New Information on Subsea Frozen Ground in the Laptev and East Siberian Seas Based on Seismic Data

As a result of five-year studies of approximately 1.3 mln sq km of the East Siberian Arctic Shelf, a boundary between areas with predominant distribution of frozen and thawed ground (Southern and Northern zones) was revealed, new information was obtained on the state of subsea frozen ground, cardinally different from all previous data. For the first time, it was established that in most part of the East Siberian shelf (57.6%, 737 thousand sq km), frozen ground completely degraded, which also reduced the area of possible gas hydrate existence. Frozen ground degraded most intensively on the shelf of the East Siberian Sea (76.9%, 665 thousand sq km). The results were obtained based on seismic records of refracted waves for 176 seismic lines of JSC MAGE and JSC RosGeo with total length of more than 34 thousand km. The correctness of the results is approved by data of drilling of a number of wells, including those of PJSC NK Rosneft. The results have great significance for the forecast of climate changes and increasing efficiency of hydrocarbon resources exploration and development.