This paper aims to provide proofs of hydrocarbons migration from petroleum reservoirs towards the surface of discharge playas. This is a case study of the discharge playa of Sidi El Hani, eastern Tunisia. The geochemistry of water of some hydrological drills in the Sahel area and of water from the discharge playa proves relatedness between the deep aquifer and the water of the discharge playa. Thus, the hydrology is now more than likely converging from the subsurface. This convergence may be an agent of transport of hydrocarbons. Concerning the organic matter within the discharge playa, high percentages of different fractions seem abnormal in such a saline context. This maturated organic matter should be viewed in the widest context of a multidisciplinary study taking into account the presence of petroleum potentials in the subsurface, the converging hydrogeology, and the tectonised region. The high percentage of Aromatic Polycyclic Hydrocarbon (APH) may be the result of hydrocarbons migration rather than anthropogenic pollution. As for the reinterpretation of previous works about the organic matter in playas done in sebkha Moknine, the contaminated organic matter, which was interpreted as a human induced activity, may have another origin from a reservoir located in the subsurface of the Sahel area. 1. Introduction Since the study of the petroleum system alone is not enough to achieve a more precise exploration, petroleum migration has recently become an important duty for petroleum exploration and assessment in petroleum basins (e.g., [1]). Over the last decades, several authors [2–7] have presented convincing evidences showing the integration of geological, geophysical, geochemical, hydrodynamic, and geothermal data as a powerful tool for understanding the relationships between groundwater and oil movement in sedimentary basins. As for the Tunisian context, some studies (e.g., [5, 8–16]) have revealed significant correlations between aquifers hydrodynamics and major conventional petroleum accumulations. Nevertheless, to satisfy this combination between the hydrogeological approach and the petroleum exploration, it is necessary first to prove the existence of a petroleum potential. Subsequently, the mechanism of migration of hydrocarbons by groundwater convergence may be discussed according to the geological context of the region. Concerning the case of the Tunisian Sahel, previous studies proved that these two conditions are quite satisfied. On the one hand, numerous geological studies and seismic investigations of the Sahel area have greatly
References
[1]
D. Chen, X. Pang, K. Liu, J. Zhang, and R. Zhang, “Experimental investigation of secondary oil migration along subtle pathways: a mechanism for hydrocarbon accumulation in lenticular basinal turbidite reservoirs,” Journal of Geochemical Exploration, vol. 101, no. 24, 2009.
[2]
S. Neglia, “Migration of fluids in sedimentary basins,” American Association of Petroleum Geologists Bulletin, vol. 63, no. 4, pp. 573–597, 1979.
[3]
J. Toth, “Cross-formational gravity flow of groundwater: a mechanism of transport and accumulation of petroleum,” The AAPG Studies in Geology, vol. 10, pp. 121–167, 1980.
[4]
W. Bishop, “Petroleum geology of East-Central Tunisia,” AAPG Bulletin, vol. 72, pp. 1033–1058, 1988.
[5]
S. Bouri, Hydrothermie de surface et potentialités hydrothermales du Nord Tunisien—Identification des principales unités hydrogéothermiques. [Thèse de 3ème Cycle], Ecole Nationale d’Ingénieurs de Sfax, Université de Sfax, Sfax, Tunisia, 1994.
[6]
N. R. Anderson, H. Wei, M. A. Hobart, and C. R. Wilkinson, “Active fluid flow in the Engerie Island area, offshore louisiana,” Geophysics, vol. 10, pp. 12–17, 1991.
[7]
J. W. Schmoker and T. R. Klett, “U.S. Geological survey assessment concepts for conventional petroleum accumulations,” in Petroleum Systems and Geologic Assessment of Oil and Gas in the Southwestern Yoming Province, WYoming, Colorado, and Utah. USGS, Southwestern WYoming Province Assessment Team, U.S. Geological Survey Digital Data Series DDS-69-D U.S., Version 1, Chapter 19, U.S. Geological Survey, Denver, Colo, USA, 2005.
