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The crustal structure of the Sahel Basin (eastern Tunisia) determined from gravity and geothermal gradients: implications for petroleum exploration

Arabian Journal of Geosciences volume 4, pages 507–516 (2011)Cite this article

Abstract

An analysis of Bouguer gravity anomaly data and geothermal gradient data obtained from bottom hole and drill stem tests temperature is used to determine the crustal structure of the Sahel Basin in eastern Tunisia and its role in the maturation and location of the large number of oil and gas fields in the region. The regional Bouguer gravity anomaly field is dominated by gradual increase in values from the northwest to southeast and is may be caused by crustal thinning as revealed by regional seismic studies. In addition, higher geothermal gradients in the same region as the Bouguer gravity anomaly maximum add an additional constraint for the existence of crustal thinning in the region. A detailed analysis of the Bouguer gravity anomaly data was performed by both upward continuation and horizontal gradients. These two techniques were combined to show that the study area consists of two structural regions: (1) the North–South Axis (NOSA)–Zeramedine region which is characterized by northwest-dipping, northeast-striking faults, thicker crust (30–31 km) and low geothermal gradients, and (2) the Mahres–Kerkennah region which is characterized by vertical, northwest-striking faults, thinner crust (28–29 km) and higher geothermal gradients. The correlation of a variety of features includes mapped and geophysically defined faults, volcanic rocks, a thinned crust and high geothermal gradients within the same location as known oil and gas fields indicate that the faults are a major factor in the location of these petroleum accumulations.

Abstract

تم تطبيق قيس شاذات بوجيه و قيس المقياس الجيوحراري لتحديد تركيبة القشرة الأرضية لحوض الساحل بالشرق التونسي ودورها في إنضاج ومكان وجود حقول النفط والغاز بالمنطقة. مكننا تحليل شاذات بوجيه من تمييز تدرج من الشمال-غرب إلى الجنوب-شرق و ذلك في توافق تام مع تدرج المقياس الجيوحراري أيضا. و يرجع هذا التدرج لشاذات بوجيه و المقياس الجيوحراري إلى هيكلة القشرة الأرضية مدعمة بنتائج الدراسات السيسميكية السابقة. يمكننا تمييز منطقتين بحوض الساحل : 1) منطقة الحد الشمال- الجنوب - زررمدين و التي تتميز بقشرة أرضية عميقة و مقياس جيوحراري عالي و عديد الفوالق باتجاه شمال-شرق - جنوب-غرب و 2) منطقة محرس - قرقنة و التي تتميز بقشرة أرضية ضحلة و مقياس جيوحراري منخفض و عديد الفوالق باتجاه شمال-غرب - جنوب- شرق. إن المقارنة بين معطيات التراكيب الجيولوجية التي تم إبرازها بالتقنيات الجيوفيزيائية و مكان وجود الأحجار البركانية إضافة إلى تحديد منطقة القشرة الأرضية الضحلة و المقياس الجيوحراري العالي مع مكان جود حقول النفط والغاز مكننا من تقديم أنموذج تركيبي لحوض الساحل.

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Authors and Affiliations

  1. Laboratoire de Géoressources, Centre des Recherches et de Technologies des Eaux, Technopôle Borj-Cedria, B.P. 73, 8020, Soliman, Tunisia

    Hakim Gabtni, Badia Chulli Zenatti & Mourad Bedir

  2. Département de Géologie, Faculté des Sciences de Tunis, University Tunis El Manar, Manar II, 2092, Tunis, Tunisia

    Chokri Jallouli

  3. Department of Geosciences, Missouri State University, Springfield, MO, 65897, USA

    Kevin L. Mickus

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  1. Hakim Gabtni
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  2. Badia Chulli Zenatti
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  3. Chokri Jallouli
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  4. Kevin L. Mickus
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  5. Mourad Bedir
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Correspondence to Hakim Gabtni.

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Gabtni, H., Zenatti, B.C., Jallouli, C. et al. The crustal structure of the Sahel Basin (eastern Tunisia) determined from gravity and geothermal gradients: implications for petroleum exploration. Arab J Geosci 4, 507–516 (2011). https://doi.org/10.1007/s12517-010-0151-0

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  • DOI: https://doi.org/10.1007/s12517-010-0151-0

Keywords

  • Tunisia
  • Sahel Basin
  • Gravity anomalies
  • Geothermal gradients
  • Oil and gas