KARST ZONES. VERY IMPORTANT TARGETS IN THE SEARCH FOR HYDROCARBON POOLS IN THE CARBONATE SEQUENCES OF THE SIBERIAN CRATON

Abstract

Most oil and gas pools found in the Lena-Tunguska oil and gas province of the Siberian craton are known to be confined to granular or fractured-granular reservoir rocks in clastic sandstone-siltstone strata. Such rocks form the basal beds of regional and zonal cyclic units ('cyclites') of Vendian-Cambrian age in the Moty group and are the main target in the search for new hydrocarbon pools in this vast province. The most urgent problem of systematic lithmologic investigations is to outline the already observed zones of fractured-cavernous karst reservoirs and find new ones among carbonate strata of the Siberian craton. Besides regional hiatuses and related zones of karst-cavern formation, the zonal hiatuses bounding zonal cyclites, levels and zones with reservoirs of this type may also be of practical importance.