Journal of Petroleum & Environmental Biotechnology

Sedimentation, eustasy and tectonic constraints of the Eocene hydrocarbon systems of the Gulf of Gabes basin, Tunisia

3^rd World Congress on Petrochemistry and Chemical Engineering

November 30-December 02, 2015 Atlanta, USA

Fatma Taktak1,2,3, Samir Bouaziz2 and Saïd Tlig3

1University of Modern Sciences, UAE 2Ecole Nationale dâ??Ingénieurs de Sfax, Tunisia 3University Tunis-El Manar, Tunisia

Posters-Accepted Abstracts: J Pet Environ Biotechnol

Abstract:

The carbonate series in the Ashtart oilfield were studied using core samples taken in drill wells; wireline logs, biostratigraphic data based on nummulites, discocyclines and operculines, and seismic data. The petrographic study in thin sections helps reconstruct mid to outer-ramp settings of carbonate facies with mixed nummulitoclasts and nummulite accumulation. The main goal is to present a comprehensive sedimentary and structural architecture for the Gulf of Gabes Basin - GGB - during the Eocene time period, using a detailed interpretation of a near 2000-km line of migrated and multi-channel seismic reflection profiles acquired by the Compagnie Generale de Geophysique - CGG- in the period 1978â??1995, to reconstitute the environments of deposition of large-scale sedimentary systems and structural elements which can be mapped in the studied basin, to those in the central and central-east provinces of Tunisia in the west. Furthermore, the geodynamic and depositional environment controls on the petroleum potential of Eocene series in the study area are also envisaged. Our study shows that transpressive stress in the study time interval, and wrenching of dominant NW-SE directed faults identified in seismic profiles, has constrained the uplift of blocks on which the carbonate shelf has formed; whereas sea-level rise and fall, and sub-sequent drowning have contributed to a carbonate-ramp development in three main stages dated middle ypresian, upper ypresian and upper ypresian-lower lutetian time periods using nummulites, operculines and discocyclines. Carbonate facies which correspond to the El Gariafm are organized in second and third order eustatic cycles which may be correlated with those defined in the global chart. Intraparticle porosity identified in coarse-grained foraminifered tests and nummulitoclasts, corrosion and dissolution of biochems due to burial diagenesis, as well as fracturing have constrained the reservoir quality. Triassic salt extrusions and magmatism associated with these deep-seated wrenching faults may have been accompanied by high heat flow and may have thus contributed to organic matter maturation in source-rocks of the Boudabbous and Chouabinefms and their migration into the Ashtart reservoir. Thick shaly series of the upper Eocene- Cherahilfm have also provided an impervious seal of the Ashtart petroleum system.

Biography :

Email: fatimtak@yahoo.fr f.taktak@ums.ae