Pipe Thickness Inversion via Fast Forward Model
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Solution Overview
Problem
Monitoring corrosion in multiple concentric metal pipes used in oil and gas exploration is complex due to non-linear signal combinations, making it difficult to accurately determine metal loss or gain using existing electromagnetic logging tools.
Innovation Solution
The method involves using an electromagnetic logging tool with a transmitter and receiver coil configuration, employing inversion techniques and a pre-computed table of responses based on higher-order non-mixed derivatives to accurately estimate pipe properties like thickness and metal loss in multiple nested pipes, accounting for non-linear variations and cross-couplings between pipe properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If electromagnetic logging tools are used to monitor corrosion in multiple concentric pipes, then corrosion detection capability is improved, but measurement precision deteriorates due to non-linear signal combinations making it difficult to accurately determine metal loss
Solution Approach 1:
The patent segments the complex multi-pipe corrosion detection problem into individual pipe assessments by using a segmented inversion approach. The system separately evaluates each pipe's contribution to the electromagnetic signals by iteratively solving for individual pipe properties (thickness, conductivity, permeability) while holding other pipes' properties fixed, thereby resolving the non-linear signal combination issue and improving measurement precision for each individual pipe.
Solution Approach 2:
The patent applies preliminary action by using a forward model to predict electromagnetic signals based on assumed pipe properties before performing the inversion. This preliminary forward modeling step establishes a baseline that guides the iterative inversion process, allowing the system to systematically refine its estimates of pipe thickness and other properties to achieve accurate corrosion measurement.
2Reliability
If traditional inversion techniques are used to estimate pipe properties, then corrosion monitoring is achieved, but productivity deteriorates due to high computational cost
Solution Approach 1:
The patent performs preliminary action by pre-computing the forward model responses for a range of possible pipe properties and storing them in lookup tables. During the actual inversion process, the system retrieves pre-computed values rather than performing full forward model calculations, dramatically reducing computational cost while maintaining inversion accuracy for corrosion monitoring.
Solution Approach 2:
The patent uses copying by creating simplified representations of the complex forward model through pre-computed lookup tables. These tables contain copied and stored responses that approximate the full forward model behavior, allowing the inversion algorithm to operate with reduced computational complexity while preserving the essential physics of electromagnetic pipe inspection.
3Productivity
If simple forward models are used to reduce computational cost, then productivity is improved, but measurement precision deteriorates due to inability to capture non-linear variations and cross-couplings
Solution Approach 1:
The patent segments the complex non-linear forward model into a series of simpler, locally-linear models through the iterative inversion process. By dividing the inversion into multiple steps where each step uses a linearized forward model with fixed parameters for other pipes, the system captures non-linear variations and cross-couplings through the sequence of linear approximations, maintaining measurement precision while improving computational efficiency.
Solution Approach 2:
The patent applies dynamics by making the forward model adaptive through iteration. The forward model is repeatedly executed with updated pipe properties at each inversion step, allowing the system to dynamically adjust to non-linear variations and cross-couplings between pipes. This dynamic approach maintains accuracy while the use of pre-computed tables keeps each iteration computationally efficient.
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 accurate and efficient estimation of pipe features, such as corrosion and collar locations, improving the accuracy of corrosion detection and reducing the computational cost by using a fast forward model that captures non-linear variations and cross-couplings, allowing for targeted well operations.
Implementation Method 1
transmitting an electromagnetic field from the transmitter into the pipe string; energizing the pipe string with the electromagnetic field to produce an eddy current in the pipe string
Implementation Method 2
measuring the electromagnetic field with the transmitter acting as the receiver
Data Source
AI summary
A method and a system for estimating a pipe property for a plurality of nested pipes. The method may comprise determining the pipe property from the plurality of measurements, wherein the pipe property identifies a feature in the wellbore, forming a pre-computed table of responses for the at least one channel comprising a plurality of points that sample the pipe property, and performing a model-based inversion to estimate the pipe property using the plurality of measurements, the nominal properties of the pipes, and a fast forward model based on the pre-computed table of responses. A system may comprise an electromagnetic logging tool and an information handling system. The electromagnetic logging tool may comprise a transmitter, wherein the transmitter is a first coil and is operable to transmit an electromagnetic field, and a receiver, wherein the receiver and is operable to measure the electromagnetic field.