Experimental Study Of Attenuation On Rocks With Different Fluids

When seismic waves propagate,energy gradually decays as distance increases.It is very important for geophysical analysis to quantitatively characterize the attenuation.Because natural seismic waves are very complicated and the collection is relatively cumbersome,similar simulations are often performed in the laboratory using ultrasonic wave signals.The ultrasonic test has the characteristics of simple operation and easy analysis,and has universal application in rock physics.In this paper,based on the laboratory ultrasonic transmission method,aluminum,lucite,artificial sandstone and natural sandstone were subjected to ultrasonic test.The experiments were conducted at normal pressure and normal temperature.The coupling agent includes honey and petrolatum.Using the obtained travel time,P-wave velocity,and wave signal,the spectral ratio method was used to calculate the quality factor.It is found that the original spectral ratio method is inaccurate in calculating the quality factor.The quality factor obtained by using the reference sample method is smaller,while the quality factor obtained by the truncation method is larger.This is closely related to the diffraction effect produced by the limited size of the ultrasonic transducer.Therefore,we use the spectral ratio method considering the diffraction effect to calculate the quality factor,and verify the validity of the method.In addition,the P-wave velocity and attenuation of artificial sandstone at different test frequencies were studied.The theory of scattering attenuation was used to explain the experimental results,which the experimental results are in good agreement with the theory.Finally,the relationship between P-wave velocity,attenuation and test frequencies for dry,water-saturated,oil-saturated natural sandstones was studied and explained separately.