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Results of an experimental study of local velocity, fluctuation and void fraction profiles in liquid plugs of an upward vertical gas-liquid flow as well as of wall shear stress distribution both under gas slugs and in liquid plugs, are presented. The conditional sampiing technique allowed to obtain instantaneous profiles of the above hydrodynamical quantities, which illuminated the real physical picture of the flow in a liquid plug. The toroidal vortex adjacent to the bottom of a gas slug is shown to determine significantly the development of the flow in a liquid plug. The intensity of this vortex is determined only by the relative velocity of the gas bubble with respect to the liquid.

In this study, the description of Enhance Oil Recovery effectivity (EOR) of surfactant denominated reagent A, at the secondary waterflooding process for heavy oil recovery from fractured-porous carbonate core samples were investigated experimentally. For this experiment have been selected two cores, 14,75 cm long and 3 cm diameter were stacked in a long 3D confining core holder. In the first step, cores have been saturated by brine. In the second step, cores have been saturated of heavy oil through the water-saturated core sample for two-phase saturation. In the third step, we provided the injecting of water through the core sample for measuring oil recovery factor (by cold water 20ºC) simulating the primary recovery at these conditions. In the fourth step, was injected of 2 pore volumes of Reagent A through the core sample for measuring oil recovery factor (by reagent A) and simulating the slug. In the fifth step and final, was injected water through the core sample for measuring full oil recovery factor (by cold water) after slug of Reagent A. In the course of experiments, oil and water productions, pressure and temperatures of system were monitored and regulated carefully.

Hydrocarbon exploration in carbonate and shale deposits seems to be less efficient than exploration of terrigenous reservoirs in the Timan-Pechora Basin. This disparity is due to a number of factors, chief of which are complexity of geological structure in areas of carbonate and shale reservoirs and complexity and unpredictability of porosity and permeability. Therefore, considerable heterogeneity of carbonate and shale reservoirs reduces efficiency of prospecting, exploration and engineering of oil deposits in carbonate reservoirs. The study of carbonate and shale reservoirs, which formed in different periods in the Timan-Pechora Basin, has highlighted importance of tectonic fractures in the evolution of complex reservoirs. These fractures are formed during local tectonic folding. The pervasive faults and fractures generated during these folding episodes in carbonate and shale rocks promote active filtration and leaching by surface and subsurface waters, containing corrosive components (CO2, H2S, etc.). Highly permeable fracture zones, which are called sweet spots, affect the processes of hydrocarbon migration and oil-gas accumulation. Exploitation experience at Usinsk, Kharyaga, Upper Vozey and other oil fields has shown, that sweet spots influence processes of oil pool formation. It is necessary to take into consideration such sweet spots when the optimal system of reservoir engineering is chosen. An integrated exploration method has been developed for finding and delineation of sweet spots. This method includes analisys of seismic and gravity exploration data, aero-space photo-interpretation, well logging data, results of core and drilling data interpretation. The use of integrated exploration is proven to be effective in finding sweet spots in carbonate and shale reservoirs. It has also enabled greater understanding of the complexities, geometry, and tectonic relationships of sweet spots formation.