Workover Rig

Test Your Knowledge

Workover Rigs Quiz:

Instructions: Choose the best answer for each question.

1. What is the primary function of a workover rig?

a) Drilling new wells b) Transporting oil and gas c) Servicing and maintaining existing wells d) Refining crude oil

2. Which of the following is NOT a key function of a workover rig?

a) Tubing running and pulling b) Well stimulation c) Downhole intervention d) Building pipelines

3. What is the purpose of the derrick on a workover rig?

a) To provide power for the rig's operations b) To store drilling fluid c) To support hoisting and lowering equipment d) To control the flow of oil and gas

4. Which type of workover rig is used in offshore oil and gas operations?

a) Land rig b) Offshore rig c) Onshore rig d) Platform rig

5. What is a key benefit of using workover rigs in oil and gas production?

a) Reducing environmental impact b) Increasing the lifespan of wells c) Improving safety standards d) All of the above

Workover Rigs Exercise:

Scenario: You are a field engineer working on a mature oil well. Production has been declining, and you suspect a problem with the tubing string.

Task: Explain how you would use a workover rig to diagnose the problem and potentially solve it. Include the following in your explanation:

• Specific operations you would perform using the workover rig.
• Tools and equipment you would need.
• Possible outcomes of the operation.

Techniques

Chapter 1: Techniques Employed by Workover Rigs

Workover rigs utilize a variety of specialized techniques to maintain and enhance the productivity of existing oil and gas wells. These techniques can be broadly categorized as follows:

1. Tubing Operations:

• Tubing Running & Pulling: Workover rigs are essential for safely running and pulling tubing strings. This involves lowering new tubing into the well or retrieving old or damaged tubing, often using a specialized "tubing spider" to handle the delicate process.
• Tubing Inspection: Workover rigs can employ specialized tools to inspect the condition of existing tubing, identifying wear, corrosion, or other potential issues that require attention.
• Tubing Repair & Replacement: If inspection reveals damage, workover rigs can perform repairs, such as welding or patching, or replace sections of the tubing entirely.

2. Well Stimulation:

• Acidizing: Workover rigs can inject acidic solutions into the wellbore to dissolve minerals and enhance flow rates. This is particularly effective in formations with low permeability.
• Fracturing: By injecting a high-pressure mixture of fluid and proppant, workover rigs can create fractures in the reservoir rock, increasing the surface area available for fluid flow.
• Sand Fracing: A specialized form of fracturing that uses sand as the proppant, effectively holding open the created fractures and maintaining improved flow.
• Nitrogen Injection: This technique introduces nitrogen gas into the wellbore to increase reservoir pressure and stimulate production.

3. Downhole Intervention:

• Plugging: Workover rigs can perform selective plugging operations to isolate sections of the wellbore, allowing for targeted interventions or reducing unwanted water or gas production.
• Sidetracking: In cases where the original wellbore is damaged or deviates from the target reservoir, workover rigs can create a new, sidetracked path to access the productive zone.
• Casing Repair: Workover rigs are equipped to repair damaged casing, including the installation of liners or sleeves to restore the well's integrity.
• Fishing: When tools or equipment become stuck in the wellbore, workover rigs employ specialized fishing tools to retrieve them, minimizing downtime and potential damage.

4. Other Operations:

• Milling: Workover rigs can perform limited milling operations to remove obstructions or prepare the wellbore for other interventions.
• Drilling: Certain workover rigs have limited drilling capabilities, allowing for minor repairs or modifications to the well.
• Wireline Operations: These specialized operations use a thin wireline to lower various downhole instruments and tools, such as packers, gauges, or logging devices.

The specific techniques utilized by a workover rig will depend on the specific needs of the well and the challenges being addressed. The efficiency and effectiveness of these techniques are crucial for maximizing the production potential of oil and gas wells while minimizing environmental impact.