POLARIZATION PROCESSING OF PS WAVES FOR ESTIMATION OF ANISOTROPY IN FRACTURED RESERVOIRS, THE YURUBCHEN-TOKHOMO PETROLEUM PROVINCE: TESTING NEW ALGORITHM
S.B. Gorshkalev, V.V. Karsten, K.A. Lebedev, A.V. Trigubov, and G.V. Volkov
Institute of Geophysics, Siberian Branch of RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Multicomponent seismic profiling, converted PS waves, polarization analysis, azimuthal anisotropy, shear wave polarization, vertical fracturing of rocks
Pages: 716-728
Abstract
Splitting and polarization of converted PS waves are used to investigate azimuthal anisotropy in sections containing vertically fractured reservoirs. The known Alford pseudo rotation algorithm for polarization analysis of 2C x 2C marine VSP data has been adapted to the specific conditions of the Yurubchen-Tokhomo petroleum province (Siberian craton) where deployment of a regular shot network is difficult because of a rugged surface topography. The 11-layer seismic model of the province includes two azimuthally anisotropic layers, the lower one corresponding to the Riphean fractured reservoir. 3C VSP and surface CMP synthetic seismograms computed for this model are described together with the procedures and results of testing of the modified algorithm. The suggested algorithm for the polarization analysis of surface shot gathers and CMP stacks includes cross correlation of traces for orthogonal components and stripping of upper anisotropic layers. All tests demonstrate high quality of the estimated anisotropy parameters.
|
