Characterization of source rocks is one of the most important goals in oil exploration. The lack of core samples in most of the drilled wells is a problem in characterising source and reservoir rocks. Many attempts are introduced to evaluate source rocks by using open-hole logging data. In the present study wire line logs (GR, RD, ROHB, PHIN and DT) are used to characterise the Upper Cretaceous source rocks in GPT oil field. Moreover, one dimension basin modelling analysis is applied to show the burial history and thermal maturation of the study area. Source rock analysis show that most of the studied units have considerable amount of hydrocarbons, but they are not potentially enough to produce indigenous oil, except for Abu Roash "F" Member which has enough potential hydrocarbons to produce indigenous oil and gas; this reflects the indigenous nature of the encountered hydrocarbons of this member. Burial history modelling of the study area show that Khoman Formation is immature, Abu Roash “D, E, F and G” members are early mature and Abu Roash “F” Member is immature in one of the study wells.