Attributes of potential hydrocarbon reservoir sandstones in the sokoto sector of the iullemmeden basin: an outcrop analogue study

Attributes of potential hydrocarbon reservoir sandstones in the sokoto sector of the iullemmeden basin: an outcrop analogue study

Author: 
Ozumba, M. B., Chima, K. I., Nwajide, C.S., Farouk, U. Z. and Rahman, U.A.
Abstract: 

The Sokoto area of Nigeria is the southeastern margin of the very extensive (ca. 1 million km2) Iullemmeden Basin – an intracratonic depression in the Precambrian Basement Complex. The basin fill succession consists of the Late Jurassic continental facies and Cretaceous marine deposits topped by Mid-Paleogene continental facies. Impressive outcrops had spurred the search for petroleum in early colonial time but the poor showing of the earliest boreholes discouraged the efforts. This study is, therefore, aimed at providing more information on one of the prerequisite attributes – reservoir characteristics using outcropping analogues for assessing the lithostratigraphic units that bear the potential reservoirs.  Hydrocarbons, possibly generated from carbonaceous fine clastics and carbonate facies of the marine deposits, could have migrated to the sandstones of the Illo and Gundumi Formations of the Continental Intercalaire Group, the Taloka and Wurno Formations of the Rima Group and the Gwandu Formation of the Continental Terminal Group, as well as the carbonate unit of the Kalambaina Formation. However, only the shales of the Taloka and the Wurno Formations may constitute effective seal facies. Additionally, the coarse to medium sandstones of the Gwandu Formation may constitute suitable reservoir facies if the interbedded ironstones prove to be good seals.

Paper No: 
1851