What Is Workover in Oil and Gas? Process, Importance, and Equipment

In the oil and gas industry, well workover refers to the maintenance, repair or remedial operations carried out on existing oil and gas wells to restore, maintain or enhance production, and ensure the integrity of the wellbore.

Well workover operations may involve repairing or replacing downhole equipment, cleaning the wellbore, modifying the well completion, increasing production, and addressing wellbore integrity issues. Many well workover operations require the use of well workover rigs and the removal of production tubing, but some operations can also be accomplished using existing tubing, such as using coiled tubing, wireline, optical cables or pressure-controlled operations equipment.

Why Is a Workover Needed?

During the operation of oil and gas wells, production or mechanical failures may occur. Well repair operations can help solve these problems and extend the service life of existing oil wells.

Common reasons for well repair include:

• Production decline due to reservoir or wellbore issues
• Faults in downhole equipment such as pumps, tubing, or packers
• Wellbore blockage caused by sand, scale, wax, or debris
• Impact on wellbore integrity due to casing or tubing problems
• Excessive water or gas production
• Need for maintenance or renovation of artificial lift systems
• Recompletion to access or isolate different production layers
• Decrease in oil well productivity due to formation damage

Whether to perform well repair is usually determined by the condition of the well, expected production increase, operational risks, downtime, and economic benefits.

What Are the Main Types of Workover Operations?

The well repair methods depend on the problems to be solved and the expected results. Common well repair operations include:

• Mechanical well repair: Repairing or replacing downhole components, such as production tubing, drill pipes, pumps, and packers.
• Well cleaning: Removing sand, scale, wax, or other deposits that hinder fluid flow in the wellbore.
• Production enhancement measures: In appropriate cases, using treatments such as acidizing or hydraulic fracturing to increase the production capacity of the formation.
• Recompletion: Modifying the completion method to access different production intervals, add new production intervals, or isolate unwanted production intervals.
• Interval isolation: Isolating specific intervals to prevent unwanted fluids (such as excessive water) from entering the production fluid.

For more detailed explanations of these operations, please refer to What are the Types of Workover Operations in Oil and Gas

Workover vs. Well Intervention

Well workover and downhole operations are closely related, but they are not exactly the same.

Well workover usually refers to large-scale maintenance or repair of existing oil wells. Downhole operations, on the other hand, is a broader concept that encompasses various operations performed on existing oil wells, ranging from simple cable operations to more complex wellbore interventions.

Workover	Well Intervention
Usually more extensive	Broader category
May require a workover rig	May use wireline, coiled tubing, or snubbing
May require removal of tubing	Often performed through existing tubing
Used for major repairs and completion changes	Includes maintenance, diagnostics, and production improvement

Through-tubing intervention can sometimes achieve the required objective without a full workover, reducing downtime and cost.

How Does a Workover Operation Work?

Although the conditions of each well may vary, typical well repair operations usually include the following steps:

• Well condition diagnosis: Engineers analyze production history, pressure data, well completion information, and operation records to identify the problem.
• Well repair plan: Clearly define the scope of the operation, required equipment, well control procedures, personnel allocation, safety requirements, and emergency response plans.
• Well condition preparation: Complete the operation preparations, install and test pressure control equipment and well repair equipment.
• Downhole operations: Execute the operation as planned, including pulling out the tubing, replacing equipment, cleaning the wellbore, repairing the wellbore or modifying the well completion.
• Testing and restart: After the operation is completed, test the oil well. Once the required production capacity and wellbore integrity are confirmed, resume production.

Workover operations involve complex equipment, well-control procedures, and operational decisions. Simulation-based training allows crews to practice these scenarios in a controlled environment before performing them in the field.

Esimtech’s Workover Simulator provides a realistic training environment for practicing workover procedures, equipment operation, and abnormal scenarios without the risks associated with live-well training.

What Equipment Is Used in a Workover?

The equipment required varies depending on the well repair objective and the condition of the well. Commonly used equipment includes:

• Well workover rig – providing lifting and transportation capabilities
• Blowout preventer and well control equipment – controlling well pressure and maintaining a barrier
• Continuous tubing operation device – supporting operations within the tubing and well cleaning operations
• Cable operation device – deploying tools and performing various downhole operations
• Pressure-controlled operation device – capable of conducting operations in pressurized wells
• Downhole tools – including fishing tools, milling tools, lifting and lowering tools, and isolation tools

Not every well repair operation requires all these systems.

Frequently Asked Questions

• How to determine whether an oil well needs well repair?

Operators usually assess the cause of the problem, expected production increase, well repair cost, downtime, and the remaining economic life of the well.

• When is well repair not suitable?

If a simpler intervention can solve the problem, or the expected benefits do not cover the well repair cost and downtime losses, operators can consider other options, such as no drilling rig intervention, production enhancement measures, or artificial lift optimization.

• How to reduce well repair downtime?

Accurate well condition diagnosis, detailed operation plans, appropriate equipment selection, and adequate pre-preparation all help to reduce non-productive time. In some cases, downhole operations through tubing can also avoid full well repair.

To Conclude

Workover operations are an important part of the oil and gas well life cycle. By repairing equipment, restoring production, maintaining well integrity, and modifying existing completions, workovers can help operators maximize the value of existing wells.

The right approach depends on the well condition, intervention objective, operational risks, and economics. Careful diagnosis, planning, well control, and execution are essential to a successful workover.