CETCO Successfully Treats Contaminated Water on Triton FPSO

CETCO Oilfield Services has successfully treated contaminated water returns on the Amerada Hess Triton FPSO.

The fluids were treated during well clean-up operations and have reduced the potential for overboard oil discharges and production upsets at the offshore installation approximately 120miles east of Aberdeen.

In total three wells at the Bittern field were treated using a combination of scale squeezes and acid stimulation.

Contaminated water returns are a common problem for the offshore industry and are often caused by the harsh fluid packages used to re-stimulate existing oil wells due to downhole scaling, sanding or skin damage caused over time.

When the surfactant packages return they can create major upsets in both oil and water treatment systems. Offering an alternative to working returns through existing production process facilities or shipping to shore for treatment, which can be a very costly exercise, CETCO's technology is designed to isolate the fluids completely preventing any upset conditions from occurring.

Returns are subsequently treated through CETCO's patented water treatment technologies, CrudeSep and CrudeSorb, and discharged directly overboard meeting all statutory requirements.

Specifically designed to treat oily water returns produced during offshore operations, both technologies are proven to significantly reduce dispersed and dissolved hydrocarbons and can be used independently or together to achieve overboard compliance.

In treating the well clean up returns on the Triton FPSO a CrudeSep 4000 skid with a CrudeSorb RFV4000 skid was utilized with the technology located downstream.

CrudeSep is a vertical, cyclonic, induced gas floatation, four phase separator incorporating gravity oil separation, enhanced by induced gas flotation and cyclonic motion. This creates centrifugal forces which separates fluids of dissimilar specific gravities.

The CrudeSorb is a proprietary adsorption media that is proven to be extremely efficient at removing both soluble and insoluble hydrocarbons from water, and, on the Amerada Hess application, was used as a final "water polisher" prior to the fluids being discharged safely overboard.

The RFV Adsorption Skid utilized comprised dual sock filter pods and adsorption vessels each designed to hold canisters of Crudesorb media.

Fluids were passed firstly through the sock filters to remove any solids or particles that may have passed through the upstream process. Downstream of the sock filters the flow was split to pass through either bank of the Crudesorb vessels. As the water flowed through the media contained within each canister, it passed through the canisters perforated center core. The fluid was conveyed downward through the stacked center cores into the vessels radial discharge header. The polished water then exited the vessel through a nozzle installed on the vessel's lower side with an oil-in-water concentration fit for discharge directly overboard.

Commenting on the CETCO's treatment of the contaminated water returns on the Triton, Barry Hanley, Triton Process Eng Coordinator, said,

"CETCO was contracted to the Triton FPSO to carry out water clean-up operations during flowbacks from several well scale squeezes and acidisation.

"This work was heavily dependant on weather conditions and the availability of dive-boats, which resulted in several changes to the schedule at relatively short notice. CETCO's response was positive and flexible throughout. The onshore support and offshore personnel were professional and highly committed to meeting our objectives throughout the contract".

The contract was worth in the region of £300,000 and also saw CETCO supply personnel to commission and run the equipment on board the unit.