Europe, OSPAR (Oslo and Paris) commission was formed to protect marine environment and until now, most of the oil & gas operators are following the disposal criteria given by this organization.

However, an issue arises in OSPAR criteria on monitoring of produced water disposal due to limitation in the instrumental analytical technique used. OSPAR stated a limit in dispersed oil parameter; but with the current analytical method (GC-FID), the total of dissolved oil and dispersed oil are given. Therefore, the readings will be higher than the actual.

In our studies, produced water is being treated with membrane filtration before being analyzed for oil content. Different types of membranes (UF or MF) are being compared during the treatment. After that, GC-FID and UV spectroscopy are used to characterize these oils. Membrane filtration proves to be an effective method in separating these two types of oil.