Reservoir Characterization of Early Jurassic Formations in Selected Wells in the Duhok Governorate, Iraqi Kurdistan Region

The succession of Early Jurassic formations was studied in terms of reservoir characters in two wells: Atrush-1 and Shaikhan-1B from the Atrush and Shaikhan oilfields, respectively, in the Duhok Governorate, Iraqi Kurdistan Region. The well Log data from these wells were used to achieve the objectives of the research. Well log data are commonly used to study petrophysical properties of the reservoir rocks. This task is accomplished through running Interactive Petrophysics software (IP). Log interpretation was supportive for: (1) Prediction of lithological characters and (2) calculation of shale volume, total porosity, effective porosity, secondary porosity, water saturation, water bulk volume, residual hydrocarbon, and movable hydrocarbon of each formation in the studied wells

Organic Petrological and Geochemical Evaluation of Jurassic Source Rocks from North Iraq

Immature Jurassic oil shale is widely distributed and frequently outcropping in North Iraq. The organic-rich Jurassic sedimentary sequence, including prolific oil shale, was recorded in Banik area in Duhok Governorate of North Iraq. This sequence was systematically sampled from the geological formations; Sehkanyian, Sargelu and Naokelekan. The organic geochemical parameters were analyzed for 72 samples as well as one oil sample. A detailed study of petrologic properties was carried out for 12 samples. Based on TOC content, the Sargelu and Naokelekan formations can be considered as good to excellent source rocks, whereas Sehkanyian Formation has no potential since the TOC does not exceed 0.1 %. The samples of Sargelu and Naokelekan formations contain both kerogen types I and II indicating marine organic matter mainly derived from algae and phytoplankton organisms proposing typical oil prone source kerogen. This is further confirmed by the predominance of alginite and liptodetrinite macerals, where liptinite maceral group contribute more than 90% relative to other maceral contents. In general, Sargelu Formation samples have Production Index (PI), Tmax and fluorescence parameters (λmax and red/green quotient) suggesting immature to early mature stage of thermal maturity. The calculated ratios of Pr/Ph, Pr/nC17 and Ph/nC18for the extracted bitumen and the oil sample, suggest generation of bitumen from marine organic matter deposited under reducing conditions at an early thermal maturity stage

Depositional environment of the upper triassic baluti formation in gara anticline, kurdistan region, north iraq : Insight from microfacies and biomarker characteristics

cknowledgements The authors are grateful to Colin Taylor from the University of Aberdeen, Department of Geology and Petroleum Geology for his great assistance during analyzing the samples by GC-MS. The authors are very grateful to the Editor in Chief Prof. Dr. Salih M. Awadh, the Secretary of Journal Mr. Samir R. Hijab and the Technical Editors for their great efforts and valuable comments.Peer reviewedPublisher PD

Static Reservoir Modeling, a Case Study from Early Cretaceous Yamama Formation, Southern Iraq

Constructing a static reservoir model or a 3D geological model is a widely used modern tool to employ subsurface information expose the setting and properties of hydrocarbon reservoirs. The current study attempts to build a 3D reservoir model of the Yamama Formation (an important oil reservoir in Southern Iraq), from digital logs data and drilling information. This would lead to a better understanding of the relationships between different reservoir elements, then expose many characteristics of the reservoir, such as the facies distribution and petrophysical properties. The data of the Yamama Formation (Early Cretaceous Carbonates) were taken from four wells of Gharraf Oilfield, Southern Iraq (GA-1, GA-2, GA-3, and GA-4). The adopted modeling approach consists of a series of steps starting with a preliminary analysis of data, followed by interpretation of these data, and terminated by geostatistical methods for building the structural model. The modeling was assisted by defining the top of each layer detected by wireline logs and final well reports of each studied well. The results of the study encompass four microfacies distributed between Inner Ramp and Mid Ramp environments. The followed 3D geological modeling scheme was capable to visualize the distribution of petrophysical properties, and the classification of Yamama Formation into several layers or reservoir units (Y1 to Y5), and thirteen subdivisions (minor units). The model could also define the places where effective porosity was enhanced. The process of Pillar Gridding, a step within the modeling, showed that the Yamama Formation is composed of two domes. The constructed model was helpful, based on the evaluation of petrophysical parameters, then to point out the most important reservoir zone (Zone Y3_top) that has Effective Porosity of (13.6%) and water saturation of around (10.6%).Godkänd;2022;Nivå 0;2022-06-02 (johcin)</p

