Oil-Gas Prospects of Jurassic Sediments of the Middle Ob Region

Sandy beds compose 15-35% of the total thickness of the Tyumen formation. These beds are distributed quite evenly along th e section. In the Vasyugan formation sandstones occur everywhere in the upper half of the formation and constitute up to 50% of t he total volume. Sandy beds are completely absent in the sec tions of the Abalak, Georgiyev, and Bazhenov formations. Two oil-gas-bearing complexes are present in the Jurassi c sediments: Lower-Middle Jurassic and Upper Jurassic. The oil pools in the Lower-Middle Jurassic sediment do not amount to much; they are not at present of much commercial interest.