The kelly bushing is a critical component of drilling rigs, playing a pivotal role in transmitting torque from the rotary table to the kelly, a hollow square or hexagonal pipe used in drilling oil and gas wells. This article delves into the concept of kelly bushing elevation, its significance, and the various aspects associated with it, drawing insights from reputable sources such as Oilfield Team, Schlumberger’s Energy Glossary, and DUG Insight User Manual.
Key Facts
- Definition: The kelly bushing is a mechanical device that transmits torque from the rotary table to the kelly, which is a hollow square or hexagonal pipe used in drilling oil and gas wells.
- Function: The kelly bushing performs two main functions:
- Transmits torque from the rotary table to the kelly, allowing the drill string to rotate.
- Allows the kelly to move vertically, facilitating the lowering and raising of the drill string.
- Types: There are two main types of kelly bushings:
- Square kelly bushings: The most common type with a square inner surface that matches the square outer surface of the kelly.
- Hexagonal kelly bushings: Less common, with a hexagonal inner surface that matches the hexagonal outer surface of the kelly.
- Installation and maintenance: Kelly bushings are typically installed on the rotary table using a crane. Regular inspection for wear and tear is important, and lubrication should be done regularly to reduce friction and wear.
- Safety: Proper design, installation, and maintenance of kelly bushings are crucial for safety. Failure of the kelly bushing can lead to accidents, and inadequate lubrication can cause the kelly to kick back or overheat, potentially causing injuries or fires on the drilling rig.
Definition and Function
The kelly bushing is a mechanical device that serves as an intermediary between the rotary table and the kelly. Its primary function is to transmit torque from the rotary table to the kelly, enabling the rotation of the drill string. Additionally, the kelly bushing facilitates the vertical movement of the kelly, allowing for the controlled lowering and raising of the drill string during drilling operations.
Types of Kelly Bushings
There are two main types of kelly bushings: square kelly bushings and hexagonal kelly bushings. Square kelly bushings, the more prevalent type, possess a square inner surface that corresponds with the square outer surface of the kelly. Hexagonal kelly bushings, though less common, have a hexagonal inner surface that matches the hexagonal outer surface of the kelly.
Installation and Maintenance
The installation of kelly bushings typically involves the use of a crane to position them on the rotary table. Regular inspection is crucial to ensure the integrity of the kelly bushing, identifying any signs of wear or tear. Proper lubrication is also essential to minimize friction and wear, thereby extending the lifespan of the kelly bushing.
Safety Considerations
The kelly bushing is a critical safety component in drilling operations. Proper design, installation, and maintenance are paramount to prevent accidents. Failure of the kelly bushing can lead to severe consequences, including the kelly becoming stuck in the wellbore, potentially resulting in a drilling accident. Inadequate lubrication can cause the kelly to kick back, posing a risk of injury to personnel or damage to equipment. Additionally, overheating of the kelly bushing can lead to fires on the drilling rig, emphasizing the importance of adhering to safety protocols and guidelines.
Conclusion
The kelly bushing plays a vital role in drilling operations, serving as a conduit for torque transmission and facilitating the vertical movement of the kelly. Understanding the concept of kelly bushing elevation is crucial for ensuring efficient and safe drilling practices. Proper installation, maintenance, and adherence to safety guidelines are essential to prevent accidents and optimize drilling operations.
References
- Kelly Bushing Design, Function, and Installation. (2023, September 30). Oilfield Team. https://oilfieldteam.com/en/a/learning/Kelly-Bushing
- Kelly bushing. (n.d.). Schlumberger’s Energy Glossary. https://glossary.slb.com/en/terms/k/kelly_bushing
- Height datums and abbreviations. (n.d.). DUG Insight User Manual. https://help.dugeo.com/m/faq/l/167077-height-datums-and-abbreviations
FAQs
What is kelly bushing elevation?
Kelly bushing elevation refers to the height of the kelly bushing measured from a reference point, typically mean sea level (MSL). It is a critical measurement used in drilling operations to determine the depth of the wellbore and the position of the drill string.
Why is kelly bushing elevation important?
Accurate kelly bushing elevation is essential for various aspects of drilling operations, including:
– Calculating the depth of the wellbore
– Determining the position of the drill string
– Ensuring proper drilling fluid circulation
– Facilitating efficient drilling and completion operations
How is kelly bushing elevation measured?
Kelly bushing elevation is typically measured using a reference point, often mean sea level (MSL), as the datum. Various methods can be employed to determine the elevation, including:
– Direct measurement using surveying equipment
– Indirect measurement using instruments like inclinometers and lasers
– Calculation based on drilling data and rig specifications
What factors affect kelly bushing elevation?
Several factors can influence kelly bushing elevation, such as:
– Rig design and configuration
– Type of drilling operation (vertical, directional, or horizontal)
– Depth of the wellbore
– Drilling fluid properties and density
– Geological conditions and subsurface formations
How is kelly bushing elevation adjusted?
Adjustments to kelly bushing elevation may be necessary during drilling operations due to various factors. Common methods for elevation adjustment include:
– Adding or removing drill pipe from the drill string
– Adjusting the position of the rotary table
– Utilizing specialized equipment like hydraulic rams or elevators
What safety considerations are associated with kelly bushing elevation?
Ensuring proper kelly bushing elevation is crucial for safety during drilling operations. Key safety considerations include:
– Maintaining accurate elevation measurements to prevent incorrect depth calculations and potential wellbore problems
– Adhering to safety protocols for handling and adjusting the kelly bushing to minimize the risk of accidents
– Implementing regular inspections and maintenance to ensure the integrity of the kelly bushing and related components
What are the consequences of incorrect kelly bushing elevation?
Incorrect kelly bushing elevation can lead to several adverse consequences, including:
– Inaccurate depth measurements, potentially resulting in drilling errors and safety hazards
– Improper drilling fluid circulation, affecting wellbore stability and potentially leading to well control issues
– Increased risk of equipment damage due to excessive stress or improper handling
How can I ensure accurate kelly bushing elevation measurements?
To ensure accurate kelly bushing elevation measurements:
– Use reliable and calibrated measuring instruments
– Follow established procedures and guidelines for elevation determination
– Regularly inspect and maintain the kelly bushing and associated components
– Train personnel on proper elevation measurement techniques and safety protocols