Assessment of the hydrocarbon potentiality of the Late Jurassic formations of NW Iraq: A case study based on TOC and Rock-Eval pyrolysis in selected oil-wells

The Late Jurassic Naokelekan and Barsarin formations of northwestern Iraq have been investigated in three wells to assess their potentiality for hydrocarbon generation

Reservoir Characterization of the Early Jurassic Butmah Formation Using Well Log Data in Selected Wells from Iraqi Kurdistan Region

The reservoir characterization of Butmah Formation (Early Jurassic) was studied in two wells: (AT-1) and (SH-1B) from Atrush and Shaikhan Oilfields respectively, in Iraqi Kurdistan Region. Well logs including; sonic, density, neutron, gamma ray, and resistivity, were employed to investigate the formation. The petrophysical properties, such as lithology, shale volume, porosity, water saturation, hydrocarbon saturation, and bulk water volume, were estimated using Interactive Petrophysics Software (IP). Water saturation, bulk volume of water, residual hydrocarbon, and movable hydrocarbon were plotted as Computer Processed Interpretation (CPI) for Butmah Formation in the studied wells. In order to check reliability of log data, lithology of the formation was detected using neutron-density cross plot and M-N cross plot. The results of log interpretation display that Butmah Formation is composed of dolomite, limestone with anhydrite and shale in the studied wells. The calculated shale volume shows low clay content. Therefore, Butmah Formation is considered as a clean formation in both wells. Porosity was estimated using porosity logs (sonic, density, and neutron) and had the average total porosity of (7% - 8%) in the two wells. Based on the determined petrophysical properties, particularly porosity and hydrocarbon saturation, it can be concluded that Butmah Formation seems potentially good in reserving oil.Godkänd;2021;Nivå 0;2021-01-04 (alebob)</p

Source Rock Evaluation and 1-D Basin Modelling Approach for the Sargelu Formation, Atrush-2 Well, Kurdistan Region-Iraq

The present study focuses on source rock evaluation of the Sargelu Formation by using core chips of rocks collected from well Atrush-2, Duhok, Kurdistan Region-Iraq. The Rock-Eval pyrolysis and vitrinite reflectance were executed. Subsequently, the selected parameters were used for source rock evaluation and 1-D Basin Modelling calibration. The upper part of the formation mainly comprises argillaceous limestone with low content of organic matter (0.64% - 1% TOC). By contrast, the lower part is dominated with shale interval and contains high amounts of TOC values (&gt;4% for 1272 - 1278 m) reveling good to very good quality source rock. Accordingly, good to very good hydrocarbon generation potential is suggested for this formation. Organic matter of the Sargelu Formation contains type II and mixed-type II-III kerogen. The values of Tmax and vitrinite reflectance (Ro%) demonstrate that the formation is thermally mature and in the oil zone. In order to construct a thermal history of the formation and determine the timing of hydrocarbon maturation and generation, the 1-D basin modelling PetroMod 2019.1 was used in this study. Based on the 1-D Basin modelling simulation and its outputs, about 3500 m of overburden have been eroded at the study area. The present-day heat flow was found to be 30 mW/m2. The organic matter of Sargelu Formation entered the early oil zone in 64 Ma and reached the main oil zone ca. 5 Ma. The formation is still in the main oil zone at present-day. In well Atrush-2, the highest rate of oil generation for the Sargelu Formation was in the 8.5 Ma, the onset of oil expulsion from Sargelu Formation was in 50 Ma and the expulsion mass has been reached 0.5 Mtons at present-day.Godkänd;2021;Nivå 0;2021-03-03 (alebob)</p