Summary
Most of the deepwater Campos Basin reservoirs, offshore Brazil, have
unconsolidated formations that require sand control. Openhole gravel packing
has proven to be the effective completion method of choice. The main objectives
were to achieve low damage ratios, maximize completion efficiencies and reduce
completion time.
The project was conducted in one of the largest deepwater offshore fields in
Brazil, Marlim Sul. This paper describes the learning curve and completion
optimization obtained during planning, execution, and post-job analysis of six
horizontal wells campaign with five water injectors and one oil producer.
A combination of integrated service lines and experienced personnel were
important to achieve excellent injectivity and productivity ratios. Several key
operations from drilling to completion contributed to successfully complete
these wells: openhole stability, drilling practices, DIFs, wellbore clean-up,
filtration, completion fluids, completion tools, sand control, gravel-pack
software simulator ,and job execution.
The efficiency of the service company was measured with a system of
penalties and rewards allowing the operator to monitor and measure the progress
of the learning curve on completion. As a final result, the partnership between
the operator and the service companies contributed to a more economic
completion cost by reducing completion time, and improving well
performance.
Introduction
Economic development of deepwater projects demands a minimum number of wells
to effectively drain the reservoir. Because of the high costs of the deepwater
subsea environment, wellbore interventions must be minimized and completion
life sufficient to achieve depletion of the reservoir.
Typical for the Campos Basin, the Marlim Sul reservoir is a Tertiary
unconsolidated sandstone, particularly within the Oligocene and the Eocene
ages, without strong water drive. It is a heavy-oil reservoir (API 17 to 24),
with 32% porosity, and 2000 mD permeability. Because of the need for high-rate
injection to maintain reservoir pressure, and since high-rate producers are
needed for economic development, Petrobras decided to develop Marlim Sul and
several of the other fields in the Campos Basin with a series of horizontal
producers and horizontal injectors (Mathis and Ratterman 2001).
Marlim Sul is a giant field located offshore Rio de Janeiro, Brazil, in the
Campos Basin. The field was discovered December 1987 and it has been under
development since 1994. It contains 1.47 billion BOE of proved reserves and an
additional 1.15 billion BOE of probable reserves. Laying in 2,625 to 8,530 ft
(800 to 2600 m) water depths, the field contains 14 reservoir blocks in a 600
square kilometer area. To lessen risks, Petrobras decided to develop the field
in four modules. The wells mentioned on this paper are part of Marlim Sul,
Module 1, with 35 wells in total (21 producers and 14 injectors) (Priandi
2004).
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
14 July 2005
- Meeting paper published:
9 October 2005
- Revised manuscript received:
23 June 2007
- Manuscript approved:
17 August 2007
- Version of record:
20 December 2007
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