Shale Movable Throat Radius Limit Determination
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Solution Overview
Problem
Current methods, such as low-temperature nitrogen adsorption and high-pressure mercury injection, are inadequate for accurately determining the lower radius limit of the movable throat in shale reservoirs due to limitations in analyzing macropores and characterizing micropores and mesopores, respectively.
Innovation Solution
A combined method using low-temperature nitrogen adsorption, high-pressure mercury injection, and nuclear magnetic resonance tests to obtain pore radii data, followed by normalization and curve analysis to determine the lower radius limit of the movable throat, considering cumulative distribution frequency and movable oil saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low-temperature nitrogen adsorption method is used, then micropores and mesopores can be analyzed in detail, but macropores cannot be effectively characterized
Solution Approach 1:
The patent combines three different testing methods (low-temperature nitrogen adsorption, high-pressure mercury injection, and nuclear magnetic resonance) into a unified testing system. Each method covers different pore radius ranges, and by merging their results through curve connection at specified boundaries (100nm and 50nm), the system achieves comprehensive characterization from micropores to macropores, resolving the limitation of individual methods
2Adaptability or versatility
If high-pressure mercury injection method is used, then macropores can be analyzed effectively, but micropores and mesopores characterization is insufficient
Solution Approach 1:
The patent integrates high-pressure mercury injection results with low-temperature nitrogen adsorption and nuclear magnetic resonance methods. The mercury injection data for macropores is merged with nitrogen adsorption data for micropores/mesopores through curve connection at the 100nm boundary, ensuring both macropore and micropore characterization capabilities are preserved in the unified system
3Adaptability or versatility
If nuclear magnetic resonance method is used, then pore radius range coverage is extensive from micropores to microcracks, but micropores and mesopores characterization is deficient
Solution Approach 1:
The patent combines nuclear magnetic resonance results with low-temperature nitrogen adsorption and high-pressure mercury injection methods. The NMR data covering the extensive pore radius range is merged with the more precise nitrogen adsorption data for micropores and mesopores through curve connection at the 50nm boundary, achieving both wide coverage and high precision in the unified characterization system
Solution Approach 2:
The patent uses curve connection boundaries (100nm and 50nm) as intermediaries to bridge different testing methods. These boundary points serve as transition zones where results from different methods are connected, allowing seamless integration of NMR's wide coverage with nitrogen adsorption's high precision for micropores and mesopores
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 provides a more accurate and precise evaluation of shale oil mobility by characterizing the complex pore structure from microspores to microcracks, addressing the heterogeneity of shale reservoirs and improving the determination of the lower radius limit of the movable throat.
Implementation Method 1
The low-temperature nitrogen adsorption method has advantages in analyzing micropores and mesopores of mud shale
Implementation Method 2
The high-pressure mercury injection method is relatively less affected by uneven distribution of the pore radii of the mud shale
Implementation Method 3
a text range of a nuclear magnetic resonance (NMR) method is most extensive, and can be applied from the micropores to the microcracks
Data Source
AI summary
A method for determining lower radius limit of movable throat of shale is provided, and it includes: performing a low-temperature nitrogen adsorption test on a target shale to obtain first pore radii; performing a high-pressure mercury injection test on the target shale to obtain second pore radii; performing a nuclear magnetic resonance test on the target shale to obtain third pore radii; obtaining a relationship diagram of distribution frequencies and pore radii according to three pore radii; distinguishing, according to the pore radii, relationship diagram data, and performing normalization processing to determining a relationship curve of normalized frequency data and the pore radii; and determining a lower radius limit of movable throat of shale according to relationship curve. A problem of describing characteristics of shale occurrence space with complex pore structures and strong heterogeneity is solved, the method is suitable for determining lower radius limit of movable throat of shale.