Summary
Cased-hole gravel packing is commonly used to control sand production from
oil and gas wells. The success of a cased-hole gravel-pack job depends on the
ability to effectively pack perforation tunnels, which act as conduits between
the reservoir and the wellbore for hydrocarbon production.
This project presents a systematic approach for removal of perforation
damage, effective gravel placement, and packing of the perforation tunnels. It
was found that dynamic underbalanced perforating (DUP) greatly increased the
ability to pack the perforation tunnels and improved the connectivity to the
reservoir. Guidelines to DUP and executing the perforation-packing job are
presented. This study also discusses the current practices commonly employed in
cased-hole gravel packing to pack perforation tunnels and the potential
limitations of these practices.
Incomplete packing of perforation tunnels is mostly encountered in
gravel-pack jobs completed with brine as the carrier fluid (water packs). The
proposed technique involves DUP before the gravel-pack operation, followed by
pumping the gravel slugs in a nondamaging carrier fluid in concentrations
ranging from 1 to 3 lbm of proppant added per gallon of fluid (ppa). These
slugs range from 5 to 7 bbl and are pumped intermittently between stages of the
completion fluid to minimize cost. The carrier fluid, by virtue of its
viscosity and mechanical suspension capability, ensures that the gravel enters
the perforations.
This technique was implemented successfully at the Abu Cluster field in west
Malaysia. This reservoir had extremely high permeability (1.5 to 3 darcies),
with sand production a major concern. Several jobs were completed with the
previously mentioned technique, and perforation-packing factors improved from 8
to 38 lbm of gravel per foot of perforations. Discussion of the placement and
production data is presented. Sand-free production has been achieved with
reduced drawdown across the sandface. The results show a linear relationship
between pack factor and normalized productivity index (PI), indicating that
gravel-packed perforations improve well productivity.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
18 August 2008
- Meeting paper published:
3 December 2008
- Revised manuscript received:
25 June 2010
- Manuscript approved:
13 July 2010
- Published online:
14 January 2011
- Version of record:
11 March 2011