Abstract
Use of slotted liner as a sand control device is widespread in SAGD
operations in Western Canada. Operating temperatures in such thermal EOR wells
can be extreme, sometimes exceeding 270°C (518°F), and the associated
compressive axial mechanical strain imposed by constrained thermal expansion
can load the pipe material beyond its proportional limit. Selection of an
appropriate slotted liner configuration is critical to ensure that structural
stability (and hence sand control) is reliably maintained during operation.
Mechanical properties of the tubular material at elevated temperature strongly
influence the compressive stability of the liner structure, but
lower-temperature properties also affect the ease of pipe slotting on a
production scale, which is typically achieved by plunging thin saw blades
through the pipe wall. Common slotting issues include breakage or unacceptably
high blade wear rates.
This paper describes the developmental basis for a new tubular material
formulation that is specifically optimized for thermal structural stability in
SAGD applications without compromising slotting performance.
Elevated-temperature mechanical properties are designed to prevent compressive
buckling failures and to minimize strain localization potential. Results of
analytical and experimental work (including stability analysis of the liner
structure, thermo-mechanical material testing, and bench-scale slotting trials)
are described.
Introduction
Ongoing rapid development of bitumen reserves in Western Canada has led to
an increased focus on developing robust tubular design bases for extreme
service conditions in in-situ recovery schemes such as SAGD. Specifically,
cemented or frictionally-constrained tubulars are subjected to
thermally-induced, deformation-controlled loading that leads to a unique set of
design challenges and more stringent requirements for post-yield material
response than those employed in traditional elastic design. Slotted liner is
used as a sand control device in a majority of SAGD wells.
Slotted liners used in thermal applications must provide a stable structure
under extreme thermally-induced compressive loading in order to maintain
wellbore access and to prevent excessive sand from entering the wellbore. While
the deformation resistance of slotted liners depends on geometric attributes
such as pipe wall thickness, slotting configuration, and slot geometry,
material properties have a considerable impact on structural stability and
localization resistance.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
2 April 2007
- Meeting paper published:
12 June 2007
- Revised manuscript received:
30 November 2009
- Manuscript approved:
5 December 2009
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