A method for in-situ observation of liquid nitrogen frozen rock microstructure
A microstructure and liquid nitrogen freezing technology, applied in measuring devices, instruments, scientific instruments, etc., can solve the problems of water-sensitive water lock reaction, high crack initiation pressure, low rock breaking efficiency of hot dry rock reservoirs, etc., and achieve image High resolution, simple sample preparation, and adjustable magnification
Active Publication Date: 2020-11-27
CHINA UNIV OF PETROLEUM (BEIJING)
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Problems solved by technology
However, the water-based working fluid-based drilling technology commonly used in the field of petroleum engineering has the following problems: low rock-breaking efficiency and high crack initiation pressure in hot dry rock reservoirs; unconventional natural gas reservoirs are prone to water-sensitive water-locking reactions
In other words, due to the different types of samples and research purposes, the selected sublimation temperature and time, electron microscope cold stage temperature, and observation voltage are also different, and the selection of the above parameters will directly affect the imaging effect. The microstructure has a big impact
Method used
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Embodiment 1
[0047] The liquid nitrogen frozen rock microstructure in-situ observation method of the present invention, such as figure 1 As shown, the following steps are included: (1) put the sliced polished coal into the digital display heating mantle, and heat it to 50°C; (2) take it out after the rock sample is heated evenly, soak it in liquid nitrogen until the internal temperature field Reach stability; (3) Take the rock sample out of liquid nitrogen and fix it on the loading disk with conductive glue; (4) Carry out vacuum treatment, sublimation treatment and coating treatment in sequence; (5) Send the sample into the cryo-electron microscope observe.
[0048] The size of the sliced and polished rock sample is 6mm×6mm×1.5mm. Four rock samples of this size can be placed on the cryo-electron microscope loading disk for observation at a time. After one sample is observed, the next one can be observed by moving the lens position, which can save sample preparation. time.
[0049] Ar...
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The invention provides a liquid nitrogen frozen rock microstructure in-situ observation method. The method comprises steps of (1) heating a polished rock sample so that the rock sample is uniformly heated; (2) fixing the uniformly heated rock sample on a sample holder; (3) soaking the rock sample in liquid nitrogen till an internal temperature field of the rock is stable; (4) sequentially carryingout vacuumizing treatment, sublimation treatment and coating treatment of the rock sample; and (5) observing the rock sample subjected to film coating treatment by using a freezing electron microscope. The method is advantaged in that the microstructure of the liquid nitrogen frozen rock can be observed in situ in an ultralow temperature environment (-185 DEG C), the temperature of the rock sample in the observation process is consistent with the actual situation of a liquid nitrogen fracturing site, and the observed thermal stress micro-crack size and other microstructures better conform tothe actual situation of the liquid nitrogen fracturing site.
Description
technical field [0001] The invention relates to the fields of petroleum and geothermal heat, in particular, the invention relates to an in-situ observation method for liquid nitrogen frozen rock microstructure. Background technique [0002] In 2018, China's dependence on foreign oil and natural gas rose to 69.8%, and its dependence on natural gas rose to 45.3%. It is expected that in 2019, China's dependence on foreign oil and gas will continue to rise. Vigorously developing geothermal resources and unconventional natural gas resources is the key to reducing dependence . However, the water-based working fluid-based drilling technology commonly used in the field of petroleum engineering has the following problems: low rock-breaking efficiency and high fracture initiation pressure in hot dry rock reservoirs; unconventional natural gas reservoirs are prone to water-sensitive water-locking reactions. [0003] The use of liquid nitrogen as a new working fluid has the advantages ...
Claims
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Patent Timeline
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IPC IPC(8): G01N23/2202G01N23/2252G01N23/2206G01N23/20058G01N23/203G01N23/2005
CPCG01N23/2005G01N23/20058G01N23/203G01N23/2202G01N23/2206G01N23/2252G01N2223/053G01N2223/0565G01N2223/071G01N2223/079G01N2223/102G01N2223/616
Inventor 杨睿月黄中伟李根生洪纯阳温海涛丛日超张逸群李敬彬
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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