| The petroleum exploration results reveal the existence of high temperature oil, but it is difficult to accurately judge and predict the ultimate depth of oil resources according to the traditional theory. Therefore, it is necessary to study how to get the reasonable value of the limit depth of hydrocarbon mixture as stable liquid phase under the burial condition. According to the formation temperature and critical condensate temperature of methane as the final evolution of hydrocarbon, the geological temperature constraint condition with the formation temperature of 300 ℃ and critical condensate temperature of -82.55 ℃ is established, as well as the identification mark of the limit formation temperature of liquid phase with condition of the formation temperature equalling to the critical condensate temperature. The analysis of the intersection point of formation temperature and critical condensate temperature shows that the limit formation temperature for the stable occurrence of liquid phase of methane is 220.82 ℃, and the corresponding buried depth is 5061.32m. For the distribution characteristics of intersection points of formation temperature and critical condensate temperature of hydrocarbon mixture in different periods and the relationship between them and the identification mark of limit formation temperature, it can be divided into four types: convergence, intersection, divergence and disorder, corresponding to different geological meanings and identification processes of limit temperature. Taking the Permian hydrocarbon fluid of well Rong 3 in Jurong Sag as an example, the predicted limit temperature is 192.91 ℃, and the corresponding depth is 5 763.58 m, which is consistent with the distribution range of high temperature oil in the study area. Therefore, the prediction method of the limit depth of hydrocarbon mixture as stable liquid phase based on component detection and phase state simulation is reasonable and applicable. |
