Downhole NMR Permeability Anisotropy Measurement

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Solution Overview

Problem

Current methods for evaluating permeability anisotropy in hydrocarbon-carrying geological formations are time-consuming and limited to laboratory investigations, making real-time in-situ assessment during drilling challenging, especially in layered or fractured reservoirs where permeability anisotropy is crucial for production and stimulation planning.

Innovation Solution

An NMR-based method for measuring restricted diffusion coefficients under downhole conditions, utilizing gradient fields to produce well-defined voxels and interpret spin-echo data, which allows for the spatial distribution of tortuosity and porosity assessment, combined with resistivity and acoustic logging to predict anisotropic tortuosity and porosity, and a regression model that integrates high-throughput logging information to estimate permeability and optimize drilling operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If 3D imaging of rock cores or extraction of cores from two different directions is used to evaluate permeability anisotropy, then measurement precision is improved, but loss of time and productivity deteriorate

Engineering Contradiction:

Improvepermeability anisotropy evaluation accuracyVSAvoidtime consumption for core extraction and laboratory investigation

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces mechanical core extraction and laboratory-based 3D imaging with an NMR-based measurement system that operates downhole during drilling. The NMR tool measures diffusion coefficients in situ, eliminating the need for physical core samples and laboratory analysis while maintaining measurement accuracy for permeability anisotropy evaluation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces NMR diffusion coefficient measurements as an intermediary parameter to indirectly determine permeability anisotropy. By measuring the diffusion of fluid molecules in the formation under different magnetic field gradient orientations, the system derives permeability information without direct mechanical sampling, thus saving time while preserving measurement precision

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If NMR diffusion measurements are performed with magnetic gradients in different directions to evaluate permeability anisotropy, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvepermeability anisotropy detection accuracyVSAvoidNMR tool configuration with multi-directional gradient fields

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the permeability measurement into three independent directional components (vertical and two horizontal orthogonal directions). By measuring diffusion coefficients separately along each principal axis using magnetic field gradients oriented in those directions, the complex task of characterizing anisotropic permeability is divided into simpler, manageable measurements that can be processed independently and then combined

Inventive Principle:

Principle #1Segmentation

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

Enables rapid and accurate assessment of permeability anisotropy in real-time, improving hydrocarbon production by aligning perforations with maximum permeability zones and optimizing fracturing processes, thereby enhancing productivity and reducing ecological risks.

Implementation Method 1

nuclear magnetic resonance (NMR)

Methodology Applied

Scientific EffectNuclear magnetic resonance: Magnetic Field

Implementation Method 2

measuring diffusion coefficients using nuclear magnetic resonance (NMR) equipment can be utilized to estimate the diffusion tortuosity

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

Since a magnetic gradient can be applied in different directions, the anisotropy of diffusion tortuosity and thus permeability can be evaluated

Methodology Applied

Scientific EffectMagnetic gradient: Magnetic Field

Implementation Method 4

utilizing gradient fields to produce well-defined voxels and interpret spin-echo data

Methodology Applied

Scientific EffectSpin echo: Echo

Data Source

PatentUS11555795B2Method for downhole determination of permeability anisotropy using NMR

Publication Date: 2023.01.17 KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS

AI summary

A method for predicting formation permeability by measuring diffusional tortuosity in several directions by pulse gradient NMR. The method comprises evaluating an anisotropic diffusion coefficient by pulsed gradient NMR, determining diffusional tortuosity from the restricted diffusion data, supplementing the NMR results with resistivity and sonic logging data, measuring anisotropic tortuosity and porosity by resistivity and sonic data and combining all components in a single fitting model. The 11-coefficient model is trained to recognize the true values of permeability by comparing the real oil permeabilities measured. in a library of oil-carrying rock cores with the NMR, resistivity and sonic correlates The fitting coefficients are extracted by minimizing the discrepancy between the laboratory measured permeabilities and the predicted values combining all rapid logging information components with the agreement-maximizing weights.