EM Telemetry Signal Modeling in Deviated Wells
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Solution Overview
Problem
Current 3D electromagnetic (EM) telemetry modeling faces challenges in predicting EM signals due to complex resistivity distributions and geometric deviations in drilling wells, particularly with the use of deep electrodes and conductive formations, which complicates signal decoding and accuracy.
Innovation Solution
The method involves straightening and dividing the well into segments, replacing it with equivalent electrical sources, and then bending it back to its original shape to estimate EM telemetry signals by summing EM fields, using computational models and codes like CWNLAT for accurate signal prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 3D EM telemetry modeling is performed with complex resistivity distributions and deviated well geometries, then signal prediction accuracy is improved, but computational complexity increases
Solution Approach 1:
The well is divided into multiple segments along its length, with each segment treated as an independent electrical current source. This segmentation allows the complex 3D EM field to be computed as a superposition of simpler fields from individual segments, reducing overall computational complexity while maintaining accuracy in representing the deviated geometry and resistivity variations.
Solution Approach 2:
The patent creates equivalent electrical current sources that replicate the EM field generation characteristics of the actual well configuration. These equivalent sources are positioned and oriented to copy the field distribution patterns, allowing simplified computation of the EM telemetry signal without directly modeling the complex physical geometry and resistivity distribution.
2Difficulty of detecting and measuring
If deep electrodes are used to detect EM signals in conductive formations, then signal detection capability is improved, but difficulty in decoding increases
Solution Approach 1:
The patent introduces equivalent electrical current sources as intermediaries between the EM signal generation and detection processes. These equivalent sources serve as a computational mediator that translates the complex interaction between the well geometry, resistivity distribution, and EM fields into a simplified model that can be easily decoded and interpreted, reducing the difficulty of signal analysis while maintaining detection capability.
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 simplifies 3D EM telemetry modeling, improves signal prediction accuracy, and reduces computational complexity by using equivalent electrical sources to simulate and estimate EM signals effectively, even in complex well geometries and resistivity distributions.
Implementation Method 1
determining an electrical current in one or more of the segments when the well is straightened. The method also includes replacing the well with equivalent electrical sources based at least partially upon the electrical current in one or more of the segments
Implementation Method 2
summing EM fields for each of the one or more segments, based at least partially upon the electrical current in the one or more segments when the well is back in its original shape, to estimate the EM telemetry signal
Data Source
AI summary
A method for modeling an electromagnetic (EM) telemetry signal includes straightening a well in a model and dividing the well into a plurality of segments. The method also includes determining an electrical current in one or more of the segments when the well is straightened. The method also includes replacing the well with equivalent electrical sources based at least partially upon the electrical current in one or more of the segments. The method also includes bending the well back into its original shape in the model and determining the electrical current in one or more of the segments by projection when the well is back in its original shape. The method also includes summing EM fields for each of the one or more segments to estimate the EM telemetry signal.