Thermal history of the permafrost zone in the vicinity of the deep Tyumen SG‐6 well, West Siberian Basin

A new software package, ICE2020 of the GALO basin modeling system, is used here to model the thermal evolution of permafrost zones in a sedimentary section of the Tyumen SG‐6 well in the Koltogor–Urengoy graben of the West Siberia Basin. Reconstruction of permafrost evolution during the last 3.5 Ma is considered as the final stage of the modeling procedure of the basin, the history of which began with continental rifting in the Late Permian. The modeling uses a real sedimentary section of the basin with the correct lithological composition of its rocks. Application of the ICE2020 package made it possible to evaluate the influence of sedimentation on the formation of permafrost zones. The calculations showed that climate variations during the Late Pliocene–Holocene led to a reduction in rock temperatures by 15–20°C in the upper 1,500 m of the sedimentary section of the SG‐6 well and by 5–10°C in the deeper layers of the section. At the same time, the results of calculations with a climate curve limited to the last 50,000 and 100,000 years differ markedly from simulations with a climate curve of the last 3.5 Ma.