Summary
Water packing is the most commonly used gravel-packing technique for
openhole horizontal completions. With this technique, the packing of a
horizontal well occurs through two sequential events, called the α wave
and the β wave. Because the carrier fluid is diverted into and must
travel through the narrow annulus between the screen base pipe and the wash
pipe all the way to the toe, pressure builds up steadily during the β
wave as the packing proceeds from toe to heel because of high friction
pressures in that annulus. This rise in pressure may result in exceeding the
fracturing pressure of the reservoir, which in turn causes a premature
screenout and an incomplete gravel pack.
This is a well-known problem, which in the past, often limited the
horizontal well length that can be gravel packed in many deepwater developments
because of a narrow operating window. Today, various methods are available to
solve this problem, including mechanical solutions that create a short cut for
fluid returns and the use of lightweight gravel that allows pumping at lower
rates without having to worry about gravel settling in the work string but
still having an α-wave height that will cover the screens.
In this paper, we present an alternative method of dealing with the pressure
rise during the ? wave, reducing the friction pressures through addition of a
friction reducer to brine carrier fluid. We first detail the laboratory-scale
experiments used for screening of many additives considered, including
laboratory-scale friction pressure measurements, compatibility with
high-density brines, gravel settling, formation, and gravel-pack damage. We
then discuss the results from full-scale friction tests conducted in pipe and
annular geometries, using the best-candidate friction reducer selected on the
basis of laboratory tests. The results indicate that a drag reduction of 20 to
70% is attained with an environmentally friendly friction reducer, with
gravel-pack retained permeability in the range of 75 to 90%, depending on test
conditions, and with minimal to no impact on gravel settling and, thus, on
α-wave height.
© 2010. Society of Petroleum Engineers
View full textPDF
(
741 KB
)
History
- Original manuscript received:
29 July 2009
- Meeting paper published:
5 October 2009
- Revised manuscript received:
5 January 2010
- Manuscript approved:
26 January 2010
- Published online:
21 June 2010
- Version of record:
13 September 2010
View Cart
