Downhole Transient Electromagnetic Pipe Signal Bucking
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Solution Overview
Problem
Current geophysical inversion methods face challenges in accurately estimating earth formation properties due to interference from pipe signals generated by conductive tools, which introduce systematic noise and uncertainty in measurements, especially during transient electromagnetic measurements.
Innovation Solution
A method and system using a downhole tool with a single transmitter and two receivers to measure and buck out pipe signals in situ, allowing for the extraction of formation signals and reducing uncertainty by employing a bucking coefficient calculation to separate pipe and formation responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional geophysical inversion methods are used, then formation property estimation can be performed, but pipe signals from conductive tools introduce systematic noise and reduce measurement precision
Solution Approach 1:
The patent segments the total measured signal into distinct components: pipe signal and formation signal. By using multiple receivers at different positions, the system can separately identify and process these components, allowing the pipe signal to be isolated and removed before formation property estimation, thereby improving measurement precision.
Solution Approach 2:
The patent extracts the pipe signal component from the total measured signal using a mathematical model that accounts for the conductive tool body's electromagnetic interference. This extracted pipe signal is then subtracted from the total signal to obtain a cleaned formation signal, eliminating systematic noise and improving the accuracy of formation property estimation.
2Measurement precision
If bucking techniques are applied to eliminate primary field interference, then sensitivity to formation parameters improves, but electromagnetic interference between conductive tool body and formation creates additional systematic noise
Solution Approach 1:
The patent introduces an intermediary mathematical model that describes the electromagnetic interaction between the conductive tool body and the formation. This model acts as a mediator to predict and account for the tool-formation interference, allowing it to be compensated for in the signal processing, thereby maintaining sensitivity to formation parameters while reducing systematic noise.
Solution Approach 2:
The patent changes the parameters of the bucking calculation by incorporating additional terms that account for the conductive tool body's interaction with the formation. By adjusting the mathematical model to include these additional parameters, the system can more accurately predict and eliminate both primary field interference and tool-formation interference, improving measurement precision.
3Measurement precision
If air-hang tests are conducted to measure pipe signals, then pipe signal characterization can be achieved, but the process is expensive and time-consuming
Solution Approach 1:
The patent enables the system to measure and characterize pipe signals in situ during normal logging operations, without requiring separate air-hang tests. The same receivers and mathematical models used for formation evaluation are applied to characterize the pipe signal, allowing the system to serve multiple functions simultaneously and eliminating the need for additional time-consuming tests.
Solution Approach 2:
The patent makes the electromagnetic measurement system multi-functional by enabling it to perform both formation evaluation and pipe signal characterization using the same hardware and mathematical framework. This universal approach allows the system to extract multiple types of information from a single logging run, eliminating the need for separate air-hang tests and reducing overall measurement time.
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 more efficient and accurate measurement of pipe signals without the need for expensive air-hang tests, allowing for real-time, in situ monitoring of pipe signal changes and improved formation property estimation, reducing errors in modeling and enhancing the precision of geophysical data inversion.
Implementation Method 1
a transmitter and two receivers spaced at different distances from the transmitter are conveyed through a borehole on a carrier
Data Source
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AI summary
Methods and systems for estimating properties of earth formations including conveying a carrier through a borehole having a transmitter, a first receiver, and a second receiver, the first receiver positioned a first distance from the transmitter and the second receiver positioned a second distance therefrom, generating with the transmitter a transient electromagnetic field, receiving a first measured signal at the first receiver, receiving a second measured signal at the second receiver, obtaining a total signal from the first measured signal and the second measured signal, determining a bucking coefficient, performing a bucking calculation employing the bucking coefficient, the first measured signal, and the second measured signal to extract a pipe signal, suppressing the pipe signal from the total signal to obtain a formation signal, estimating a formation property from the formation signal, and adjusting a drilling operation based on the estimated property of the formation.