The polymer-injection project in the Dalia field, one of the main fields of Block 17 in deepwater Angola, represents a world first for both surface and subsurface aspects. Thorough, integrated geoscience and architectural studies led to the decision to initiate a polymer-injectivity test on a single well, followed by a continuous injection of polymer on one of the four subsea lines delivering water to the field. The complete paper describes the main results of the pilot phase.
A subsea development scheme with water injection for full pressure maintenance was chosen for the Dalia field together with gas reinjection. Very early in the geoscience studies, oil viscosity was identified as the main limiting factor to water-injection recovery. Polymer injection was positively screened as a potential enhanced-oil-recovery method for the field.
Extensive feasibility studies of polymer flooding were initiated in 2003, 3 years before production start-up. A phased approach was chosen to assess and reduce the main uncertainties of the project, consisting of the construction of a powder-polymer solution-preparation skid, a single-well injectivity test, a longer injection period through one of the injection lines (supplying three wells), and the drilling of a sampler/producer well to assess in-situ viscosity, while continuing surface and subsurface studies....
Polymer Injection in Deepwater Field Offshore Angola
10 May 2016