The dissertation is devoted to the solution of the actual problem - geophysical characteristic and examination of geological and petrophysical properties of tight-gas reservoir rocks of Spivakivsky gas-bearing area of DDB, and also offers usage a technique for allocation of the most perspective intervals in order to perform an intensification and industrial exploration of central-basin gas deposits.
Based on the results of laboratory studies of the core material, which was lifted from wells that revealed upper and middle Carboniferous deposits of Spivakivsky gas-bearing area and included routine (measurement and determination of open porosity, gas permeability, bulk and mineralogical density, and carbonateness), special (determination of the residual water saturation and compression limits of the samples), macroscopic description of the full-size core, and also studies of rock sections under the microscope, allowed to characterize the lithological and petrophysical properties of tight gas reservoirs A complete analysis of these results allowed to identify three systems of fractures in the full-size core material: the most pronounced and developed - subvertical fracturing, layer fractures and curved fractures, oriented at different angles to the core axis. The void space is composed of intergranular and compaction voids, and voids in clay minerals. It is established that low reservoir properties are caused by catagenetic transformations, but not by lithological features. Reservoirs properties measured by the core are: φ - 4.5-9%, k - 0.01 - 0.5 mD, Sw,i -68-82%; and the volumetric parameters for Kasimovian and Moscovian deposits: φ, in - 4.5-10.5%, Hef - 7.1-24 m, Sg-37-65%.
First determined the structure of the void space of upper and middle Carboniferous sediments, tight gas deposits of Spivakivsky gas-bearing district. The main type of pores in the studied void space are: intergranular, tight voids and microfractures. It is determined a relationships between increasing in the total volume of voids and simultaneous increase in the number of intergranular voids and tight voids. It is established that the major of the void space is intergranular voids, their content varies from 2 to 5.7%. Tight voids are present in all intervals and their amount is 0.5 - 7%. As for fractures, the upper ones mentioned are present in almost all intervals, their content ranges from 0.002 to 0.33%. The presence of microfractures is quite important in the study of tight gas deposits, and the results of modeling the structure of the void space and the allocation of fracture zones showed the prospect of Svyatogirska area intervals (considering that the fractures porosity coefficient in the intervals more than 0.1%).
A multi-mineralogical model has been built and refined for tight gas reservoirs of the Moscovian stage. Using the modelling results, we obtained a coherent synthetic bulk density log, information, which is extremely important during modeling the elastic properties of the geological environment.
For the first time for the studied region the possibility of modeling of the shear wave velocity from a limited set of logging data and empirical equations (Greenberg-Castagna equation) and the results of modeling a multimineralogical model was shown in practice. During applying the real curve obtained after the interpretation of the materials of the monopode acoustic tool, and synthetic, there is a difference in the intervals of sandstones, which caused the influx of gas. For potentially productive compacted rocks - reservoirs, the value of the removed DTS curve is higher than the DTS modeled by 5.9% - 24.2%.
According to the results of laboratory research of samples porosity and capillary pressure curves, during calculating reserves, it is proposed to use the limit value of the open porosity - 4.5%.
When comparing the synthetic and real velocity curves of S-waves, intervals with a porosity value close to the limit were identified and considered as promising.
