Produced Water
Produced water is water trapped in underground formations that is brought to the surface during oil and gas exploration and production. In traditional oil and gas wells, produced water is brought to the surface along with oil or gas.
Oil and
gas reservoirs normally contain amounts of water, oil, solids, condensates and
gas. When oil and gas are processed, water is separated and pumped back into
the reservoir in order to maintain the right pressure in the well.
Alternatively, the water is discharged to the sea or sewerage. Both methods
involve a set of conditions and strict regulations, aimed at preventing well
contamination and water pollution.
When the oil and gas reservoirs are depleted, water content may be as much as
98% of the total fluids being produced. As a result, the handling and treatment
of produced water up to the required quality levels becomes an increasing cost
factor in the total Life Cycle Cost of an operated asset.
Nowadays, it has become essential to recover and use this water again due to the more and more stringent environmental limits (the components of produced water must exhibit persistent, toxic or bio accumulative properties) and the always increasing water demand.
Produced Water Treatment
Produced waters are characterized by a high content of salt and oil that render necessary to device a specific treatment train in order to decontaminate them, as for example with respect to a municipal wastewater. Typically, produced water contains high concentrations of aromatic hydrocarbons e.g BTEX (benzene, toluene, ethylbenzene, xylene), NPD (naphthalene, phenanthrene e dibenzotiophene) and PAH (polycyclic aromatic compounds), minerals, radioactive substances, dissolved gases, scale products, waxes, microorganisms and dissolved oxygen.
Our solutions for removal of hydrocarbons and/or suspended solids from the produced water are divided into systems for both Onshore and Offshore locations, each with the most appropriate and effective technologies.
To remove hydrocarbon components from produced water, biological, physical and chemical methods are available. In offshore extraction facilities due to space constraints, compact physical and chemical treatment technologies are preferred such as photo-electrocatalytic processes, hydrocyclones, coagulation and flocculation . Most of these techniques are only suitable for pretreatment of wastewater for in situ reuse, e.g. reinjection for enhancing oil recovery. On the contrary, membrane technology may be successfully used to remove hydrocarbons from oil-contaminated wastewater, also in the presence of a high salinity. Membrane processes offer several advantages over conventional treatments such as compact module, lower energy consumption, environmental friendliness and high quality product independently on fluctuations in feed quality. Because of the presence of dissolved and suspended oil in untreated produced water, the membrane equipment may become fouled, thus increasing operation costs. At this purpose, the vibrating membrane technology process VSEP® (Vibratory Shear Enhances Process) is a technology that limits membrane fouling.
