This paper describes the development, history, and successful deployment of
the world's two deepest through-tubing-conveyed electrical submersible pumps
(TTCESPs). These are the first TTCESPs deployed inside of 7-in. casing.
Electrical submersible pumps (ESPs) are a form of artificial lift that consists
of a pump, motor, and electric cable, typically deployed by a rig and connected
to electric power at surface. Their advantage is that they create greater
drawdown than other forms of artificial lift, thus achieving higher production
rates. However, conventional ESPs require expensive workover rigs to replace
pumps, the component that fails most frequently. ConocoPhillips Alaska
developed TTCESP technology to replace failed pumps rapidly and economically.
In this system, a rig conventionally deploys the electric cable, motor, and
seal sections with a special latching device for the pump. The pump is pulled
and replaced with slickline (wireline) or coiled tubing, eliminating the
requirement of a rig.he original through-tubing-conveyed (TTC) systems were
developed for 7 5/8-in.-cased wells. During approximately the past 10 years, it
was common belief that they could not be deployed at the Milne Point field in
Alaska because of the limitations of its smaller wells (7-in., 26-lbm/ft
casing). This paper discusses the enabling technologies that were developed to
allow running TTCESPs in 7-in. casing, including a wellhead spoolpiece and
low-clearance ESP clamps.
West Sak TTCESP run-time data indicate that the time between rig workovers
(RWOs) will increase from 3.5 to 6 years. Pumps can be replaced for 5-10% of
rig costs without the safety and environmental impacts associated with rigs.
Additionally, production impacts while waiting for a rig are eliminated because
slickline and coiled-tubing units are readily available on the North Slope of
Alaska. TTC pumps can easily be upsized or downsized to optimize pump flow rate
because of changes in production rates. This technology is of interest in areas
where rig costs are high, including Arctic, remote, and offshore locations. It
is also beneficial where rig availability is low.
© 2011. Society of Petroleum Engineers
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- Original manuscript received:
22 March 2011
- Meeting paper published:
8 May 2011
- Manuscript approved:
25 May 2011
- Published online:
26 October 2011
- Version of record:
22 November 2011