Method for measuring convective mixing process velocity field in porous medium based on nuclear magnetic resonance imaging

Abstract

The invention relates to a method for measuring a convective mixing process velocity field in a porous medium based on nuclear magnetic resonance imaging, and the method belongs to the technical field of convective mixing process velocity field measurement. The method comprises the steps of carrying out upper-lower layered saturation on two kinds of solutions with different densities in the porous medium at first, placing a sand-filled pipe saturating the two kinds of solutions with different densities in an inverted manner and then placing the sand-filled pipe into a nuclear magnetic probe quickly, adopting a spin echo sequence method added with phase encoding gradient pulses to obtain a proton density image of a fluid and converting the proton density image into a phase image, making difference between the phase image and a stationary state phase image under the same pulsed gradient to obtain a phase shifting image, and measuring to obtain a porous medium convective mixing process velocity field by adopting a phase method. The method realizes the unconventional fluid distribution situation required by convective mixing, is applied to the nuclear magnetic resonance imaging technology, carries out visual observation on the convective mixing process velocity field by non-contact and non-interference means, and does not disturb flow of the fluid.

Description

technical field [0001] The invention belongs to the technical field of velocity field measurement of a convective mixing process, and relates to a method for measuring the velocity field of a convective mixing process in a porous medium based on nuclear magnetic resonance imaging. Background technique [0002] The dynamic evolution process of fluid interface is an important aspect of fluid dynamics research. The study of fluid phase interface stability plays a key role in both basic scientific research and industrial production processes. We focus on the fact that in the gravitational field, because the density of the upper fluid is higher than that of the lower fluid, the high-density fluid in the upper layer at the two-phase fluid interface migrates downward under the action of gravity, while the lower-density fluid at the interface moves upward, resulting in a convection process in the vertical direction , this phenomenon is called "convective mixing". The convective mi...

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Problems solved by technology

[0005] The present invention provides a method for measuring the velocity field of the convective mixing process in porous media based on nuclear magnetic resonance imaging in order to solve the problem in the prior art that it is difficult to measure the velocity field during the convective mixing process in the porous medium

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