[8]
H. Kouas and H. Ben Dhia, “Hdrogéologie pétrolière en Tunisie Centrale: réservoirs du Serdj, Abiod et El Garia,” in 2ème Congrès National des Sciences de la Terre, p. 13, Tunis, Tunisia, September 1990.
[9]
I. Yangui, A. Ben Gacha, H. Kouas, and H. Ben Dhia, “Hydrodynamisme et accumulations d’hydrocarbures en Tunisie Centrale,” Revue Tunisienne d’Energie, vol. 1, pp. 15–23, 1990.
[10]
H. Ben Dhia and M. N. Meddeb, “Thermal regime and hydrodynamics in Tunisia and Algeria,” Geophysics, vol. 56, pp. 1093–1102, 1991.
[11]
H. Ben Dhia, F. W. Jones, M. N. Meddeb, and S. Bouri, “Shallow geothermal studies in Tunisia: comparison with deep subsurface information,” Geothermics, vol. 21, pp. 503–517, 1992.
[12]
S. Bouri, A. L. Mimi, R. B. Akhy, S. Tajina, F. Bellouti, and H. Ben Dhia, “Les potentialités hydrogéothermiques de la Tunisie Centre-Nord,” Africa Geoscience Review, vol. 5, pp. 339–355, 1998.
[13]
S. Bouri, M. Gasmi, Y. Zarhloule, A. Limayem, and H. Ben Dhia, “Traitement intégré des données de température: outil pour la recherche des hydrocarbures,” Africa Geoscience Review, vol. 10, pp. 259–265, 2003.
[14]
I. Ben Abdallah, Etude du potentiel hydrogéothermal du Cap Bon: Traitement intégré des données de surface et de subsurface [M.S. thesis], Ecole Nationale d’Ingénieurs de Sfax (ENIS), Université de Sfax, Sfax, Tunisia, 2004.
[15]
A. Limayem, Modélisation de bassins sédimentaires pour l’évaluation du potentiel pétrolier: Application au Golfe de Hammamet [Ph.D. thesis], Ecole Nationale d’Ingénieurs de Sfax (ENIS), Université de Sfax, Sfax, Tunisia, 2004.
[16]
S. Bouri, M. Gasmi, M. Jaouadi, I. Souissi, A. L. Mimi, and H. Ben Dhia, “Integrated study of surface and subsurface data for prospecting hydrogeothermal basins: case of the Maknassy basin (central Tunisia),” Hydrological Sciences Journal, vol. 52, no. 6, pp. 1298–1315, 2007.
[17]
M. Bedir, Géodynamique des bassins sédimentaires du Sahel du Mahdia (Tunisie orientale), de l’Aptien à l’actuel sismo-stratigraphie, sismo-tectonique et structurale. [Thèse de troisième cycle], Université El Manar Tunis, Tunis, Tunisia, 1989.
[18]
H. Gabtni, “Apport de la gravimétrie à l’étude des structures profondes du Sahel de Tunisie (cas de la région de Kairouan-Sousse-Monastir),” Comptes Rendus Geoscience, vol. 337, no. 16, pp. 1409–1414, 2005.
[19]
S. Khomsi, M. Bédir, and M. G. Ben Jemia, “Mise en évidence d’un nouveau front de chevauchement dans l’Atlas tunisien oriental de Tunisie par sismique réflexion. Contexte structural régional et r？le du Trias salifère,” Comptes Rendus Geoscience, vol. 336, pp. 1401–1408, 2004.
[20]
S. Khomsi, M. Bédir, M. Soussi, M. G. Ben Jemia, and K. Ben Ismail-Lattrache, “Mise en évidence en subsurface d’événements compressifs éocène moyen–supérieur en Tunisie orientale (Sahel): généralité de la phase atlasique en Afrique du Nord,” Comptes Rendus Geoscience, vol. 338, pp. 41–49, 2006.
