The Cañadon Perdido field (Argentina) is an old field first produced by depletion and recently by waterflood. The reservoir lies in continental fluviatile deposits. The oil viscosity is about 100 cp. The unfavorable water-oil mobility ratio makes the waterflood efficiency low. Thus a polymer solution injection was studied to improve the oil production, considering the favorable temperature and salinity. The preparation of a pilot and the estimation of the economical efficiency of the process are presented. The paper presents the tasks integrated in the study:

  • Laboratory (selection of polymer, measurements of its characteristics inside and outside the reservoir rock).

  • Geological and reservoir engineering modelling of the pilot zone, including geostatistical simulation.

  • Design of the pilot surface facilities and estimation of costs of a field extension.

The conclusions of the study are:

  • A polymer solution is efficient to produce additional oil.

  • The reservoir conditions allow to use polyacrylamide, the cheapest polymer.

  • If confirmed by the pilot results, polymer injection could be economically attractive.

The reservoir is composed of sandy-silty-


shally facies representing the Yacimiento El Trebol formation (upper part of Bajo Barreal Though polymer flooding was formation) and corresponding to a fluvial contemplated as a promising Improved Oil environment. The Tertiary transgressive Recovery (IOR) method in the late 70's and marine sediments of Salamanca formation are early 80's when oil price was high, it is sealing the continental series. presently not a widely applied recovery In the Cañadon Perdido field, five process. The present paper shows that, when stratigraphic layers have been identified. The reservoir conditions are favorable, polymer two uppermost, A and B constitute an upper injection is an economically attractive process. interval, well separated from a second group composed of C, D and E. The upper interval 1. PRESENTATION OF THE FIELD was first put into production in the 30's. The second deeper interval started producing in the The Cañadon Perdido field is located in 40's. the San Jorge basin, North East of the Province of Chubut, in Argentina, 25 km North of The reservoirs are found at a depth of Comodoro Rivadavia city. The field has been about 900 m below the ground surface. The operated by YPF since its discovery in 1928. structure is rather flat, and the series are The oil is rather heavy (22 °API and crossed by NW-SE faults. around 100 cp in reservoir conditions). The reservoir has been produced a long time by 1.2. Production history depletion, under dissolved gas drainage. A The upper interval (A, B) was initiall

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