Subsea Running Tool Encoder and Displacement Sensor
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Solution Overview
Problem
In subsea drilling operations, the movement of surface platforms due to ocean currents and winds causes the drilling riser to curve, leading to inconsistencies in the transmission of torque and weight from the surface to the wellhead, resulting in inaccurate measurement of turns and displacement of subsea running tools, which affects the proper placement and actuation of devices in the wellbore.
Innovation Solution
A system comprising a running tool with an encoder to detect relative rotation and an axial displacement sensor to measure movement, connected to a transmitter that communicates data to the surface, allowing real-time monitoring of relative turns and displacement at the subsea wellbore, ensuring accurate placement and anchoring of subsea wellhead components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If surface platforms are used to conduct subsea drilling operations, then drilling operations can be performed in deep water, but the platforms are subject to ocean currents and winds causing the riser to curve and the running string to contact the riser wall, resulting in inaccurate measurement of turns and displacement at the running tool
Solution Approach 1:
The patent introduces encoder and displacement sensor systems as intermediary measurement devices installed on the running tool itself. These sensors directly measure turns and displacement at the tool location, serving as an intermediary between the running string and the measurement objective, thereby eliminating the need to rely on surface platform measurements that are affected by riser curvature and environmental forces.
Solution Approach 2:
The patent replaces the mechanical measurement approach (monitoring running string turns and displacement at the surface platform) with electronic sensing systems (encoders and displacement sensors) installed on the running tool. This substitution allows direct electronic measurement of the running tool's position and orientation, eliminating the mechanical transmission errors caused by riser curvature and running string contact with the riser wall.
2Length of moving object
If the running string is made long to reach deep wellheads, then subsea devices can be deployed at greater depths, but the running string segments twist relative to one another, absorbing turns and displacement, which further reduces measurement accuracy
Solution Approach 1:
The patent moves the measurement dimension from the surface platform (remote location) to the running tool itself (downhole location). By installing sensors directly on the running tool, the measurement is performed at the actual location where turns and displacement need to be known, eliminating the cumulative errors that occur over the long length of the running string.
3Force
If the riser curves due to platform movement, then the running string contacts the riser wall and becomes anchored, but this causes the actual torque and weight applied to the device to be less than applied at the surface, creating discrepancy in turns and displacement measurements
Solution Approach 1:
The patent introduces direct measurement sensors on the running tool as an intermediary to capture the actual turns and displacement at the point of application. This intermediary measurement system directly observes the running tool's state without relying on the force transmission path through the curved riser, thereby eliminating the discrepancy between applied force and actual device actuation.
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
Enables real-time measurement and confirmation of the proper landing and setting of subsea devices, ensuring that the running string has anchored to the riser, thereby improving the accuracy and reliability of subsea operations.
Implementation Method 1
An encoder is positioned between the stem and the body and to detect relative rotation between the stem and the body
Implementation Method 2
An axial displacement sensor is positioned between the piston and the stem and to detect relative axial motion between the piston and the body
Data Source
AI summary
A running tool generates signals in response to setting of a subsea wellhead device that correspond to actual rotation and displacement of the running tool in the subsea wellhead. The running tool includes an encoder that generates a signal corresponding to the number of rotations of a stem of the running tool relative to a body of the running tool. The running tool also includes an axial displacement sensor that generates a signal corresponding to the axial displacement of a piston of the running tool relative to the body. The signals are communicated to the surface using an acoustic transmitter located on the running tool and an acoustic receptor located proximate to a drilling platform at the surface. The signals are communicated to an operator interface device from the receptor for further communication in a manner understood by an operator.