Drift (tool)

Drifting the Wellbore: Ensuring a Smooth Run with the Drift Tool

In the demanding world of oil and gas exploration and production, ensuring smooth and efficient operations is paramount. One crucial step in this process is drifting the wellbore, a procedure involving the use of a specialized tool called a drift.

Drifting is a critical quality control measure used to verify the clearance within the wellbore prior to running any tool string or piece of equipment. This process allows for the identification of any potential obstructions or constrictions that might hinder the smooth passage of the desired equipment.

The Drift Tool:

A drift is essentially a solid, cylindrical tool with a specific diameter. The drift's diameter is carefully chosen based on the dimensions of the equipment to be run downhole, leaving a designated clearance margin.

The Drifting Process:

The drifting process is straightforward:

Lowering the Drift: The drift tool is lowered down the wellbore on a wireline or tubing string.
Checking for Obstructions: As the drift travels down the wellbore, it encounters any potential obstructions or constrictions.
Identifying Issues: If the drift encounters any significant resistance or fails to pass through a specific section of the wellbore, it indicates a potential issue.
Resolving the Issue: Depending on the nature of the obstruction, the wellbore may need to be cleaned or reamed to ensure adequate clearance for the equipment.

Benefits of Drifting the Wellbore:

Prevents Tool String Damage: Drifting ensures sufficient clearance, preventing expensive damage to the tool string or equipment.
Reduces Operational Delays: By identifying obstructions early, potential delays caused by equipment snagging or failure are minimized.
Increases Safety: A well-drifted wellbore ensures the safe passage of the tool string, minimizing the risk of accidents.
Optimizes Performance: Drifting allows for efficient operation of equipment by ensuring it can move freely through the wellbore.

Conclusion:

Drifting the wellbore is an essential procedure in oil and gas operations. It ensures smooth, efficient, and safe deployment of equipment by verifying the clearance within the wellbore. Using a drift tool allows for early identification of potential obstructions, allowing for necessary action to be taken before equipment is run downhole. This ultimately translates to cost savings, improved operational efficiency, and enhanced safety in oil and gas exploration and production.

Test Your Knowledge

Drifting the Wellbore Quiz

Instructions: Choose the best answer for each question.

1. What is the primary purpose of drifting the wellbore?

(a) To remove debris from the wellbore (b) To measure the depth of the wellbore (c) To verify the clearance within the wellbore (d) To stimulate the production of oil or gas

Answer

2. What type of tool is used for drifting the wellbore?

(a) A drill bit (b) A wireline (c) A drift tool (d) A packer

Answer

3. What is the main characteristic of a drift tool?

(a) It has a flexible design (b) It is a solid, cylindrical tool with a specific diameter (c) It is used to stimulate oil and gas production (d) It is used to measure the depth of the wellbore

Answer

(b) It is a solid, cylindrical tool with a specific diameter

4. Which of the following is NOT a benefit of drifting the wellbore?

(a) Prevents tool string damage (b) Reduces operational delays (c) Increases safety (d) Increases the rate of oil or gas production

Answer

(d) Increases the rate of oil or gas production

5. If a drift tool encounters significant resistance while being lowered down the wellbore, what does it indicate?

(a) The wellbore is clean and ready for equipment (b) The wellbore is too shallow (c) A potential obstruction or constriction in the wellbore (d) The drift tool is malfunctioning

Answer

Drifting the Wellbore Exercise

Scenario:

You are a wellsite engineer responsible for overseeing the drilling and completion of an oil well. You have just received a report indicating that the drift tool encountered resistance at a specific depth in the wellbore.

Task:

Identify three possible reasons for the drift tool encountering resistance.
Explain how you would investigate each reason.
Describe the corrective actions you would take based on your findings.

Exercice Correction

**Possible Reasons:** 1. **Debris or scale buildup:** The wellbore might be partially obstructed by debris or scale deposits. 2. **Casing damage:** A section of casing might be damaged, causing a constriction. 3. **Formation collapse:** The formation surrounding the wellbore might have collapsed, creating an obstruction. **Investigation:** 1. **Run a wireline logging tool to identify potential debris, scale, or formation collapse.** 2. **Utilize a caliper tool to measure the internal diameter of the wellbore and identify any casing damage.** **Corrective Actions:** 1. **Debris/scale:** Use a milling tool or a coiled tubing system to clean the wellbore and remove the obstruction. 2. **Casing damage:** Depending on the severity of the damage, consider options like repairing the casing, replacing the damaged section, or running a larger-diameter casing. 3. **Formation collapse:** Consider using a cementing operation to stabilize the formation or employing other techniques to prevent further collapse.

Books

Petroleum Engineering Handbook: This comprehensive handbook provides detailed information on various aspects of oil and gas exploration and production, including wellbore operations and equipment.
Drilling Engineering: This book offers in-depth coverage of drilling operations, including wellbore geometry, tool string design, and essential quality control procedures like drifting.
Well Completion Engineering: This book focuses on the completion phase of well development, highlighting the importance of wellbore preparation, including drifting, for successful completion operations.

Articles

"Drifting: A Critical Step in Wellbore Preparation" (Journal of Petroleum Technology) This article discusses the importance of drifting in ensuring smooth wellbore operations and outlines the process and benefits.
"Case Study: Using Drift Tools to Prevent Tool String Damage" (Oil & Gas Journal) This article presents a real-world example of how drifting prevented tool string damage and saved operational costs.
"Understanding and Avoiding Wellbore Obstructions" (SPE Journal) This article delves into the causes of wellbore obstructions and presents best practices to prevent them, highlighting the role of drifting in this process.

Online Resources

Society of Petroleum Engineers (SPE): The SPE website offers numerous articles, presentations, and technical papers related to wellbore operations, including drifting. Search for keywords like "drifting," "wellbore clearance," and "tool string damage."
Oil & Gas Journal: This industry publication provides news, technical articles, and case studies related to oil and gas exploration and production, including topics like wellbore preparation and drift tools.
Schlumberger: This oilfield services company offers extensive online resources about drilling and completion operations, including information about drift tools and their applications.

Search Tips

"Drift Tool" + "Wellbore Preparation": This search will provide relevant results focusing on the use of drift tools in preparing wellbores for equipment runs.
"Drifting" + "Case Studies": This search will identify examples of how drifting has been applied in real-world scenarios and the results achieved.
"Drift Tool" + "Technical Data": This search will help you find technical specifications and dimensions of various drift tools available on the market.