Structural Controls on the Formation of Coalbed Methande Accumulations in the Donets Basin

Abstract

The Donets Basin (Ukraine/Russia) contains one of the major coalfields in the Europe. Thermal maturation of concentrated in coal seams and dispersed coaly mass has led to formation of an enormous methane resource. The hydrocarbon system of the study area has a strong structural component in relation with releasing jogs within the intrabasional principal displacement zone (PDZ). Results of 2-D numerical models were used to reconstruct gas migration routes and to localize deep-seated methane accumulation zones. We inferred that the higher amounts of trapped methane are located at 4 km depth with estimated maximum values of 38 Mt of methane within the junction of the Kalmius-Torets and Bakhmut Depressions with strong structural control by non-inverted pull-apart jogs. During multiple Cimmerian-Alpine dextral reactivations of PDZ these jogs had been served as dilatational domains and the most favorable places for localizing of abnormal heat flows and hot fluids transport responsible for thermogenic gas generation with further trapping in high-permeability and fractured secondary reservoirs.