The Iraqi Geological Journal http://igj-iraq.org/igj/index.php/igj <p>The <strong><em>Iraqi Geological Journal (IGJ)</em></strong> is a peer-reviewed and indexed journal, issued twice a year in English by the Union of Iraqi Geologists (UIG).&nbsp;</p> The Union of Iraqi Geologists en-US The Iraqi Geological Journal 2414-6064 DOLOMITIZATION AND POROSITY EVALUATION OF KHURMALA, GARA ANTICLINE, DOHUK AREA, KURDISTAN REGION, IRAQ http://igj-iraq.org/igj/index.php/igj/article/view/129 <p><em>The Khurmala Formation (Late Paleocene – Early Eocene) is well exposed at the southern limb of Gara mountain, Dohuk area, Kurdistan Region of north Iraq. The thickness of the formation is 94.5 meters, and generally consists of buff to grey, medium to thick-bedded stromatolitic dolostone alternating with thin beds of buff to dark gray shale or marlstone. Shale interlayers increased in thickness upwards. The studied section been divided into three units based on shale ratio. The focus of this study is to investigate type and origin of the dolomite and its impact on the evolution of its porosity using field observation, petrologic and petrographic investigations with SEM microscopy. The common dolomite types include: (1) Unimodal, cryptocrystalline to fine crystalline dolomite of nonplanar&nbsp;&nbsp; mosaic. This type is associated with the relics of the stromatolites and commonly recognized at the upper part. (2) Unimodal fine to medium crystalline&nbsp;&nbsp;&nbsp; , planar-e to Planar-s dolomite mosaic, which is associated with dolomite horizons showing ghosts or relics of benthic forams, algae, ostracods and other bioclasts. The other types are less common and includes (3) Porphorotopic dolomite and (4) Bimodal medium to fine, planer-e to planar-s dolomite mosaic. The latter is associated with dolostone horizons display important moldic and vug porosity. Molds, vugs and intercrystalline porosity are noticed in all types but with variable percentages. Fenestral porosity are common in the stromatolitic dolomite of type one. The vertical distribution of the different type of dolomite and its porosities indicate cyclic alternation of the studied Khurmala section which imply effective eustatic control on deposition and dolomite diagenesis.&nbsp; The dolomitization resulted from a possible combined effect of sea water refluxion and sabkha evaporation mechanisms.</em></p> Basim Abed Al-Qayim Ashti T. Barzani ##submission.copyrightStatement## 2019-11-26 2019-11-26 1 17 PROVENANCE AND DEPOSITIONAL ENVIRONMENT OF THE CARBONATES FROM BALUTI FORMATION (LATE TRIASSIC), KURDISTAN REGION, IRAQ http://igj-iraq.org/igj/index.php/igj/article/view/91 <p><strong><em>The carbonate of Late Triassic Baluti Formation, Kurdistan Region, Iraq was geochemically investigated to interpret provenance, depositional environments and sources of the rare earth elements (REEs) based on major, trace, and rare earth elements geochemistry. The predominance of Ca and the low percentage of Mg suggest that mineral phase is calcite at Sararu; in contrast, the dominance of MgO is in Sarki indicates the carbonate is subject to intensive dolomitization. P and Sr are dominated over the other elements, especially for Sararu carbonate. &nbsp;The positive correlation of ΣREE with Ti, Al, K, Sc, V, Rb, Y, Zr, and Nb and negative correlation with Ca in addition to slight enrichment of LREE suggest an input of siliciclastic sediments from the continent. The low values of the Y/Ho ratio (29.83 to 33.85) relative to marine water and approach of Ce anomaly to 1.0 refer to increasing the clastic flux from the adjacent continent and freshwater intrusion to seawater during the precipitation of Baluti carbonates. &nbsp;The low abundance of Cr, Ni, Co, and the Th/Sc, La/Sc, Cr/Th ratios indicate the felsic source rocks; this is confirmed by the slightly LREE enriched and flat HREE patterns and a slightly high average of (La/Yb)<sub>sn</sub>. Low authigenic U contents, U/Th ratios and slightly negative Ce anomalies suggest the Baluti carbonates were precipitated under oxic conditions and shale at Sarki section was influenced by suboxic conditions. The high Mg/Ca and low Sr/Ca ratios reflect shallow marine environments for Baluti carbonates with diagenetic effect especially in Sarki section. The Mn/Sr ratio implies the Sararu samples have higher degrees of preservation relative to Sarki. Most of REE contents in Sararu is attributed to the terrigenous origin, and the weak non-significant positive correlation of Si, Ti, and Al with REE content suggest little contribution in the Sarki and the biogenic carbonate from the seawater may play a role in the REE concentration. These carbonates possess non-seawater</em></strong><strong><em>-like REE patterns with slightly LREE enrichment and HREE depletion, and characterized by –ve Ce*. </em></strong></p> Faraj H. Tobia Baran H. Mustafa ##submission.copyrightStatement## 2019-11-27 2019-11-27 18 35 GEOHISTORY ANALYSIS AND BASIN DEVELOPMENT OF THE LATE BERRIASIAN-APTIAN SUCCESSION, SOUTHERN IRAQ http://igj-iraq.org/igj/index.php/igj/article/view/116 <p><strong><em>The studied succession is deposited during late Berriasian-Aptian interval, which is represented by the Zubair, Ratawi, Yamama formations. The present study includes stratigraphic development and basin analysis for 21 boreholes (Rachi-1, 2; Rifaei-1, Diwan-1; Ratawi-1, 2; Halfaia-5; West Qurna 12, 15; Nahr Umr-7,8; Zubair-47,49; North Rumaila-72, 131, 158; Suba-7; Majnoon-2, 3 and Luhais-2, 12) distributed within 13 oil fields in the southern Iraq.