Self-Adjusting Drilling Deflection With Sensors for Directional Wells
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Solution Overview
Problem
Existing drilling methods for directional wellbores using fixed bends in drilling assemblies result in uneven boreholes, increased stress and vibration on components, and higher friction, leading to reduced build rates and increased drilling time and expense.
Innovation Solution
A self-adjusting deflection device in the drilling assembly allows the lower section to tilt relative to the upper section when stationary for curved drilling and straighten when rotated, using sensors and downhole drives to control drilling direction and reduce stress on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed bend (AKO) is used in the drilling assembly to drill curved wellbore sections, then the drill bit can be tilted to form curved sections, but this produces uneven boreholes, induces high stress and vibrations on mud motor components, and creates high friction between the drilling assembly and wellbore
Solution Approach 1:
The patent replaces the fixed bend (AKO) with a dynamic system comprising a tiltable lower drilling assembly that can adjust its orientation relative to the upper drilling assembly. The lower assembly is tilted by applying a tilting moment through stabilizers positioned at specific locations, allowing the drill bit to orient in the desired direction without a fixed mechanical bend. This dynamic tilting mechanism eliminates the continuous contact friction and stress concentrations inherent in fixed bend systems while maintaining the ability to drill curved wellbore sections.
2Reliability
If the angle of the bend of the AKO is reduced to reduce stresses on the drilling assembly components, then stress on components is reduced, but the maximum build rate is reduced and additional time and expenses are required to drill the wellbore
Solution Approach 1:
The patent changes the fundamental parameter from a fixed geometric bend angle to a dynamic tilting angle that can be adjusted independently of build rate requirements. By applying controlled tilting moments through the stabilizers, the system can achieve high build rates with larger effective tilt angles without the stress constraints that limit fixed bend systems. The tilting moment magnitude and stabilizer positioning can be optimized to simultaneously achieve high productivity and component reliability.
3Ease of operation
If a fixed bend is used to provide a selected tilt to the drill bit, then curved wellbore sections can be drilled, but the bend contacts the inside of the wellbore as the drilling assembly rotates, creating high friction
Solution Approach 1:
The patent extracts the tilt-generating function from the fixed bend (AKO) and relocates it to the drill bit assembly itself through the tiltable lower drilling assembly. The lower assembly is tilted relative to the upper assembly by applying a tilting moment, which orients the drill bit in the desired direction without requiring a fixed bend that contacts the wellbore during rotation. This separation of the tilt function from the rotation function eliminates the friction problem while maintaining directional control capability.
Data Source
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AI summary
An apparatus for drilling a directional wellbore is disclosed that in one non-limiting embodiment includes a drive for rotating a drill bit, a deflection device that enables a lower section of the drilling assembly to tilt about a member of the deflection device within a selected plane when the drilling assembly is substantially rotationally stationary to allow drilling of a curved section of the wellbore when the drill bit is rotated by the drive and wherein the tilt is reduced when the drilling assembly is rotated to allow drilling of a straighter section of the wellbore, and a tilt sensor that provides measurements relating to tilt of the lower section. A controller determines a parameter of interest relating to the tilt for controlling drilling of the directional wellbore.