Logging Tool Electric Dipole Magnetic Sensor Bed Boundary Detection
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Solution Overview
Problem
Current subterranean formation evaluation methods, particularly induction-type logging tools, face limitations in accurately detecting bed boundaries at distances beyond the transmitter-receiver offset, reducing sensitivity and effectiveness in geosteering operations.
Innovation Solution
The method involves generating an electric dipole in a borehole to create a magnetic field, sensing magnetic flux with a coil positioned axially away, and identifying bed boundaries based on the measured magnetic flux, allowing for detection of boundaries both axially and radially spaced from the dipole, with various orientations of the dipole and magnetic flux measurement paths to enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If induction-type logging tools use the stronger out-of-phase response to detect bed boundaries, then bed boundary detection capability is improved, but sensitivity to distance to bed boundary diminishes beyond the transmitter-receiver offset length
Solution Approach 1:
The patent changes the measurement parameter from using the stronger out-of-phase response to using the weaker in-phase response. This parameter change allows detection of bed boundaries at greater distances beyond the transmitter-receiver offset, as the in-phase response maintains sensitivity over longer distances despite being inherently weaker in magnitude
Solution Approach 2:
The patent introduces an intermediary approach by using magnetic flux measurements as an intermediate step to detect bed boundaries. The magnetic flux serves as a mediator that carries information about bed boundaries at distances beyond what direct electromagnetic induction can detect, enabling extended range detection
2Length of moving object
If the in-phase response is used to measure formation resistivity, then detection distance is improved, but the signal strength is much weaker compared to the out-of-phase response
Solution Approach 1:
The patent uses magnetic flux as an intermediary to amplify or preserve the weak in-phase signal. By measuring magnetic flux rather than directly measuring the weak in-phase voltage, the system can detect signals at greater distances without being limited by the inherently weak signal strength of the in-phase response
Solution Approach 2:
The patent substitutes the traditional electrical measurement approach with a magnetic field measurement approach. Instead of measuring electrical voltage directly (which is weak for in-phase responses), the system measures magnetic flux, which provides better distance sensitivity and allows the weak in-phase signal to be effectively utilized
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 significantly improves the detection of bed boundaries at greater distances, providing enhanced sensitivity and accuracy in geosteering operations by utilizing the magnetic flux measurements to indicate the presence and direction of bed boundaries, enabling safer drilling and more precise geosteering.
Implementation Method 1
using a coil in the borehole at a location spaced axially away from the electric dipole to sense magnetic flux that is generated by the electric dipole
Data Source
AI summary
A logging method and system for imaging forward and lateral sections of a subterranean formation. An electric dipole source generates electromagnetic field in the formation that is sensed with magnetic flux sensor that is spaced a distance away from the electric dipole source. The resulting electric dipoles can be axial or transverse, and magnetic flux sensors can sense magnetic fields oriented axially or orthogonally. The axial and transverse electric dipoles can be collocated, and magnetic flux sensors that sense axial or orthogonal magnetic fields can be collocated. Analyzing changes in the magnitude of signals sensed by magnetic flux sensors can indicate the presence and distance of bed boundaries that are ahead and lateral to the electric dipole source.