</em></strong> <strong><em>The back-stripping process determined the original direction of basin depocenter for the studied succession. The Yamama basin in the study area stretches from southeast to southwest with single depocenters, it was located in the southeast of the study area near wells Mj-2, Mj-3.NR-8 and WQ-15 and stretched to the new position southwest near wells NR-7, RU-131, RU-158, ZB-47 and ZB-49. The Ratawi Formation is represented by one depocenter located in the southwest of the study area near wells Rc-1, Rc-2, Lu-12 and Ru-72. The Zubair basin in the study area has two depocenters, the first depocenter is located to the north of the study area near well Dn-1, while the second one is located at the northwest area near wellsSu-7, Lu-12, Rc-1, RC-2 and Rt-1.</em></strong></p> Aiad A.H. Al-Zaidy Taisir G.Z. Al-Mafraji ##submission.copyrightStatement## 2019-11-27 2019-11-27 36 52 UTILIZING CORE AND NMR DATA TO IDENTIFY ROCK-TYPE AND PORE THROAT RADIUS FOR MISHRIF FORMATION IN WEST QURNA OILFIELD http://igj-iraq.org/igj/index.php/igj/article/view/155 <p><strong><em>The middle Cretaceous Mishrif Formation represents the main carbonate reservoir in southern Iraq, charactered by heterogeneity and complexity vertically and laterally, this reservoir encompasses six facies that graduated from mid-ramp facies to supratidal facies. Mishrif Formation in West Qurna oilfield consists of three main reservoir units namely mA, mB1 and mB2 with two cap rocks units CR</em></strong><strong><em>Ⅰ</em></strong><strong><em> and CR</em></strong><strong><em>Ⅱ</em></strong><strong><em>. Rock type and pore throat radius govern the relationship between porosity and permeability. Porosity and permeability are important petrophysical parameters for reservoir evaluation and can be determined directly from core analysis or indirectly using the NMR logging tool. Core data from four wells and NMR data from one well were used to determine the rocks type and the pore throat radius. In this study, Lucia rocks type plot between the porosity and permeability was used to define the classes of Mishrif units’ characteristics. Rocks type of Mishrif Formation was wackestone and packstone in mB2 unit. The mB1unit exhibits increasing in the grain dominated class1. Whereas, unit mA showed a mud-dominated class 3 again. Winland plot was utilized to determine the pore throat radius depending on the mercury injection test with 35% mercury saturation. The unit mB2 marked as mesopores and macropores. Megapores and macropores attribute increased in mB1in the northern part of West Qurna oilfield unit due to increasing shoal and rudist bioherm facies, the mA unit revealed increasing in meso-porous and decreasing in mega-porous. NMR data was correlated with core data and the results supported this reservoir characteristic</em></strong>.</p> Maher J. Ismail Fahad M. Al-Najam ##submission.copyrightStatement## 2019-11-27 2019-11-27 53 69 APPLICATION OF 2D RESISTIVITY METHOD FOR DAM SITE INVESTIGATION IN MIRAKAN AREA, QUSHTAPA DISTRICT, ERBIL, IRAQI KURDISTAN REGION http://igj-iraq.org/igj/index.php/igj/article/view/157 <p><strong><em>Subsurface investigations have significant and substantial effects on the design of dams or any hydraulic structures. The proposed dam is located to the north of Mirakan village within Qushtapa district, Erbil governorate, Iraq. 2D resistivity method was applied to determine the suitability of the Mirakan site for dam construction. The results (</em></strong><strong><em>Pseudo-sections) indicated that the top surface layer of the studied area shows medium to high resistivity which ranges from 75 to more than 360 ohm.m, and it consists mainly of coarse grain materials like gravels, pebbles and, boulders, while in some location fine grain materials like clays and silts appeared. The thickness of this top surface, recent sediment is ranging from 8 to 18 m. The middle part of the Pseudo-sections displays a layer of high resistivity ranges 40– 65 ohm.m, it has been detected within Bi Hassan Formation; it is mainly composed of the conglomerate. The lower part of the pseudo-sections illustrates a layer of low resistivity which represents the fine material deposits of the Bi Hassan Formation and the resistivity ranges from 7–20 ohm. m. There are no faults have been detected in this location as well as there is no evidence of the existence of cavities and there are no risky sources. So, the study area is suitable for dam construction. To sum up, the results reveal that the studied area has the potential to withstand the weight of the dam and natural disasters.