Adjustable Sub for Borehole Spiraling Control
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Solution Overview
Problem
Spiraling of boreholes during drilling operations due to uneven load distribution between drill bits and reamers, leading to torque buildup, premature wear, and potential BHA sticking in wellbores.
Innovation Solution
A sub device is installed on the drill string between the reamer and drill bit, capable of adjusting its length to balance axial and torsional loads, using mechanisms like hydraulic rams, spring-based grub screws, or magneto-rheological fluids to maintain constant torque and prevent spiraling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a reamer is used to enlarge the wellbore, then the circulating pressure of drilling fluid is reduced, but the borehole becomes spiraled due to uneven load distribution between drill bit and reamer
Solution Approach 1:
A load-balancing device is introduced as an intermediary component between the drill bit and reamer. This device includes a first load cell that measures axial load on the drill bit and a second load cell that measures axial load on the reamer, enabling real-time monitoring and balancing of loads to prevent spiraling while maintaining the pressure reduction benefit of reaming
Solution Approach 2:
The system employs feedback control by continuously measuring axial loads on both the drill bit and reamer through load cells, comparing these measurements, and adjusting the extension length of the reamer accordingly. This closed-loop feedback mechanism maintains balanced loading to prevent borehole spiraling while preserving the circulating pressure reduction advantage
2Productivity
If the reamer cuts at different speed than the drill bit, then the load distribution varies causing compression and tension in BHA, but this variation causes the borehole to become spiraled
Solution Approach 1:
The reamer is designed with dynamic adjustability through an extendable mechanism controlled by a actuator. The extension length is dynamically adjusted based on real-time load measurements from load cells, allowing the system to adapt to varying drilling speeds and formation conditions while maintaining balanced load distribution and preventing spiraling
Solution Approach 2:
A feedback control system continuously monitors axial loads on the drill bit and reamer, and automatically adjusts the reamer extension length to maintain optimal load balance. This dynamic feedback adjustment compensates for speed differences between cutting structures, preventing borehole spiraling while allowing high productivity drilling speeds
3Strength
If the load is not balanced between cutting structures, then cutting speeds differ causing wear, but failing to balance the load causes greater difference in rates at which reamer and bit will drill
Solution Approach 1:
The load-balancing device uses feedback control to continuously monitor axial loads on both cutting structures and adjust the reamer extension length accordingly. This maintains balanced loading that equalizes cutting speeds, preventing premature wear while ensuring consistent drilling rates between the bit and reamer
Solution Approach 2:
The system automatically self-regulates by using load cell measurements to control the actuator that adjusts reamer extension. This self-service mechanism continuously optimizes load distribution without external intervention, maintaining balanced cutting speeds and consistent drilling performance while extending the durability of cutting structures
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
The sub device effectively balances loads across cutting structures, reducing borehole spiraling, preventing BHA sticking, and improving drilling efficiency by maintaining optimal torque and penetration rates.
Implementation Method 1
a plunger which moves in response to a rheologically-activated fluid which changes its viscosity in the presence of a changing magnetic field
Implementation Method 2
a hydraulically-activated ram which moves the main body relative to the lower section
Data Source
AI summary
An apparatus and method for alleviating spiraling in boreholes is disclosed. The apparatus includes a sub, which adjusts the length of the bottom-hole assembly in response to tension/compression, flexural bending and/or torque measurements made above and below the reamer so that the drill bit and the reamer cut at the same depth rate. The sub is connected between the drill bit and the reamer. The apparatus further includes measurement devices disposed on the bottom-hole assembly above and below the reamer, which are capable of measuring the tension/compression, flexural bending and torque in the bottom-hole assembly. The method includes use of a data processor, which determines which operational output signals to supply to the sub in order to adjust its length and thereby accomplish the desired drilling rates.