Summary
Oilfield-cement compositions capable of self-healing cracks/fractures in set
cement without depending on contact with a fluid, such as water or oil, are
presented in this laboratory study. Traditionally, such compositions include
additives that are capable of swelling when exposed to fluids such as water or
oil, for example. Dependence on additives to swell and block flow channels
after contact with a specific type of fluid hinders the self-healing
effectiveness of the cement composition. As a result, designing cement
compositions for field applications requires prior knowledge of the type of
fluids that the cement may come into contact with, not only through the
productive lifetime but also after abandonment of the well.
Results from testing cement compositions containing a new class of
elastomeric additives that do not depend on the nature of the fluid to seal
cracks are presented in this paper. The elastomeric materials were chosen such
that they have suitable chemical functionalities for binding strongly with
cement and metal surfaces, and either have low melting points, as in the case
of semicrystalline polymers, or have low glass transition temperatures
(Tg), as in the case of amorphous polymers. Low viscosity or
flowability of the elastomers at test temperature and the ability to bind to
cement surfaces appear to be two key factors for their effectiveness. The test
methods included static thermal healing, measurement of retained mechanical
properties after self-healing, and fluid-flow-rate measurements through cracked
cement samples. The results show that the elastomers are effective in thermal
healing of broken cement parts, in partial retention of mechanical properties,
and in preventing fluid flow through failed cement samples.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
4 August 2009
- Meeting paper published:
21 April 2009
- Revised manuscript received:
17 December 2009
- Manuscript approved:
23 December 2009
- Published online:
21 June 2010
- Version of record:
13 September 2010
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