</em></strong></p> Payman Salih Othman Galawezh Bakr Bapeer Hawkar Bapeer Bakir ##submission.copyrightStatement## 2019-11-27 2019-11-27 70 77 SIMULATING PRE AND POST STACK MIGRATION FOR 2D SEISMIC LINE IN BALAD-SAMARRA AREA, CENTRAL IRAQ: A SEISMIC UNIX IMPLEMENTATION http://igj-iraq.org/igj/index.php/igj/article/view/120 <p><strong><em>Migration is a process by which reflectors are re-positioned to their true subsurface locations. The accuracy of the migrated velocity model and time determines the subsurface imaging quality. For complex structures, the reflecting and/or diffracting energy from source points will not vertically be oriented beneath the common mid-point (CMP). However, an acceptable migrated velocity model is usually performed by several parameters. Stolt migration method is applied to a 2D seismic line within Salah Al-Din province (Balad-Samarra area), central Iraq. To understand the effect of Stolt migration method and parameters used in the migration, a simulated synthetic model has been made with the same field parameters for the studied seismic line and with the same vertical cross-section of the geological subsurface layers. This model is constructed to generate raw seismic data, which was reprocessed using Seismic UNIX (SU) package in the post and pre-stack migration situation. Stolt migration is applied in the time domain for the modeled processed data to test the effects of changing the values of each parameter. A suitable migrated velocity values deduced from the analyzed model is tested for real surveyed line and the images results for the subsurface structures are accurate without diffraction. The results indicate that pre-stack time migration is best due to the lateral velocity variation and structural complexity and velocity analysis confirm that pre-stack is better than post-stack time migration.</em></strong></p> Fadhil Abdulabass Obaid Ali M. Al-Rahim ##submission.copyrightStatement## 2019-11-27 2019-11-27 78 90 MICROFACIES AND DEPOSITIONAL ENVIRONMENT OF MISHRIF FORMATION, NORTH RUMAILAOILFIELFD, SOUTHERN IRAQ http://igj-iraq.org/igj/index.php/igj/article/view/154 <p><strong><em>Mishrif Formation is one of the main oil reservoirs in southern Iraq. This study analyzes the microfacies and depositional environment for Mishrif Formation in North Rumaila oilfield. The study was based on the analysis of 17 wells core. The Mishrif Formation represents deposition in a carbonate platform ramp system, with scattered patch reefs and shoals developed across the ramp margin and the platform top. </em></strong><strong><em>It is characterized by skeletal grains (bioclasts) which are dominated such as foraminifera, rudist, calcareous Algae and other skeletal grains included mollusks shell fragments with Chondrodonta sometimes, and Echinoderms while non-skeletal grains are less abundant which are represented by Peloids and Ooids. According to the petrography analysis of Mishrif Formation, the fossils are dominated in the formation, four groups of these fossils are diagnosed, and these are Oligosteginid, Alveolinids, Dicyclina and Miliolids. Can be identified and build the sedimentary model with microfacies which apply to the Mishrif Formation. The sedimentological and stratigraphic analysis of Mishrif Formation core led to identification of 16 facies association, seven of which are found in the mB unit (lower part of the Formation) whereas they are deposited in outer ramp, mid ramp, ramp margin and lagoon, while nine in the mA unit (upper part of the formation) which are deposited in intraplate basin, mid ramp, inner ramp, ramp margin and lagoonal supra tidal</em></strong><em>.</em></p> Muslim M. Al-Ali Maher M. Mahdi Rasha A. Alali ##submission.copyrightStatement## 2019-11-26 2019-11-26 91 104 CLIMATIC WATER BALANCE FOR ISHAQI AREA, SALAH AL-DEAN GOVERNORATE, IRAQ http://igj-iraq.org/igj/index.php/igj/article/view/111 <p><strong><em>In any natural area or water body, evapotranspiration is one of the main outcomes in the water balance equation. It is also a crucial component of the hydrologic cycle and considers as the main requirement in the planning and designing of any irrigation project. The climatic parameters for the Ishaqi area are calculated from the available date of Samarra and Al-Khlais meteorological stations according to a method for the period (1982–2017) according to Fetter method. The results of the mean of rainfall, relative humidity temperature, evaporation, sunshine, and wind speed of the Ishaqi area are 171.96 mm, 49.67%, 24.86 C°, 1733.61 mm, 8.34 h/day, and 2.3 m/sec, respectively. Values of Potential Evapotranspiration are determined by utilizing equation Thornthwiat, Lerner's methods. is applied for computation water balance. The water surplus amount of the study area is 89.9 mm, while the water deficit amount of the study area is 884.228 mm. The type of climate was determined by applying three climate classifications. The area was considered as arid climate according to the Mather and Brown &amp; Cocheme classification.</em></strong></p> Moutaz A. Al-Dabbas Marwa A. Abdulla ##submission.copyrightStatement## 2019-11-27 2019-11-27 105 115