Nested Pipe Logging With Hybrid Frequency-Time Inspection
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Solution Overview
Problem
Conventional electromagnetic logging techniques face challenges in inspecting nested downhole pipes due to degraded vertical resolution for outer pipes in frequency-domain tools and impractically high dynamic range and sampling rates required by time-domain tools, limiting their effectiveness in accurately characterizing multiple pipe layers.
Innovation Solution
A hybrid frequency- and time-domain logging technique that combines composite waveforms, including continuous wave responses in the frequency domain and pulse responses in the time domain, processed using model-based inversion to determine pipe parameters, thereby improving vertical resolution and relaxing dynamic range and sampling rate requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If time-domain techniques are used to sample both leading and trailing portions of the decay response, then sensitivity to both inner and outer pipes is achieved, but impractically high dynamic range and sampling rates are required
Solution Approach 1:
The patent segments the inspection process into two distinct parts: frequency-domain measurements for inner pipe inspection and time-domain measurements for outer pipe inspection. By dividing the single complex time-domain sampling task into separate frequency and time domain components, the system avoids the need for impractically high dynamic range and sampling rates while maintaining sensitivity to both inner and outer pipes.
Solution Approach 2:
Instead of requiring the time-domain tool to capture the entire decay response with extremely high dynamic range, the patent uses partial action by combining it with frequency-domain measurements. The frequency-domain component handles the inner pipe inspection that would otherwise require excessive dynamic range in time-domain sampling, allowing the time-domain component to focus on outer pipes with more practical requirements.
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
The hybrid approach provides enhanced vertical resolution for both inner and outer pipes with reduced dynamic range and sampling rate demands, enabling more accurate inspection and characterization of nested downhole pipes compared to conventional methods.
Implementation Method 1
when the transmitter coil emits the primary transient EM fields, eddy currents are induced in the casing
Implementation Method 2
These eddy currents then produce secondary fields which are received along with the primary fields by the receiver coil
Data Source
AI summary
Electromagnetic logging tools to inspect nested pipes using hybrid frequency- and time-domain logging techniques are disclosed. The disclosed logging system and processing workflows combine frequency-domain and time-domain techniques to overcome the disadvantages of using frequency-domain or time domain tools in isolation.