Baluti Formation of the Rhaetian (Late Triassic) age is composed mainly of dolomite, the unit formed with dolomitic limestone, dolomitic breccias and limestone begins with gray or dark gray colored and sugar textured dolomitic limestones including micrite with shale horizons. Baluti Formation was deposited in carbonate platform, and slumped to deeper margins forming carbonate debrites and breccias of various types.
Petrographic examination of the dolomites reveals various crystal habits and textures of the dolomites. Planktonic bivalve, calcisphere and echinoid spicules were found in the Baluti Formation settled in deep-margin carbonate environment. Nine dolomite-rock textures were identified and classified according to the crystal-size distribution and crystal-boundary shape. These are made of unimodal, 1) very fine to fine-crystalline planar-s (subhedral) mosaic dolomite; 2) unimodal, medium to coarse-crystalline planar-s (subhedral) mosaic dolomite; 3) coarse to very coarse crystalline planar-s (subhedral) dolomite; 4) medium to coarse-crystalline planar-e (euhedral) mosaic dolomite; 5) medium to coarse-crystalline planar-e (euhedral) dolomite; 6) coarse to very coarse-crystalline non-planar-a (anhedral) dolomite; 7) coarse to very coarse-crystalline non-planar-c (cement) dolomite; 8) polymodal, planar-s (subhedral) to planar-e (euhedral) mosaic dolomite. Dolomitization is closely associated with the development of secondary porosity; dolomitization pre and post diagenetic dissolution and corrosion and no secondary porosity generation is present in the associated limestones. The most common porosity types are non-fabric selective moldic and vugy porosity and intercrystalline porosity. These porous zones are characterized by late-diagenetic coarse-crystalline dolomite, whereas the non-porous intervals are composed of dense mosaics of early-diagenetic dolomites. The distribution of dolomite rock textures indicates that porous zones were preserved as limestone until late in the diagenetic history, and were then subjected to late-stage dolomitization in a medium burial environment, resulting in coarse-crystalline porous dolomites. Baluti dolomites have been formed as early diagenetic at the tidal-subtidal environment and as a late diagenetic at the shallow-deep burial depths.
Nasiriya field is located about 38 Km to the north – west of Nasiriya city. Yammama, a giant lower cretaceous reservoir in Nasiriya field which is lithologically formed from limestone. Yammama mainly was divided into three main reservoir units YA, YB1, YB2 and YB3 and it is separated by impermeable layers of variable thickness. An accurate petro physical evolution of the reservoir is of great importance perform an excellent geological model so that four petro physical properties which are shale volume, porosity, water saturation and permeability was re-evaluated. The volume of shale was calculated using the density and neutron logs (VSH-DN) rather than using gamma ray log because of presence a uranium content in the formation that make
... Show MoreThe 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 MoreSeismic instantaneous phase attribute was applied for conventional seismic interpretation (structural interpretation) on 3D seismic cube of 1914.72km² of Samawa-Diwan area, located in the south part of Iraq within Muthna governorate. Instantaneous phase section is very important to detect structural and stratigraphic features. Six reflectors represent Upper Jurassic and Cretaceous formations were defined from synthetic seismogram of wells in study area, then picked over seismic cube. Fault boundaries maps for each horizon were drawn depending on horizon contacts then fault planes were constructed. Finally, a 3D structural model was constructed in time domain, then converted to depth domain by using 3D average velocity model. Structurall
... Show MoreThe Central Marshes are one of southern Iraq's most important wetlands and ecosystems. A study on evaluating soil quality and water quality in terms of chemical properties at certain sites in the southern Iraqi Central Marshes has been conducted to investigate their types and suitability for enhancing the agricultural reality of most field crops. Soil and water samples were collected from 15 sites and transferred to the laboratory. In the lab, the following parameters were determined: electrical conductivity (EC), total dissolved salts (TDS), organic materials (OM), pH, gypsum, and total sulfate content (SO3). The tests conducted on the samples indicated that it could be said that the soil of the Central Marshes
... Show MoreElectrical resistivity methods are one of the powerful methods for the detection and evaluation of shallower geophysical properties. This method was carried out at Hit area, western Iraq, in two stages; the first stage involved the use of 1Dimensional Vertical Electrical Sounding (VES) technique in three stations using Schlumberger array with maximum current electrodes of 50m. The second stage included the employment of two dimension (2D) resistivity imaging technique using dipole-dipole array with a-spacing of 4m and n-factor of 6 in two stations. The 1D survey showed good results in delineating contaminated and clear zones that have high resistivity contrast. Near the main contaminated spring, the 2D resi
... Show MoreThe resistivity survey was carried out by using vertical electrical sounding (VES) and 2D imaging techniques in the northern Badra area, Eastern Iraq. Eleven VES points distributed on two parallel profiles and six 2D imaging stations were applied using long survey lines.
In general, two types of aquifers are recognized in the study area. The first is the Quaternary aquifer, which appears in all geological sections and inverse model of 2D imaging stations (2DS).This aquifer can be divided into upper and lower aquifers as shown in (2DS1), (2DS3), and (2DS4). Generally, the thickness of this aquifer ranges between (30-200 m) which occurs at a depth of (10-30m) according to geological sections, while its thickness ranges between (35-180m)
This paper includes studying the microfacies evalution of Mauddud Formaion in
four wells(Rt-2, Rt-5, Rt17 and Rt-19). Seventy-seven(77) sampels were collected
of above mentioned wells. Based on fossil content of the samples under study, four
main microfacies were identified: packstone , wakestone , grainstone and lime
mudstone microfacies ,which deposited in shallow open marine and restricted
marine environments. Petrographic examination of thin section indicated that
diagenesis vary in intensity from one site to another, such as dissolution,
cementation, compaction, dolomitization and micritization, which led to the
improvement and deterioration of porosity. The dominant pore types are vuggy,
interparticle and
The Yamama Formation was studied in three wells (Fh-1, Fh-2, and Fh-3) within Faihaa oil field, south Iraq. Thin sections were studied by using the polarizing microscope examination in order to determine microfossils and biozone. Thirty-five species of benthic foraminifera were recognized, including four index species. In addition, twelve species of calcareous green algae were recognized, including two index species. Other fossils that were recognized in Yamama Formation include Gastropoda, Bryozoa, Coral, Rudist, and Pelecypoda.
Six biozones were observed, which are Charentia cuvillieri sp. (Range Zone of Berriasian age), Psudochryalidina infracretacea
... Show MoreFifteen samples of limestone, marls and, clay from the Fat'ha Formation are obtained from the location of Bashiqa village, Bashiqa anticline, Northeastern Iraq. A detailed investigation is carried out, during which twenty-four species of calcareous nannofossils identified, twenty- one are descried from other regions while three are left under an open name because of lack of material or insufficient samples. Besides, seventeen species of Ostracoda fossils were picked and diagnosed, including two subspecies, belonging to ten genera, and four subgenera.
The recorded calcareous nannofossil assemblages include two biozones which are from the lower to the upper part of the section: (1) Helicosphaera ampliaperta Interval Bio
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