[21]
R. Ghribi, Etude morpho-structurale et évolution des pléo-champs de contraintes du Sahel tunisien: implications géodynamiques [Ph.D. thesis], Faculté des Sciences de Sfax, Sfax, Tunisia, 2010.
[22]
E. Essefi, Multidisciplinary study of Sidi El Hani Saline environment: the history and the climatic variability [M.S. thesis], Faculty of Sciences of Sfax, University of Sfax, Sfax, Tunisia, 2009.
[23]
E. Essefi, J. Touir, M. A. Tagorti et al., “Modeling of the chaotic behavior of Sidi El Hani discharge playa, Tunisian Sahel: which exogenous factor commands this saline environment? The subsurface flow or the climatic variability? Oral communication,” in Proceedings of the 4th International Congress Geotunis, 2009.
[24]
E. Essefi, J. Touir, M. A. Tagorti, and C. Yaich, “Effect of the groundwater contribution, the climatic change, and the human induced activities on the hydrological behavior of discharge playas: a case study Sidi El Hani discharge playa, Tunisian Sahel,” Arabian Journal of Geoscience, vol. 6, no. 10, pp. 3997–4009, 2013.
[25]
E. Essefi, Wet aeolian sedimentology and sequence stratigraphy within the terrestrial in Eastern Tunisia: implications for wet aeolian sedimentology and sequence stratigraphy on Mars [Ph.D. thesis], National Engineering School of Sfax, Sfax, Tunisia, 2013.
[26]
R. Chairi, “Natural and anthropic organic contribution in environment evaporitic of oriental Tunisia: Moknine’s sebkha,” Le JournaL de L’eau et de L’environnement, pp. 41–55, 2004.
[27]
R. Chairi and Z. El Sami-Djellouli, “Characterization of organic matter deposited in the oriental zone from Moknine hypersaline environment, oriental Tunisia,” Chinese Journal of Geochemistry, vol. 24, no. 4, pp. 345–351, 2005.
[28]
R. Chairi, “Sedimentological study of sediment from an hypersaline system of oriental Tunisia in recent quaternary: Moknine sebkha,” Quaternaire, vol. 16, no. 2, pp. 107–117, 2005.
[29]
R. Chairi, S. Derenne, S. Abdeljaoued, and C. Largeau, “Sediment cores representative of contrasting environments in salt flats of the Moknine continental sabkha (Eastern Tunisia): sedimentology, bulk features of organic matter, alkane sources and alteration,” Organic Geochemistry, vol. 41, no. 7, pp. 637–652, 2010.
[30]
H. Ben Jmaa, Le système endoréique de Sidi Al Hani, Chrita et Mechertate: Paléoenvironnement et dynamique récente [Ph.D. thesis], Université de Tunis, Tunis, Tunisia, 2008.
[31]
N. Laridhi Ouazaa, étude minéralogique et géochimique des épisodes magmatiques mésozo？ques et miocènes de la Tunisie, [Thèse d’état], Université de Tunis, Tunis, Tunisia, 1994.
[32]
M. Bedir, “Tectonic and basin structuring of eastern Tunisia seismogenic sites,” 2010, http://www.docstoc.com/.
[33]
A. Amari and M. Bedir, “Les bassins quaternaires du sahel central de la Tunisie. Genèse et évolution des sebkhas en contexte décrochant compressif et distensif,” Géodynamqiue, vol. 4, no. 1, pp. 49–65, 1989.
[34]
E. Essefi, M. A. Tagorti, J. Touir, and C. Yaich, “Modeling of the chaotic behaviors at Sidi El Hani discharge playa, eastern Tunisia: contribution of the philosophy of causality to solve complex chaotic systems in geology and biology,” Tunisian Journal of Medicinal Plants and Natural Products, vol. 7, pp. 116–128, 2012.
[35]
E. Essefi, G. Komatsu, A. G. Fairén, H. Ben Jmaa, F. Rekhiss, and C. Yaich, “Spring mounds at Sidi El Hani saline environment, eastern Tunisia: terrestrial analog for Mars,” in Proceedings of the 43rd Lunar and Planetary Science Conference, 1229 (abstract), Houston, Tex, USA, March 2012.
