Evaluation of Organic Matter in the Yamama Formation at West Qurna Oil Field, Southern Iraq

Abstract

Yamama Formation (Valanginian-Early Hauterivian) carries a special economic importance, since it represents one of the well known oil reservoirs southern Iraq. To evaluate the organic material contents of this formation an organic geochemical study was conducted. A total of 58 out of 227 previously collected and described core samples were analysed using pyrolysis method; these samples represent five oil wells which are distributed over West Qurna (WQ) field. The organic material of the selected samples were separated then analyzed using Rock-Evaltechnique.The organic geochemical data confirm that the Yamama rocks of WQ field represent a source rocks that posses a poor to very good properties depending upon the quantitative evaluation of petroleum potential (PP) and total organic carbon (TOC). The source rocks were thermally matured except in some few samples found at depth below 3700 m. These samples were exceeded the maturation stage leading to the formation of pyrobituminous layer of variable thickness. Most of Yamama organic matters were related to type II kerogen that produces oil and gas prone. Few samples are related to type III kerogen that produces gas prone.