Lower Cretaceous Aptian-Albian formations - new exploration play in Shaim region

Abstract Lower Cretaceous Leushinskaya (LSH) and Vikulovo (VK) formations have recently tested oil and gas for the first time in the Shaim Region located in the western border of West Siberian Basin (WSB). Before that, these formations were known as hydrocarbon reservoirs only in Krasnoleninskoye region (Kamennoye field) where they produce oil from VK sandstones and siltstones. The presence of commercial gas accumulation in the Cretaceous section in this part of the basin is also new, as no gas fields had been discovered before 2013. The aim of this paper is to present the evaluation of a new play and new reservoirs for this region in the Vikulovksaya and Leushinskaya formations. The main studies and their results are shown. The evaluation comprises the following works: –2 D seismic interpretation, including the identification and evaluation of "bright spots"–Core analysis – lithological description and sedimentological study, which was used later for correlation verification; petrophysical analysis – routine and special.–Wire line log interpretation of exploration wells, which was challenging due to lithology of the formations. As a result of those works, Ourinskouye field was discovered in 2013. Two oil and gas deposits were defined and evaluated within Leushinskaya and Vikulovskaya formations. Based on 2D interpretation and core sedimentological analysis gross depositional environments were defined. As a result of wire line log evaluation – main parameters for in place volumetric calculations were acquired. According to the Minprirodi report, Ourinskoye field is the largest discovery in two years in West Siberia basin.