Iraqi National Journal of Earth Science

The current study deals with the rock successions of the Chia Gara Formation (Late Jurassic- Early Cretaceous) in two outcrop sections (Rania and Barsarin) from the northern part of Iraq. The successions are composed of hard limestone and dark grey fissile shale containing bituminous materials, with phaciod structures in its lower part, and Ammonite fossils in its upper part.
The Chia Gara Formation in the study sections conformably underlies the Barsarin Formation. However, it conformably overlies the Balambo Formation in the Rania section, while it is conformably overlain by the Sarmord Formation in the Barsarin section.
Petrographic examination has revealed that the most abundant skeletal grains are ammonite, radiolaria and calcispheres. However, siliceous sponge spicules and ostracode are locally present and occur in a minor amount in the micritic groundmass.
The detailed facies analysis of the rock successions of the Chia Gara Formation reveals that they are composed of three main microfacies and two lithofacies. The microfacies include lime mudstone, lime wackestone, and lime packstone, these microfacies are subdivided into seven submicroficias. On the other hand, the lithofacies comprise limestone and shale lithofacies. Based on the evidence from microfacies, lithofacies, the Chia Gara Formation was inferred to be deposited in a deep marine environment. Thus, the lower, middle and, upper part of the successions was deposited in the upper bathyal, middle bathyal and, outer shelf setting respectively.

Chemical, mineralogical and physical evaluation of sediments accumulated in Al Wand Dam shows that the sediments have a high percentage of silt with medium plasticity. The chemical and mineralogical analyses reveal that (SiO2) is the main chemical component of the sediments, which indicates the high content of quartz from one hand, and clay minerals (montmorillonite, chlorite) and calcite on the other hand. Three groups of laboratory bricks are formed forming (8) samples using the semi-dry pressing method and a single-axis hydraulic press with a pressure of (250) kg/cm2. Then these samples were fired at a temperature of (950) °C according to a special program, with a time increment of (4) degrees Celsius per five minutes, and a soaking time of only one hour. The samples prepared from the sediments are characterized by longitudinal and volumetric shrinkage for sites (A, B, C) of (0.9_1.1_1.3%) (4.4_4.1_4.2%) respectively. Compressive strength and water absorption percentage for samples (A, B, C) have amounts of (73_85_76 kg/cm2), (_27.5_27.2 26.1%) respectively. While blooming is (light to non-existent). Based on the Iraqi Standard Specification No. 25 (1993), the sediment samples accumulated in the Al Wand Dam reservoir are found to be suitable for the manufacture of class (C) bricks.

Analysis and comparsion of fold style in the Chia Gara anticline, which is located in the high folded zone of Iraq have been done between the rocks of the Late Cretaceous (Bekhme Formation) and rocks of the Paleogene (Pila-Spi Formation) using the harmonic analysis of Fourier's mathematical method. The study on two traverse shows a difference vertically and laterally in the fold style between the two formations despite the similarty existing in the lithology and competance. This reveals that the fold being affacted and changed its style in the Pela Spi Formation larger than the shape in the Bekhme Formation This indicates that the fold was greatly affacted by listric fault on the Pila Spi Formation than Bekhme Formation due to reactivation of the reverse movement on that fault during the time of collision (continental-continental) between Arabian and Eurasian plates.

For its vastness and range of crops, the Khazir River Basin is an important agricultural region. Since groundwater supplies domestic and agricultural water, it is heavily pumped there. This study maps groundwater contamination risk and identifies high-risk locations. GIS is utilized for computations and producing maps of vulnerable water-bearing units. The most influential factors that play a major role in groundwater pollution have been considered and are the heart of DRASTIC model. A Digital Elevation Model (DEM) of 30 meters resolution is used to create the slope map (topography map) of the area. Due to the fact that the land in the study area is intensively utilized for agricultural purposes where fertilizers are always used for improving crop production, two types of DRASTIC models have been run under two scenarios, one is standard denoted as (S-DRASIC), and the other is a pesticide DRASTIC approach denoted as (P-DRASTIC). The results clearly show that the areas of shallow groundwater depths, porous aquifer media, highly permeable soil media, low slope terrains, thin and permeable vadose zone and finally an aquifer of high hydraulic conductivity revealing a high vulnerability to contamination.

