Summary
The ultrahigh-pressure-jet-assisted drilling technique can increase the rate
of penetration (ROP) greatly. A downhole boost compressor and an
ultrahigh-pressure polycrystalline-diamond-compact (PDC) bit with dual-flow
channels are the core techniques of ultrahigh-pressure-jet-assisted drilling.
During recent years, the China University of Petroleum, Beijing (CUPB), has
focused on theoretical and experimental research--for example, the hydraulic
structure and performance of downhole boost compressors, boosting theory,
reversing control, rock-breaking mechanics under ultrahigh-pressure-jet
conditions, and structural-design theory of ultrahigh-pressure PDC bits with
dual-flow channels. On the basis of theoretical research, CUPB has designed and
manufactured two generations of downhole-boost-compressor prototypes. At the
same time, five oilfield-test experiments have been performed in the SINOPEC
ZhongYuan oil field and CNPC TuHa oil field, China. As these experimental
results showed, a downhole boost compressor and an ultrahigh-pressure PDC bit
with dual-flow channels can increase ROP by over 50% under the five different
sets of experimental conditions, and can meet the field-operation requirement.
This research, outlined in the paper, played a leading role in the development
of the ultrahigh-pressure-jet-assisted drilling technique.
As one of the main techniques to increase ROP,
ultrahigh-pressure-jet-assisted drilling is always a popular research project,
and since the 1960s, research institutes worldwide have made significant
progress (Veenhuizen et al. 1996, 1997a, 1997b; Butler et al. 1990). To date,
the ultrahigh-pressure-jet-assisted drilling technique has gone through three
main stages of development: the ground equipment to boost the pressure
(1960s-70s), the ultrahigh-pressure-drill system with dual-flow paths
(1980s-90s) (Maurer 1980), and the downhole boost compressor (1990s-present)
(Wang 2005, 2008). For downhole boost compressors, there are three different
structures: turboboost, screw boost, and piston boost. Compared with the first
two structures, piston-boost compressors have a much simpler structure, shorter
total length, and better application for deviated wells and horizontal wells
(Liu 1993; Meng 1997).
CUPB has long been focused on research on a downhole boost compressor that
is based on piston-boost structures. The main research results are as follows:
boosting theory, downhole-boost-compressor hydraulic structural-design theory,
downhole-boost-compressor material research, ultrahigh-pressure-jet
hydraulic-character research, structural design of ultrahigh-pressure PDC bit
with dual flow channel, and rock-breaking mechanisms of ultrahigh-pressure PDC
bits with dual-flow channels. In 2005, CUPB successfully manufactured the first
generation of prototypes of downhole boost compressors and ultrahigh-pressure
PDC bits with dual-flow channels, and updated to the second generation in 2008.
In this process, more than 10 repetitions of laboratory and field experiments
were completed, and these results can play a positive role in the development
of ultrahigh-pressure-jet-assisted drilling techniques.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
14 May 2010
- Revised manuscript received:
14 April 2011
- Manuscript approved:
9 February 2012
- Published online:
27 June 2012
- Version of record:
1 July 2012
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