articles

 

 A modern method for 2D and 3D surface-related multiple elimination is considered. The multiple prediction phase is analyzed as the forward wavefield extrapolation procedure. Such approach allows detection of inevitable kinematical and dynamical distortions of the model obtained. These distortions should be compensated for at the adaptation phase.

An algorithm for non-stationary kinematical and dynamical adaptation of the predicted multiple model to the real noise events is proposed. It is stated that satisfactory multiple prediction for 3D wide-azimuth gathers can be achieved only in simple cases. Real data examples are shown.

In article are resulted comparison of statistical methods for definition of an informative set of seismic attributes. The description of a technique of the given comparison is resulted. Conclusions about efficiency and applicability of statistical methods for the decision of the given problem become. Results have been received according to one of the areas of region of Western Siberia.

Narrow-azimuth orthogonal surveys with relatively low fold impose strong acquisition footprints on PP and PS seismic data. Here we analyze several narrow-azimuth and wide-azimuth multiconiponent surveys and estimate the influence of different acquisition geometries on the recorded datasets. We believe that the efficient
multiconiponent seismic investigations should be based on presurvey justification of the acquisition geometry and the trace density per sq. km by comparing the bin attributes for alternative 3D/3C shooting geometries and the processed synthetic cubes obtained with the aid of 3D raypath modeling.

 A velocity analysis technique is proposed for each CDP, with correction of the time curve for near-surface inhomogeneity. The calculations are made in a homogeneous earth model using the t₀ corrections diagram.

While creating a model of geological environment on every stage of research it is necessary to draw on all results of preceding works. In this connection a calibration data problem takes place. The purpose is to remove of seismic record distinctions related to technological factors. In current paper the phase spectrum matching method of vertical seismic profiles is examined as the aspect of forming of the generalized seismic projects.

In this article we compare results derived with the use of two alternative approaches to a reservoir properties prediction based on seismic data. One of them incorporates direct forecast via correlation between target properties and any physical characteristics of the medium reconstructed from seismic data (i. e. acoustic impedance, AVO parameters). Another approach is to use mathematical methods such as multi-attribute and neural network analysis to establish relationship between reservoir properties and a set of dynamic parameters of the wave field. Also we introduce a problem of a net thickness prediction in a sense of reservoir/non-reservoir classification of the productive interval and discuss on possible ways of its solution.

Predicting geologic indicators, such as lithologic composition, reservoir properties and oil saturation in Jurassic T1(J2), T2(J3+J4) and T3(J5) horizons and within the upper portion of the pre-Jurassic section from seismic data, far from being simple, is implemented using Omega SPS, HRS-Geo technology and Geo-
Graphix R2004.1, v.8.5, interpretation system. Special preprocessing flow ensures that S/N ratio is high and seismic amplitude characteristics are preserved as cognitive information about components of the geologic rocks. The results, thus obtained, allow predicted potential oil-saturated prospects to be tested.

In East Siberia oil deposits as a rule are connected with local area with high concentration of cracks/fractures. These areas have rather strong impact not in reflected waves only but in scattered ones as well. It should be noted that reflected waves provide information about regular geological interfaces while scattered waves localize local geological objects and their interior structure. So, in order to improve resolution and to provide high physical essence of seismic images both these families of waves should be used. On this way reliable correlation between scattered energy and collector capacity for vend-reefean geological structures are proven.

Considerable quantity of oil reserves is concentrated in Tyumenskaya formation of Western Siberia. This  formation is characterized by essential vertical and lateral geological variability. In spite of this Tyumenskaya formation contains reservoirs of high
capacity which are able to supply commercial production of oil. Complex of special methods of geological modeling is proposed. These methods are based both on processing and interpretation of seismic and well data. Main results of methodical complex's application are detailed geological 3D models of reservoirs in Tyumenskaya formation which are used as a base for optimal exploration and development.

On the basis of the analysis of the available data seismic of activities on Western Siberia the main gentle places on detection and opening-up new small dimensions uplifts. By some writers the multistage seismic survey is offered to use padding systems of analysis of low velocity layer and top of part section by activities MSL, MRW. But as demonstrate the substantial data, the geologic self-descriptiveness of such activities is low-level (realization of these activities descends, as a whole, economic efficiency of seismic survey), that is connected to a feature of formation of a wave pattern in a winter season. The applying of the available approaches on analysis of a top with usage of speeds Vcdp and adjusted seismograms CDP with the gated in high frequency static corrections, does not allow to detect small dimensions uplifts. The writers on the basis of activities executed within several years, came to a unequivocal conclusion that the technique of activities under the registration of surface heterogeneities should in the radical be changed. That will allow essentially to increase efficiency of seismic activities.

The main goal of the presentation is to share experience accumulated by authors in theoretical and practical aspects of borehole seismic tomography. Short overview of different algorithms is given. Borehole seismic investigation in civil area is presented. Equipment description and tomography model are shown.

Studied is the seismic model of the Earth in the form of a set of point diffractors, and its relationship with the Born approximation is considered. It is shown that the wavefield in a homogeneous medium cannot be represented as a set of waves caused by independent secondary sources. Analyzed is the Huygens‘ principle for continuous media.