Workover Operations

Workover Operations

Bullheading

Bullheading is a term used to describe killing the well by forcing formation fluids back into the formation. This involves pumping kill weight fluid down the tubing and, in some cases, down the casing.

The bullheading method of killing a well is primarily used in the following situations:

1. Tubing in the well with a packer set. No communication exists between tubing and annulus.

2. Tubing in the well, influx in the annulus, and for some reason, cannot circulate through the tubing.

3. No tubing in the well. Influx in the casing. Bullheading is simplest, fastest, and safest method to use to kill the well.

   Note	Tubing could be well off bottom also.

4. In drilling operations, bullheading has been used successfully in areas where hydrogen sulfide is a possibility.

Example calculations involved in bullheading operations:

• Using the information given below, calculations will be performed to kill the well by bullheading. The example calculations will pertain to a above:

  • DATA: Depth of perforations = 6480ft

  • Fracture gradient = 0.862psi/ft

  • Formation pressure gradient = 0.401psi/ft

  • Tubing hydrostatic pressure (THP) = 326psi

  • Shut-in tubing pressure = 2000psi

  • Tubing = 2-7/8 in. ? 6.5lb/ft

  • Tubing capacity = 0.00579bbl/ft

  • Tubing internal yield pressure = 7260psi

  • Kill fluid density = 8.4ppg