DOI: 10.11648/j.ajpa.20261403.12 ISSN: 2330-4308

Lithofacies Analysis and Petrophysical Relationships of Zubair Formation in X, XX and XXX Oil Fields, Southern Iraq

Haider Al-Tarim, Zainab Al-Khalidi
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The current study is including the lithofacies analysis and petrophysical evaluation related to depositional development for Zubair Formation in X, XX and XXX oil fields (X-1, XX-5 and XXX-2). Zubair Formations was deposited in the Mesopotamian Zone during the Barremain age which belong to the Early Cretaceous epoch. Depositional settings and related facies that were interpreted using the supplied parameters and distribution of the observable lithofacies, there are three main associations of deltaic facies in studies succession: - Delta Front Association Facies, Back Shore Association Facies, Delta Plain Association Facie. The succession under study is separated into three main units utilizing well logging technologies (GR, SP, and DT). The upper part is primarily made up of sand layers with thin shale beds, the middle member is made up of thin layers of sandstone with a predominance of shale, and the lower member is primarily built of shale with less sandstone: - Lower unit shale dominated, Middle unit sandstone dominated and upper unit sand/shale dominated. The lower petrophysical zone of Zubair succession is represented by the shale dominated rock units, with low to non-pores rock unit (type III). Active porosity type (I) is present in low to moderate levels within the shale bands lithofacies across all examined wells. The middle zone in the studied succession is split into two subzones. The upper subzone exhibits high to moderate levels of active porosity (type I), whereas the lower subzone shows moderate levels of active porosity (type II) and a low to non-porous rock unit (type III) due to a significant amount of shale content. This zone represents the middle section of the Zubair succession within the shale-dominated layers. The upper zone consists of high to medium-sized active porosity rocks (Type I) due to well-graded coarse granitic sandstones. These features correspond to shale-dominated rocks and low to medium shale grades.

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