SPE Drilling & Completion
Volume 24,
Number 4,
December 2009,
pp. 581-589
Summary
Owing to the narrow drilling margin that exists between the pore-pressure
and the fracture-pressure gradient, drilling in depleted-reservoir,
high-pressure/high-temperature, and deepwater environments is universally
recognized as being technically challenging.
A number of field techniques are available for mitigating many of the
drilling problems encountered. Included among these are specialized fluid
engineering that involves the use of chemical- and particulate-based treatments
for minimizing or preventing losses. In many instances, these techniques can be
used to strengthen or stabilize the wellbore when drilling at or near the
fracture gradient, thereby potentially eliminating the need for intermediate
casing strings.
This paper discusses particulate-based-treatments design for sealing
fractures. Substantial experience gained from innovative laboratory testing has
highlighted the mechanisms and many factors that determine the effectiveness of
the fracture seal. The particle-size distribution (PSD) relative to the
fracture aperture, particle morphology, volumetric concentration, rheological
properties of the fluid, and fluid-loss control influence whether the seal is
established within the fracture or at the fracture mouth. Understanding this
distinction is important with respect to selecting the optimum treatment and
its application for given field conditions. Parameters critical for optimizing
the treatment have been identified and are discussed in the context of
laboratory and field experience.
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History
- Original manuscript received:
17 December 2007
- Meeting paper published:
4 March 2008
- Revised manuscript received:
9 February 2009
- Manuscript approved:
23 February 2009
- Published online:
15 October 2009
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