articles

 

The image of the subsurface in the VSP method can be formed by two methods: kinematic inversion and migration. The first of them allows to obtain the thick layered velocity model together with the boundaries geometry corresponding to this model. Migration of VSP records is based on this model, and the more it is accurate, the more reliable is the image of subsurface details obtained by migration. During the last two decades two these directions continued to develop along with development of different VSP modifications, which are characterized by their inherent technologies and significant differences. In the article different methods of subsurface image formation characteristics are considered along with their advantages and disadvantages.

The paper presents a concept and basic scope of work for technology of estimating stress and deformation of the rocks and pore pressure propagation using conventional seismic data. This technology is based on the model of the discrete fractured media, and incorporates fluid dynamic and geomechanic factors influencing seismic waves propagation. In the paper we outline basic physical assumptions, determine the place of this technology in modern sequence of seismic reservoir characterization methods in order to predict the elastic and reservoir properties for effective exploration and safe drilling.

It was proposed a method for prediction of the occurrence of fourteen day Moon–Sun resonances of gravitational tides and deformation waves caused by fluctuations of the barycenter in Earth–Moon system. The magnitude estimations of stress-strain state of geological media caused by the resonances are demonstrated. It was proved the possibility of the use of gravitational tidal resonances energy for direct oil and gas exploration. Standing waves appearing in the oil and gas deposits and caused by the resonances of gravitational tides were registered. It was proposed the technology for direct oil and gas exploration – fluid resonance seismic measurement on the basis of registration of tidal influences.

In the paper problems of improving the production efficiency of seismic exploration at oil and gas fields are considered. The way of this problem solution is demonstrated – it is based on the use of the different seismic waves classes: reflected, scattered, and microseismic emission waves. Combining CDP, SLEC (Seismic Location of Emission Centers) and SVSL (Side-View Seismic Location) and the use of these waves can provide independent and the most reliable information about the oilfield: traps, heterogeneity and uneven fluid saturation, distribution of open fractures in the reservoir and etc. This seismic methodology can significantly improve the main indicator of the efficiency of geological exploration – the successful results of exploration wells drilling, the location of which is determined by the results of combining the seismic surveys. The examples of this methodology application are demonstrated.

In the article for the terrigenous producing horizons of Angara-Lena and Levoberezhnoe gas fields various approaches based on sonic, gamma ray logs and petrophysical data for Vendian reservoirs porosity estimation were studied. Porosity cutoff values for Parphenovo and Bokhan sandstones were established on the basis of quantitative petrophysical technique. Established statistical relations between porosity and log values agree with core data, the capacity estimation of producing horizons was made.

The optimization-based deghosting method for marine seismic data acquired with arbitrary towed streamer geometry is proposed. A model of the receiver-side ghost is obtained from the basic concepts of the wavefield extrapolation theory. The algorithm is implemented in the spectrum domain and implies the solution of a set of linear equations at each frequency.

Properties of the deghosting operator for the marine seismic data acquired with a towed streamer of arbitrary shape are studied in the paper. It is shown that the proposed operator is robust with respect to random noise. The impact of the alias effect is demonstrated. The choice of the optimal solver for the system of linear equations that arises while inverting the modified Kirchhoff integral is discussed.

In the previous articles of this series, the deghosting algorithm was presented for the data acquired with marine seismic streamers of arbitrary geometry. The algorithm was designed for traditional single-component seismic. The proposed optimization procedure allows one to obtain an assessment of the reflection coefficient of the free surface and to estimate the acoustic wave propagation velocity in the water layer. Here, in the final paper of the series, the algorithm is being tested on synthetic and real marine seismic gathers. The effectiveness of the proposed approach is being demonstrated and the place of the algorithm in the seismic data processing graph is discussed. As a result of this study, the algorithm was developed that allows for deghosting in most practically important cases, thereby expanding the signal bandwidth and increasing the resolution. In addition, the guidelines for the use of the algorithm were provided and the ways of its interaction with other processing procedures were proposed.

Basalt traps top mostly have complex three-dimensional topography. This is a reason for ineffective multiple attenuation in 2D seismic with only two-stage methods consisting of multiple wavefield prediction followed by its adaptive subtraction from the input data. We demonstrate that the combination of the prediction/subtraction approach with kinematic filtering provides optimal de-multiple processing for 2D seismic lines in areas with basalt traps.

This paper is a continuation the previous two of the same name. In the papers the deghosting problem in marine seismic data processing is considered. The first paper describes the general problem and its solutions in the case of horizontally deep-towed streamers. The second paper considers the case of slanted streamers and pairs of horizontal streamers, one towed vertically above the other. Kinematic filtering solutions of deghosting problem for this kind of acquisitions were described in detail in these articles. This paper focuses on some aspects of 3D seismic data processing in the context of the deghosting problem.

For velocity model building it is necessary to know travel times of waves. The general assumption for reflected waves is that travel times can be expressed analytically (usually by hyperbola or polynomial), and all deviations from this function result from statics. However, in some cases such parametrization results in distorted velocity model. Description of travel times by more complex function (i. e. more detailed) is not always possible, because reflections occurring in near-surface have low effective fold. Quite simple and at the same time efficient modification of the conventional method consists in keeping of the trend of static corrections and using the trend for kinematic inversion. This modification is described in the paper.

The electric elastic waves source – Spark in seismic exploration is quite efficient in studies on land and in the sea. Its design, technique of application and parameters of the produced oscillations are well studied for high-energy electrical discharges. At the same time, this method of elastic waves excitation can be used in laboratory measurements and physical modelling. It can be especially effective for acoustic measurements of unconsolidated sediments from the bottom of aquatorium. But for these purposes the poorly studied electrical discharge source with energies of the first tens of joules and joules is needed. The article is devoted to experimental studies of this source.

The paper discusses the methodology and results of seismic monitoring in the ore deposit area. Brief, about 15 minutes long, increase the intensity of the microseisms level we call here “micro-seismic storm”. The results of data processing by the method of seismic emission tomography lead to the conclusion that the increase of the amplitudes of the microseisms is associated with the deep fault zone, and two closely spaced emission areas at different depths are localized. The search of seismoactive zones in the other time intervals do not lead to meaningful results.

The problem of geoecological prediction generated by powerful technogenic and natural explosions for the surrounding environment and society is considered. The greatest interest represents the study of seismic and acoustic effects of the explosions on industrial, inhabited and biological objects. Destructive influence of acoustic waves from explosions can be amplified by the influence of external meteofactors – directions and velocity of a wind, temperatures of the air, atmospheric conditions and the near surface ground properties. Influence of the listed factors defines necessity of carrying out the numerical and natural experiments to estimate the ecological risks caused by explosions. In our work vibroseismo-acoustic method is presented with numerical and experimental results of its application.