US Dept of Labor

Occupational Safety & Health AdministrationWe Can Help

Back to eTools

Oil and Gas Well Drilling and Servicing eTool

Servicing Workover

JSA
Fig. 1. Example of a workover rig

Fig. 1. Example of a workover rig

Workover activities include one or more of a variety of remedial operations on a producing well to try to increase production.

Hazards related to workover activities may include:

Sand cleanout operations are performed to remove buildup of sand in the wellbore.

Potential Hazard:

Additional Information:

  • Standards. American Petroleum Institute (API).
    • RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Wireline Service. (2007, March).

Liners and casing are essentially the same and repair procedures are the same for both. Casing can be damaged by corrosion, abrasion, pressure, or other forces that create holes or splits. A packer is run down the well to locate the hole in the casing. Fluid is pumped into the casing above the packer. A loss of pressure indicates a hole in the casing. The following are the principal methods for repairing casing:

  • Squeeze cementing.
  • Patching a liner.
  • Replacing casing.
  • Adding a liner.
  • Opening collapsed casing.

Potential Hazard:

Sidetracking is the workover term for drilling a directional hole to bypass an obstruction in the well that cannot be removed or damage to the well, such as collapsed casing that cannot be repaired. Sidetracking is also done to deepen a well or to relocate the bottom of the well in a more productive zone, which is horizontally removed from the original well.

To sidetrack, a hole (called a window) is made in the casing above the obstruction. The well is then plugged with cement below the window. Special drill tools, such as a whipstock, bent housing, or bent sub are used to drill off at an angle from the main well. This new hole is completed in the same manner as any well after a liner is set.

Potential Hazard:

  • The hazards associated with sidetracking are similar to Drilling.

Plug-back places a cement plug at one or more locations in a well to shut off flow from below the plug. Plug-back is also used before abandoning a well or before sidetracking is done.

There are two methods for placing a cement plug in a well:

Potential Hazard:

Back to Top

Thank You for Visiting Our Website

You are exiting the Department of Labor's Web server.

The Department of Labor does not endorse, takes no responsibility for, and exercises no control over the linked organization or its views, or contents, nor does it vouch for the accuracy or accessibility of the information contained on the destination server. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. Users must request such authorization from the sponsor of the linked Web site. Thank you for visiting our site. Please click the button below to continue.

Close