BUR (drilling)

Test Your Knowledge

BUR Quiz: Build-Up Rate in Drilling

Instructions: Choose the best answer for each question.

1. What does BUR stand for in drilling?

a) Bit Uplift Rate b) Build-Up Rate c) Bottom Up Rate d) Borehole Uplift Rate

2. Which of the following factors does NOT directly influence Build-Up Rate?

a) Mud weight b) Formation properties c) Ambient temperature d) Rotary speed

3. What is a potential consequence of uncontrolled Build-Up Rate?

a) Increased wellbore stability b) Reduced drilling costs c) Wellbore collapse d) Improved trajectory accuracy

4. Which technology allows for real-time monitoring of Build-Up Rate?

a) Mud logging b) Wireline logging c) MWD (Measurement While Drilling) d) Seismic surveys

5. Adjusting which drilling parameter can help control Build-Up Rate?

a) Mud density b) Drilling depth c) Rig horsepower d) Drilling fluid viscosity

BUR Exercise:

Scenario:

A wellbore is being drilled with the following parameters:

• Weight on Bit (WOB): 40,000 lbs
• Rotary Speed: 100 RPM
• Mud Weight: 12.5 ppg

The wellbore is currently at an inclination of 30 degrees. The drilling engineer observes that the Build-Up Rate is 1 degree per 100 feet drilled.

Task:

1. Calculate the expected inclination of the wellbore after drilling 500 feet.
2. Analyze the potential consequences of this BUR for the wellbore stability and trajectory.
3. Suggest two possible actions the drilling engineer can take to control the BUR and achieve the desired trajectory.

Techniques

BUR in Drilling: A Comprehensive Guide

Introduction: This guide expands upon the concept of Build-Up Rate (BUR) in drilling, providing detailed information across various aspects, from fundamental techniques to real-world case studies.

Chapter 1: Techniques for Controlling Build-Up Rate (BUR)

Controlling BUR involves a multifaceted approach encompassing adjustments to drilling parameters, utilization of specialized tools, and the application of directional drilling techniques. This chapter delves into these methods.

1.1 Adjusting Drilling Parameters:

• Weight on Bit (WOB): Reducing WOB can significantly decrease BUR. However, excessively low WOB can reduce Rate of Penetration (ROP) and increase drilling time. Optimal WOB needs to be carefully determined based on formation characteristics and bit type.
• Rotary Speed: Similar to WOB, rotary speed impacts BUR. Higher rotary speeds generally lead to higher BUR. Optimizing rotary speed involves balancing ROP with BUR control.
• Mud Weight: Increasing mud weight provides additional downhole pressure, counteracting formation pressure and reducing the tendency of the wellbore to deviate. However, excessively high mud weight can cause formation damage and increased friction.
• Torque and Drag: Monitoring torque and drag provides insights into friction between the drillstring and wellbore. High values suggest potential for increased BUR and may indicate the need for adjustments to drilling parameters or the use of specialized tools.

1.2 Specialized Tools and Equipment:

• Mud Motors: These tools provide directional control through the use of turbines driven by drilling mud. They allow for precise control of the wellbore trajectory and BUR, particularly in challenging formations.
• Positive Displacement Motors (PDM): PDMs offer more precise control of BUR compared to traditional rotary steerable systems (RSS) due to their ability to provide a constant flow rate regardless of formation variations.
• Rotary Steerable Systems (RSS): RSS provide real-time control over wellbore trajectory by using adjustable pads or jets to steer the drill bit. This allows for continuous adjustments to BUR based on downhole conditions.
• Bent Sub: A bent sub is a downhole tool that induces a build-up in the wellbore inclination. Its angle can be adjusted to achieve the desired BUR.

1.3 Directional Drilling Techniques:

• Walking Technique: This technique uses continuous directional changes to build or drop inclination gradually, allowing for precise control of BUR in challenging formations.
• Whipping Technique: This involves a series of rapid changes in the drillstring's direction to achieve a desired wellbore inclination. It is often used for rapid directional changes.
• Sliding Technique: The drillstring slides while the drill bit remains stationary, allowing for changes in inclination and azimuth without affecting the ROP.

Chapter 2: Models for Predicting and Simulating Build-Up Rate

Accurate prediction of BUR is essential for effective well planning and execution. This chapter explores various models used for this purpose.

2.1 Empirical Models: These models rely on correlations developed from historical drilling data and empirical observations. They are relatively simple to use but may lack accuracy in diverse geological settings.

2.2 Mechanistic Models: These models incorporate the fundamental principles of rock mechanics and fluid dynamics to simulate the interaction between the drill bit, drillstring, and formation. They provide a more accurate representation of the complex interactions influencing BUR but are more computationally intensive.

2.3 Finite Element Analysis (FEA): FEA is a powerful numerical technique used to simulate the stress and strain fields in the wellbore and surrounding formations. It allows for detailed analysis of wellbore stability and prediction of BUR under various drilling conditions.

2.4 Software Integration: Many commercial software packages integrate these models, allowing for real-time predictions and simulations during the drilling process.

Chapter 3: Software for BUR Management

Several software packages facilitate BUR management and trajectory prediction. This chapter explores some of the key features and functionalities.

• Well planning software: These programs allow engineers to design well trajectories, predict BUR, and simulate drilling operations. Examples include Compass, Petrel, and Kingdom.
• Real-time drilling monitoring software: These systems integrate data from downhole tools (MWD/LWD) to provide real-time monitoring of BUR and wellbore inclination. They enable adjustments to drilling parameters for optimal trajectory control.
• Data analysis and visualization software: These tools facilitate the analysis of large drilling datasets, allowing for identification of trends and patterns in BUR and other drilling parameters. Examples include Spotfire and Tableau.

Chapter 4: Best Practices for BUR Management

Effective BUR management relies on a combination of careful planning, rigorous execution, and continuous monitoring.

• Pre-Drilling Planning: Thorough geological characterization, realistic wellbore trajectory design, and selection of appropriate drilling parameters are crucial.
• Real-time Monitoring and Control: Continuous monitoring of BUR using MWD/LWD data allows for proactive adjustments to drilling parameters.
• Regular Communication and Collaboration: Effective communication between the drilling team, engineers, and geologists is essential for timely decision-making.
• Post-Drilling Analysis: Analyzing post-drilling data helps identify areas for improvement in BUR management strategies for future wells.

Chapter 5: Case Studies of BUR Management in Drilling

This chapter presents real-world examples showcasing effective and ineffective BUR management strategies. Specific case studies would illustrate how different geological conditions, drilling techniques, and technologies have impacted BUR, leading to success or challenges in achieving the desired wellbore trajectory. Each case study would highlight lessons learned and best practices to be implemented in future drilling operations. (Note: Specific case studies would require confidential industry data, which is unavailable here. However, the structure for such a chapter is provided.)

This comprehensive guide provides a framework for understanding and managing BUR in drilling operations. Successful BUR management is crucial for efficient, safe, and cost-effective drilling.