Multiplexed Borehole Transmitters for Resistivity Monitoring
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Solution Overview
Problem
Current methods for monitoring reservoir conditions and optimizing hydrocarbon recovery, particularly in enhanced recovery techniques like waterflooding and CO2 injection, face challenges in remotely determining and monitoring formation resistivity effectively, especially in partially drained or viscous oil reservoirs.
Innovation Solution
A multiplexed transmitter system is employed within a borehole, using a shared conductive loop with frequency-dependent materials to derive resistivity distribution by applying distinct drive signals, allowing for the characterization and monitoring of subsurface electromagnetic fields and optimizing hydrocarbon recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple transmitters are used to monitor reservoir conditions at different depths, then measurement precision and monitoring capability are improved, but device complexity and cost increase
Solution Approach 1:
Multiple transmitters are combined into a single multiplexed transmitter assembly that can operate at different depths in the borehole. The system uses a single cable with multiple transmitter elements that can be selectively activated, merging the functionality of multiple independent transmitters into one integrated unit, thereby reducing overall system complexity while maintaining measurement precision
Solution Approach 2:
The multiplexed transmitter system is designed to perform multiple functions: it can operate at different depths, use different frequencies, and measure different formation parameters. This multi-functional design allows a single device to replace multiple specialized transmitters, reducing device complexity while improving measurement precision through selective activation of appropriate transmitter elements
2Productivity
If multiple transmitters operate simultaneously at different frequencies, then productivity and monitoring efficiency are improved, but signal interference and measurement reliability deteriorate
Solution Approach 1:
The multiplexed transmitter system activates different transmitter elements in periodic sequences rather than simultaneously. Each transmitter element is activated at specific time intervals with assigned frequencies, allowing the system to maintain high productivity through rapid sequential operation while avoiding signal interference that would compromise measurement reliability
Solution Approach 2:
The system dynamically adjusts which transmitter elements are active based on monitoring requirements. The multiplexing scheme allows dynamic allocation of frequencies and activation sequences to different transmitter elements, optimizing both productivity and reliability by adapting the operational configuration to specific measurement needs while minimizing interference
3Device complexity
If a single shared conductive loop is used for multiple transmitters, then device complexity is reduced, but signal isolation and measurement precision worsen
Solution Approach 1:
The system introduces frequency-dependent coupling elements as intermediaries between the shared conductive loop and individual transmitter elements. These intermediaries enable signal isolation by allowing only specific frequencies to pass to each transmitter, maintaining measurement precision while using a single shared cable structure, thus reducing device complexity without sacrificing precision
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 enables precise monitoring and optimization of hydrocarbon recovery by accurately determining formation resistivity and production parameters, enhancing the efficiency of hydrocarbon extraction processes.
Implementation Method 1
A multiplexed transmitter system is employed within a borehole, using a shared conductive loop with frequency-dependent materials to derive resistivity distribution by applying distinct drive signals
Data Source
AI summary
A borehole resistivity distribution system includes a cable having an array of transmitters along a shared conductive loop. Each of the transmitters is coupled to a corresponding frequency-dependent material or device. An application of a first drive signal to the cable excites the transmitters, to obtain a first measurement, the first drive signal having a first frequency and a first amplitude. An application of a second drive signal to the cable excites the transmitters, to obtain a second measurement, the second drive signal having a second frequency and a second amplitude. At least the first frequency is different from the second frequency, or the first amplitude is different from the second amplitude. The system further includes a processor coupled to receive the first and second measurements, to derive, based at least in part on the measurements, a resistivity distribution around a borehole.