Research On Inversion Method In Transversely Isotropic Media With A Tilted Symmetry Axis

The isotropy is formed due to the different speed between thelow-speed wave in the shale and the high-speed wave in the stratum.When the stratum is rotated, the symmetry of medium will be not vertical.The TTI medium with the tilted symmetry axis will be formed. It isnecessary that the research is from the traditional layered media tonon-uniform anisotropy media in order to solve the problem of the oil andgas exploration and extraction. In the past, the research is mainly focusedon the HTI, VTI, orthogonal media, and monoclinic media. The currentresearch about the TTI media only stay s on the three componentssimulation in two-dimension space. In this paper, it mainly studied the 3Dsimulation for the TTI media by rotating the space coordinates in thehorizontal interface. It is one of the most difficulty studies on the researchof 3D TTI media. A few people study the three-dimensional acoustic TTImedia. In this paper, it simulates and analyzes the 3D acoustic wave fieldof TTI medium by using the staggered grid finite difference .Grechka and Tsvankin only study the anisotropy media and theelliptical distribution of the NMO velocity, but not simulate and analyze theNMO elliptical attribute of the acoustic TTI media. In order to study theNMO elliptical attribute, we firstly study the 3D phase velocity in the TTImedia, and then deduce the formula of NMO velocity by the phase velocity.Finally, we simulate and analyze the ellipse attitude of NMO velocity. Theresult shows that the relation between the NMO velocity and azimuth will be affected by the strike angle and dip angle of TTI med ia.For the seismic inversion and process, the Non-hyperbolic can supplythe rich information. Therefore, the research of the quartic moveout is veryimportant. We study the coefficient expressions of the quartic moveout,and analyze the relations between the coefficient and the strike and dipangle. The result shows that the relations will be two -line distribution whenthe layer is horizontal. And when the reflect interface is tilted, the relationswill be very complicated. When the tilted angle is 10 or 1 5 degree, thedistribution will is the rose-line. If the angle increases from 10 degree to 15degree, the coefficient of 90 and 270 degree will increase, but decrease inthe angle of 0 and 180 degree. When the angle is from 30 to 60 degree, therelation will be the earthnut line and the coefficient of 45 degree is max.When the layer tilts to 75 degree, the curse line will be two -line of rotating90 degree.Grechka offered the method of inversion for the anisotropy parametersin the TTI media by using the S-wave and P-wave velocity, and the positionof P-wave SH wave, and SV-wave. Based on the relation between theNMO velocity and the parameters of Thomsen, we deduce the equation ofinverting the fracture parameters of the TTI media. And then, we discussthe theory of the mix-inversion method and the non - linearity invert method.For TTI media, we find that the mix -inversion is not available. Therefore,we chose the genetic algorithm to computer and analyze the data ofThomsen parameters and fracture angle. Based on this, it can be extendedto use in the tilted and reflect interface. We study and invert the quarticmoveout parameters of the long offset.In this paper, we deduce the equation of inverting the fractureparameters of the TTI media by using the qu artic moveout parameters. Inaddition, we make use of the genetic algorithm to invert these parameters.The results show that the equation and inversion method is available androbust. So, our research is successful and reaches the previous aim.