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 target multiple zones, resulting in complex directional wells with 50–60°
maximum hole angles. The wells are completed using dry trees from the TLP and
are produced primarily from massive, fine-grained, Pleistocene reservoirs.
These reservoirs require sand control to prevent sand production at the
expected drawdowns planned during the life of the wells. To help ensure
high-rate, long-life completions, the producing zones are frac packed. The
average perforated interval during the initial completion program was 310 ft,
with a maximum perforated interval of 571 ft.
The typical production-casing string for the wells consists of 10 3/4-in.
casing with an 8 1/16-in. production liner. Drift diameter through the tapered
production casing is 9 1/2 and 6 1/2 in., respectively. The 6 1/2-in. drift
diameter allows using common-sized screens and packers. The wells are generally
completed with a 4 1/2 × 3 1/2-in. tapered-tubing string.
Premium screens with shunt tubes are used on the wells because of the long
deviated intervals. The "frac-pack" stimulation treatments are pumped
at rates of 27 to 40 bbl/min with a viscoelastic-surfactant (VES) carrier
fluid. Washpipe-conveyed downhole-pressure and -temperature gauges and
radioactive tracers are used to help analyze the treatment results.
This paper will discuss screen-selection philosophy in silt/very-fine-sand
reservoirs, carrier-fluid selection, perforation strategy, and ability to frac
across shale intervals. The paper also will cover the effectiveness of
achieving a frac pack with premium screens with shunt tubes, on the basis of
downhole-pressure and –temperature and radioactive-tracer information, and will
discuss revised operational practices that resulted in zero- to negative-skin
completions across long, perforated intervals, which continue to produce
sand-free after extreme reservoir depletion.
© 2009. Society of Petroleum Engineers
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- Original manuscript received:
21 November 2006
- Meeting paper published:
20 February 2007
- Revised manuscript received:
1 July 2008
- Manuscript approved:
24 September 2008
- Published online:
16 March 2009
- Version of record:
1 March 2009