The structure of the pore space of Tournaisian reservoir rocks in the southeast of Tatarstan Republic

Abstract

The article shows the main types of structures of the porosity of the Tournaisian reservoirs from the southeast of Tatarstan. The main type of pore space is intergrain porosity, while the fractures have a subordinate significance. They are analyzed in detail main factors of the origin of the pore space of the Tournaisian reservoir rock. There are include depositional, diagenetic, structural and tectonically factors. The depositional factor is the selectivity of rock types as reservoirs, only two lithological types of limestone have industrially significant reservoir properties and represented by peloidal and crinoid-peloidal packstones. The diagenetic factor realizes via secondary leaching of carbonate rocks during burial diagenesis of rocks. Leaching processes provide the main increase in rock porosity. On the one hand, the structural and tectonic factor provides the possibility of oil charge in the structure, on the other hand, it shows the heterogeneity of the distribution of porosity depending on the position of the reservoir rocks on the structure. The highest porosity values are characteristic for the crest part, lower for the flanks and minimal for the deflections of the oil-bearing structures.