Depositional Environments, Facies Distribution, and Porosity Analysis of Yamama Formation in Majnoon Oilfield. Sequence Stratigraphic Approach

Abstract

Due to the importance of petroleum exploration and production in the oilindustry and developments. Therefore, this study targets one of the more important reservoir rocks in Iraq, which it Yamama Formation in the Majnoon oilfield, southern Iraq. The facies distribution showed that the formation was deposited on a ramp platform. Seven main carbonate facies were distinguished in the studied area. Based on these facies, Yamama Formation was represented to deposit on a ramp setting, that consist of different sedimentary environments. The main depositional environments represented by the shoal, middle -outer ramp and deep outer ramp environments. Eventually, the Yamama Formation is divided into two main sequences. The lower part of the formation was a regression phase that deposited highstand system tracts, named Yamama sequence one. The upper was a transgression phase deposited transgressive system tracts named Yamama sequence two. The diagenetic processes showed that the early and late dissolution and cementation are important that affected the reservoir characteristics. Dolomitization is not an active process in the formation. Petrophysical properties represented by primary and as well as secondary porosity were studied and processed to evaluate the reservoir characteristics. The data were obtained from wireline logs and core data from plugs and thin sections. Good reservoir property units were located in a high-energy shoal environment and found in other environments depending on secondary porosity and dissolution processes activity. According to porosity cut-off, the formation was divided into five units that have porosity more than the lower limit of the worthy values.

The Influence of Diagenesis Processes on the Reservoir Properties of Hartha Formation in Selected oil Fields, Northern Iraq

“…Diagenesis is affected by the Hartha Formation environment, which is the Inner -Middle-Outer Ramp [2] [14] The pore types in the Hartha Formation throughout the studied core samples in wells A and B consist of a mixture of primary and secondary types (Table -1). Intercrystalline, vuggy and cavern porosity are the dominant porosity types in the studied samples, followed by interparticle and fracture porosity (Figure 2).…”

Evaluation of Petrophysical Properties Using Well Logs of Yamama Formation in Abu Amood Oil Field, Southern Iraq

“…The Yamama basin in the south of Iraq such as Majnoon oil field and other fields is indicated as a ramp setting in a stable flank of the carbonate platform. The ramp setting effects on the stacking patterns of the Yamama Formation (Idan et al, 2020). The formation which is a heterogeneous carbonate supply, is one of the significant oil generation stores in southern Iraq, deposited during the Lower Cretaceous period inside the primary retrogressive depositional cycle (Barriasian -Aptain ) south of Iraq .This cycle is reached out from shore to profound bowl by the Zubair ,Ratawi, Yamama ,Shuaiaba and Sulaiy formations (Budy,1980 andAqrawi et al, 2010).…”

Study of Petrophysical Properties of the Yamama Formation in Siba Oilfield

“…Generally, as demonstrated byKennedy (2015). There are two sources of data when dealing with these properties, instrumental methods that measure the properties against depth which called logs and the actual samples that almost represent the formation that we are dealing with such as cuttings and cores (Idan et al, 2020). Cross plots are common methods to exhibit effect of combinations of logs react to porosity and lithology and they give a visual vision into the type of lithology mixtures (Liu, 2017) .The quantitative evaluation of a hydrocarbon units in a reservoir requires a correct prediction of the shale volume which causes a blockage to the pore space and reduce the amount of permeability and as a result reduce the reservoir quality (Poupon and Gaymard, 1969).…”