Nowadays, the exploration of unconventional reservoirs is a big challenge, therefore large investments have been made ​​in order to the develop technologies for understanding and drilling these kind of reservoirs. The Helium survey has proved to be effective in unconventional fields, for instance, a tight sandstone area in the Aprelskoye field, District Beloyarski in Western Siberia. The reservoir belongs to the Tyumen Formation of low permeability. The field was discovered in 1982 via a first well outside the Helium survey area. The oil reserves are concentrated in the terrigenous sediments of Jurassic age from lower - middle.

 

         In summary, the geology of the Tyumen formation consists of alternating sandstones and shales, and conglomerates with gravelites in the basal parts. The genesis of the formation is continental and involves large variation in thickness of the productive sandstones, with low correlation to one another well, even at small distances, resulting in the alternation of dry holes and productive. The sediments are strongly compressed and have primary intergranular porosity. The flow of high commercial oil production has only been possible in areas where there was the formation of secondary porosity. The layers are characterized by low sand content and are intercalated with siltstones, sandstones and shales (average permeability is very low: 58 mD).

 

       The Aprelskoye field where the Helium gas survey has showed characteristics of lithological traps of stratigraphic character (no structural trapping). In 2006, the Helium survey was done at the same time that the well 5 was being drilled (see map on the right). The result was a dry well. In 2007, after Helium prospection and following AGI's recommendations, well 6 was drilled, which had flow of 30 m3 of oil per day (164 bbl / day). The gray areas represent the high oil prospecting zone.