The Paleocene benthic foraminiferal zonation of the Umm Er Rhadhuma Formation from the borehole (K.H 12/7), South Anah City (Western Iraq), has been re-studied and re-analyzed precisely based on the large benthic foraminifera (LBF). They are represented by two biozone Rotorbinella hensoni Partial Range Zone, recorded from the Lower and middle parts of the Umm Er Rhadhuma Formation and Lockhartia praehaimei Partial Range Zone determined Uppermost of this unit, and dated to be the Selandian – Thanetian stage. Almost all the biogenic (micro and macro) and non-biogenic constituents, including large benthic foraminifera, Algae, Echinoderm, Bryozoans, Oyster, Gastropod fragments, and peloids, in addition to lithofacies types, indicate that this succession belongs to the Umm Er Rhadhuma Formation. Furthermore, the Paleocene shallowing upwards succession is recognized from seven identified microfacies (MF1 to MF7), which suggests three significant facies associations. A broad inner ramp represents them and is warm shallow open normal marine water (FA1). In contrast, the second facies association represents by the predominated bioclastic sand shoal facies association (FA2) and finally reaches the semi-restricted lagoon facies associations (FA3). The interaction between the local tectonic disturbance along Rutba high and eustatic sea level mainly controls the development of two sequence boundaries of Type-1 (SB1) that occurred respectively at the Cretaceous /Palaeogene K- Pg boundary and Paleocene /Eocene boundary. The Paleocene depositional system starts with major transgression during the Selandian above a sequence boundary of type one (SB.1), that separates the Late Cretaceous (Maastrichtian) successions of the Tayarat Formation from the overlying Paleocene succession with a significant gap, covering the whole Danian age (That is the top of Tectonic Megasequence AP. 9). The predominance of retrogradation staking tract indicated the transgressive system tract during the late Selandian and early Thanetian as a result of an increase in the sea level rise and expanded accommodation space. The highstand system tracts show aggradational and then change to a progradational stacking pattern by the end of the Thanetian and mark significant sea level drawdown with a new sequence boundary of type one between them.
The aim of this study is to investigate the sedimentation environments and diagenetic processes of the Ibrahim Formation (Oligocene-early Miocene) in Zurbatiya, eastern Iraq. The Ibrahim Formation is comprised mostly of clayey micrite and skeletal grains composed of planktonic foraminifera, calcispheres, radiolaria, and benthic foraminifera. Glauconite and pyrite were documented in some restricted zones of this formation; they reflect quiet and reducing conditions. Radiolaria were identified in Late-Oligocene which was not known previously at this age regionally in carbonate formations of the Arabian Plate (AP). Mudstone, wackestone, and planktonic foraminiferal wackepackstone are the main microfacies that are affected by dissolutio
... Show MoreThis study deals with establishing the depositional environment of the Fatha Formation through facies analysis. It also deals with dividing the formation into units based on the rhythmic nature. Data from selected shallow wells near Hit area and deep wells at East Baghdad Oil field are used. Five major lithofacies are recognized in this study, namely, greenish grey marl, limestone, gypsum (and/or anhydrite), halite and reddish brown mudstone (with occasional sandstone).The limestone lithofacies is divided into three microfacies: Gastropods bioclastic wackestone microfacies, Gastropods peloidal bioclastic packstone, and Foraminiferal packstone microfacies.The lithofacies of the Fatha are nested in a rhythmic pattern or what is known as sh
... Show MoreRecords of two regionalized variables were processed for each of porosity and permeability of reservoir rocks in Zubair Formation (Zb-109) south Iraq as an indication of the most important reservoir property which is the homogeneity , considering their important results in criterion most needed for primary and enhanced oil reservoir .Z and F tests that were calculated for the two above mentioned properties of pair units of Zubair Formation have shown the difference in depositional energy and different diagenesis between units IL and AB , DJ and AB , and the similarity in grains size , sorting degree , depositional environment and pressure gradients between IL and AB units , LS and IL units ; also the difference in the properties above betw
... Show MoreThe Barremain-Aptian succession represented by two types of deposits, Clasits deposits of Zubair Formation. This formation is the most significant sandstone reservoir in Iraq, Deposited in fluvio- deltaic, deltaic and marine environments during the Barremain to Early Aptian age.
