Drillstring Design for Extended Reach Wells
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Solution Overview
Problem
Current methods for designing drillstrings in deviated wellbores struggle to accurately calculate downhole weight-on-bit (DWOB) and rotating torque profiles, often leading to buckling issues due to incomplete accounting of wellbore friction and hydraulic forces, which can reduce drilling efficiency and increase the risk of lock-up.
Innovation Solution
A method and system that determine baseline torque and tension profiles for a drillstring off-bottom, using surface weight-on-bit (SWOB) input to calculate WOB and rotating torque profiles, and assess the likelihood of buckling, allowing for adjustments to design parameters and operational parameters to maintain operational torque limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If drillstring tension is increased to prevent buckling, then drillstring stability is improved, but the ability to transmit sufficient downhole weight-on-bit is reduced
Solution Approach 1:
The system dynamically adjusts drillstring operational parameters including tension, torque, and weight-on-bit based on real-time buckling risk assessment. By continuously monitoring drillstring behavior and modifying operational parameters, the system optimizes the balance between maintaining drillstring stability and ensuring sufficient weight-on-bit for effective drilling operations.
2Manufacturing precision
If drillstring torque is increased to maintain rotational control, then drilling precision is improved, but the risk of lock-up due to buckling increases
Solution Approach 1:
The system implements continuous feedback monitoring of drillstring torque, tension, and rotational behavior to detect early signs of buckling. When buckling conditions are detected, the system provides real-time alerts and recommends corrective actions, enabling operators to adjust torque and rotation parameters to prevent lock-up while maintaining drilling precision.
Solution Approach 2:
The system performs preliminary buckling analysis using calculated profiles of tension and torque along the drillstring before operational issues arise. By identifying potential buckling zones and conditions in advance, the system enables proactive adjustment of drilling parameters to prevent buckling-related failures before they occur.
3Productivity
If drillstring design is optimized for high weight-on-bit, then drilling efficiency is improved, but buckling resistance is reduced
Solution Approach 1:
The system transitions from static drillstring design to dynamic operational optimization by continuously monitoring and adjusting operational parameters. The system calculates real-time tension and torque profiles to assess buckling risk, enabling the drillstring to operate at optimal weight-on-bit levels that adapt to changing downhole conditions, thereby maintaining both drilling efficiency and buckling resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a more accurate simulation of drillstring behavior, reducing the likelihood of buckling and ensuring sufficient DWOB transmission while maintaining operable torque levels, thereby enhancing drilling efficiency and preventing lock-up.
Implementation Method 1
A major portion of the drillstring is generally suspended in the borehole in tension
Implementation Method 2
portions of the drill string may be in tension while other portions are in compression
Implementation Method 3
The drillstring touches the walls of the boreholes, creating additional friction
Implementation Method 4
Buckling is a deformation of the drillstring caused by the drillstring not being able to support an imposed compressive force
Implementation Method 5
Rotation of the bit through the drillstring, combined with a WOB, causes the bit to penetrate subsurface formations
Data Source
AI summary
Designing a drillstring in for use in a wellbore, such as a deviated or horizontal wellbore, particularly with application to extended reach wellbores. Method comprises determining the downhole weight-on-bit transmitted by a drillstring by determining a baseline tension profile and baseline torque profile in a drill string rotating off-bottom, and then using such profiles in conjunction with a selected surface weight-on-bit slack-off value to calculate a drillstring tension profile and rotating torque profile with the bit on bottom and having weight applied thereto. The method includes buckling limit checks and rig operational limit checks to determine if sufficient torque and DWOB can be transmitted through the drillstring, and to determine whether the drill string remains operable even though portions thereof may be in a buckled condition.