Summary

Regional cross-sections were modeled using 2D hydrocarbon generation and fluid flow modeling software (IES Petromod v3.0). Modeling was done to determine time of hydrocarbon generation and expulsion relative to trap development, reason for hydrocarbon emplacement in Upper and Middle Carboniferous, Permian and Triassic reservoirs and reasons for water wet, but good quality lower Carboniferous reservoirs. Modeling focused in the Kolva Swell and Khoreyver Depression areas. Major conclusions obtained from 2D modeling are: 1. Vertical fault migration is required to explain hydrocarbon distributions in the North Timan Pechora basin. The vertical extent of faults will control the degree of charge in Upper Carboniferous and Permian reservoirs. Lack of faults will still result in charge to lower Visean (Tournasian) section from vertical migration. 2. Modeling the Carboniferous Serpukhovian (C1s) interbedded limestone and evaporites as a continuous facies results in overpressures in Devonian reservoirs, and allows charge of Lower Carboniferous reservoirs. Charge of Permian and Lower Carboniferous reservoirs from Devonian and/or Ordovician sources is possible if Devonian reservoirs become overpressured, and are hence bypassed during vertical migration of hydrocarbons along faults. A discontinuous C1s seal facies will result in primarily charge of Devonian reservoirs with oil and gas of moderate GOR and some charge of Permian and Lower Carboniferous Tournaisian (C1t) reservoirs with gas and high GOR liquids. 3. In the Kolva Swell area where Permian reservoirs are present-day charged with oil and retrograde condensates, the C1s seal facies may be, or have been in the past, more continuous to allow vertical charge of these reservoirs. Another explanation, not tested in the modeling is that Permian reservoirs to the north were charged by greater fault throw. Based on model results, wet Permian reservoirs are not likely due to charge timing problems, but to potential for vertical migration governed by pressure regime.