Onshore and Offshore EOR Applications in Brazil: A Review Study

Abstract This study reviews the existing oil and gas fields in Brazil located both onshore and offshore. Focus is on geology and production history of Santos, Campos, Reconcavo, Sergipe, and Potiguar Basins. We mainly reviewed the geological and reservoir characteristics of these basins, their production history, applied enhanced oil recovery (EOR) methods, and we finally made some EOR recommendations which may help to increase hydrocarbon recoveries in each basin. At the beginning of the current decade, Brazil was producing almost 2 MM barrels of oil per day. Nowadays, the pre-salt fields alone (that started operating 15 years ago) produce an average of 1.67 MM bbl/d with a 2.73 MM bbl/d total daily oil production. In other words, the oil production from the basins other than the pre-salt fields started to decline of more than 50% in their production levels. The divestment of many assets, located both onshore and offshore, opens a window of opportunity and a need for the new owners to apply EOR methods to bring back production to higher levels and recover their investments. By reviewing the data from three onshore fields from Reconcavo, Sergipe, and Potiguar and two offshore fields from the Campos basin, this paper has discussed issues and assessed alternatives that may similarly be applicable to other fields in the same basins. Buracica, Carmopolis, and Canto do Amaro fields presented almost none to low increase in production. One of the reasons may be credited to paraffin wax deposition. To avoid wax deposition and increase oil production, we proposed to combine two methods; a thermochemical method to avoid the buildup of wax with the addition of surfactant to the injected fluid to reduce the interfacial tension between water and oil and increase recovery. Both Jubarte and Marlim have achieved success with waterflooding but currently, a continuous decline is observed. Polymer flooding is proposed as a solution in these cases. The pre-salt fields are still ramping up production at very high rates. Hence, as an alternative, in those reservoirs, CO2-WAG might be applied in the near future before reaching a decline in the oil production. This study briefly discusses the status of the oil and gas fields in Brazil both located onshore and offshore. Moreover, it provides quick recommendations for the existing problems in Brazil during oil and gas production via EOR methods.