Successful Strategy for Waterflooding Project Implementation in an Extra Heavy Oil Field

Abstract

Chichimene is the third most important field of Colombia, with an original oil in place of USD 3.1 million barrels, 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; because of this, it was necessary to urgently implement an enhanced oil recovery project, since without immediate intervention, the reservoir and field production would be seriously affected. A thorough screening process was performed among diverse EOR options, and waterflooding was selected as the best alternative for maintaining reservoir pressure and increasing the recovery factor. The main challenge was to have a rapid implementation for the entire reservoir, considering that this region has reported community issues derived mainly from water management disagreements and inconformity with stringent labor requirements. Additionally, lengthy environmental permits and high deployment expenditures were factors that affected field development plans. The research of an effective technology for the field-specific conditions and a low deployment cost indicated dumpflood as the best alternative, since it enabled injection from a deeper water formation to an upper production target zone through a smart BHA, substantially reducing injection facilities investment and operational costs. Time savings were identified, eliminating additional requirements for environmental permits. 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 the field. Models of the production and injection zones evidenced the pressure needs and the necessary BHA adjustments to meet the target rates and to define the completion model with the specific equipment to perform the operation. Implementation started in the South West area of the field and was deployed with three waterflooding patterns in a record time of three months. After nine months of operation, the reservoir pressure augmented in the surrounding wells, and the failure indicator of the electrical submersible pumps was reduced by a factor 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 and therefore over 20,000 barrels of oil equivalent were incorporated to the proved reserve balance.

Study on Viscosity Reducer Flooding Technology for Deep Low Permeability Extra Heavy Oil Reservoirs

“…Deep low permeability extra heavy oil reservoirs refer to the oil reservoirs with buried depth more than 2200 m, reservoir permeability lower than 300 md, and crude oil viscosity greater than 10000 mPa•s at 50°C. Deep low permeability extra heavy oil reservoirs have the characteristics of deep burial depth, high formation pressure, low permeability, and poor crude oil fluidity, which leads to great difficulty in development and low productivity of a single well [1][2][3][4][5][6][7][8][9][10]. At present, there is no clear and reasonable development method for the economic and effective production of this type of heavy oil reservoir.…”