Effects of thermal cracking of hydrocarbons on the homogenization temperature of fluid inclusions from the Niigata oil and gas fields, Japan

In the Shin-Kumoide SK-1D well of the Niigata oil and gas field in Japan, the Th of hydrocarbon inclusions decreases from 73 to 30 °C between 4040 and 4810 m in depth successively. This temperature range is lower than the present formation temperature by from 60 to 140 °C, and shows a trend opposite to the normal geothermal gradient. Therefore, it should reflect the degree of the thermal cracking after trapping rather than the trapping temperature.