Facies Control of Reservoir Distribution in the Lower Devonian Deposits on the North-East of Timan-Pechora Basin

The Lower Devonian deposits (Ovinparm horizon) of the North-East of Timan-Pechora basin is mainly composed of dolomites and to a less extent of limestones and argillites. The accumulation of the Lower Devonian sediments took place in the shallow sublittoral zone and the adjacent vast tidal plain. Sedimentation heterogeneity of the Lower Devonian deposits caused different intensity of their post-sedimentation transformations such as leaching, dolomitization and fracturing, which effected complex morphology of the pore space. Data acquired in this research show that the secondary dolomites of the carbonate shoals facies and sublittoral facies with bioclastic-microbial-algal sedimentation are the key reservoirs of the Lower Devonian deposits.