Well Logs Data Prediction of the Nahr Umr and Mishrif Formations in the Well Noor-10, Southern Iraq

Abstract

Well logs data are the most widely used data to evaluate subsurface rocks, their petrophysical properties include porosity, permeability and fluid saturation. They are essential for the hydrocarbon reserves estimations and perforation zones determination for production purposes and fields development. Well logging operations of the targeted reservoirs could not be done in NO-10 Well, Noor Oilfield, Southern Iraq due to some problems related to the well condition. The gamma-ray and sonic logs were the only recorded logs, while neutron, density and deep resistivity logs are missed. The missing neutron, density and deep resistivity logs of the Early Cretaceous Nahr Umr Sandstone and the Late Cretaceous Mishrif formations of the well NO-10 were produced and compared together using the Artificial Neural Network ANN in Petrel software. The results show that the total correlation of the ANN Nahr Umr model for the neutron, density and deep resistivity logs are 0.81, 0.49 and 0.51 respectively. Interestingly, the ANN Mishrif Formation model recorded 0.88, 0.92 and 0.81 for neutron, density and resistivity logs respectively. The results show excellent relationships between the original and the predicted logs in the Mishrif model, unlike the Nahr Umr model expect in ANN of the neutron log. It was expected that the total relationships are low in Nahr Umr due to the lithology variation that includes interbedded consolidated and unconsolidated sandstone interbedded with the shale. It is also observed that the gamma log shows low values and the caliper logs is smoothed in the Mishrif. In contrast, the Nahr Umr sandstone logs show that many washouts have occurred. Therefore, logs' responses highly possible to be affected in the Nahr Umr Formation which leads to a decreasing in the coefficient of determinations.

Anomalous porosity preservation in the Lower Cretaceous Nahr Umr sandstone, Southern Iraq

“…. Generalized stratigraphic column of the well NO-13, Noor Oilfield, showing the age, depth, and thickness of each formation, sonic (DT) log which relatively reflects the compaction trend from depth 1680-4176 m (adapted from [Mohammed et al, 2020]). Sixteen wells were drilled in the Noor Oilfield, 6 of them were penetrated the Nahr Umr Formation at depth exceeds 4000 m. The temperature exceeds 100 ∘ C at the top of the formation in the well NO-13 and up to 103 ∘ C at the main sand member at a depth of 4099 m. Eight samples were selected from the cored sections correspond to different facies with different effective porosity (Figure 3).…”

“…Structural zones and locations of most Iraqi oil/gas fields. Complied after different sources [Aqrawi et al, 2010;Al-Khafaji, 2014;Mohammed et al, 2020].…”

Lithological Study of Mishrif, Rumaila, Ahmadi and Mauddud Formations Using Vp/ Vs Ratio, Acoustic Impedance and Well Logging at Amara Oil Field, Southern Iraq

“…Many studies were done using well log data in multiple results, (Al-Baldawi, 2020) determined the pore type and porosity trend by convert sonic and neutron porosity or density porosity to velocity deviation log using means of time average equations in Mishrif Formation taking data from two wells in Halfaya oil field. (Mohammed et al, 2020) produced and compared the missing neutron, density and deep resistivity logs together using the Artificial Neural Network ANN in Petrel software. of the Early Cretaceous Nahr Umr Sandstone and the Late Cretaceous Mishrif formations of the well Noor-10.…”

Digital Rock Analysis: An Alternative Method to Predict Petrophysical Properties, Case Study From Mishrif Formation

“…The Mishrif Formation contains up to 40% of the Cretaceous oil reserves in Iraq, and about 30% of the total Iraqi oil reserves (Mohammed et al, 2020). Petrophysical properties like porosity, saturation, and permeability are essential reservoir rock properties used in the determination of hydrocarbon volume in place.…”