Specificity of the seismic material obtained in complex seismo geological conditions (swamp zone)

Abstract

The main objective of the work is the description of new technical and methodological tools used by Yuzhmorgeologiya JSC when conducting CDP 3D field seismic surveys in the estuaries of the Slavyansk district of the Krasnodar Region in 2014-2015. The main results of the experimental work are presented; the choice of survey parameters and their impact on the quality of the seismic recording is validated: digging-in of the seismic source points BOLT 2200LL-BHS, the number of excitation accumulations and the required depth of recorder sensors. Geophones “SVG-6” were used as sensors of the recorders, which were crushed with a metal pole with a fastening at the end to a depth of 1.0-2.5 m until steady contact with a solid surface (dense soil, clay base) was achieved, reducing the negative impact noise (microseism) from the root system of reeds (Fig. 2A, B). Grouping the SVG-6 with six consecutive geophones (GS-20DX) increased the sensitivity of the equipment to weak signals being excited in a weakly consolidated layer, and its robust design and metal eye, made it possible to extract the geophone from a well completely filled with water and sludge. The basic properties of the upper part of the section (near-surface section) of the studied area are given according to the drilling data with a brief description of the lithological characteristics of the section to a depth of 10 m. Seismograms obtained at one site in different seismic and geological conditions are shown. The dependence of the distribution of values of root-mean-square amplitudes and dominant frequencies over the area on the surface conditions of excitation and reception of vibrations is revealed. This dependence is also observed in the preliminary time sections. The main factors affecting the quality of the obtained seismic material were analyzed. Based on the present study, the authors validate the need for the use of an integrated approach to analyzing the quality of seismic data when working under complex seismic and geological conditions. As a conclusion, the main recommendations for seismic exploration in the estuaries are presented.