In the last few years in Donetsk basin, the gas content of the coal formations got definite prospects. There are the open gas fields in coal-bearing series already in the northern part of Donbass and Donetsk-Makeyevskyy coal areas. Presently the determination of the prospects of gas content of the other areas of Donbass is an urgent question, including Central coal area where there is the field of “Novodzerzhinskaya” mine.
The aim of the research is examination of the peculiarities of the tectonic structure and formation fields of western abridgement of Gorlovka anticline, as well as the structural and tectonic-physical characteristics of gas sources forecasting.
The main idea - the location of the gas traps is conditioned by structural tectonic-physical characteristics of rock massif.
The research object - western abridgment of Gorlovka anticline.
The research subject - tectonic structure and deformation fields of western abridgment of Gorlovka anticline, their connection with the gas sources.
In geological structure of the field of “Novodzerzhinskaya” mine there are the sediments of set of rocks С25, С26, С27 of middles section of carbon and partially С31и С32 sediments of upper carbon. Lithologically the coal bearing deposits are represented by interleaving of argillite, aleurolite, sand-rock including narrow bands of limestone and coal. The coal-bearing deposits are almost everywhere on the territory blocked by quaternary formations consisted from various genetic type of rock and soil stratum, loess-type clay and loams. In tectonic sense the field of Novodzerzhinskaya mine is situated on the periclinal closing of the basicс fold structure of Donbass – Main anticline. The main anticline – is a typical line fold followed through the whole southeastern direction of Donetsk basin. On the western abridgment within the bounds of which the estimated area is situated, the anticline is characterized by asymmetric structure.
During the processing of materials and interpretation of the results the computer programs were used, designed by GIN Russian Academy of Science, DonNTU, Institute of Physics of the Earth of Russian Academy of Science and Moscow Geological Prospecting Academy. Mainly the computer program GEOS was used. Reconstruction of the fields of tectonic deformation and tectonic stress are realized in accordance with the methodology of kinematics analysis of fractureв-tearing structures, developed by O.I.Gushchenko, Mostrikov A, Vasylyev N.V. etc. The input data were joined into the groups (84 groups) per 20–30 and more fractures in accordance with the location in the survey points (points were situated evenly as far as possible along the minefield) for the reconstruction the field parameters there. Then the value of total deformations field parameters in each mesh point was calculated according to the smoothed data, based on the results of polish. The axis orientation of basic normal deformations (E1, E2, E3,) were defined, their correlation (Lode-Nadai coefficient — Meps), also the relative amount of vertical component of strain ellipsoid (z-component). The axis orientation of deformations fields enabled to evaluate the direction of tectonic movements. The values of Lode-Nadai coefficient enabled to determine the distribution of the zones of rock massif compression and expansion. Z-component of strain ellipsoid is characterized by relative vertical movements. It be should noted that only total tectonic deformations are examined; (only brittle deformations are implied). When the results in GEOS are received with the help of Excel, the sorting by value of Lode-Nadai coefficient — Meps was composed and relative amount of vertical component of strain ellipsoid (z-component), which were used for the further researches. For the maps development of indices value distribution the software package Surfer was used, that allowed graphically demonstrate the digital information (distribution of Lode-Nadai coefficient values and z-components along the horizontal of “Novodzerzhinskaya” mine).
At the result of the researches and actual material processing the orientation of the basic normal deformations (E1, E2, E3) was determined (fig.1), their proportion (coefficient Lode-Nadai — Meps)(fig.2), and the relative amount of vertical component of strain ellipsoid (z-component)(fig.3).
Fig.1 Scheme of total deformation field of “Novodzerzhinskaya” mine: 3- calculation marks of field parameters of deformation with the direction of one of the strain axis; 1-7 – type of deformation field: 1- strike-slip, 2- thrust-strike-slip, 4- fault-thrust, 5- fault-strike-slip, 6- thrust, 7- fault
Fig. 2 Distribution Scheme of Lode-Nadai coefficient value.
Fig. 3 Distribution scheme of value of Z – component.
In the result of the conducted researches, up-to-date data were received about the field characteristics of the total tectonic deformations of western abridgement of Gorlovka anticline. In the consequence of the calculations, the values of Lode-Nadai coefficients were received (Meps) and vertical component of strain ellipsoid. After comparison of which on the test section the zones were revealed that are situated in conditions of stretching and uplifting of day surface. The areas that are in such conditions in equal measure, could be favorable for gas accumulation of (gas traps).