articles

 

The main properties are reviewed and the examples of practical use of duplex wave migration (DWM) basing on a Kirchhoff-transformation are adduced. Efficiency of the DWM is demonstrated at analysis of a block  structure of geologic medium in miscellaneous seismic conditions experimentally. The further advancing of a migration technique directional on the seismic imaging  without limitation of angle of boundaries are showed. The relevant role of transmitted converted waves is in particular indicated at formation of such images under the surface seismic data.

 

The paper presents results of testing the “sector” AVOA analysis algorithm by model data for conventional narrow azimuth towed streamer 3D data. It is shown that different observations multiplicity subject to offsets and azimuths results in increasing errors of detection of fracture orientation. The algorithms and computer programs have been created for reconstruction of data. Algorithm based on 3D DMO (dip-moveout) transformation creates missing seismograms. Second algorithm approximates observed reflections amplitudes and calculates the amplitudes in empty intervals of azimuths and offsets. Testing the algorithms showed that data reconstruction increases the precision of determination of fracture orientation in 3⁰ – 7⁰.

In most cases theoretical investigation of forming and propagation of seismic waves in anisotropic elastic can be done by a numerical simulation of the process. This paper contains an original and efficient approach to the computation of wavefields generated by the axial-symmetric source which is located inside the fluid-filled borehole. The numerical simulation is performed with the help of finite-differences on staggered grids. In order to get rid of artificial reflection from the outer boundaries of the target area the two approaches are used. The first is Perfectly Matched Layer which is one of the most efficient ways to solve the problem for wide rangeof models. Nevertheless, where are a number of models for which the approach can not be implemented. This phenomenon is also discussed in the paper. In order to deal with theses model authors propose an original construction of domain distension based on Optimal Grids. The theoretical results presented in the paper are supported with representative numerical experiments.

Surface elastic waves in a real ground are experimentally investigated. Features of change of spectral structure indicating on presence of elastic exchange processes in a ground are found out at distribution of a wave. The explanation of local increase in wave energy is given.

When reflected waves data processing is applied the  heterogeneity of the upper part of the section compensation is carried out using static corrections. Statics model correctly describes the problem of  compensation in the case of the vertical geometry of the rays in the area of heterogeneity and leads stacking velocity shifts, if this condition is not satisfied. Conditions of vertical rays is not performed if the main factor is the heterogeneity of the variable terrain surface. Solution to the problem of this heterogeneity type compensation was investigated by analytical and  numerical methods.

This article considers variations of the residual error of parameter Hcdp = t₀*Vcdp/2 with depth in case of static correction accounting for near-surface effect caused by variations of high-velocity layer thickness. We consider anomaly size being less or comparable to typical source-receiver offset range. Main conclusion is that variations of the residual error may go in both directions depending on the ratio between anomaly size and the source-receiver offset.

The efficiency of seismic compressional and converted waves surveys is considered in the article. Recommendations of model based 3C survey design for obtaining high quality data are given. The modeling approach is developed using 2D synthetic & real data, and it is shown that usage of both PP and PS data leads to accuracy growth in reflection detection. In conclusion, vertical resolution limits of PP/PS waves are analyzed and perspectives of PP/PS joint use in processing are studied.

At development of new fields of the hydrocarbons which are being in complex geologic conditions and at development of aging fields with not up to the end the extracted reserves arise problems of specification of boundaries of productive reservoirs. Traditionally as the methods of application used for definition of zones of mudding, apply LOG detailed correlation and emanating of headers according to LOG. At spacing interval between wells more than 1 km fidelity of delimitation of zones of mudding on the floor space has low veracity. The geologic models constructed only according to exploratory wells, image a real constitution of headers on the floor space with the big inaccuracy. Use neural 3D a seismic facies analysis partially fills the absent information on allocation of headers between wells. The mutual facies analysis of LOG data and seismic surveys with teaching on holes allows to determine more precisely zones of mudding, to allocate river facies and the zones of headers complicated by a tectonics. Produced article describes the method of application and the received results of joint application of a seismic facies analysis 3D, data of LOG detailed correlation on trial both to development wells and data of a core. On practical examples models of seismic Jurassic facies are demonstrated to benches on one of fields of Western Siberia.

The paper demonstrates results of scattered wave field applied to delineate natural and industrial fracturing zones. The principle of the method consists in definition of the seismic field scattered constituent generated in the presence of open fracturing of rocks. Presented are the results of approaches used to restore scattering events. For this purpose synthetic seismic gathers are computed using finite difference approximation technique of 2D scalar wave equation with absorbing conditions of high order. Considered are results of natural and industrial fracturing study in geological environment. The case study is based on the data derived from West Siberian oil fields.

By the example of the Ombinskoe field the effective pay prediction technology of the Middle Jurassic, realized in PANGEA software, is shown. Fluvial sandstones of this stratigraphic unit are characterized with physical-lithological heterogeneity of oil reservoir in wide range both in lateral, and in vertical. As a result of the works the geological model of the effective pay has been created, the concept of the deposits geological structure has been developed, effective thickness maps has been used at estimation of the reserves. New drilled wells have shown that average divergence of the effective thickness prediction is not exceed 2.8m, and relative error of the effective thickness prediction is 0.2, that corresponds to recommended typical level of accuracy for the West Siberia.

The composition of the wave field observed on the CMP regional profiles, which intersected the known kimberlite fields in western Yakutia, is dominated by the scattered waves associated with Earth’s crust heterogeneities of different scales. Within the kimberlite fields some anomalous changes have been determined in integral amplitude characteristics of the scattered wave field that can be identified with kimberlite-forming systems including crust-mantlediapir.

The article describes the probable application of acoustic methods for exploring the condition of different types of foundation. Both the experimental investigation results and numerical experiment results are demonstrated in the article; the latter is received by using a finite-element analysis of acoustic wave fields in cylindrical piles and foundation plates (touching the soil mass). The defined kinetic and dynamic features of the wave field must be taken into account when creating different methods for exploration of piled foundations.

This Article is devoted to the inspection of the main PM VSP equipment parameters and the possibility of its application at standard and large depths conditions, such as: high temperature, pressure and very long geophysical cable. There was made a comparative analysis of different parameters of registration systems (digital and with TIM) and given the conclusions of effectiveness of using those technical solutions and construction methods of equipment to achieve the necessary registrations parameters.