Reliability of results of use of complex geophysical studies in the process of control of development of oil and gas deposits

Abstract

The paper considers modern methods for determining the position of gas-liquid contacts in terrigenous deposits at oil and gas condensate fields in Ukraine. The results of laboratory studies of a representative core collection (87 samples) in the petrophysical laboratory of IFNTUOG made it possible to establish the reservoir parameters and lithological characteristics of reservoir rocks of Carboniferous and Neogene sediments, which made it possible to reliably estimate the reservoir parameters of productive formations. The results of well studies, in particular, obtained during the isolation of oil and gas-saturated reservoir rocks and monitoring the dynamics of changes in oil-water and gas-water contacts, made it possible to form an optimal informative complex of geophysical methods for effective prospecting and development of oil and gas fields. Direct studies of the identified reservoir rocks made it possible to establish that the geological sections of the Jurassic, Cretaceous and Neogene systems of prospecting areas are filled with both hydrophilic and hydrophobic lithotypes of rocks, which have different effects on the readings of electrical and radioactive methods. Reasonably, the maximum value of the electrical resistivity, the maximum oil saturation coefficient (Кo), as well as the minimum value of the water saturation coefficient (Кw), which is typical for oil and gas-saturated formations, must correspond to the condition for displaying these parameters in completely water-saturated rocks. In this case, the boundary of the transition zone will be displayed by the bottom of the maximum radio-saturated layer and the top of the aquifer in this rock. Confirmation of the above is seen from the fragments of geophysical data processing, electrical and neutron studies in the presence of low and high salinity, drilling fluids and drilling fluids. The analysis of the efficiency of using the methods of pulsed neutron-neutron logging (PNNL) and neutron gamma-ray logging (NGL) when monitoring the change in the position of the GLC to prevent watering of productive formations is carried out. According to the research results, it is proposed to use a complex of nuclear physical methods in the process of monitoring the dynamics of changes in NWC, in particular, neutron gamma logging, repeated neutron logging, as well as in the process of drilling conducting electrical methods of imaginary resistance and unauthorized potentials.