Ultrasonic Measurement Method Of Fluid Distribution In Core Flooding Experiment

Real-time monitoring the dynamic fluid distribution in the core is one of the key issues about experiment research with the physical simulation equipment of high temperature and high pressure.A non-intrusive ultrasonic transmission method to monitor the fluid distribution is proposed in this paper,which uses the change of ultrasonic velocity and amplitude attenuation to infer the 2D dynamic distribution of fluid in the core at different moments.An ultrasonic field test platform was designed to monitor fluid distribution in the sandstone core.The platform is made up of PXI modular hardware platform and Lab VIEW graphical software development platform with NI virtual instrument technology.The wave data analysis software and the dynamic field pattern software for processing experimental data were designed,therefore the automation of experimental process and data analysis is achieved.The three kinds of displacement experiments(water injection,water-oil displacement and gas-oil displacement)were performed with the platform,in which twelve probes were used to test distribution of fluid by ultrasonic transmission during the displacement experiment.With the arithmetic combining thresholding method and curve fitting method,the arrival time and amplitude of the first wave were calculated from the filtered wave data,which were closely related to velocity and amplitude attenuation of ultrasonic transmission.The displacement front can be found to have arrived in terms of discontinuity point of ultrasonic wave velocity,and the velocity can reflect the change of fluid fractions.The displacement front can also be found to have arrived in terms of discontinuity point of ultrasonic wave amplitude.And the wave amplitude can also reflect the change of fluid fractions.In this paper,the changes of arrival time caused by displacement can map fluid fractions,and then the fluid distribution in the core can be obtained by combining the fluid fractions with the distribution of probes.The displacement experiments indicate that the ultrasonic field test platform can run well and satisfy the needs of these experiments.By data analysis,some conclusions can be reached.The ultrasonic velocity changes can reflect the displacement front and map the fluid distribution,and the ultrasonic amplitude changes can also reflect the displacement front.In a word,the ultrasonic transmission method is an effective non-intrusive method to monitor the dynamic fluid distribution in the core.