Campos Basin: Lessons Learned and Critical Issues To Be Overcome in Drilling and Completion Operations
Authors: Juiniti R. , Salies J. , Polillo A. 
Published: October 2008

Drilling and completion in Campos Basin have been in constant evolution, from the first subsea wells and fixed platforms to latest horizontal wells in deepwater. This paper will first present the lessons learned with drilling and completion in shallow water to latest wells drilled and completed in Roncador in the range of 1,800 meters of water depth. Exploratory drilling will be also addressed. The main points to be presented are: well design, horizontal and multi lateral wells, well head design, well control, operations with dynamic positioning vessels, completion and sand control techniques and their evolution.

Second, this paper will address some challenges presenting the problems as PETROBRAS see them, what are the solutions that we are adopting and what do we expect from the industry. The issues that will be presented are: well design for production of heavy oil, dual gradient drilling, intelligent completion systems for monitoring and controlling multiple zones, production or injection from or into a single well, isolation inside horizontal gravel-packed wells, gravel packing long horizontal sections under very low formation fracture gradient.

Introduction

Campos Basin exploratory activities started in 1971 first with jack ups (Penrod 89) and later with moored drillships that culminated with the discovery of Garoupa field in 1974 at 124 meters of water, soon followed by other shallow water discoveries (Namorado, Enchova, Pargo and others) that came on stream in subsequent years.

Petrobras started in 1984 a deepwater exploratory campaign with successful discoveries as Albacora (1984), Marlim (1985), Albacora Leste (1986), Marlim Sul (1987) and Roncador (1996).

Campos Basin developments along these 25 years of production have imposed many learnings and challenges in the drilling and completion operations.

Several projects were implemented from shallow to ultra deepwater using jack ups, fixed platforms, moored floating rigs and dynamic positioning (DP) rigs in drilling, completion and workover operations.

These different projects required different approaches and the key was to use the learnings of each field development in future projects.

The most important evolution in drilling and completion operations was seen when we moved towards deeper water. It allowed, in conjunction with the subsea hardware evolution to put the first deepwater well on stream in September 1984 (well 3-PU-2-RJS at 307 meters of WD) and the first ultra deepwater field on stream in 1999 (Roncador).

In general, the geological carachteristics in Campos Basin are: shallow reservoirs, no occurrence of shallow gas or HPHT formations.

Moreover, the environmental conditions in Campos Basin are mild but with high currents.

On the other hand several critical issues have to be still overcome in drilling and completion operations to cope with the challenges of producing in ultra deepwater (2,000 - 3,000 meters) as: steep slope seabed, shallow and unconsolidated reservoirs (Miocene and Oligocene) and expensive operations. Nowadays there are 650 wells drilled in WD up to 1,500 meters and 114 wells drilled in WD deeper than 1,500 meters. Ultra deepwater under going field developments will lead Petrobras domestic production to reach 1.9 million barrels of oil per day by 2005.