Hydrocarbon generation characteristics of Qingshankou Formation shale in Songliao Basin based on organic geochemical parameter correction

Abstract

Summary Due to the influence of hydrocarbons especially adsorbed hydrocarbons on the detection of organic geochemical parameters S2 and TOC, the hydrocarbon generation model established deviates from the actual situation. This study takes Qingshankou Formation shale of Songliao Basin as an example and establishes a set of correction method. Through correction, the actual hydrocarbon generation model was established, the adsorbed hydrocarbon content were clarified. The results show that the measured parameter values are greater than the actual ones, which leads to the “lag effect” of the hydrocarbon generation model established based on the measured value, and prolongs the hydrocarbon generation window of organic matter; The organic matter enters the hydrocarbon generation threshold at Ro∼0.5%, reaches the hydrocarbon generation peak at Ro∼1.0%, and hydrocarbon generation process basically ends at Ro∼1.3%; The content of adsorbed hydrocarbons is a dynamic change process and can be divided into three stages based on maturity Ro: 0.5∼0.9%, 0.9∼1.3% and >1.3%, showing the characteristics of “first increasing, then stabilizing, and then decreasing”. Ro between 0.9∼1.3% is the most abundant stage of adsorbed hydrocarbon, up to 6mg/g-rock. The heavy hydrocarbon correction coefficient of S1 decreases with the increase of maturity, and the average value is 2.52.