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#105541

Magnloia Deepwater Experience-Frac Packing Long, Perforated Interavals in Unconsolidated Silt Reservoirs


Luke F. Eaton, SPE, Wrandall Reinhardt, SPE, ConocoPhillips; J. Scott Bennett, SPE, Devon Energy Corporation; Kenyon Blake, SPE and Hugo Morales, SPE, Slumberger

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 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 of27 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.