High resolution sequence stratigraphy and reservoir characterization of the hartha formation in ahdab oilfield

Abstract EN

The Hartha Formation is one of the economically important formations which deposited during the Creataceous period, and the most heterogeneous from one place to another because of the complexities of sedimentary basin and the movements that influenced it.

This research is interested in studying the Upper Campanian-Lower Maastrichtian succession (Hartha Formation) in Ahdab oilfield (Ad-1) which located in the middle of Iraq within the Mesopotamian basin (Tikrit-Amara Subzone).

The present study includes two parts ; the first is facies analysis and stratigraphic history, and the second is the study of petrophysical properties and reservoir characterizations for this succession.

Facies analysis enable the recognition of six main facies associations in the studied succession ; these are basinal, open shelf margin, foreslope, rudistbiostorm, Shoal and restricted platform (lagoon).

The Hartha succession represents deposition of two cycles of third order, these cycles where deposited during successive episodes of relative sea level rises and still stand.

There are nine petrophysical horizons observed in the studied succession named (I, II, III, IV, V,VI, VII, VIII and IX), four of them are good reservoir horizons which are : (III, IV, VI, and VIII).

The dolomitized horizon as (II, V and VII) are matching with the still stand or regressed sea level, where during these stages the diagenesis processes (dolomitization and cementation) were active.

The permeability-porosity relationship for the carbonate rocks showing a good match with the general facies and petrophysical properties for the studied succession.