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Course 903 - Well Site Completion and Servicing Safety

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Workover and Abandonment Operations Safety

workover rig

Introduction

Workover activities include one or more of a variety of remedial operations on a producing well to try to increase production. Four or more people will work on the workover rig site. The rig is used to complete and stimulates, repairs and maintains an existing well.

Potential Hazards:

  • guy wires
  • live gas production lines (high pressure) from existing well
  • liquid fuels, hydraulic fluids,
  • existing producing gas wells
  • tanks & pits with flammable liquids, chemicals
  • single egress/ingress access road

Sand Cleanout

Sand cleanout operations are performed to remove buildup of sand in the wellbore. Potential hazards and solutions are similar to those for well servicing.

Repairing Liners and Casing

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, usually salt water or oil, but sometimes mud, is pumped into the casing above the packer. A packer is a piece of downhole equipment that consists of a sealing device, a holding or setting device, and an inside passage for fluids.

A loss of pressure indicates a hole in the casing.

Potential Hazards:

  • getting pinched fingers and hands from tongs and slips
  • being struck by swinging tubing and tubing elevators
  • getting caught between the joint and tongs or stump
  • being struck by the tubing hanger wrench if it should slip
  • getting fingers and hands pinched and caught between tubing hanger and tubing head

Possible Solutions:

  • Keep all fingers and hands away from pinch points.
  • Instruct workers to be on alert when on the rig floor and pipe racking area.
  • Avoid placing hands on the end of the tubing stump.
  • Use the correct tools for each task.
  • Inspect the tools before use.
  • Use coiled tubing.

Sidetracking

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.

well

Potential Hazards and Solutions:

  • The hazards and solutions associated with sidetracking are similar to drilling.

Abandoning the Well

A well is abandoned when it reaches the end of its useful life or is a dry hole.

  • The casing and other equipment is removed and salvaged.
  • Cement plugs are placed in the borehole to prevent migration of fluids between the different formations.
  • The surface is reclaimed.

Removing Casing

The rig is used to remove the casing and plug the well. The wellhead is removed. After the casing is cut off, it is removed..

Potential Hazards:

  • Being struck by rig equipment (such as casing jacks, power tongs, and casing elevators).
  • Being exposed to other hazards similar to those encountered during regular drilling or workover operations.

Possible Solutions:

  • Solutions are similar to those found in tripping out/in and casing operations.

Plug-Backs

Plug-back is used before abandoning a well or before sidetracking is done.

Plug-back is the process of placing a cement plug at one or more locations in a well to shut off flow from below the plug. Cement plugs are placed in the borehole to prevent migration of fluids between the different formations. This also prevents the migration of gas or fluids to the surface.

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

  • plug-back using tubing
  • plug-back using a dump bailer

Potential Hazard:

  • being struck by pressured lines when pumping cement

Possible Solution:

  • Instruct personnel to stand clear of pressurized lines.

Instructions

Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Which of the following activities include one or more of a variety of remedial operations on a producing well to try to increase production?

2. The potential hazards associated with workover activities on a well site include all of the following, except _____.

3. Which of the following activities are performed to remove buildup of sand in the wellbore?

4. Which of the following activities is the 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?

5. Which of the following activities is used before abandoning a well or before sidetracking is done?


Have a great day!

Important! You will receive an "error" message unless all questions are answered.