This paper describes the design and qualification process used to select a reservoir drill-in fluid (RDF) for the Peregrino field offshore Brazil, and the successful application of this fluid. The Peregrino field is located east of Rio de Janeiro in the southwest Campos Basin area. Approximately 2.3 billion barrels of oil are in place in the Peregrino reservoir. The productive sands in this variable reservoir typically exhibit permeabilities between 6 and 15 Darcy, and are unconsolidated with interbedded shales. Peregrino crude oil is heavy (13API) and viscous. The estimated recoverable volume of crude oil is 300 million to 600 million barrels. The selected fluid, a NaCl brine-weighted water-based mud employing KCl and Glycol additions for shale stabilization, was used to drill the first wells at Peregrino. Penetration rates were high and zero non-productive time occurred. To achieve this drilling performance in the high permeability, unconsolidated, heavy oil reservoir, an extensive fluid selection process was performed to optimize the drill in fluid for maximum well productivity. Key test results reviewed in this paper include: Bridging solids optimization, lubrication, shale inhibition, fluids compatibility, filtercake lift off and backflow performance, breaker fluids and formation damage The reservoir sections of the wells were successfully drilled, open-hole-completed with sand screens and gravel packed with 100% efficiency.

The paper discusses the aspects of the multi-disciplinary well construction process (WCP) that is being applied in the development of Peregrino field located offshore Brazil. Peregrino field is a heterogeneous sandstone reservoir containing a large volume of viscous oil in a complex depositional geological environment. The field development is based on a large number of long horizontal and multilateral wells equipped with high energy-demanding Electrical Submersible Pumps (ESP) for artificial lift.The well construction process covers the feasibility, concept selection, detailed plan and execution phases. The efforts towards a multi-disciplinary process allow cost optimization, risk mitigation and production and reserves maximization. Multi-disciplinary teams include not only the usual subsurface disciplines (geophysics, geology, operations geology, petrophysics, reservoir and production technology) but also drilling, completion, topside and operations from an early stage.In viscous oil fields it is especially important to meet the requirements in reservoir properties, well length and completion design to develop such a field economically. The applied WCP is allowing Peregrino field to achieve its goals in terms of numbers and quality of wells planned and drilled. More than 20 wells have been drilled so far with very good results. Peregrino is now producing at plateau production with a daily oil production potential of 100,000 bbl.