Device and method for analyzing mechanical properties of hydrate sediments based on low-field nuclear magnetism

Abstract

The invention provides a device for analyzing mechanical properties of hydrate sediments based on low-field nuclear magnetism. The device comprises a miniature reaction kettle body mounted on a low-field nuclear magnetic resonance analyzer, a confining pressure cavity positioned in the reaction kettle body, a radio frequency coil arranged on the outer side of the reaction kettle body, a reaction kettle upper end cover, a reaction kettle lower end cover, a hole pressure control module, a confining pressure control module, an axial pressure loading plunger, an axial pressure loading reaction frame and an axial loading control module. The invention discloses an experimental device based on combination of low-field nuclear magnetic resonance detection and three-axis shearing and a corresponding testing method. According to the method and the device, macro-mechanical data of a hydrate reservoir are obtained on a low-field nuclear magnetic resonance platform, meanwhile, micro-pore structureevolution characteristics of the hydrate reservoir in the loading process are obtained, and technical support is provided for cross-scale research of the mechanical property and the deformation mechanism of the natural gas hydrate reservoir.

Description

technical field [0001] The invention relates to the field of basic physical property evaluation of natural gas hydrate reservoirs, in particular to a device and method for analyzing the mechanical properties of hydrate-containing sediments based on the combination of low-field nuclear magnetic resonance (LF-NMR) and triaxial experiments. Background technique [0002] The dynamic response characteristics of reservoir mechanical parameters during hydrate production are crucial to the safety evaluation of hydrate test production. Artificially synthesizing hydrate-containing samples in the laboratory and performing core-scale mechanical test analysis are the main means to obtain the mechanical properties of hydrate-bearing reservoirs. However, large-scale tests can only obtain macroscopic mechanical parameters, and cannot describe the mesoscopic failure process of hydrate-containing sediments. Therefore, it is an important trend of current development to combine macroscopic mec...

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Problems solved by technology

[0007] Aiming at the inability to evaluate the change of the smaller-scale microscopic damage process during the sediment loading process in the prior art, the present invention proposes a device for analyzing the mechanical properties of hydrate sediments based on low-field NMR, including: The micro-reactor body installed on the low-field nuclear magnetic resonance analyzer, the confining pressure chamber located in the reactor body, the radio frequency coil arranged outside the reactor body, the upper end cover of the reactor, the lower end cover of the reactor, and the pore pressure control module and The confining pressure control module also includes: an axial pressure loading plunger, an axial pressure loading reaction frame and an axial loading control module; the upper end cover of the reactor is the same as the outer diameter of the reactor body, and the upper end cover of the reactor is provided with a pore pressure fluid outlet and the confining pressure fluid outlet, the lower end cover of the reactor is provided with a confining pressure fluid inlet; the axial pressure loading plunger is installed through the lower end cover of the reactor, and its center is provided with a hole pressure fluid inlet, and its lower part is provided with a diameter larger than the axial pressure loading plunger. The disc of the plunger, the axial pressure loading reaction frame is set on the lower part of the axial pressure loading plunger, the disc divides the inner cavity of the axial pressure loading reaction frame into two, and the axial pressure loading reaction frame is set The axial pressure loading fluid inlet and the axial pressure unloading fluid inlet; the end of the axial pressure loading reaction frame is provided with a displacement sensor bracket, and the displacement sensor is in contact with the axial pressure loading piston to dynamically monitor the displacement of the axial pressure loading piston; the axial loading Control module to control loading and unloading of axial pressure

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