PETROLEUM FORMATION AND THE THERMAL HISTORY OF THE EARTH'S SURFACE

Abstract

Petroleum reservoirs are known to depths of‐10 km, and their ages extend to ‐ 700 m. y. † Since ltemperature is important to petroleum‐forming processes, the thermal history of this region is analyzed. From the geologic record, average surface temperature values are derived for recent geologic time adn 2.5 b. y. BP. These data are applied to the Newton cooling law to obtain a value of 2.63×10‐11 yr‐1 for the heat transfer constant for the Earth surface/space system. This in turn, yield an approximate average cooling rate for the surface of 7°C per b. y. Profiles of average surface temperature over geologic time are constructed for high, middle and low latitudes. Respective initial average surface temperatures at these latitudes were 13.6°, 41.6° and 59.6°C. Two tests are applied to the cooling curves to cheek their validity. First, they are used with teh rate constant for the mantle outgassing of water vapor and the Clausius‐Clapeyron equation ot calculate the accumulation and average temperature of liquid surface water over geologic time. The results are consistent with teh geologic record pertaining ot the history of water‐borne sedimets, glaciation and life. Second, the calcualted thermal characteristics of the surface are compared with publushed date for the mantle. They agree to within 2%. The surface < 10°C for the temperature change of a petroleum resrvoir buried at a depth of 10kkm over the past 700 m. y. The change for reservoirs of resrvoir age ot petroleum‐forming processes lies mainly in the increased opportunity for geologic change such as depth of burial or igneous actifity that would alter conditions within the reservation.