Jilin University

Chen Chen

Youhong Sun

Wei Guo

Jun Xue

Zupei Zhang

Jianguo Zhao

Valery Konstantinovich Chistyakov

Xitong Li

Jiangpeng Zhao

Dongbin Pan

Huiwen Xu

Han Zhang

Qinghua Wang

Chengcai Jin

Lianghao Zhai

Guosheng Li

Ying Zhang

Jiang Zhu

Ying Zhu

Rui Jia

The present invention discloses a pressurized test device and method for in-situ mining natural gas hydrates by jets, relating to the field of exploitation of marine natural gas hydrates. The device comprises an injection system, a jet breakup system, an annular pressure system, an axial pressure system, a backpressure system, a vacuum system, a simulation system, a collecting and processing system and a metering system, all of which can operate independently by controlling pipe valves on pipelines. The loading of the confining pressure of the device is independent of the loading of the axial pressure, without interference to each other. Meanwhile, the jet breakup process of natural gas hydrate-containing sediments can be observed in real time by a video camera.

Pressurized test device and method for in-situ mining natural gas hydrates by jets

A forced cooling circulation system for drilling mud, which includes a refrigeration unit (), a secondary refrigerant tank (), a coaxial convection heat exchanger () for mud and a mud pond (), is disclosed. The refrigeration unit () is in connection with the secondary refrigerant tank () and the coaxial convection heat exchanger () for mud via a pump (), and the coaxial convection heat exchanger () for mud is in connection with the mud pond () via a pump () and pipelines. Heat exchange tubes of the coaxial convection heat exchanger () for mud are disposed as a double-layer structure or a multi-layer structure, and the inner heat exchange tubes () are mounted inside of the outer heat exchange tubes (). The secondary refrigerant or the mud is circulated in the annular space between the inner heat exchange tubes () and the outer heat exchange tubes (), and the mud or the secondary refrigerant is circulated in the inner tubes (). The flow of the circulated mud is opposite to that of the circulated secondary refrigerant, and insulation material () is painted on the external wall of the outer tubes ().

Forced cooling circulation system for drilling mud

The present invention relates to a sampler for gas hydrates by hole bottom freezing, the sampler comprises a fisher, a wire-line coring mechanism and an outer barrel, and it further comprises a refrigeration portion, a low temperature control portion and a frozen insulation sample portion, which constitute an inner barrel assembly located inside the outer barrel together, wherein a refrigerant in the refrigeration portion is injected into the frozen insulation sample portion under a control of the low temperature control portion, so that a cooling medium in the frozen insulation sample portion is always kept under a predetermined temperature, and a core sample of gas hydrates is frozen at the bottom of a drill hole. The invention also relates to a sampling method using the sampler as mentioned above. In the invention, the temperature of the sample can be decreased by using an external cooling source to suppress hydrate decomposition, the critical decomposition pressure of gas hydrates can be reduced by active decreasing the temperature of the sample, and the stability of gas hydrates is maintained by a passive pressure drop. The method of the present invention need not to keep the pressure of the sample, and is simple to obtain a core sample of gas hydrates with higher fidelity.

Sampling method and sampler for gas hydrates by hole bottom freezing

Growing community of inventors

Changchun, China

Chen Chen