The current study aimed to show the utility of the velocity deviation technique in determining the porosity types of Sheikh Allas Formation in the Kirkuk oil field. Log data collected from two wells in the study area (k-218, and k-246) were analyzed. 46 thin section slides performed by different cutting samples at certain depths were used to identify porosity types. The sonic log was utilized to estimate the true velocity, while neutron and density logs were employed to estimate porosity. Velocity deviation was calculated by subtracting the porosity log velocity from the sonic log velocity. The results revealed that there is a significant agreement in the directions of increase and decrease between the secondary porosity produced by the dolomitization and the velocity deviation. The amount of dolomite in well k-218 increased significantly, as indicated by the higher neutron porosity than density porosity. The high agreement between the neutron porosity and density porosity in well k-246 indicates that the dolomitization process has little effect in this well. By observing the velocity deviation curves, it was found that there is a clear difference between the two wells in the types and depths of the porosities. The secondary porosity in well k-246 does not exceed 5%, while it reaches 15% at some depths in well k-218. It is the most obvious difference between the two wells, resulting from the increase in the percentage of dolomite in well k-218, which may indicate the proximity of well k-218 to the coastal environment. Furthermore, the abnormally high primary porosity that appears at various depths in well k-218 is a feature of this well. A high consistency between the thin section information and the velocity deviation technique in terms of porosity types and their locations was observed. Resistivity logs are also used in this study to identify the permeability locations.

The Piran Limestone Unit in Kani Rash in Piran Sub-district is studied in order to determine the stratigraphical and palaeontological relationships. Based on the general geology and structural relations of the thrust units in the surroundings, the most representative layers are selected. The total number of the collected samples is 13. The same number of the thin sections are prepared and examined under the microscope. Biofacies assemblages are determined from thin sections using the polarized microscope. Based on the occurrence of Fasciculithus tympaniformis sp., Heliolithus riedelii sp., Reticulofenestra sp., Prinsius sp., Sphenolithus anarrhopus sp., and Sphenolithus moriformis sp., the age of this unit is determined to be Middle Thanetian.

The main goal of this study is to figure out how safe rock formations are that have buildings on them and are often visited for research or exploration. In order to do this, the rock masses will be measured with the RMR and CRMR systems. Field and laboratory data are used to gather for these two systems; the RMR system has six parameters, while the CRMR system has eight parameters. The classification method for rock masses is a valuable tool for both geologists and geotechnical professionals, as it enables them to address stability issues and recommend appropriate support systems for the rock masses. Rock masses are rated as fair by the Rock Mass Rating (RMR) classification, necessitating a support system. Ain Al-Dawaar appears into the good category, however the other two caverns fall into the fair group according to the CRMR approach. Therefore, a development process is required for all the caves.

Estimating the surface runoff that reaches the dam’s reservoir is an urgent demand in the design of dams construction projects and managing water resources. There are many techniques used to estimate the runoff generated from rainfall. This research aims to compare the peak and volume of runoff that enter to the Duhok Dam reservoir in Duhok City in Northern Iraq by two widely used techniques, Soil Conservation Service Curve Number (SCS- CN) and Rational Method. Integrated GIS with remote sensing data are used to apply both techniques over the dam catchment. The Digital Elevation Model (DEM) of 30 m resolution and Sentinel (2A) image of 10 m resolution of 17th February 2016, incorporated with FAO soil group as well as interpolation of rainfall data of four stations have been used to produce the objectives maps for these methods. The result of surface runoff depth shows that the values range from 568 mm to 777 mm by the SCS-CN method and 142 mm to 646 mm by the rational method. According to this study, the SCS-CN method provides proper results of runoff estimation by considering different characteristics of the runoff and according to the size of the watershed.

