Online Journal for E&P Geoscientists

Davies, Roger ^*1; Simmons, Mike ¹; Bater, Lucy ¹
(1) Neftex Petroleum Consultants Ltd, Abingdon, United Kingdom.

Southern Iraq oil fields have been in production for decades, contain some of the largest remaining hydrocarbon reserves in the world and have considerable untested deeper exploration potential, yet much remains to be learnt about the geology of this area. While important new data have been published on southern Iraq, there are significant contradictions in published interpretations of the local sequence stratigraphy when compared to updated interpretations of Arabian Plate sequence stratigraphy (Sharland et al 2001, 2004, Davies et al 2002, Simmons et al 2007, van Buchem et al 2011). These contradictions have important implications for understanding and predicting the reservoir geology of individual fields. In contrast, several detailed analyses of the Jurassic and Cretaceous reservoir, source and seal horizons of neighbouring Kuwait have been published. These include comprehensive sedimentological descriptions of both carbonate and siliciclastic reservoirs as well as regional sequence stratigraphic analyses. There are also important descriptions of reservoir behaviour during appraisal and production. Among the important factors identified in the aforementioned studies are the recognition of lateral facies changes at the regional and field scales, and the role of sequence stratigraphic organisation in controlling reservoir heterogeneities and consequent dynamic reservoir behaviours. Integration of newly published information on Iraqi fields with the detailed descriptions of Kuwaiti analogues facilitates prediction of the regional sequence stratigraphy and reservoir architecture in both producing and prospective portions of southern Iraq oil fields, and should provide pointers to likely reservoir behaviour during production. Examples will be presented for both siliciclastic and carbonate reservoirs including the Yamama, Zubair, Mauddud, Nahr Umr and Mishrif Formations.