Summary
Zakum Development Company (ZADCO), with the support from shareholders and
the cooperation of Abu Dhabi Marine Operating Company (ADMA-OPCO), successfully
completed the final design of the Multilateral Completion (MLC) system for
Reservoirs A and B through Multilateral Tie Back System (MLTBS) project. Well
T-2 in the Upper Zakum field was recompleted as dual lateral/dual producer
using a Re-Entry Drilling System (RDS) Version 2 and a Dual Bore Deflector
(DBD) oriented and set on a latch coupling in the 7-in. liner hanger
assembly.
According to Technology Advancement Multilateral (TAML) level specification,
the final MLC is categorized as TAML Level-4 E-2-PN-D/4-TR-SEP (Level-4,
existing well application, two junction, producer with natural lift, dual
completion, tubing re-entry, separated flow). The multilateral liner hanger
system (i.e., accommodating a latch coupling in 7-in. liner hanger assembly to
have a certain access to the upper lateral) was the first successful
application of that kind in the world.
The teamwork and integrated approach for the trial planning and
implementation, as well as lessons learned from a predesign trial (TAML Level-4
E-2-PN-D-TR-SEP using straddle assembly) for Well T-1 completed in 2000, have
led to reaching the final goal of the MLC in Well T-2, which provides ZADCO
with the following reservoir benefits:
- Independent coiled tubing access to the upper (Reservoir A) and lower
laterals (Reservoir B) through a dual completion to perform effective
stimulation and reservoir monitoring.
- Full bore access to each lateral immediately after pulling out the
completion, which is an additional feature to the predesign of an MLC for Well
T-1.
- Allow selective water shut off to cope with water breakthrough into the
upper-cased lateral.
- Possibility of extending well life by drilling a secondary lateral through
a window joint installed in the upper-cased lateral.
Moreover, another MLC trial, installed in the quadrant multilateral well
RL-2 in 2005, has been successfully implemented by using mechanically selective
through tubing re-entry equipment. This success was largely because of the
lessons learned from a similar MLC design implemented in well RL-1 in 2001.
These successful trial implementations proved the MLC system is applicable
for any new/re-entry wells in ZADCO reservoirs, which provides new methods of
reservoir management, and creates new completion strategies for ZADCO field
development.
This paper covers the MLC strategies, lessons learned through the successes
and failures and the additional challenges planned for the future of the MLTBS
project.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
6 September 2006
- Meeting paper published:
5 November 2006
- Revised manuscript received:
9 June 2008
- Manuscript approved:
21 August 2008
- Published online:
16 March 2009
- Version of record:
1 March 2009
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