Summary
Hydrates present challenges to drilling, cementing, and producing in
deepwater environments. If the hydrates are destabilized during well
operations, gas or solids could rise to the surface and create problems.
Therefore, there is a compelling need to prevent destabilization of hydrates
from drilling to producing operations in the life of the well.
The volume of cement slurry in the surface casing is great because of the
large annulus, and this slurry volume results in a great amount of heat
generated during slurry hydration. Further, during production, hydrocarbons
could increase the temperature of the surrounding formation. These factors
could destabilize the hydrates.
Cement slurries are designed to lower the heat of hydration while meeting or
exceeding the other properties needed for successful deepwater cementing. Heat
of hydration is reduced by a factor of more than two when compared to the
conventional cement-slurry design. The improved cement-slurry designs lower
considerably the thermal conductivity of the set cement sheath.
Laboratory tests designed to measure and optimize the heat of hydration are
discussed and field implementation of these slurries and results are presented.
Results presented in this paper should help the industry construct and produce
wells without destabilizing the hydrates, thus, promoting well safety and
economics.
Introduction
As the global demand for hydrocarbons increases, the industry is exploring
for resources in challenging environments such as deeper waters and extremely
high-pressure/high-temperature formations (Barcelos et al. 1994; Biezen and
Ravi 1999). There are many challenges in the construction and production of
deepwater wells (Ravi et al. 1999). One topic not discussed in any detail, at
least in the open literature, is the challenge posed by the presence of
hydrates. The current paper discusses solutions to the challenges posed by
hydrates during cementing. However, the challenge posed by hydrates in
deepwater environments cannot be analyzed in isolation from the other
challenges.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
30 January 2008
- Meeting paper published:
4 March 2008
- Manuscript approved:
9 September 2008
- Published online:
31 July 2009
- Version of record:
28 September 2009
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