This paper describes an extended well test (EWT) campaign using intelligent completions in a presalt reservoir. Brazil is recognized as a promising deepwater province because of large oil discoveries in the presalt polygon. One such discovery contains an estimated eight billion barrels of recoverable oil and is considered to be one of the largest fields recently identified. Several challenges and risks are associated with ensuring economic returns, such as properly constructing wells and extracting value from their lifecycles. Most presalt fields contain thick carbonate reservoirs with significant variations in vertical permeability and unknown behavior affecting long-term production. Most of those uncertainties can be reduced using extended well testing; however, the solution implemented uses multizone completions to perform EWT, providing a new level of reservoir understanding.
To better understand reservoir behavior during production, several options were analyzed for the first EWT to help minimize uncertainties concerning the extensive pay zone. Drilling wells provides valuable rock and formation knowledge; however, this information is not sufficient to simulate formation flow behavior during the field lifecycle and reduce production uncertainties. In addition, current oil market conditions imposed another challenge to maximize output during EWT, impacting some well designs and the campaign strategy. A triple-zone intelligent completion was envisioned as the optimum solution to be applied for properly understanding how each interval would behave under production or injection.
EWT was performed on two producers and one injector. Based on project requirements, gas and water had to be reinjected into the reservoir. Additionally, using two producers allowed the operator to maximize oil output while performing the EWT with production details from each zone rather than the entire well. Both producers were completed with dual-zone intelligent completions systems because of technical limitations, while the injector was completed as planned with three zones.
Proper planning, preparation, and experience from other projects contributed to the campaign success in such a challenging exploratory completion. During preparation, several evaluations and studies were performed to help ensure the proper technology was selected and the system could withstand the extremely high flow rates with high scaling potential expected along with other flow assurance concerns.
A future commissioning campaign in this field should allow further evaluation of the applicability of this concept to other fields, which is promising for reservoir evaluation studies.