[36]
E. Essefi, G. Komatsu, A. G. Fairén, M. A. Chan, and C. Yaich, “Alignment of fault spring mounds at El-Guetiate, Southeast Tunisia: terrestrial analogue implications for martian tectonics,” in Proceedings of the 44th Lunar and Planetary Science Conference, 1229 (abstract), Houston, Tex, USA, 2013.
[37]
E. Essefi, G. Komatsu, A. G. Fairén, M. A. Chan, and C. Yaich, “Groundwater influence on the aeolian sequence stratigraphy of the Mechertate-Chrita-Sidi El Hani system, Tunisian Sahel: analogies to the wet-dry aeolian sequence stratigraphy at meridiani planum, terby crater, and gale crater, Mars,” Planetary and Space Science, 2013.
[38]
E. Essefi, J. Touir, M. A. Tagorti, and C. Yaich, “Record of the climatic variability and the sedimentary dynamics during the last two millennia at sebkha Dkhila, eastern Tunisia,” ISRN Geology, vol. 2013, Article ID 936198, 9 pages, 2013.
[39]
E. Essefi, H. Ben Jmaa, J. Touir, M. A. Tagorti, and C. Yaich, “d. Record of the climatic variability and the sedimentary dynamics during the last two millennia at sebkha Souassi, eastern Tunisia,” Global Change IGBP. In press.
[40]
L. Langhi, Y. Zhang, A. Gartrell, J. R. Underschultz, and D. N. Dewhurst, “Fluid flow behaviour in reactivated hydrocarbon traps: assessing fluid circulation along natural complex fault systems using numerical fluid flow simulation,” Journal of Geochemical Exploration, vol. 101, no. 57, 2009.
[41]
H. Boussiga, I. Sa？dane, H. Belayouni, M. Dogga, and M. Chekir, “Proposal for a decontamination of wastewaters produced by oilfields in Tunisia,” Geo-Eco-Trop, vol. 30, no. 2, pp. 35–40, 2006.
[42]
C. Delmas-Gadras, Influence des conditions physico-chimiques sur la mobilité du plomb et du zinc dans un sol et un sédiment en domaine routier [Ph.D. thesis], Université de Pau et des Pays De L’Adour U.F.R Sciences, 2000.
[43]
P. A. Cranwell, “Lipids of aquatic sediments and sedimenting particulates,” Progress in Lipid Research, vol. 21, no. 4, pp. 271–308, 1982.
[44]
B. P. Tissot and D. H. Welte, Petroleum Formation and Occurrence, Springer, Berlin, Germany, 2nd edition, 1984.
[45]
P. Baranger and J. R. Disnar, “Non-aromatic biomarkers associated with a Palaeogene salt formation (Bresse, France),” Organic Geochemistry, vol. 13, no. 4–6, pp. 647–653, 1988.
[46]
P. Baranger, J. R. Disnar, G. Farjanel, and P. Fourmont, “Confrontation de données géochimiques et optiques quantitatives et qualitatives sur la matière organique associée aux séries salifères de Bresse,” Bulletin de la Societe Geologique de France, vol. 8, pp. 967–978, 1989.
[47]
V. Thiel, M. Merz-Prei？, J. Reitner, and W. Michaelis, “Biomarker studies on microbial carbonates: extractable lipids of a calcifying cyanobacterial mat (Everglades, USA),” Facies, vol. 36, no. 1, pp. 163–172, 1997.
[48]
G. Eglinton and R. J. Hamilton, “Leaf epicuticular waxes,” Science, vol. 156, pp. 1322–1335, 1967.
[49]
S. J. Schropp, F. G. Lewis, H. L. Windom, J. D. Ryan, F. D. Calder, and L. C. Burney, “Interpretation of metal concentrations in estuarine sediments of Florida using aluminum as a reference element,” Estuaries, vol. 13, no. 3, pp. 227–235, 1990.
