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Vol. 1 (1998 year), No. 1
Blyas E.A., Sereda A.-V.I.
Definition of Layered Medium Parameters on Borehole Seismic Observation Data by the Inverse Dynamic Task Method
The given paper deals with the problem of definition of the 1-D layered medium parameters from zero-offset VSP data. The solution of the problem has two steps: first, the acoustic parameters between the receivers are defined, then the impedance and absorption below the borehole bottom are forecasted. To solve the first problem the equalities have been obtained that correlate the wave spectra with the layered parameters. As soon as the number of equalities exceeds the number of unknown parameters the method of least squares is applied and the functional minimum is achieved with the help of conjugated gradients' method. The given work shows the principal opportunity to define the strata densities and velocities within the section between the receivers. In the second part the minimum meansquare non-coincidence between the medium reaction (that is determined after the first task solution) and the reflection coefficients for the set of non-elastic horizontal layers has been defined. The conjugated gradients' method is applied to achieve the numerical solution for both problems.
(in Russian, стр.14, fig. 3, tables. 0, ref 16, MS Word 95, MS Word 95 356 Kb)
Vol. 1 (1998 year), No. 2
Blyas E.A.
Definition of three-dimensional inhomogeneous layered velocity model from reflection seismic data
The given paper deals with the problem of 3-D velocity layered model definition from reflection seismic data. It gives the description of basic methods for the named problem, gives the compare analysis, discusses advantages and disadvantages of these methods. It demonstrates a new iteration algorithm for the determination of the medium model with inhomogeneous curve-linear layers which does not require the wave front curvature. It is evident from the work that in order to define velocities in the inhomogeneous strata one has to solve an inverse problem for the model with locally-homogeneous layers. It demonstrates the optimization algorithm that does not require multiple solution of the direct problem and reduces time-consumption significantly.
(in Russian, стр.18, fig. 2, tables. 0, ref 19, MS Word 95, MS Word 95 98 Kb)
Vol. 1 (1998 year), No. 2
Blyas E.A., Shavina L.I.
Some approaches to processing and interpretation of borehole seismic observations and results of applications
The paper describes a general approach to the processing and interpretation of borehole seismic observations. The interpretation is advised to be carried out in four stages each solving its own problems. The solution of one of them is considered in greater details - that is the task of regular wave definition from three-component observations. There is an optimization method offered to solve the problem, that specifies the shape and amplitude of a single wave. The optimization is fulfilled with the help of a conjugated gradients' method, the only unknown quantities are time delays, wave amplitudes and shapes find themselves on the eigenvalue numbers and vectors of the symmetrical matrix. The paper shows the examples of software application to VSP data from the Northern Samotlor field. The application of the given approach has given the possibility to obtain deep sections with frequency up to 170 Hz and to predict the productive layer properties in the well vicinity.
(in Russian, стр.20, fig. 3, tables. 0, ref 3, MS Word 95, MS Word 95 520 Kb)
Vol. 3 (2000 year), No. 1
Blyas E.A., Rozhkov A.S.
Construction of high-speed models on the data of vertical seismic profiling
The problem of the layered model velocity identification from borehole seismic data is considered in the paper. For solving this problem two steps have been suggested. First, the travel-time arrivals have been defined, then a continuous curve has been constructed by the least squared method.
(in Russian, стр.6, fig. 2, tables. 0, ref 8, MS Word 95, MS Word 95 48 Kb)
Vol. 9 (2006 year), No. 3
Blyas E.A., Sereda A.-V.I.
Determination of reflectivity coefficients of longitudinal and transverse waves using seismograms of longitudinal waves
A new approach for prestack inversion of NMO CDP gathers has been described. The main difference of conventional approach is that we combine two steps (AVO analysis and inversion) into one procedure. This approach has an advantage of using wavelet at the very beginning while the conventional approach utilizes wavelet only at the second stage. We also use the linearization approach for reflectivity inversion and reflectivity constraints, which allows us to reduce essentially cost of operations. This approach also gives us the possibility to take into account wavelet from the very beginning. The approach of taking into account priory information about density-velocity relations has been suggested. It also uses thick layer properties as constraints to stabilize the solution. Two modifications (in the time and frequency domain) have been suggested.
(in Russian, стр.14, fig. 8, tables. 1, ref 12, Adobe PDF, Adobe PDF 378 Kb)