Due to information scarcity of the study area, so this work is an attempt to uncover important subsurface Nubia sandstone oil reservoir characteristics mainly in terms of porosity using petrographic description in addition to porosity measurements for the core samples got from two wells (GH404-A2A and GH404-A3B) at South-Ghara oil field, Gulf of Suez region. The studied Nubia sandstones are mainly classified as quartz arenite. The recorded quartz varieties indicate that the studied Nubia sandstone in the two wells have been derived from plutonic and high rank metamorphic rocks. The general scarcity of feldspar could be attributed to its decomposition due to the low topography associated with warm and humid climate.
The total porosity of the (15) selected sandstone samples representing the Nubia sandstone is measured by a Helium porosimeter. The average measured value for the studied samples of the Nubia sandstone is 15.24% and 12.22% for the two wells GH404-A3B and GH404-A2A respectively. The values indicate a fair porosity. Based on the petrographic investigation, the recorded porosity is of type interparticle. The precipitated cement in the form of iron oxides, calcite, evaporate and silica (as quartz overgrowth or chalcedony) is the most effective factor in reducing the primary porosity of the studied rocks. Also, authigenic clay minerals and feldspar have reduced the primary porosity.

Fourteen soil samples are collected from different stations in Al-Zubair City. The inductively coupled plasma mass spectrometry (ICP-MS) is applied for determination of (Pb, Zn, Ni, Cd, Co, Fe, Cu, Mn, Cr and as) to assess the level of pollution in soil. The grain size analysis indicates that soil of silty sand type with low content of clay. The acidity of the soil is acidic to slightly alkaline in most stations and have low to moderate content of total organic carbon (TOC) and salts (E.C). The mean concentration of heavy metals follows the order: Fe>Mn>Zn>Cr>Ni>Pb>Cu>As>Co>Cd. Based on Igeo and PI value, the results reveal high pollution level for both Cd and Zn especially in Kut Al-Markaz, Al-Faraha and Al-Thoahrat stations, whereas IPI indicates low to moderate levels. On the other hand, EF of heavy metals is in decreasing order: EFCo>EFCd>EFAs>EFPb>EFZn>EFNi>EFCu>EFCr>EFMn. Generally, the pollution of Al-Zubair soil is attributed to the anthropogenic sources like the industrial emission of Al-Shuaiba oil refinery, oil exploration processes, vehicle emissions in the center of city as well as the waste of petrochemical company nearby Al-Zubair City

Abstract: The Baba Formation succession (Middle-Late Oligocene) is studied within the wells (K-1) and (K-2) in Kirkuk oil field, northeastern Iraq. The formation thickness in the first well is about (45) meters and in the second well is about (65) meters respectively. The formation consists of hard limestone, brown in color and dolomitic limestone. The formation consists of many benthic foraminifera as (Miliolid) and planktonic foraminifera as (Globigerina aselli, Globigerina ampliapertura, Globigerina praebulloides, Catapsydrax dissimilis, Chilogumbelina sp., Globigerina ciperoensis, Paragloborota liaopima), In addition to Nummulites fichteli, Nummulites vascus and a few of Lepidocyclina sp., echinoderms, bryozoa, and algae, and their fragments. The Microfacies appear to be highly affected by many diagenesis processes such as dolomitization, compaction, cementation, dissolution and recrystallization. The formation is composed of three main microfacies, which in turn are divided into (11) secondary microfacies whose general characteristics are similar to the characteristics of the microfacies proposed by Flugel, namely (RMF-2, RMF-3, RMF-5, RMF-7, RMF-13, RMF-16). Based on the results of the microfacies analysis, it is found that the sedimentary environment of the Baba Formation is the carbonate ramp environment, as the facies of the Baba Formation spread within the restricted environment of the inner ramp, which was characterized by the spread of the millolid fossils to the middle ramp environment with the distribution of Nummulites shells, and towards the outer ramp with the presence of planktonic foraminifera.

