Petrophysical properties and reservoir development of Albian succession in Nasiriya oil field, southern Iraq

Abstract EN

The carbonate-clastic succession in the studied wells is represented by the nahr umr and mauddud formations deposited during the Albian sequence.

this study includes petrophysical properties and reservoir characterization of this succession in 5 wells within the nasiriyah oil field.

according to values and shape of gamma ray logs and shale values, the studied formations were subdivided into five zones named; A, B, C, D, and E.

three types of rocks were identified in these zones according to their total porosity: type i: high-moderate active porosity rocks; type 2: high-moderate inactive porosity rocks and type 3: low-non porous rocks.

according to the relationship of resistivity-porosity and hydrocarbon saturation two reservoir horizons have been identified in this study within the nahr umr formation.

the mauddud formation, on the other hand, does not show any hydrocarbon in the studied succession, due to the overwhelming presence of shale strongly affected by diagenetic processes such as cementation and compaction.

horizon 1 appears in the upper sand member of nahr umr formation, encountered in wells no.1, no.2, and no.3.

this type of rocks is characterized by high-moderate porosity (effective porosity) with low volume of shale and high deep resistivity.

the thickness of this type ranges from 21 m to 48.5 m.

horizon 2 is represented by breaded river lithofacies, occurring in all the studied wells except no.3.

it is divided into two sub-horizons in well no.5.

this type of rocks is 12.25-57 m thick and characterized by high-moderate porosity with low volume of shale and high deep resistivity.