Full-wave Synthetic Acoustic Logs In Saturated Cracked Media

The subject belongs to the acoustic full wave trains logging areas.Full wavetrain in Acoustic Logging is a major breakthrough in the technological developmentof acoustic logging which makes a regular record of the sliding longitudinal wave(arrival time and amplitude) extended to the records of the sliding longitudinal waveand sliding transverse wave spreading along the wall of borehole and the records ofthe guided wave in the fluid in the wells between the borehole wall and theinstrument’s shell in the pit. Therefore, in order to obtain these important stratuminformation, first, the velocity change, amplitude fading, frequency dispersion andotherwise of various partial wave included in full wave train must be considered tomake sure that these characteristics have relations with which character of stratum, sowe should study the characteristics of wave propagation in stratum with differentproperties. Numerical Simulation of anisotropic formations (such as horizontal strata,porous formations, and fractured strata) problems still need to continue in-depthresearch. For the lateral stratigraphic problems, the main five elastic parameters forsolving wave equation, Hooke’s law derive the horizontal strata. Pore formationsimulation using the Biot wave theory. The rocks of the Earth’s surface media; manycontain a large number of pores and fissures, such as carbonate strata. Fissures on thesonic log response extract fissure formation parameters, it is necessary to numericalsimulation, kinematic and kinetic parameters of the partial wave analysis of thefractured nature of wave train on fissure formation.Based on this idea mentioned above, in this paper, the author utilizes a computerto do the numerical calculation of the theory wave profile of wave acoustic logging,and uses the calculated two dimension spectrum combined with time-domainwaveform to study and analyze the influence of the change of various stratumparameters to various partial waves in full wave train. It includes the following fouraspects.By calculating the acoustic field two-dimensional spectrum and time domainwave column of oil layer and water layer, it can be seen that the contribution oftransverse wave and pseudo-rayleigh wave of acoustic wave in oil-bearing formationis bigger than in water bearing ground and the energy of transverse wave andpseudo-rayleigh wave is higher. The contribution of stoneley wave in oil-bearingmedium become smaller than water bearing ground, the amplitude and energy ofstoneley wave is on the small side.1. We derive and solve a isotropic formation and3kinds of wave equation inanisotropic formations, specific solutions are used in the form of boundary conditions.Numerical simulations of axial wave under various formations are abttained. 2. Using two-dimensional spectrum to analysis of sound field. Two dimensionspectral functions of formation parameters, through maps two-dimensional spectracan be seen in full-waveform is not the nature of waves, wave patterns and wavedispersion and attenuation properties.3. Introduction of the Hudson on fissure formation of scattering theory, findingthe fractured pore formation of equivalent elastic modulus, and then to the equation oftransverse isotropy medium, strike a fractured medium wave to discuss the fracturednature of relationships and the entire waveform, wave.4. For the focus of this article, the numerical simulation of pore formation andcrack formation, Biot-Rosenbaum sound field numerical model on the basis of theory,taking into account the dynamic effects of permeability, introducing dynamicapproximate calculation of permeability formula, numerical calculation of fluidsaturated porous medium in borehole acoustic field of two-dimensional spectroscopy.Theory of numerical model out of the fast compressional wave in a borehole, slowp-wave and s-wave dispersion curves, calculated for a given stratum theory of wellreceived a point on an axis corresponding to the sound pressure waveform and gottheir two-dimensional spectrum. Theoretical calculation model and based on Hudson’sfractured formation of fluid-filled boreholes in Monopole field, analysis of sound fieldwith the variation of three main parameters (fracture orientation, matrix permeabilityand porosity) of fractured formation..