The Nahr Umr Formation is considered one of the main reservoirs produced in southern Iraq. It is one of the important siliciclastic deposits of the Cretaceous sequence of Iraq oilfields. Zubair oil fields ZB-190 and ZB-047 were chosen to study areas. This study depends on the available core and cutting samples to determine the facies analysis, depositional environments, petrographic characteristics and diagenesis processes. Based on the description of the core and the borehole, six types of facies were distinguished in the Nahr Umr Formation, resulting in an intercalated sandstone and shale with a thin layer of siltstone. The petrographic study of the clastic part of the Nahr Umr Formation showed that the sandstone is composed mainly of quartz arenite. Diagenesis processes affecting the Nahr Umr Formation are two types compaction and cementation processes. The sedimentary environment of the Nahr Umr Formation was represented by the deltaic fluvial environments. These environments appear in the central and southwestern parts of the study area. Sequence stratigraphy in the Nahr Umr Formation is beginning by sequence boundary type one (SB1) and sequence boundary type two (SB2) that appeared in the upper part of the formation. The other surfaces were represented by the end of the deposition of the Nahr Umr Formation and the emergence of the transgressive ravinement surface (TRS) within the transgressive system tract (TST)and The maximum flooding surface (MFS) was distinguished in the middle of the formation and each of these surfaces has a lateral extension along the study section.
The identification of a bed’s lithology is fundamental to all reservoir characterization because the physical and chemical properties of the rock that holds hydrocarbons and/or water affect the response of every tool used to measure formation properties. The main purpose of this study is to evaluate reservoir properties and lithological identification of Nahr Umr Formation in Luhais well -12 southern Iraq. The available well logs such as (sonic, density, neutron, gamma ray, SP, and resistivity logs) are digitized using the Didger software. The petrophysical parameters such as porosity, water saturation, hydrocarbon saturation, bulk water volume, etc. were computed and interpreted using Techlog software. The lithology prediction of Nahr
... Show MoreThe litholog of Nahr Umr Formation was evaluated using the Acoustic Impedance (AI), Vp/Vs ratio cross plot colored by petrophysical properties (Vsh, PHIT, PHIE, and Sw) in Am-6-Am-10 wells. Bulk density is an important physical property that reflects matrix density and fluid density that exist in rocks pores. It is used as the main parameters to estimate physical characteristics (porosity, water saturation, shale volume, and others). AI was calculated using RHOB and VP logs. Shear velocity was calculated using Greenberg Castagna equations used for estimating the Vp/Vs ratio and the result Showed that the Nahr Umr Formation is composed of two main lithological units. The upper unit (depth 3540m -3672m) is composed of limestone (li
... Show MoreThe Zubair Formation is the most significant sandstone reservoir in Iraq which deposited during the Barremian. The study area is located in the central part of Iraq at the Kifl oil field, in the northern part of the Mesopotamian Zone.
The petrographic study showed that quartz mineral is the main component of the sandstone in Zubair Formation with very low percentage of feldspar and rare rock fragments to classified as quartz arenite sandtone. There are five lithologic changes (lithofacies) that have characterized the studied succession: - well sorted quartz arenite, poorly sorted quartz arenite, poorly sorted graywacke, sandy shale, and shale. These lithofacieses were deposited in the deltaic environments as three associate
... Show MoreThis study aims to determine the petrophysical characteristics of the three wells in the Kifl Oilfield, central Iraq. The well logs were used to characterize hydrocarbon reservoirs to assess the hydrocarbon prospectivity, designate hydrocarbon and water-bearing zones, and determine the Nahr Umr Formation's petrophysical parameters. The Nahr Umr reservoir mainly consists of sandstone at the bottom and has an upper shale zone containing a small proportion of oil. The geophysical logs data from three oil wells include gamma-ray, resistivity, neutron, density, acoustic, and spontaneous potential logs. A gamma-ray log was employed for lithology differentiation, and a resistivity log was used to determine the response of distinct zones
... Show MoreThe lower Cretaceous sandstones of Zubair and Nahr Umr formations are the main producing reservoirs in Subba oilfield in southern Iraq. Key differences in their petrophysical and depositional attributes exist affecting their reservoir characteristics. The evaluation of well logs and core porosity-permeability data show better reservoir properties in Nahr Formation. The Litho-saturation logs indicate greater thickness of oil-saturated reservoir units for Nahr Unr Formation associated with lower values of shale volume, and higher values of effective porosity. In addition, higher values of permeability for Nahr Umr Formation is suggested by applying porosity-irreducible water saturation cross plot. The reducing reservoir quality of Zub
... Show More3D seismic reflection study was applied to Abu Amood oil field which is located at the southern part of Iraq within DhiQar province that carried out by oil Exploration Company to an area of 1534.88 Km2 for studying Nahr Umr Formation. Synthetic seismogram was prepared by using available data of well (AAM-1) in order to define and picking the reflectors on the seismic section. These reflectors are (Top of Nahr Umr Formation and middle unit of Nahr Umr Formation which represents the layer of sand). The seismic section time slice maps confirmed that the Nahr Umr Formation was not affected by faults and the faults may probably present in the Ratawai and Yamama Formations, where the variance attribute applied on seismic sections showed that t
... Show MoreRPT is a method used for classifying various lithologies and fluids from data of well logging or seismic inversion. Three Formations (Nahr Umr, Shuaiba, and Zubair Formations) were selected in the East Baghdad Oil field within well EB-4 to test the possibility of using this method. First, the interpretations of the well log and Density – Neutron cross plot were used for lithology identification, which showed that Nahr Umr and Zubair formations consist mainly of sandstone and shale, while the Shuaiba Formation consists of carbonate (dolomite and limestone). The study was also able to distinguish between the locations of hydrocarbon reservoirs using RPT. Finally, a polynomial equation was generated from the cross plot domain (AI versus V
... Show MoreThe Kumait Oil field was interpreted using 3-D seismic data from Oil Exploration company. The Shuaiba Formation (Cretaceous Age) reflector is detected.Structural map of formation is prepared to obtain the location and direction of the sedimentary basin and shoreline. Depth maps was drawn depending on the structural interpretation of the picked reflector and show several structural feature as closures.The seismic interpretation of the area approves the presence of some stratigraphic features in the studied formation. Some distributary mound and flatspot were observed within the study area, but they are not continuous due to the tectonic effects. These activity elements give reasonable explanation for the hydrocarbon distributi
... Show MoreReservoir study has been developed in order to get a full interesting of the Nahr Umr formation in Ratawi oil field. Oil in place has been calculated for Nahr Umr which was 2981.37 MM BBL. Several runs have been performed to get matching between measured and calculated of oil production data and well test pressure. In order to get the optimum performance of Nahr Umr many strategies have been proposed in this study where vertical and horizontal wells were involved in addition to different production rates. The reservoir was first assumed to be developed with vertical wells only using production rate of (80000–125000) STB/day. The reservoir is also proposed to produce using horizontal wells besides vertical wells with production rat
... Show MoreReservoir study has been developed in order to get a full interesting of the Nahr Umr formation in Ratawi oil field. Oil in place has been calculated for Nahr Umr which was 2981.37 MM BBL. Several runs have been performed to get matching between measured and calculated of oil production data and well test pressure. In order to get the optimum performance of Nahr Umr many strategies have been proposed in this study where vertical and horizontal wells were involved in addition to different production rates. The reservoir was first assumed to be developed with vertical wells only using production rate of (80000–125000) STB/day. The reservoir is also proposed to produce using horizontal wells besides vertical wells with pr
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