Transient Electromagnetic Tool Pipe Signal Correction
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Solution Overview
Problem
Geophysical inversion models face uncertainty due to electromagnetic interference from conductive tools, leading to inaccurate formation property estimates, as existing techniques like bucking do not adequately account for pipe signals, resulting in systematic noise and errors in model inversion.
Innovation Solution
A method using a transient electromagnetic tool with a single transmitter and two receivers to measure pipe signals and apply a correction operation, suppressing the pipe signal through a bucking coefficient calculation, enabling a faithful representation of the formation response by combining total bucked signals with error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional bucking techniques are used to eliminate systematic noise from conductive tools, then the primary field interference is reduced, but electromagnetic interference from pipe signals creates additional systematic noise
Solution Approach 1:
The total measured signal is segmented into distinct components: primary field response, pipe signal response, and formation response. By using multiple receivers at different positions, each component can be isolated and processed separately, allowing the pipe signal to be identified and removed without affecting the formation measurement
Solution Approach 2:
A pipe signal correction model is introduced as an intermediary component that mediates between the raw measured data and the final formation properties. This model characterizes the pipe signal response and uses it to correct the total signal, eliminating the harmful pipe interference while preserving the formation response
2Measurement precision
If pipe signal correction is applied to remove electromagnetic interference, then formation property estimation accuracy is improved, but the complexity of the inversion process increases
Solution Approach 1:
The pipe signal correction is performed as a preliminary step before the main inversion process. By pre-characterizing and removing the pipe signal response from the total measured signal, the inversion process receives cleaner data with reduced systematic noise, simplifying the subsequent inversion while improving accuracy
Solution Approach 2:
The correction process transforms the measured signal by applying parameter changes based on the pipe signal model. The pipe signal response is characterized by specific parameters that describe its behavior, and these parameters are used to adjust the total signal, converting it from a noisy measurement to a corrected formation response
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 reduces uncertainty in formation property estimates by accurately removing pipe signal interference, improving the accuracy of geophysical models and reducing errors in inversion processes, allowing for more precise geo-steering and measurement-while-drilling operations.
Implementation Method 1
A transient electromagnetic tool with a single transmitter and two receivers measures pipe signals and applies a correction operation
Data Source
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AI summary
Methods and systems for estimating properties of formations penetrated by boreholes are provided, 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 from the transmitter, generating a transient electromagnetic field with the transmitter, obtaining a total signal from signals received by the first receiver and the second receiver, performing a bucking calculation to obtain a pipe signal, applying a correction scheme to the total signal to generate a corrected formation property signal, wherein the correction scheme is V corr = V meas - P ∗ V meas , wherein Vcorr is a correction signal, Vmeas is the total signal, and P is the pipe signal, estimating a formation property from corrected formation property signal to select a model of the formation, and adjusting a drilling operation based on the estimated property of the formation.