involve injecting chemicals into the reservoirs. These have a dual objective:
· to optimize the efficiency of waterflood by injecting polymer-modified water with higher viscosity;
· to increase recovery by injecting surfactants and alkalis that displace more of the residual oil trapped in the reservoir matrix.
Focus - acting at different scales
The mechanisms involved in chemical EOR processes act at either the macroscopic or the microscopic scale, depending on the chemicals employed.
Polymers are long chains of molecules that raise the viscosity of water as they «uncoil». By narrowing the gap between injection water viscosity and oil viscosity, these chemicals act at the macroscopic scale to improve the «piston» effect of the waterflood., surfactants and alkalis act at the microscopic scale. Surfactants are molecules with a hydrophilic head and a lipophilic tail: this dual affinity for water and oil is what displaces the oil fraction bypassed by conventional recovery techniques. Alkalis limit the adsorption of the surfactants by the reservoir rock, thus preventing surfactant loss as the waterflood advances through the deposit.
The World s First Viscosified Water Injection Pilot factors make EOR more difficult to implement in the deep offshore context than in conventional reservoirs, namely:
· constraints related to the architecture of deepwater developments;
· the higher cost of field pilots.its tradition as a deepwater pioneer, Total is the first in the world to address the challenge of polymer-viscosified water flooding, on Dalia (Angola). in 2003, three years before the field came onstream, this project illustrates an important aspect of Total s EOR strategy: these technologies are not confined to mature oilfields, but have a role to play in new developments as well.
«Polymer-viscosifiedwaterflooding could raise recovery by 8% over 10 years.»
Upon completion of injectivity tests of polymer-viscosified water in 2009, the field pilot was installed on three water injection wells on Camelia, one of the four Dalia reservoirs. A sampling well was drilled in 2011 behind the polymer-enhanced waterflood front. Over the course of 2012, samples check the presence and quality of the polymers, quantify the actual viscosity of the polymer-enhanced water and update the reservoir model. If results are on par with expectations, injections of polymer-viscosified water will be deployed to the entire Camelia reservoir and should result in approximately 8% additional recovery over ten years.
5. Improving Performance on Tomorrow s Mature Fields
is the time to prepare for tomorrow s aging deepwater facilities. Reinforcing their safety and reliability will depend on careful monitoring and the development of more effective inspection and repair solutions.2017, the Group will be operating nine deepwater FPSOs versus five today, along with 450 to 500 subsea wells. This change of scale will mean more subsea installations and more subsea processing - all involving increasingly sophisticated technologies.already on stream or still on the drawing board, these fields are locate...
