SPE Drilling & Completion
Volume 25,
Number 4,
December 2010,
pp. 509-517
Summary
Significant fluid loss while drilling through fractured formations is a
major problem for drilling operations. From field experience, we know that the
type and rheological parameters of the drilling fluid have a strong impact upon
the rate and volume of losses.
A mathematical model for Herschel-Bulkley [yield-power-law (YPL)]
drilling-fluid losses in naturally fractured formations is presented. As a
result, the effect of rheological properties of drilling fluid such as yield
stress and shear-thinning/-thickening effect (flow-behavior index) on mud
losses in fractured formations is investigated. We found that the yield stress
can control the ultimate volume of losses while the shear-thinning effect can
tremendously decrease the rate of losses. Therefore, mud losses in fractures
can be minimized by optimizing the rheology of the drilling fluid properly.
The model also allows for quantitative analysis of losses that take into
account fluid rheology to characterize the fractures. Hydraulic aperture of
conductive fractures can be obtained by continuously monitoring mud losses and
fitting field records of mud losses to the model. The proposed model is very
useful not only for drilling applications but also for well-completion design
and fractured-reservoir-characterization purposes. To examine the validity of
the model, a practical application of the proposed technique is demonstrated
through a field example of mud-loss measurements in a fractured well in the
Gulf of Mexico.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
18 August 2009
- Meeting paper published:
1 April 2008
- Manuscript approved:
12 March 2010
- Published online:
14 October 2010
- Version of record:
16 December 2010
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