Downhole Rotor Positioning for Accurate Mud Pulse Uplink
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Solution Overview
Problem
Conventional mud pulse telemetry systems for downhole communication in hydrocarbon recovery operations face limitations such as slow sampling rates, poor accuracy, and economic inefficiencies, particularly when positioning of up-hole sensors is compromised or when using standpipe pressure sensors.
Innovation Solution
A method involving a motor, gearbox, modulator rotor, and relative position measurement system is used to determine the absolute position of the rotor, allowing for accurate communication of untethered downhole systems by modulating mud flow pressure through defined open and closed positions, enabling real-time data transmission and overcoming jamming events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional mud pulse telemetry systems are used with standpipe pressure sensors, then communication can be established, but the sampling rate is slow and accuracy is poor
Solution Approach 1:
The patent replaces the mechanical standpipe pressure sensor system with a magnetic field-based detection system. A magnetic field generator in the downhole tool interacts with a magnetic field sensor at the surface, eliminating the need for mechanical pressure sensing and enabling faster, more accurate data transmission without the limitations of conventional mud pulse telemetry.
Solution Approach 2:
The patent introduces drilling fluid as an intermediary medium to couple the magnetic field from the downhole tool to the surface sensor. The drilling fluid serves as a magnetic coupling medium that allows magnetic field signals to pass from the subsurface to the surface, enabling high-speed data transmission through the fluid column without requiring direct mechanical or electrical contact.
2Loss of information
If conventional mud pulse telemetry systems are used, then data can be transmitted, but economic costs increase due to operational inefficiencies
Solution Approach 1:
The patent employs periodic magnetic field signaling at high frequencies to transmit data through the drilling fluid. By using rapid periodic magnetic field cycles rather than slow mechanical pressure pulsations, the system achieves faster data transmission rates, reducing the time tools remain stuck and decreasing overall operational costs and energy consumption.
3Ease of operation
If up-hole sensors are positioned for signal reception, then communication can occur, but positioning is compromised due to obstruction from other equipment
Solution Approach 1:
The patent replaces the mechanical alignment-dependent pressure sensor system with a magnetic field-based system. The magnetic field sensor at the surface can detect signals regardless of the precise angular position or orientation of the downhole tool, eliminating the need for careful sensor positioning and alignment that plagues conventional systems.
4Productivity
If fast data transmission is achieved, then productivity improves, but signal to noise ratio requirements increase
Solution Approach 1:
The patent uses drilling fluid as a magnetic coupling intermediary that efficiently transmits magnetic field signals from the downhole tool to the surface sensor. This magnetic coupling through the fluid provides strong signal transmission with high signal-to-noise ratio, enabling fast data transmission rates without the information loss that would otherwise occur at high speeds.
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 precise location tracking and efficient data transmission of downhole equipment, reducing economic costs and operational inefficiencies by providing accurate positioning and faster data transfer, even in the presence of debris or obstructions.
Implementation Method 1
The modulator is designed to open and close at specific intervals, thereby creating a pressure variation of the fluid
Implementation Method 2
a magnetic field generator in the downhole tool and a magnetic field sensor at the surface positioned above the wellbore and in communication with the magnetic field generator through the drilling fluid
Data Source
AI summary
The disclosure provides methods of communication for untethered systems. The method includes defining a window for sampling a torque-related current and a modulator rotor relative position-related parameter; using the defined window, recording local maximum and local minimum values of the torque-related current versus a modulator rotor relative position-related parameter of a rotor of a rotary pulser system in the untethered system; identifying at least one of consecutive torque-related current minimum values and consecutive torque-related current maximum values based on a periodicity; computing an absolute modulator rotor position based on the periodic maxima and minima of the torque-related current; and controlling the modulator rotor using the absolute modulator rotor position to modulate uplink signals to a surface environment.