The Study Of Damage Factor In Poroelastic Media

After a complete survey of researching porous media, from the point of view of detecting the media by seismic wave, and applying the methodology of analyzing soil pore structures, I define the pore structure fractal dimension in damage factor as the fracton dimension(spectral dimension), a parameter which indicating the dynamic property of pore structure. The larger the fracton dimension, the larger the damage factor. The fracton dimension is related to the tortuosity of pore structure. Tortuosity of connected and unconnected pores must be included in the studying of seismic wave. But in the domain of percolation, only the connected pore is considered. In natural rock, the unconnected pore takes only a little part in the total pore. Generally, I consider the two tortuosities are close to each other.Physical experiment is an intuitionist means of studying the damage factor. Damage factors of artificial corundum sandstone at different pore pressures and confining pressures are obtained from three datasets of ultrasonic wave velocity, one group of compressional velocity (P) and two groups of shear velocity (S1, S2). The damage factors are proportional to the pore pressure and inverse proportional to the confining pressure. The comparison of damage factors of corundum sandstone and natural rocks disclose the important effects of cracks to damage factor. The damage factor decrease rapidly when the confining pressure increasing, as a result of the closing of cracks in natural rocks. And we consider that the dispersion in damage factors of compressional velocity and shear velocity is related to the pore fluids.The digital rock and numerical simulating technology could be a supplement to physical experiment. We apply a hybrid method of processed based method and simulating annealing method to reconstruct the digital rock, which is constraint by the petrophysical parameter and the information of pore structure extracted from 2D photos of corundum sandstone. After an optimizing process, the digital rock is input into a graphic analyzing program. Then we get the medial axis of pore space. The static mercury invading curve is simulated. As a try, the fracton dimension and tortuosity are calculated on digital rock.An attempt is taken to analyze the formation of T1X by means of the damage factor. Damage factor and tortuosity curves of reservoirs are calculated using logging curves. Volumes of damage factor, tortuosity and gamma ray are obtained by a combined inversion of logs and seismic data. By integrating datasets of geology and geophysics, together with the gamma ray volume, one profile nearby well is analyzed to study the distribution of damage factor and tortuosity.The whole study of this thesis which begin with the theory of damage factor, and then the study of physical experiment and numerical simulation, finally ended with the application of damage factor of analyzing the T1X formation allowing the author to consider that the seismic prospecting will become the oil and gas seismology in the future. And an important tool for the study of hydrocarbon system.The main progress of this work is the application of digital rock in studying of damager factor, and the application of damage factor theory to real seismic data.