Resistivity Lookup Table Segmentation for Faster Well Logging
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Solution Overview
Problem
Logging tools face significant memory and processing challenges due to the computational demands of resistivity lookup and Lagrange interpolation, which are essential for determining wellbore and formation properties using electromagnetic waves.
Innovation Solution
Implementing a segmented lookup table with polynomial coefficients for resistivity calculations, reducing the need for interpolation and minimizing memory and processing requirements by segmenting data into groups that can be represented by low-order polynomials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistivity lookup and Lagrange interpolation are used to determine wellbore and formation properties, then measurement precision is improved, but device complexity and processing requirements increase
Solution Approach 1:
The resistivity lookup table is divided into multiple segments, each representing a specific resistivity range. Instead of performing complex Lagrange interpolation across the entire table, the system identifies the appropriate segment and applies simplified interpolation within that segment, reducing computational complexity while maintaining measurement precision.
2Measurement precision
If resistivity lookup and Lagrange interpolation are used to determine wellbore and formation properties, then measurement precision is improved, but memory consumption increases
Solution Approach 1:
The lookup table is segmented into multiple smaller tables, each covering a specific resistivity range. This segmentation allows the system to load only the necessary segment into memory during operation, significantly reducing memory consumption while preserving the accuracy benefits of having a comprehensive lookup table.
Solution Approach 2:
Instead of loading and processing the entire lookup table in memory, the system loads only the partial segment that is currently needed for the measurement. This partial action approach reduces memory requirements while maintaining the precision that would be achieved with the full table.
3Measurement precision
If resistivity lookup and Lagrange interpolation are used to determine wellbore and formation properties, then measurement precision is improved, but processing time increases
Solution Approach 1:
By segmenting the lookup table and identifying the appropriate segment first, the system limits subsequent interpolation operations to a smaller data range. This segmentation strategy reduces the number of calculations required for Lagrange interpolation, thereby decreasing processing time while maintaining measurement 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 significantly reduces computational resources needed for resistivity calculations, improving processing speed and memory efficiency by up to 79.16% and memory usage by 70%, respectively, while maintaining accuracy.
Implementation Method 1
A resistivity tool may transmit electromagnetic waves through a formation which may be received by a receiver
Data Source
AI summary
A method for well logging may comprise: inserting a downhole tool into a wellbore penetrating a subterranean formation wherein the downhole tool comprises: a transmitter; a receiver; a memory configured to store at least one look up table with polynomial coefficients; and a processor coupled to the memory; obtaining a measurement using the resistivity tool; and generating a resistivity output using the measurement as an input to a polynomial with polynomial coefficients sourced from the look up table.