Theoretical And Numerical Study Of Modified Biot's Models, Acoustoelectric Well Logging And Acoustic Logging While Drilling Excited By Multipole Acoustic Sources

This thesis developed Biot-Tsiklauri model and investigated the properties ofelastic waves in generalized Biot-Tsiklauri model and BISQ model, and studied theproperties of acoustoelectric well logging and acoustic logging while drilling in boththe impermeable and permeable formation excited by multipole acoustic sources. Elastic waves propagation measurements are useful and convenient tools forinvestigating the inner properties of fluid-saturated porous media. In the theory ofelastic waves propagation through porous media, acoustic velocity and attenuation insediments and porous rocks are related to physical properties of the material.Understanding of the whole mechanism involved in acoustic energy dissipation andvelocity dispersion during the passage of an elastic wave is an important andinteresting problem of acoustics and geophysics. Biot's theory has been a successful tool for interpreting experimental data, andapplied in sciences as diverse as geophysics. However, there are many examples ofreal earth materials for which Biot's theory does not seem to explain the dispersionand attenuation very well. Various additions and corrections to Biot's theory havebeen attempted. As a matter of fact, in real fluid saturated rocks with thin cracks, Biotand squirt-flow mechanisms coexist and dominate the dispersion and attenuation. Theunited Biot and squirt flow mechanism model is presented by Dvorkin and Nur(1993). From then on, this model has been drawing much attention. Since the strongattenuation of slow waves in porous media, it is difficult to be detected, so that peopleusually underestimate the effect of slow waves. Actually, slow waves will playimportant roles in converted waves on the interface of porous rock with other mediumand the conversion mechanism of seismoelectric field. In this paper, the slowcompressional wave (P2-wave) in porous media based on BISQ model is investigated.The low frequency approximate expression for velocity and attenuation of P2-wave ispresented. Comparing with Biot model, BISQ model predicts that: the attenuation ofP2 waves is very large at low frequency and decrease with characteristic squirt flowlength (R) increasing, the velocity low frequency limit is not zero and decrease withR increasing, the ratio of pore fluid-displacement and bulk-displacement is similar to 167英文摘要 abstractattenuation and phase is different from that of Biot model; The seepage flow inducedby P2 wave at the fluid-porous media interface is more large than that of Biot model.Two conclusions are induced from BISQ model: there is no squirt mechanism inin-viscid fluid-saturated porous media and there is no "dynamic compatibility"phenomenon in viscid fluid-saturated porous media. The effect of squirt flow on thereflection and refraction coefficients predicted by BISQ model is noticeable. Theeffects of the characteristic squirt flow length on the acoustic guided wavespropagation in borehole is also investigated. The numerical simulation of fullwaveforms shows that the characteristic squirt flow length influence on the amplitudeof mode waves. Attenuations of Stoneley waves, pseudo-Rayleigh waves, flexuralwaves, screw waves and higher modes are enhanced due to the exist of thecharacteristic squirt flow, however velocity dispersion of those guided waves is nearlyindependent of the characteristic squirt flow. We may use this property to estimate thecharacteristic squirt flow length by attenuation coefficients of the guided waves fromacoustical logging data. For a classic Newtonian fluid, Biot's theory can be used to describe interaction offluid-saturated solid with the sound. But for oil and other hydrocarbons oftenexhibiting significant non-Newtonian behavior, they are not proper again. As a stepforward, the novelty in the present work is to combine models of Tsiklarui whichintroduced non...