Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

The East Siberian platform is a huge habitat of energy resources that potentially contains 8~10 billion tons of oil and 26~30 trillion m3 of gas, and furthur exploration would considerably increase the reserves. The platform is an extraordinary and oldest productive petroleum system on the earth where oils were generated in Precambrian and kept intact since. The platform established on a stable craton consolidated through Archean to the end of Early Proterozoic, and flat-lying, largely undeformed strata of geologic ages covering from Riphean to Neogene were deposited. The source rock is hypothesized to be Riphean organic-rich shales that were deposited in passive type platform margin. Presently, these shales are strongly deformed, variably metamorphosed, and exposed in orogenic belts such as the Baikal-Patom and Yenisey complexes. The major reservoirs are Lower Vendian continental and/or shallow marine sandstones. Porosity of productive intervals ranges from 10 to 15%. Permeability varies widely from near zero to hundreds of millidarcies, and is strongly related to fracturing and diagenetic changes. The preservation of oil and gas for such an extremely long period is attributed to the presence of thick Lower Cambrian salt beds that act as excellent seals. Both structure and stratigraphy played important roles in hydrocarbon generation, migration and trapping. Major hydrocarbon accumulations occurred in structural traps except for the Kovykta field. The traps are anticlinal drapes over basement highs. The Lena-Viluy oil and gas province has the different petroleum system. The source rock is the Permian coal beds, and the Upper Paleozoic to Jurassic clastic rocks consist of reservoir and seal. The Permian coals generate gases owing to the type of organic matter (Type III) and deep burial. According to the maturity data, the Permian sequence entered the oil window in Triassic, and the gas window in Jurassic. The Upper Paleozoic to Jurassic clastics were deposited in variable environments from continental to paralic that include fluvial, lacustrine, paludal, and deltaic environments.