Forecast of Unconventional Reservoir in the Clay-carbonate Sediments of the Lower Triassic of the East Manych Trough

Abstract

Summary For the first time the pecularities of shales (argillites and argillaceous limestones) of the Lower Triassic Formation of the East-Manych depression (the North Caucasus) as non-traditional reservoirs for a shale gas resources are discussed. The comparison (geochemical and petrophysical information) with the Lower Cretaceous Pearsall Formation ( South Texas) is completed. The Pearsall formation is in the dry gas window of hydrocarbon generation (mean random vitrinite reflectance values, Ro=1.2–2.2%). For organic matter of the Lower Triassic Formation Ro ranges from 1.16 to 1.75%. Conventional petrophisical measurement techniques of the Pearsall core samples indicates that porosity ranges from 1.6–6.7 to 10%, similar to that for shales of the Lower Triassic Formation − 5%. Ordinary permeability measurements range from 0,003 to 0,062 md in the cores of the Pearsall Formation and 0.3 md in shales of the Lower Triassic Formation. There discovered closed and opened fractures in this formation to 5000m, but they are absent in the Formation Pearsall. Using our three inventions we found the genesis of these fractures.