Effect of Hydrate Formation on the Gas Permeability of Turonian Low Cemented Reservoirs

Summary Turonian reservoirs of the Western Siberia are one of the most promising hydrocarbon sources of the above senomanian sediments. However, gas reserves, associated with the Turonian deposits, are difficult to recover, due to the peculiarity of their composition, occurrence conditions and the properties variability course by possible hydrate formation. In this regard, the experimental modeling of the gas permeability of Turonian siltstones, characterized by low absolute permeability, under favorable conditions for hydrate formation were carried out. Experiments of gas filtration through moisture-saturated samples of Turonian siltstone under P-T conditions of the methane hydrate existence present gas permeability decreases caused by significant pore hydrate accumulation. In this study it was revealed that the hydrate accumulation and gas permeability of the Turonian siltstone is greatly influenced by their moisture content. So, with moisture saturation increasing from 57% to 75%, the total permeability naturally decreased, and the variations of gas permeability under conditions of hydrate formation were significantly reduced. It can be explaining by lower hydrate formation intensity caused by high degree of pore water saturation. The obtained results provide an opportunity to assess the optimal moisture content of Turonian siltstones, which causes the maximum gas permeability reduce by hydrate accumulation.