Sedimentary-migration of the magmatic hypothesis for the formation of oil

Abstract

As a result of physical and chemical modeling of hydrocarbon formation conditions at the Ereminsko-Chonsky oil cluster (Leno-Tungusskoy oil and gas province), it was found that at the stage of sedimentogenesis at (T = 35 °C, P = 0.1 MPa) methane and organic matter accumulate at the bottom of the reservoir. With diagenesis (T = 60 °C and P = 5-10 MPa) at a depth of 60-100 m, films and oil droplets are observed in the formation of source formations in rocks, pentane C5H12 appears from liquid hydrocarbons. At the stage of catagenesis at a depth of 250 C6H14 hexene is formed, and at 2000 m - C7H16 heptene, at 3100 m - octane C8H12 and at 3800 m (at T = 90 °C and P = 110 MPa) - nonane C9H20. During the period of apocatagenesis and metamorphism (at T = 105 °C and P = 450 MPa), C10H22 dodecane is formed at a depth of 13-15 km, and C11H24 undecane is formed at T - 200 °C. When the temperature rises to 250 °C and the pressure reaches 490 MPa, at a depth of about 15 km, a large group of liquid hydrocarbons from dodecane C12H26 to pentadecan C15H32 and solids from hexadecan C16H34 to octadecane C18H38, as well as other groups, form in the basement rocks. When the pressure becomes 850 MPa, isoprenoids are observed at a depth of 25 km: from C19H40 to nonadecane to C24H50 to tetracosane, etc. Based on the simulation, it becomes obvious that it is not possible to explain the conditions for the formation of hydrocarbons in the range up to 25 km using only one of the hypotheses biogenic or abiogenic and a new sedimentary-migration-magmatic hypothesis of oil formation is proposed. Its essence is as follows: to a depth of 3800-4000 m, the source of hydrocarbons is methane, which accumulates at the bottom of water bodies, and organic matter of rocks, and at a depth of 13-15 and 25 km - mantle deep methane.