Tectonic Development of Yenisei-Khatanga Regional Trough and its Influence on Petroleum Systems Evolution

摘要

The study area is located in the southern part of the Taimyr Peninsula: from Lake Taimyr in the east to left bank of Yenisei river and Yenisei bay in the west. The complex tectonic history of the YKRT had influenced the nature of the generation, migration and accumulation of hydrocarbons in region thought time. The beginning of the search for hydrocarbon deposits is timed to the 30s of the last century. Searches were mainly conducted on swells. There is no large discoveries of hydrocarbon fields in region. One of the reasons for this is the underestimation of the role of tectonic events in the accumulation of hydrocarbons. Paleotectonic reconstructions of regional seismic profiles fragments were carried out in order to clarify the structural-tectonic model of the development of YKRT. The obtained patterns of tectonic development were taken into account when restoring the evolution of the elements of hydrocarbon systems with three- dimensional basin modeling. Basin modeling is a method of studying the subsoil, which allows integrating into a single model a wide range of geological and geophysical information. The simulation results allow to predict and localize oil and gas accumulation zones. As a result of paleotectonic reconstructions, it was possible to restore the history of the region. Basin modeling allows one to estimate the accumulation of hydrocarbons, and trace in time the formation and destruction of deposits. Also simulation results grant ability to compare history of accumulation with different stages of the basin development. The start of the YKRT formation is associated with triassic rifting. Subsequently, the region experienced a series of tectonic activation episodes. Because of structural inversion in the Late Triassic era, an asymmetric swell was formed. The next activation was timed to the end of the Jurassic period. At that time the regional system of strike–slip faults and the megaswells were formed. The final episode of activisation is timed to the end of Oligocene time. At that stage territory of the YKRT experienced general rise, the reactivation of strike–slip faults and the growth of swells. Analysis of hydrocarbons accumulation through time reveals a good correlation between the volumes of accumulated hydrocarbons and the main stages of the basin evolution. Results of this analysis help to identify the main stages of the formation and destruction of hydrocarbon deposits. The tectonic activity of the region and erosion processes were the determining factors for the accumulation of hydrocarbons. Thus, because of tectonic activisation of region at the end of Jurassic period more than 50% of the accumulations were destroyed. Results of the performed comprehensive analysis allow to take a fresh look on YKRT oil-and-gas-bearing potential when conducting further geological prospecting and exploration works to discover gas and oil. The most promising territories are associated with the submerged parts of the region — Central Taymyr and Boganida-Zhdanikha chutes.