Multi-Channel Telemetry for Subsurface Well Logging Data
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Solution Overview
Problem
The existing methods for subsurface to surface data transmission in hydrocarbon exploration face challenges due to limited signal carrying capacity, particularly when combining multiple logging tools, which results in bandwidth limitations and inefficiencies, especially with imaging tools that generate large amounts of fine-grained data.
Innovation Solution
A multi-channel signal modulation system that dynamically adapts to transmission conditions by partitioning bandwidth into separate channels, optimizing data rates, and continuously monitoring signal-to-noise ratios and error signals to ensure reliable and efficient data transmission, using techniques such as differential and convolution encoding, and Hilbert transforms to reduce carrier reliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple logging tools are combined into one tool string to reduce the number of trips, then productivity is improved, but the quantity of data to be transmitted increases beyond the cable's signal carrying capacity
Solution Approach 1:
The patent divides the available bandwidth into multiple separate channels, each capable of carrying a portion of the total data stream. This segmentation allows the tool string to transmit data from multiple logging tools simultaneously without exceeding the cable's overall signal carrying capacity, thus enabling combined tool strings while maintaining data transmission within bandwidth limits.
2Measurement precision
If imaging tools are included to provide fine-grained measurements, then measurement precision is improved, but the data transmission rate required exceeds the cable's bandwidth
Solution Approach 1:
The patent segments the high-volume data from imaging tools across multiple channels, distributing the transmission load. Each channel operates at a manageable data rate that the cable can handle, while collectively they transmit the full high-precision imaging data set, thus maintaining measurement detail without requiring excessive transmission speed from any single channel.
Solution Approach 2:
The patent transitions from a single-dimensional data transmission approach to a multi-dimensional approach by utilizing multiple channels simultaneously. This allows parallel transmission of data streams, effectively increasing the total data throughput capacity beyond what a single channel could achieve, thereby supporting high-precision imaging tools.
3Ease of operation
If cable diameter is reduced for safety reasons, then ease of operation is improved, but the frequency response and signal carrying capacity are limited
Solution Approach 1:
The patent compensates for the limited signal carrying capacity of smaller-diameter cables by segmenting data transmission across multiple channels. This allows the cable to safely maintain a reduced diameter while still achieving sufficient total bandwidth through the combined capacity of multiple channels, thus preserving both safety and data transmission capability.
Data Source
AI summary
A method and system for transmitting data through a transmission medium between surface and subsurface transceivers. A surface transceiver and a subsurface transceiver are each configured to selectively transmit over a plurality of transmission channels, each transmission channel having a range of frequencies within the total frequency bandwidth. The surface transceiver is adapted to initialize a channel to determine at least one parameter affecting the current maximum data rate for transmission of information through the channel using a given transmission methodology. At least one of the channels uses carrierless phase/amplitude (CAP) modulation for its transmission methodology. The surface transceiver and the subsurface transceiver adapt to cooperatively periodically test a channel by transmission of a calibration signal from the subsurface transceiver to the surface transceiver. Control circuitry compares the received calibration signal with the calibration signal, responding to the result of the comparison to adjust at least one parameter as necessary to achieve an optimum rate of data transmission through said channel.