Hydrate sediment CT triaxial testing device

Abstract

The invention provides a hydrate sediment CT triaxial testing device, and belongs to the technical field of geotechnical engineering foundation physical property measurement. Aiming at the deficiencyof the invention of a visualization testing device for natural gas hydrate sediment mechanical properties, the hydrate sediment CT triaxial testing device is subjected to redesigning and optimization,under the premise that the hydrate reservoir static force, the dynamic properties and the creep property can be obtained, the stability in the scanning rotating process of a triaxial apparatus, the hydrate sample temperature control accuracy and the penetrating property of X-rays of a triaxial apparatus pressure chamber are improved, the optimal CT imaging effect is obtained, and powerful hardware support is provided for the verification of the reservoir deformation mechanism in the decomposition process of a hydrate.

Description

technical field [0001] The invention relates to a CT triaxial test device for hydrate deposits, which belongs to the field of geotechnical engineering basic physical property measurement. Background technique [0002] Hydrate deposits are a metastable structure with complex mechanical behavior characteristics. The mining process often involves microstructural changes such as hydrate phase transition, particle migration, and cement structure destruction. Mechanism analysis to clarify the formation mechanism of geological disasters such as stratum subsidence and submarine landslides induced by natural gas hydrate decomposition. [0003] The triaxial instrument is a commonly used geotechnical testing instrument for simulating the stress state of the formation. However, the existing natural gas hydrate triaxial instrument, due to the need to meet the conditions of low temperature and high pressure, generally has a large volume and weight, and also has problems such as poor X-ra...

AI Technical Summary

Problems solved by technology

However, the existing natural gas hydrate triaxial instrument, due to the need to meet the conditions of low temperature and high pressure, generally has a large volume and weight, and also has problems such as poor X-ray penetration performance and inconvenient rotation scanning, so it cannot be realized with X-ray CT. The organic combination of visualization devices such as the inspeXioSMX-255CT stage has a weight limit of 9kg, and the sample height is ≤30cm, so it is impossible to observe the microstructural changes during the deformation process of hydrate deposits

Therefore, in 2014, Dalian University of Technology first innovatively proposed a visualization test device for the mechanical properties of gas hydrate deposits, realizing the organic combination of gas hydrate triaxial instrument and X-ray CT 201410357319.X, but the device There are some problems in the actual use process: 1. Since the loading device is on the upper part of the triaxial instrument main body, the center of gravity of the triaxial instrument is too high. Therefore, during the X-ray scanning rotation process, the triaxial instrument main unit is not stable enough, which easily leads to the obtained CT image ghosting; 2. The low-density materials such as pure aluminum or aluminum alloy used in the pressure chamber of the device have good thermal conductivity and are easy to cause heat loss. If the temperature of the sample is controlled by injecting pre-cooled hydraulic oil, when the test time For a long time, the temperature of the hydraulic oil is greatly affected by the environment, which may cause hydrate decomposition and ultimately affect the accuracy of the test data; 3. The pressure chamber of the device adopts an integrated design, which does not fully consider the characteristics and functions of the structural design of each part. If the upper part of the pressure chamber is made of high-strength, low-density aluminum alloy, and the wall of the pressure chamber is made of engineering plastics with better penetration properties, better CT imaging results can be obtained

Images