Exclusively patented by Total, the Flex procedure can, for the first time ever, use the same equipment to filter the different types of process water requiring treatment in the production stage. This innovative solution is just about to enter its industrial phase, and is expected to bring significant benefits and improved performance. The stakes are sizable, because oil extraction actually produces more water than oil and consumes about as much water as the volume of petroleum produced!
The filtration technologies currently available for process water are varied and specific to the nature and composition of the water being treated. Therefore, the organic membranes used to filter seawater used in offshore facilities are incompatible with treating water loaded with hydrocarbons. This means they cannot be used to treat production water. In addition to this, none of this dedicated filtration equipment is flexible: their media filters are large, heavy, and unsuited to the changing conditions of treatment processes.
A conclusive water treatment pilot project
With the Flex solution, it’s a whole different ball game. This innovative, never-before-seen approach involves a single filtration unit that can be used for both seawater and production water. Flexible and effective, Flex can adapt to the different water production profiles, which vary throughout the lifetime of an oil field as the amount of production water gradually increases and the need for seawater to be reinjected decreases. It meets the toughest quality requirements for the surface discharge of such water or its injection into a reservoir, necessary to maintain the pressure.
Flex is the result of five years’ work and collaboration between various Group and Total E&P Congo teams. The pilot project that we headed up in Djeno proved the viability of our concept by testing all possible water profile configurations: production water, seawater, liquid mixtures, etc.
While there, we also developed and successfully tested two additional Flex processes:
- The Flex process, which involves ultrafiltration using ceramic membranes at a filtration threshold of 0.04-0.5 microns, supported by modules spread out across several trains. This modularity means that membranes designed for treating seawater can gradually be replaced by membranes designed for production water. This reversible process can be used to filter incompatible water types and prevent them from mixing together.
- The Full Flex process, which is designed for compatible water types that are mixed prior to treatment. Its membrane filtration design is flexible enough to adapt to different operational parameters and optimize the filtration conditions accordingly. This is where the appeal behind the process lies.
Flex optimizes water treatment and cuts costs
The two processes mean that a single filtration unit can be used to treat two different water types at the same production site, whereas previously two separate systems were needed. This generates substantial savings, both in terms of investments (design, engineering, procurement, construction, pipework and collectors) and operating expenses (maintenance, spare parts, chemicals and inspections). A simulation carried out on 120,000 barrels of water per day showed that, for example, Flex can save €12 million in ex-works costs for filtration, free up 504 m3 of space (18 m long, 8 m wide and 3.5 m tall), and reduce the weight of filtration equipment by 170 tons.
Thanks to the expertise acquired and the operational data collected, Flex is now ready to move into its industrial phase. It can now be used every time two different process waters need to be treated at the same oil site. And the stakes are high, because this is a near-constant requirement for our offshore operations. Flex will bring us four major advantages: a higher proportion of reinjected or reused production water; less waste; fewer water samples taken from the natural environment; and reduced costs. Opportunities abound already, especially in the Middle East, where water management is a particularly sensitive issue.
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