The Preliminary Results of the Yurkharovskoe Field (West Siberia) 2D Petroleum System Modeling

Sergey Astakhov

"2D petroleum system modeling (PSM) of the Yurkharovskoe field is conducted in order to understand distribution of the hydrocarbon accumulations. The another main purpose of numerical simulation is to reduce risks when making the exploration decisionsThe field has the several zones of gas and gas-condensate reservoir systems accommodated within Upper and Lower Cretaceous. The most prominent having the largest volume is Cenomanian dry gas reservoir. The main exploration trend at the moment is the Tyumenskaya suite (Middle Jurassic terrigenous formation) which is situated below the main producing reservoirs. The two wells were drilled and have penetrated upper intervals of the Tyumenskaya suite. One of the wells penetrated into the pay sands with the commercial gas-condensate inflow. However, the second well has the negative result (water inflow), despite the fact that the target hypsometric level is more higher in respect to the first well. Another problem is the historical question about the origin of dry gas Cenomanian reservoir all over the north part of the West Siberia Megabasin. The initial phase combined the various seismic data in order to obtain a compositional depth seismic section from Yamburg ridge (with the same name super-giant gas-condensate field) stretching to the west part of the Bolshehetskaya depression. The coulisse section visualize a local depression between Yamburg and Yurkharovskoe ridge incusing the gas-condensate field being the object of the investigation. The correlated horizons were used for further lithological and geochemical facies constrain. The final result is extremely sensitive to the geothermal evolution of the basin due to changing of the geodynamic conditions. The “dog leg” shape of the measured vitrinite reflectance vs depth profiles is substantiated by the Triassic and Jurassic hydrothermal activity (Galushkin, 2007). Additonally, restoration the paleowater depth is the other boundary condition having a strong influence for the modeling results. The parameters are derived from the sedimentological investigation of the rock samples taken from the core The method used to solve the geological problem is the iterative searching of the best model fit by performing different scenarios of 2D basin modeling. Initially, the lithological model of the sand bodies (lenses) with facies transition zone from deltaic to shallow marine is considered. By the several scenarios (simulation runs) it was shown the critical importance of the fault tectonics for Middle Jurassic petroleum system effectiveness in Tyumen suite reservoirs. The preliminary result implicates following initial conclusions: - The big part of the Cenomanian dry gas has the origin from the deepest source rocks (most likely Triassic suite and Lower Jurassic); - The case study exhibited applicability of the method, i.e. a potential use of PSM to make a prognosis of accumulations in thin bedded sand lenses such as Tyumenskaya suite. "

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013