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.

This work is a simulation of sand production mechanics using an elasto-plastic ftnite element formulation. An open vertical well was considered in order to simulate the performance of near-wellbore unconsolidated sand during hydrocarbon production.In the simulation procedure, the assigned values of the initial stress fteld around the wellbore were taken from previous sand arching experiments conducted at the Colorado School of Mines on a similar well conftguration using 20/40 frac sand. The mechanical rock properties used in simulation were also taken from previous experimental work. The model did not require fluid properties such as density and viscosity be determined. The values of cohesion and pressure drop across the open well sandface were varied in the simulation of hydrocarbon production through the considered wellbore.Through multiple simulations, the effect of these variations on the stability of the sand surrounding the wellbore was observed. In this study, stability is considered to be elastic behavior and plastic behavior is assumed to indicate failure.It is concluded that sand production from a well can be modeled using the elasto-plastic ftnite element formulation. The stability of the sand around the wellbore depends on the pressure-drop across the sand face and the cohesion of the sand grains. The model presented can provide information on whether a producing zone will exhibit sand production problems.

In a drilling/production operating environment, wellbore instabilities arise in all three stages of a well’s life span: drilling, stimulation and production phases. The timing and severity of the occurrence of such borehole problems dictate which method of stability analysis should be used. Pseudo-3D codes are plane-strain, non-isotropic subsets of full 3D numerical and analytical codes. Their speed, portability, and ease of use have popularized them among operations engineers. There are numerous versions of pseudo-3D stress analysis, from simple linear-elastic to sophisticated poroelastic-plastic, each with its own advantage that suits a particular wellbore problem. Simple linear elastic codes are re-emerging in popularity because of ease of use and field-calibration schemes.

Among the many advantages provided by a horizontal well, it permits better knowledge of the reservoir, as well as implies an increase in productivity. The main objective is productivity. The main objective is to drill reliably, safely and economically. To accomplish this, it is essential not to compromise the wellbore stability, which typically requires an increase in the mud weight. This work provides a method to design the weight of the drilling mud to hold the fluid pressure, avoid collapse and breakdown of the formation. A knowledge of the formation breakdown pressure is also necessary in production operations such as hydraulic fracturing, secondary recovery, squeeze cementing or matrix acidizing. This work reports the study of rock mass behavior resulting from underground excavation and injection of fluids by applying finite element simulation methods and rock mechanics, to simulate the wellbore stability and onset to hydraulic fracturing for horizontal wells. The stress redistribution analysis simulates three individual effects: the wellbore (hoop stress) effect, the internal pressure effect and the fluid flow effect. Non-linear material behavior is described by the Mohr-Coulomb yield criterion. A number of examples are presented regarding the wellbore stability of a horizontal well considering fluid injection, the nature of the injected fluid, nature of the rock and orientation of the wellbore with respect to the least initial stress and impermeable barriers.

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