Summary
ConocoPhillips is developing the Magnolia field with a tension leg platform
(TLP) in 4,674 ft of water at Garden Banks Block 783 in the Gulf of Mexico. The
wells produce primarily from thick, fine-grained, Pleistocene reservoirs.
Because of the long lengths of the producing reservoirs and large variations in
sand-grain sizes/permeabilities, premium screens with shunt tubes in
conjunction with cased-hole frac packs have been used to complete the
wells.
The third well, A1ST1BP1, was completed using the same techniques as were
used successfully on the first two wells. The A1ST1BP1 completion failed during
initial unloading, allowing unacceptable rates of sand production. The well was
worked over, and the tubing with eight control lines and a premium-sand-control
screen with shunt tubes were retrieved/fished from the well with minimal
problems. The retrieved screens had collapsed around the perforated base pipe.
The well was reperforated, new screens run, and a second frac pack pumped. When
laying down the washpipe after the second frac pack, erosion marks indicated an
apparent second screen failure.
A detailed examination of both A1ST1BP1 frac-pack jobs was conducted in
conjunction with laboratory collapse and erosion testing of the premium
screens. Collapse testing revealed that the screen lost sand control at less
than 1,000 psi. The collapse rating stated by the manufacturer was greater than
7,000 psi. The erosion tests demonstrated that inflow from supercharged
reservoirs into the wellbore could erode holes in the premium screen. Revised
operational procedures were used in six subsequent frac packs without any
additional failures and zero-to-negative completion skins.
This paper will discuss the failure modes of the two frac-pack/premium-screen
sand failures, workover planning and execution to remove tubing with multiple
control lines and fish screens with shunt tubes from close-tolerance casing,
and procedural revisions developed to successfully frac-pack the subsequent
Magnolia reservoirs.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
9 November 2006
- Meeting paper published:
20 February 2007
- Revised manuscript received:
2 June 2008
- Manuscript approved:
24 September 2008
- Published online:
16 March 2009
- Version of record:
1 March 2009
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