Rovina et al. described the aggressive TSO fracpacks utilized in the Roncador field offshore Brazil. TSO designs achieving 6 lb/ft2 16/20 CarboLite resulted in well rates exceeding 20,000 bopd. Despite the relaxation of Saucier’s criterion, the use of the larger proppant has been successful at controlling fines migration.
The key issue to develop the Roncador field, located in ultra deep water offshore Campos Basin, in Brazil, is the maximization of production rate keeping the completion reliability, avoiding premature high workover costs involved in that scenario. Roncador reservoir has a succession of thick turbidite sandstones containing 31° API oil, requiring sand control and water injection to maintain reservoir pressures above saturation's. The distance between the pay zones are as short as 12 meters, becoming the first problem to fit the gravel assembly in such a short space. Flexibility in the completion is provided by an internal string with sliding sleeves. When water coning occurs in any zone, the sleeves shall be closed using slick line in a light workover.
The paper will describe the main challenges to carry out three stacked frac-packs in a subsea well drilled in water depths above 1800 m, considering the experience acquired from the first three deviated subsea wells, working in dynamic positioned rigs. Special procedures were adopted to prevent failures during the completion, such as: rigid control of fluid cleanness and gel properties, selection and operation of service tools suitable to that environment (heaving, risk of rig drive-off) and careful design for frac-pack based on minifrac data.
The drives for equipment selection will be reviewed, including the choice of perforation charges, gravel equipment and sliding sleeves. The good results obtained in those frac-packs, using the Tip Screen Out technique, reducing the skin effect compared to conventional gravel pack, will be presented too.
Author(s): Paulo S. Rovina, Carlos A. Pedroso, Arthur B. Coutinho, Luis F. Neumann, Petrobras
Paper Number: SPE 63110