Petroleum Characterisation of Salambo Formation by Organic Petrography and Organic Geochemistry (Gulf of Gabes-Tunisia)

Halima Inoubli
Entréprise Tunisienne d'Activités Pétrolières (ETAP), BP n° 83 1073-Momplaisir-Tunis, Tunisia

The combination of petrographic and geochamical results allows better petroleum characterisation of the Oligocene-Miocene lithostratigraphic level(Salambo Formation) known only in boreholes of the East Southern Gabes basin throught the tunisian-lybian boundary. Organic matter from five wells has been analysed by the Rock-Eval pyrolysis and microscopically in transmitted and reflected lights.This study leds to the understanding of the marly Salambo Formation petroleum characteristics and its possible capacity to generate oil and gas. This Oligocene-Miocene column is, in general, poor in organic matter(TOC is less than 0.5%); nevertheless the unit below 2000 m (Lower Salambo Formation)is the exception; organic matter is well preserved (TOC is ranging from 0.66 to 1.97% and PP is up to 1.5Kg of HC/t of rock). In general, this organic matter is a mixture of type III and II kerogens, dominated by herbaceous palynomorphous and ligno-cellulosic tissus with some amorphous material. In addition to the proven source rocks within the area which are the early Turonian Bahloul and the Ypresian Bou Dabbous Formations, and due to its good geochemical quality below 2000 m and its vertical and lateral extension,the Lower Salambo Formation might locally play a role in the petroleum history of the Gabes basin. To confirm, even more,the petroleum interest of this horizon, this study must concern others tunisian and especially lybian wells which cross the Oligocene-Miocene column, along the tunisian-lybian boundary.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece