Experimental Study And Application Of Ultrasonic Propagation Characteristics In Shale

The establishment of dynamic mechanical parameter model based on ultrasonic propagation characteristics of rock is a conventional method to solve dynamic parameters of reservoir.However,Southeast Chongqing shale bedding,the ultrasonic wave propagation characteristics and other rocks has a larger difference between the mechanical characteristics of shale reservoirs using the conventional dynamic mechanical model parameters calculated with the real formation characteristics of bias.Secondly,the deformation and failure of shale is very subtle,even in the long horizontal section of oil based drilling fluid are still well leakage,collapse instability problems,therefore,how to effectively monitor the deformation of the shale and timely,it is important to predict shale stability.Therefore,the shale in southeast area of Chongqing as the research object,to clarify the ultrasonic wave propagation in shale,and the basis for the establishment of the dynamic mechanical model parameters of shale,and the research on ultrasonic propagation characteristics of the further development of shale in the process of failure,the use of ultrasonic means to monitor the implementation of shale deformation,acoustic characteristics the shale deformation and failure,and explore the application based on the ultrasonic characteristics in rock stability.Based on the shale gas wells in southeast area of Chongqing as an example,combining with the geological data,outcrop and core underground work as follows,and obtain the corresponding knowledge:①To carry out ultrasonic testing in Southeast Chongqing shale,affected the bedding structure on the propagation characteristics of ultrasonic shale was proposed based on the wave theory,a numerical simulation method for shale ultrasonic transmission experiment,field finite difference simulation results and experimental results of the physical model correlation coefficient is greater than 80%;② By using numerical simulation method to explore the influence of ultrasonic propagation characteristics of bedding scale,density and angle,and then use the method of statistical analysis of acoustic parameters of grey system simulation results,found that the wave velocity and acoustic attenuation of bedding structure used to characterize shale;③The shale acoustic mechanics experiments were carried out.It was found that the shale wave velocity was about 80%of its peak intensity.The wave velocity can predict the stability of rock,and the ultrasonic amplitude can reflect the damage process of rock;④Based on the ultrasonic velocity and attenuation coefficient of shale,a dynamic mechanical parameter calculation model is established.Through the verification of underground core,it is found that the effect is better than the traditional lateral isotropic and homogeneous model;⑤Carry out the mechanical synchronous sound cube shale experiment,while monitoring the changes of crack failure process of shale.The results showed that the shale should all be the evolution process of stress-strain curve and crack with similar rules,divided into 5 stages,and shale as a heterogeneous material,the stress-strain curve can well describe the failure characteristics,the amplitude and wave velocity from the main point of view,with the help of thermodynamic equilibrium theory,the deformation process of shale are more accurately described.The results of this study to deepen the understanding of the propagation characteristics of shale of ultrasonic wave,establishes the dynamic mechanical model parameters of shale,the failure process and the use of ultrasonic parameters to describe the shale,results have a certain significance of physical properties and stability of ultrasonic shale.