Successful Strategy for Waterflooding Project Implementation in an ExtraHeavy Oil Field

摘要

Chichimene is the third most important field of Colombia,with an original oil in place of USD 3.1 millionbarrels,producing an extra heavy oil of around 8 API,characterized by high viscosity and reduced mobility.The estimated recovery factor was around 3%,and the reservoir pressure was declining drastically; becauseof this,it was necessary to urgently implement an enhanced oil recovery project,since without immediateintervention,the reservoir and field production would be seriously affected.A thorough screening process was performed among diverse EOR options,and waterflooding wasselected as the best alternative for maintaining reservoir pressure and increasing the recovery factor.Themain challenge was to have a rapid implementation for the entire reservoir,considering that this regionhas reported community issues derived mainly from water management disagreements and inconformitywith stringent labor requirements.Additionally,lengthy environmental permits and high deploymentexpenditures were factors that affected field development plans.The research of an effective technology for the field-specific conditions and a low deployment costindicated dumpflood as the best alternative,since it enabled injection from a deeper water formation to anupper production target zone through a smart BHA,substantially reducing injection facilities investmentand operational costs.Time savings were identified,eliminating additional requirements for environmentalpermits.The main concern was that this technology has never been implemented for extra heavy oils.Simulations in a steady state simulator validated the feasibility of the dumpflood technique in thefield.Models of the production and injection zones evidenced the pressure needs and the necessary BHAadjustments to meet the target rates and to define the completion model with the specific equipment toperform the operation.Implementation started in the South West area of the field and was deployed with three waterfloodingpatterns in a record time of three months.After nine months of operation,the reservoir pressure augmentedin the surrounding wells,and the failure indicator of the electrical submersible pumps was reduced by afactor of 20%.As a major milestone,the average field production climbed by approximately 10,000 bbl/d.Considering the successful results,the project was extended to 20 waterflooding patterns in other areas of the field,the waterflooding project was approved and sanctioned one year after the pilot startup andtherefore over 20,000 barrels of oil equivalent were incorporated to the proved reserve balance.