Chase

Test Your Knowledge

Quiz: Chasing the Open

Instructions: Choose the best answer for each question.

1. What is the primary goal of a chasing operation? a) To clean out debris from the wellbore. b) To measure the exact depth of the well. c) To determine the wellbore's accessibility and identify obstructions. d) To stimulate oil production in the well.

2. Which type of chasing operation involves running the pipe against an obstruction to test its resistance? a) Simple Chase b) Bumping Chase c) Wireline Chase d) Casing Chase

3. What is the main benefit of conducting a chasing operation? a) Increased oil production. b) Reduced downtime and improved safety. c) Accurate measurement of the well's depth. d) Easier access to the wellbore for maintenance.

4. What type of pipe is typically used for chasing operations? a) Plastic tubing b) Wooden beams c) Steel drill pipe or casing d) Aluminum wire

5. Which of the following is NOT a type of chasing operation? a) Simple Chase b) Bumping Chase c) Wireline Chase d) Drilling Chase

Exercise: Wellbore Assessment

Scenario:

You are an engineer preparing for a planned workover operation in a well. A recent chasing operation revealed the following data:

• Pipe used: 4.5" casing
• Depth reached: 8,500 ft
• Encountered Resistance: At 7,800 ft, the pipe experienced significant resistance and stopped moving.

Task:

1. Based on the provided information, analyze the wellbore's condition.
2. Identify any potential issues that might hinder the upcoming workover operation.
3. Suggest the necessary actions to address these potential issues.

Techniques

Chasing the Open: A Guide to Wellbore Pipe Runs

Chapter 1: Techniques

Chasing operations employ various techniques depending on the wellbore's condition, the objective of the chase, and available equipment. The core principle remains the controlled introduction of a pipe into the wellbore to assess its patency. Several key techniques are highlighted below:

• Simple Chase: This is the most basic technique. A pipe, typically drill pipe or tubing, is run to a predetermined depth. The ease or difficulty of running the pipe, along with any perceived resistance, provides initial information about the wellbore's condition. The primary goal is to confirm the wellbore's openness to that depth.

• Bumping Chase: This technique involves intentionally running the pipe against a suspected obstruction. The force required to move the pipe, or the inability to move it at all, provides information about the nature and firmness of the obstruction. This helps determine the severity of the blockage. Careful monitoring of the rig's weight indicator and pump pressure is crucial during this procedure.

• Wireline Chase: Smaller diameter pipes or specialized tools are run through the wellbore using a wireline. This technique is particularly useful for accessing tighter spaces, inspecting specific areas, and collecting detailed data. It allows for more precision and the use of specialized sensors. The lighter weight of the wireline also reduces the risk of damaging the wellbore.

• Casing Chase: This technique focuses on confirming the proper seating and integrity of the casing. A casing string, or a specialized tool designed to evaluate casing condition, is run to its designated depth. The process assesses for potential issues like collapsed sections, perforations, or cement channeling. This is essential for ensuring the well's structural soundness.

• Rotating Chase: This technique is applied when there's a suspected obstruction that may be dislodged by rotation. The pipe is rotated while being run, aiming to clear debris or minor blockages. This method requires careful control to avoid causing further damage.

Chapter 2: Models

While not in the traditional sense of mathematical models, understanding the wellbore's geometry and the behavior of the pipe within it forms an implicit model. Several factors influence the success and interpretation of a chase operation:

• Wellbore Geometry: The diameter, deviations, and overall profile of the wellbore are critical. Variations in diameter or unexpected bends can impact the ease of pipe running. Pre-existing well logs and surveys are essential for planning and interpreting chase results.

• Fluid Dynamics: The presence of fluids (e.g., drilling mud, water, oil) within the wellbore impacts friction and pipe movement. Fluid viscosity, pressure, and the presence of gas pockets can influence the results.

• Pipe Properties: The pipe's diameter, length, weight, and stiffness affect its behavior in the wellbore. Selecting the appropriate pipe size and type is crucial for obtaining accurate and reliable information.

• Obstruction Characteristics: The size, shape, hardness, and location of any obstruction determine the resistance encountered during a chase. Analyzing the resistance encountered helps characterize the obstruction.

Chapter 3: Software

Specialized software assists in planning, executing, and analyzing chase operations. These tools frequently integrate with well logging and data management systems. Key features often include:

• Wellbore Modeling: Software can create 3D models of the wellbore based on existing survey data, allowing for visualization of potential challenges.

• Pipe Running Simulation: Some software packages can simulate the behavior of the pipe during the run, predicting potential problems and optimizing running parameters.

• Data Acquisition and Analysis: Software tools collect and analyze data from sensors placed on the pipe (or wireline) during the chase, providing real-time feedback on pipe movement, pressure, and other relevant parameters.

• Reporting and Documentation: Automated reports document the chase operation, including depth measurements, encountered resistance, and any identified issues.

Specific examples of software used in the oil and gas industry (many are proprietary) could be mentioned here, though their names are often withheld due to commercial sensitivities.

Chapter 4: Best Practices

Effective chase operations require careful planning and execution. Best practices include:

• Thorough Pre-Job Planning: Review existing well logs, surveys, and operational history to anticipate potential problems.

• Appropriate Pipe Selection: Choose a pipe with a diameter suitable for the wellbore and strong enough to withstand expected forces.

• Careful Monitoring: Continuously monitor the pipe's movement, weight, and any changes in pressure during the operation.

• Accurate Depth Measurement: Use precise instruments for measuring the pipe's depth and the location of any obstructions.

• Detailed Documentation: Record all relevant data, including pipe specifications, running parameters, and any observations.

• Safety Precautions: Adhere to strict safety procedures to minimize risks during the operation.

Chapter 5: Case Studies

(This section requires specific examples of chase operations. The following is a template for case studies that would need to be populated with real-world data):

Case Study 1: Successful Clearance of a Partial Blockage

• Wellbore: [Well Name and Location]
• Problem: Suspected partial blockage at [Depth] due to [Cause].
• Technique: [Type of chase used, e.g., bumping chase with drill pipe].
• Results: Blockage successfully cleared after [Actions taken]. The well was then successfully completed.

Case Study 2: Identification of a Severe Wellbore Restriction

• Wellbore: [Well Name and Location]
• Problem: Difficulty running pipe during simple chase.
• Technique: [Type of chase used, e.g., wireline chase for detailed inspection].
• Results: Severe restriction identified at [Depth] due to [Cause]. Further intervention, such as fishing operations, was required.

Case Study 3: Confirmation of Casing Integrity

• Wellbore: [Well Name and Location]
• Problem: Potential issues with casing integrity after previous operations.
• Technique: Casing chase with specialized tool.
• Results: Casing integrity confirmed. The well was deemed safe for subsequent operations.

These case studies would illustrate the different scenarios encountered during chase operations and demonstrate the importance of appropriate techniques and thorough analysis. Each case study should highlight the specific challenges, the methods used to overcome them, and the lessons learned.