Source Rock Evaluation of Cretaceous and Tertiary Series in Tunisia

Jean-Louis Oudin

Tunisia represents a mature hydrocarbon province with a long exploration history. In the Sfax-Kerkennah and Gabes Gulf areas, the hydrocarbon accumulations are located in series of Cretaceous and Tertiary age. To estimate the petroleum potential of this region, an evaluation of the source rock quality of the Cretaceous and Tertiary series was undertaken. In the Sfax-Kerkennak area, most of the wells studied indicate that, in the Tertiary, Ypresian and lower Lutetian show good organic content but, taking into account the potential productivity, only the Ypresian can be considered as a potential source rock. In the Cretaceous, mainly studies in the offshore area of the Gabes Gulf, the amount of organic matter is fair and it is chiefly located in Albian and Cenomanian. The V aconian with its quite good potential is a valuable source rock.

Due to the difference in the environment of deposition for these two possible source rocks--the Ypresian with its lagoon facies being carbonate and the Vraconian shaly--variations in the type of organic matter can be noted, although both are of marine origin. The hydrocarbons generated from these source rocks reflect these variations and permit us to correlate the different crude oils found in this area with their original source beds.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.