Experimental capabilities of seismic emission tomography for solving the problems of searching and exploration of deep hydrocarbon accumulations

The standard seismic prospecting has been designed to investigate thin layering at shallow depths. At depths more than 4 km the rocks are significantly compacted, change their properties and it is often impossible to trace clear horizons by reflected waves. In the crystalline basement and lower horizons of the sedimentary cover the block structure of rocks is clearly manifested. Taking this into account geological models should be developed and other predictive indicators should be used when searching for hydrocarbon accumulations. For the study of great depths more informative seismic methods are emission and transmission tomography which have been developed in detail in seismology. This article discusses prognostic indicators different from seismic prospecting and presents experimental results confirming the success of emission tomography in their detection using the example of field studies at developed hydrocarbon deposit and other geophysical objects. The range of working depths of research covers the entire crust of the Earth including the crust-mantle transition zone. Keywords: seismic emission; emission tomography; rocks; hydrocarbon deposits.

Research on Technology and Application of Buried Faults Identification in Urban Underground Space

With theurbanization rate's rising and three-dimensional expansion and development of urban, the identification of underground buried faults has become the key factor of earthquake risk in urban underground space and surface area. As a typical method of detecting blind faults in underground space, shallow seismic prospecting technology plays an important role in judging and avoiding potential risks such as underground faults in the process of urban expansion and site selection. In this paper, shallow seismic prospecting technology is adopted, and optimized processing technologies such as parameter test, tomographic correction, pre-stack denoising, fidelity and consistency processing, correction iteration, migration imaging, and time-depth relationship deduction are adopted. Underground faults are identified and interpreted in the studied urban area, and fault risk assessment is carried out based on fault characteristics, scale, distribution and overlying strata, thus providing suggestions for regional pattern and construction of urban planning.

Frequency Domain Full Waveform Inversion Method of Acquiring Rock Wave Velocity in Front of Tunnels

Ahead geological prospecting, which can estimate adverse geology ahead of the tunnel face, is necessary in the process of tunnel construction. Due to its long detection range and good recognition effect on the interface, the seismic method is widely used in tunnel ahead prospecting. However, the observation space in tunnels is quite narrow compared to ground seismic prospecting, which leads to some problems in the acquisition of wave velocity, including: the velocity of the direct wave is used to replace the wave velocity of the forward rock approximately; the arrival time information of seismic waves is the main factor in time-travel inversion or the tomography method, which is sufficient to provide a simple model rather than deal with complex geological conditions. In view of the above problems, the frequency domain full waveform inversion method in ground prospecting is introduced to tunnel seismic prospecting. In addition, the optimized difference format is given according to the particularity of the tunnel environment. In this method, the kinematics and dynamics of the seismic wavefield are fully used to obtain more accurate wave velocity results. Simultaneously, forward modeling and inversion simulations on tunnel samples with typical adverse geological bodies are given here, which verified the validity and reliability of the proposed method.

Structural features of the lower permian salt-bearing series and the character of salt-tectogenesis manifestations in the northern and northwestern margins of the Сaspian depression. Paper 1

The detailed evaluation of the accumulated geological-geophysical data, particularly on the inner structure of the saltbearing series in the margins of the Caspian Depression, the mechanism of salt-tectogenesis manifestation, its reflection in the structure of the salt table and association with the structural inhomogeneities of the subsalt bed is presented. The authors attempt to acquire additional indirect criteria for predicting the structure of the subsalt bed by means of analyzing the structure of the salt-bearing series and the character of salt-tectogenesis manifestation. The problem solution is based on the complex analysis of the data from drilling and seismic prospecting.

GEOELECTRIC SECTION OF THE LITHOSPHERE OF THE KHANKA MASSIF ALONG THE POZHARSKOYE VILLAGE–SHKOTOVO SETTLEMENT PROFILE FROM MT SOUNDINGS

The geoelectric section of the lithosphere is constructed down to a depth of 150 km based on the results of MT soundings carried out along the profile crossing the Khanka Massif from north to south. The crust and upper mantle structure of the massif is investigated. It has been found that the Khanka Massif is divided into the northern and southern parts bordered by the northern restriction of the Spassk Zone. A higher resistivity observed in the upper part of the section and the upper mantle is typical of the southern part of the massif. The northern part is characterized by two extended low-resistivity areas located beneath the southern boundaries of the Matveevka and Nakhimovka zones that penetrate from the upper mantle up to the surface. A comparison of the results obtained with the seismic prospecting and gravimetric data has shown their direct or indirect consistency.

About wireless synchronization of a GPR receiver and transmitter when plotting a hodograph.

The processing of the hodograph data of a monopulse georadar with wireless synchronization is similar to the method of reflected waves in seismic prospecting but has particular differences. The paper describes for the first time the effect of the appearance of steps in the image of the recorded video signal when the receiving and transmitting units of the georadar are moving apart on the example of studies in the mine workings of a potassium salt deposit. Using a kinematic correction in GPR in consideration with the effect of synchronization via electromagnetic wave is especially important for deep research with a large spacing of antenna units.