A.A. RYASNOY (VSEGEI), E.N. SAVELEVA (RN-­BashNIPIneft)

Influence of secondary processes on reservoir properties of carbonate rocks in the Vereysky oil and gas field (North­West of the Republic of Bashkortostan)

Detailed lithologic and petrographic studies were carried out. It was identified that the Vereysky horizon rocks are represented by twelve main lithotypes, which dramatically differ in the character of interrelation between reservoir parameters that is controlled by secondary (postsedimentary) processes. Data of optical­microscopic examinations and laboratory studies of the poroperm properties made it possible to identify that the postsedimentary processes such as leaching, calcitization, recrystallization, silification and sulphatization are the main factors affecting the reservoir properties of carbonate rocks. Structural and textural features of reservoir rocks of the Vereysky horizon and the degree of their postsedimentary transformation are reflected in the character of distribution and interrelation of reservoir properties across the section.
Keywords: Vereysky oil and gas field, carbonate reservoirs, postsedimentary processes, porosity, permeability.