Schlumberger

BCF Ball-Activated Firing Head

The ball-activated firing (BCF) head has a small diameter and is used in CT operations. It allows the deployment into a well of a perforating gun or other explosive device, such as a severing tool, or a cutting device on a CT string. For wells being abandoned, the BCF head allows the operator to circulate the well until it is clean and then to perforate, spot a cement plug, and circulate again to clean after the plug has been placed—all during one trip in hole with the CT. The BCF head can be used to shoot guns underbalanced and to drop guns or perforate without killing a well to minimize formation damage. The BCF head is available for high-pressure, high-temperature applications, and it supports multiple perforating techniques and the combination of other deployment systems. The BCF head is recommended for use with guns 42.9 mm [1.69 in] or smaller in diameter.

The head uses the same hydrostatic firing mechanism as tubing-conveyed perforating firing heads, requiring a minimum hydrostatic pressure to fire. The initiation of the downhole detonation is controlled from the surface by first circulating a ball down to the BCF head. When the ball reaches the head and closes the circulating path by sealing the ball seat, the firing mechanism is activated by the differential pressure buildup across the operating piston, rather than by the absolute bottomhole pressure. For this reason, a well can be perforated in overbalanced or underbalanced condition and when existing perforations are present.

Benefits

  • Circulation flexibility—Allowed in both directions before and after the guns are fired. Underbalanced perforating conditions are easily established. The BCF head also allows circulation after the guns are fired.
  • CT compatibility—The firing head can take a combination of shear pins and can be connected to any CT string by means of a crossover connector.

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