We present a 3D Fourier finite-difference depth migration (FFD) method for waves in transversely isotropic media with a vertical axis of symmetry (VTI).The method can accommodate a wide range of anisotropy rather than weak anisotropy. The downward-continuation operator is split into three downward-continuation operators. This method can handle the strong lateral velocity variation. A complex treatment of the propagation operator is applied to mitigate inaccuracies and instabilities due to evanescent waves. Tests show that the method improves the image quality.
Fomel, Sergey (University of Texas at Austin) | Backus, Milo (University of Texas at Austin) | Fouad, Khaled (University of Texas at Austin) | Hardage, Bob (University of Texas at Austin) | Winters, Glenn (Fasken Oil and Ranch Ltd.)
Application of multicomponent seismic exploration produces multiple images of the same subsurface. For a successful interpretation of multicomponent images, it is crucially important to register them in the same coordinate frame. Accurate registration of time-domain im-ages also provides an effective estimate of the interval
The prolific Roncador field, discovered by Petrobras in 1998 in Brazil''s Campos Basin, is associated with a pronounced seismic amplitude anomaly within the Upper Cretaceous level. This association raised hopes and opened the door for new prospectivity in the Upper Cretaceous of the northern Campos and Espirito Santo Basins. Questions remain, however, regarding the causative nature of these amplitudes, whether accumulations are always characterized by some sort of amplitude, and whether the limits of seismic resolution can now be pushed even further allowing for discrimination between heavy (18 API) and light oil (>30 API). This paper presents the analysis done by combining concepts and models of rock physics with seismic acoustic impedance. The calibration of rock properties from well logs and core information to the seismic response provides a more reliable seismic prediction in terms of lithology, porosity, texture, pore fluid, and thickness.
Silva, M.B.C. (Group of Technology and Petroleum Engineering, GTEP PUC‐Rio: ) | Rodriguez&hyphen, C. (Petrobras/UN‐Rio/ATP‐Ro/Res) | Fontoura, S.A.B. (Group of Technology and Petroleum Engineering, GTEP PUC‐Rio: )
This paper presents a robust method to solve both hyperbolic and non-hyperbolic NMO equations. This method is based upon the optimization algorithm called
By expressing the surface consistent equations as a matrix operation, a multigrid method was adapted to separate source and geophone statics. Dividing residual statics into source and receiver components is done to prevent statics shifts from altering the structure of the data. The method is compared to an approximation allowing us to perform a direct inversion, and a Gauss-Seidel relaxation method, frequently in use in production processing. Multigrid shows a greater ability to resolve the long wavelength components of the statics on a synthetic data set.
Spatial distribution of traces in seismic data is often irregular. This fact may lead to errors in both time and depth imaging and subsequent tasks, including AVO analysis and interpretation. I suggest a new approach to compensate the irregularity based on Voronoi diagrams that is specially useful for Kirchhoff migration or any other integral process (such as dip moveout (DMO), offset or azimuth continuation, for example) is applied to the data. This technique merges the field of computational geometry and geophysics. I address complications due to the edges of the survey and analyze stability problems intrinsic to the method. I propose solutions to these problems.
Barton, Penny (University of Cambridge) | Owen, Tim (Carrack Measurement Technology) | Gulick, Sean (University of Texas at Austin) | Urrutia, Jaime (Universidad Nacional Autonoma de Mexico) | Morgan, Joanna (Imperial College London) | Warner, Michael (Imperial College London) | Christeson, Gail (University of Texas at Austin) | Rebolledo, Mario (Centro de Investigacion Cientifica de Yucatan)
We present a methodology for quantitative integration of geological information with seismic data using rock physics theories, formulated in the framework of an inverse problem. We illustrate this method with fracture characterization of hydrocarbon reservoirs. There are different types of information that can be used to study fractures, such as geologic, seismic, and well-log, and each one of them contributes in a different way to fracture characterization. Thus, by using these different sources of information, we can better constrain the predictions on the fracture parameters, such as fracture density and orientation. The various types of data from geology and seismic can be combined quantitatively using rock physics theories if we translate them into the common language of probability theory. This probabilistic approach allows us to integrate quantitatively the various types of information and also to estimate the uncertainty in our predictions.