Synthetic T1-T2 Map Generation from NMR Marginal Distributions
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Solution Overview
Problem
Current well logging methods for generating T1-T2 maps are time-consuming and costly, requiring extensive data processing and specific acquisitions, while acquiring only marginal distributions of T1 and T2 cannot generate these maps directly, limiting the evaluation of reservoir properties such as porosity and hydrocarbon saturation.
Innovation Solution
A method to generate synthetic T1-T2 maps from marginal distributions of T1 and T2 relaxation times using log-normal functions, decomposing these distributions into two-dimensional functions with set amplitudes, means, and standard deviations to reconstruct the maps efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used to acquire T1-T2 maps through extensive data processing and specific acquisitions, then measurement precision is improved, but loss of time and productivity deteriorate
Solution Approach 1:
The patent creates a synthetic T1-T2 map as a copy or representation of the actual T1-T2 map by using log-normal function decomposition and reconstruction. Instead of acquiring the full T1-T2 map through time-consuming measurements, the method generates a synthetic version that preserves the essential fluid typification and quantification information, achieving comparable results with significantly reduced acquisition time
Solution Approach 2:
The method extracts only the essential information needed for fluid evaluation by acquiring separate marginal distributions of T1 and T2 relaxation times rather than the complete joint distribution. This extraction approach captures the necessary characteristics for fluid identification while eliminating redundant data acquisition, reducing measurement time while maintaining measurement precision for the intended application
2Measurement precision
If traditional methods are used to acquire T1-T2 maps, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The synthetic T1-T2 map serves as an efficient copy that enables rapid formation evaluation without requiring the full measurement protocol. The copied structure preserves fluid typification capabilities while dramatically improving productivity by avoiding extensive data acquisition and processing
Solution Approach 2:
The method segments the T1-T2 map acquisition into separate marginal distribution measurements for T1 and T2 relaxation times. This segmentation allows independent, faster measurements that can be processed separately and reconstructed, improving overall evaluation efficiency while maintaining the precision needed for fluid characterization
3Loss of time
If only marginal distributions of T1 and T2 are acquired, then loss of time is reduced, but loss of information occurs
Solution Approach 1:
Log-normal functions serve as intermediaries that bridge the gap between separate marginal distributions and the joint T1-T2 distribution. By decomposing the marginal distributions into log-normal components and reconstructing the joint distribution through these intermediary functions, the method recovers the essential joint distribution information without requiring direct measurement of the full T1-T2 space
Solution Approach 2:
The method transforms the problem from directly measuring the joint T1-T2 distribution to measuring and transforming marginal distributions using log-normal parameter decomposition. By changing the mathematical representation from joint probability to product of marginal log-normal distributions, the method recovers information about fluid typification while reducing acquisition 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 allows for faster and cost-effective evaluation of geological formations by generating accurate synthetic T1-T2 maps, enabling the typification and quantification of fluids without the need for extensive data acquisition, thus reducing operational costs and time.
Implementation Method 1
nuclear magnetic resonance (NMR) tools. In general terms, an NMR tool measures the response of the spins of atomic nuclei present in fluids when subjected to magnetic fields. The atomic nucleus of the fluid exhibits a precession movement around the axis defined by the applied magnetic field, generating a measurable effect.
Implementation Method 2
During measurements, a constant magnetic field (B0) causes the protons in the hydrogen nuclei to precess, aligning themselves parallel to the direction of that field. Thus, a transmitting antenna generates a second magnetic field (B1) oscillating by radio frequency, perpendicular to the constant magnetic field B0
Implementation Method 3
As soon as the oscillating magnetic field B1 is turned off, the nuclei begin to return to the orientation defined by the constant magnetic field B0 and the intensity of the acquired signal decays exponentially. The characteristic times of the process of hydrogen nuclei returning to their original orientation, after turning off the field B1, are known as formation relaxation times, called T1 (longitudinal magnetization recovery time) and T2 (transversal magnetization decay time).
Data Source
AI summary
The present invention falls within the area of well logging to evaluate formations in oil and gas producing fields. Particularly, the present invention describes a method for generating synthetic T1-T2 maps from marginal distributions of nuclear magnetic resonance logging tools, wherein the method comprises: decomposing marginal distributions of T1 and T2 relaxation times into an initial sum of log-normal functions with the same amplitudes and different means and standard deviations; setting the initial amplitudes, means and standard deviations so that the sum of log-normal functions corresponds to the marginal distributions of T1 and T2; and using the amplitudes, means and standard deviations set in a sum of two-dimensional log-normal functions to generate a synthetic T1-T2 map.