GHEORGHE BRANOIU, TUDORA CRISTESCU, IULIAN NISTOR ESTIMATION OF THE COMBUSTION TEMPERATURE PROFILE IN A ROMANIAN OIL FIELD Developing and producing of the heavy crude oil involved significant economic and technological challenges. The oil industry ability to prospect and capitalize the huge world heavy oil resources both economically and environmentally friendly will be crucial in helping meet future energy needs. Thermal oil recovery is one of the three types of techniques belonging to Enhanced Oil Recovery. It is applied for increasing the cumulative of crude oil that can be produced in an oil field. One of the oldest thermal oil recovery is in-situ combustion or fireflooding applied for the first time about 100 years ago. Despite in-situ combustion has not found widespread acceptance among operators like other thermal processes (such as steam injection), analysis of the successful projects indicates that the process is applicable to a wide range of oil reservoirs, especially to heavy crude oils. An important monitoring parameter of thermal oil recovery process is represented by thermal regime especially in heavy oil fields in which a high-temperature regime must be occur as the in-situ combustion to be successful. In the paper the authors are using thermal analysis (thermogravimetric and thermodifferential analysis) for investigation of the thermal regime involved in the production process of an oil reservoir by in-situ combustion.