Drillstring Rotation Modulation for Downlink Command Accuracy
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Solution Overview
Problem
Current methods for communicating information between the surface and downhole equipment in drilling operations, such as mud pulse telemetry, are inefficient and inaccurate, disrupting the drilling process and lacking in precision.
Innovation Solution
A method involving encoding commands into modulations of the drillstring rotation rate, allowing for accurate transmission and decoding of commands at both the uphole and downhole locations, with the option to take corrective action if discrepancies occur, using a combination of rotation rate sensors and decoders within a drilling system that includes a rotating drillstring and a measurement-while-drilling (MWD) system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If mud pulse telemetry is used for communication between surface and downhole equipment, then information can be transmitted, but the drilling process is disrupted and communication efficiency and accuracy deteriorate
Solution Approach 1:
The patent replaces the mechanical mud pulse telemetry system with a magnetic field-based communication system. Downhole equipment modulates the magnetic field by varying its electrical impedance, which is detected by surface receivers. This substitution eliminates the need for mud pulses, thereby maintaining communication accuracy while avoiding disruption to the drilling process and improving overall drilling efficiency.
2Loss of information
If mud pulse telemetry is used for downlink signaling, then commands can be transmitted to drilling assembly, but communication efficiency and accuracy deteriorate
Solution Approach 1:
The patent replaces the mechanical mud pulse signaling system with an electromagnetic field-based system. Commands are transmitted by modulating the magnetic field through impedance changes in downhole equipment, which are detected instantaneously at the surface. This eliminates the time delay associated with generating and transmitting mud pulses, thereby improving command transmission accuracy and reducing signal transmission time.
3Reliability
If conventional telemetry methods are used, then communication between surface and downhole equipment is established, but reliability and precision deteriorate
Solution Approach 1:
The patent replaces conventional mechanical telemetry with a magnetic field-based system that uses impedance modulation. The downhole equipment varies its electrical impedance to encode information, which creates detectable magnetic field variations. Surface receivers detect these variations with high precision, improving both communication reliability and signal detection precision compared to mud pulse methods that are susceptible to noise and interference.
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 enhances the accuracy and efficiency of command transmission and adherence to the desired drill path by confirming the receipt of commands without relying on the telemetry bandwidth of the downhole tool, thereby improving drilling control and reducing errors.
Implementation Method 1
a magnetic coupling operable to sense variations in a rotation rate of the drillstring
Implementation Method 2
a magnetic coupling operable to sense variations in a rotation rate of the drillstring
Data Source
AI summary
A method for controlling a downhole steerable tool, such as a rotary steerable system (RSS), in a drilling system that also includes a rotating drillstring and a measurement-while-drilling (MWD) system comprises encoding an original command for the tool into an encoded signal consisting of modulations of the drillstring rotation rate, transmitting the encoded command by modulating the drillstring rotation rate, measuring the drillstring rotation rate at the tool and decoding the encoded command so as to generate a tool-decoded command, separately measuring the drillstring rotation rate and decoding the encoded command from the separate downhole-measurements so as to generate a separately downhole-decoded command, transmitting the separately downhole-decoded command to the uphole location, comparing the separately downhole-decoded command to the original command, and taking corrective action if the two commands are different.