The paper is aimed at the one-dimensional petroleum system modeling in a well section of the Tolonskoye gas-condensate field. Tectonically, it is confined to the Khapchagai megalithic bank located in the central part of the Vilyui hemisyneclise. The modeling identifies burial and thermal history of the sediments in the Paleozoic, Mesozoic and Cenozoic, quantitive evaluation of generation power and oil-window- and gas-window-entry time of the source rocks. According to the present research, the Kuonam source rock reached up to the oil window 449 Ma in the Katian age and gas window 410 Ma in the Pragian age. The Permian source rock top reached up to the oil window 249 Ma in the Olenekian age. The Permian source rock middle did to the gas window 258 Ma in the Wuchiapingian age. The Kuonam source rock had already been beyond the oil and gas windows by ending the sedimentation of the Nedzhelin and Monom seal rocks for the Upper Permian and Lower Triassic reservoirs. There was consequently no appropriate environment for the hydrocarbon accumulations generated by marine organic matter to be preserved. The Permian source rock top and middle are found to be in the oil and gas windows at the present time, respectively. The hydrocarbon accumulations principally generated by terrestrial organic matter can therefore be in the Upper Permian and Lower Triassic reservoirs. Maximum temperature values and rapid change in organic matter maturity in the Late Permian and Early Triassic imply trap rocks in the sediments. Generation power of the Kuonam source rock and Permian source rock bottom is completely exhausted. The Permian source rock top, by comparison, is of significant generation capability. The generation balance of the source rocks is 18.942 BT of hydrocarbons (hydrocarbon equivalent), with the Permian source rock contribution being essential. The remaining source rock potential is 5.187 BT of hydrocarbons (hydrocarbon equivalent). Complying with the initial commercial reserves of the Tolonskoye field the reservoir balance is up to 0.7 % in relation to the generation balance.
Acknowledgement. The reported study was funded by RFBR, project number 19-35-90039.
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