Role of Elisional Water Exchange in the Hydrodynamic Field Formation in the Yamal–Kara Depression

Аннотация

Unique material pertaining to the hydrodynamics of petroliferous rocks in the Yamal–Kara Depression has been summarized for the first time in the last 30 years. The region is distinguished by a wide development of anomalous high formation pressure (C_a up to 2.21) in both Jurassic and Lower Cretaceous rocks. Results of the study of filtration-capacity properties and hydrodynamic characteristics of reservoir rocks in the Jurassic–Cretaceous section suggest a dominant role of the elisional water exchange in the formation of modern structure of the hydrodynamic field. Elisional lithostatic system located at a depth of about 2–2.5 km begins to acquire features of elisional thermodehydration. At the current development stage of the basinal aquifer system, spacious piezomaximum zones (Bol’shaya Kheta and Kara megasyneclises) became internal water load (supply) zones with the maximal hydrogeological closedness in the Earth’s interior. Piezominimum zones extending along the main centers of oil-and-gas generation match the largest oil-and-gas fields (Vankor–Suzun, Bovanenkovo, Urengoi, and others). At present, we can define in the study region two types of natural aquifer systems: (i) elisional type prevailing in the internal sectors (e.g., Yamal–Kara Depression); (ii) infiltrational type prevailing in the external (marginal) sectors (West Siberian sedimentary basin).