The area of study is located in the Mesopotamian Zone at S
The Barremain-Aptian succession represented by the Clasits deposits of Zubair Formation. This formation is the most significant sandstone reservoir in Iraq which deposited in fluvio- deltaic, deltaic and marine environments during the Barremain to Early Aptian age. The area of study is located in the Mesopotamian Zone at Southern part of Iraq which represented by five oil fields (Nasira, L
... Show MoreSedimentary structures of Gercus Formation in NE Iraq was little studied in the last decades. In this study the identified sedimentary structures display alternative graded and fining upward cycles, load and flute casts, submarine channels, sand and clay balls and pillow structures, convolute and slump beddings, of marine turbidity origin. The foreland part of Tethys basin characterized by deep marine Tanjero and Kolosh Formations followed by the Gercus formation with conformable relationships. The Eocene aged Flysch comprises predominantly litharenitic sandstones and interbedded mudstones, both of turbiditic affinities and most likely derived from a NE Arabian Plate source. The sediments provide excellent examples of distal fan sands as
... Show MoreIn the Rumaila oilfields in southern Iraq, the Zubair Formation was deposited in a shallow environment as three main facies, delta plain, backshore, and delta front depositional conditions indicating a transition from delta front and delta plain to a highstand level due to the finning upward mode. The facies of the Zubair clasts show well-sorted quartz arenite sandstone, poorly sorted quartz arenite sandstone, clayey sandstone that has not been properly sorted, sandy shale, and shale lithofacies. The minor lithofacies were identified using well-logging methods (gamma ray, spontaneous potential and sonic logs) and petrography. The Zubair clasts are of transition environment that appears to be transported from freshwater and deposited
... Show MoreThe middle Cenomanian – early Turonian Mishrif Formation, a major carbonate reservoir unit in southern Iraq, was studied using cuttings and core samples and wireline logs (gamma‐ray, density and sonic) from 66 wells at 15 oilfields. Depositional facies ranging from deep marine to tidal flat were recorded. Microfacies interpretations together with wireline log interpretations show that the formation is composed of transgressive and regressive hemicycles. The regressive hemicycles are interpreted to indicate the progradation of rudist lithosomes (highstand systems tract deposits) towards distal basinal locations such as the Kumait, Luhais and Abu Amood oilfield areas. Transgressive hemicycles (transgressive systems tract deposits)
... Show MoreA surface section of the Gercus Formation (Middle-Late Eocene) was studied in Berafat area, Dohuk Governorate, Northern Iraq. The Gercus Formation consists of a mixed siliciclastic sediments, evaporates and carbonate sequences in the studied region, predominantly in the upper and middle parts. Nevertheless, it usually consists of upward-fining carbonate-rich sandstone cyclothems, marl, conglomerate and siltstone along with a gypsum lens and thin micrite carbonate beds. The Gercus Formation was deposited in delta and delta front of occasionally depositional environment which is represented by red-brown claystone and reddish-brown mudstone lithofacies. Cross bedded pebbly sandstone, trough cross-bedded sandstone and lamin
... Show MoreThis study focuses on determining the heterogeneity of Yamama Formation and its spatial distribution in south of Iraq using three indices namely, Coefficient of Variation, Lorenz Coefficient, and Dykstra – Parsons Coefficient. The porosity and permeability values from eleven wells in south of Iraq (Basra and Maysan oil fields) are used for computing heterogeneity indices. Ordinary kriging technique is used to interpolate the computed indices and to show the spatial distribution of these indices over the study area. Results indicated that the average values of Lorenz and Dykstra – Parsons Indices are 0.73 and 0.86, respectively which refer to the extremely heterogeneity nature of Yamama Formation in the study area.The spatial distribu
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