Summary
This article details the planning and execution phases of the first openhole
gravel-pack (OHGP) operation performed with the alpha-/beta-wave deposition
technique using a nonaqueous system as a carrier fluid. The operation was
performed at Marlim field, offshore Brazil, and constitutes the first field
implementation of a research and engineering effort that started two years
ago.
The idea in this first field operation was to avoid many changes in the
original well design for the area and to concentrate novel steps in the fluid
for gravel packing openhole design, friction loss evaluation, fluid
substitution, and rheology characterization. On the basis of these results,
optimized procedures were proposed for the operation. A broad description of
the technical aspects, field pumping profiles, and packing quality is also
presented.
Introduction
Most of the large production wells in sandstone reservoirs require sand
control because of the poorly consolidated formations. OHGP is among the most
popular solutions for sand control in offshore deepwater reservoirs and
accounts for approximately 95% of the operations in such scenarios on the
Brazilian coast. The petroleum industry has developed a number of fluid systems
for a successful OHGP, including a water-based drill-in fluid (DIF) and gravel
carrier fluid (widely applied in Brazil) (Marques et al. 2007; Farias et al.
2007) or using a synthetic DIF and water-based gravel-carrier fluid (McKay et
al. 2000).
In spite of the industry’s effort to develop high-performance water-based
fluids (Parlar et al. 2004; Aldea et al. 2005), the use of synthetic fluids
guarantees superior wellbore stability, lubricity, inhibition, and drilling
performance. Substituting synthetic DIF for water-based gravel-carrier fluids
is a complex operation because of the potential for fluid interaction,
formation damage, and problems of offshore logistics. Another challenge is to
provide a reliable sand-control technique in the horizontal section with
operational safety and minimum formation damage. Parlar et al. (2004) presented
field implementations of OHGP operations considering high-viscosity nonaqueous
fluid (NAF) and alternate path concepts.
The field job detailed herein is the first field implementation of a
corporate program within Petrobras that focused on developing technology for
performing OHGP with NAF systems, considering alpha- and beta-wave deposition.
This gravel-pack placement strategy is considered to be reliable,
cost-effective, and widely validated within Petrobras using brines as carrier
fluids. The ability to run such operations with NAF systems allows aims of the
application in different scenarios, such as the following:
- "Infill drilling" projects, considering re-entries in existing
vertical wells in mature fields. The strategy includes opening an 8 1/2-in.
window in the 9 5/8-in. casing, drilling buildup and reservoir sections in the
same phase, and enabling the use of conventional screens and sand-control
equipment.
- Reduction of time and costs in the execution of conventional horizontal
wells by drilling buildup and reservoir sections in the same phase and
performing OHGP with a compatible carrier fluid.
- Execution of horizontal wells with OHGP in reservoirs sensitive to aqueous
fluids.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
10 August 2007
- Meeting paper published:
11 November 2007
- Revised manuscript received:
19 January 2009
- Manuscript approved:
10 February 2009
- Published online:
20 August 2009
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