Abstract
Carmópolis Field in Sergipe/Alagoas Basin in northeastern Brazil is the country's largest onshore oil accumulation at 253 MMm3OOIP and a current total oil production of 2,880 m3/d. Discovered in 1963, it was quickly put into primary production. Waterflooding followed in 1971 at the central portion of the field. The combination of adverse fluid mobility ratio, reservoir heterogeneity and the lack of proper selective injection, led to the quick decline of production. Immediately, a major program of selective plugging, stimulation and selective injection was able to stabilize production. Waterflooding was then extended to the entire main block of the field. Well pattern was changed from five to nine-spot arrangement, with a corresponding downsizing in well spacing and injection rates. Carmópolis has also experienced several pilot projects for Enhanced Oil Recovery (EOR): polymer flooding, steamflooding and in situ combustion, respectively.
This past history of Carmópolis Field and the significance of waterflooding to oil production in Brazil with approximately 1,850 MMm3OOIP currently submitted to this method of recovery, led to the selection of Carmópolis as the target for one of the projects in the portfolio of PRAVAP - Petrobras Strategic Improved Oil Recovery (IOR) Program. The scope of this project included the review of the waterflooding operation through improved reservoir characterization and flow simulation, as well as the investigation of other IOR methods that might reverse the production declining trend. This paper summarizes the outcome of this project that went from lab research to field testing and led to the approval of operational implementations worth US$ 34 million NPV.