A composite biostratigraphic study has been carried out from four selected sections representing an interval between the Cretaceous/Paleogene (K/Pg) boundary within the Imbricated Zone (Chwarta – Mawat), Sulaimani area, Kurdistan region, northern Iraq. The study covers the Maastrichtian successions, represented by the upper part of the Tanjero and Aqra formations, and the Paleogene succession, represented by the lowermost portion of the Suwais Group. The biostratigraphic study is based on the Large Benthic Foraminifera, supported by planktic foraminifera, Calcareous Nannofossil biozone, and ammonite biozones, which are in turn compared with the local and international biozones. The recorded large benthic foraminifera biozones are: - Loftusia minor, Loftusia coxi, Orbitoides media, and Lepidorbitoides socialis Assemblages Zone (indicates early Late Maastrichtian age). Loftusia morgani, Siderolite calcitrapoides, Orbitoides apiculatus Assemblage Zone (indicates middle Late Maastrichtian age). Loftusia persica-Loftusia elongata Assemblage Zone (indicates late Late Maastrichtian age). The Pseudoguembelina hariaensis Partial Range Zone (CF3) recorded in Kato and Maukaba sections shows a middle Late Maastrichtian age. The recorded Calcareous Nannofossils are related to the Micula murus-Micula prinsii (CC26) Assemblage biozone recorded for the first time in the studied area and almost of Late Maastrichtian age but not extend to the latest Maastrichtian. Also, for the first time, an ammonites biozone was recorded in this area and represented by Hoploscaphites constrictus crassus Partial Range Zone (indicates early Late Maastrichtian). As a result, the K/Pg represents a significant gap (about 5my) and unconformity with 500m conglomerates.

The microfacies are identified within the Jaddala Formation in wells (Ja_40, K_243, and K_411) in northeastern Iraq and from the petrographic study. it is found that most of the skeletal grains consist of planktonic forams such as (Globigerina, Globorotalia, Acarinina, and Subbotina). Benthonic foraminifera is low, while non-skeletal granules are limited to quartz and phosphate grains, and the groundmass is mainly brown to light micrite. The lithology is affected by diagenetic processes such as compaction, cementation, dissolution, recrystallization, and authigenic minerals such as pyrite. Based on the petrographic study, the microfacies are divided into three main microfacies identified as Lime Mudstone Microfacies (LMJ), Lim Wackstone Microfacies (LWJ) and Lime Packstone Microfacies (LPJ) which are divided into two Submicrofacies Planktonic Foraminiferal Lime Packstone Submicrofacies (LPJ1) and Bioclastic Lime Packstone Submicrofacies (LPJ2). The depositional environment of the formation is determined depending on the Microfacies content of the fossil’s planktonic foraminifera and benthonic foraminifera as well as its comparison with the standard microfacies. Three main environments for the sedimentation of the Jaddala Formation are distinguished depending on the classification of the environments set (toe_ of_ slope, deep shelf, and deep sea). This difference in environments is caused by a difference in the topography of the sedimentary basin.

The Kirkuk oil field is one of the Iraqi large and old oil fields, as it was produced in the thirties of the previous century (twentieth century). The production of oil for long periods may lead to a decrease in the pressure of the hydrocarbon flow inside the wells, which may require development operations for these wells, and these operations require sufficient knowledge of the petrophysical properties, of which is the porosity as the most important property of the rocks.
The main objective of this study is to evaluate the proportions and types of porosity within the rocks of the Bajawan Formation, which is considered one of the oil-producing Tertiary formations in the Kirkuk oil field.
In this study, twenty thin sections are examined as well as porosity logs are analyzed for three wells drilled in the Baba dome (K-183, K-218, and K-246). Baba dome is one of the three domes of the Kirkuk anticline.
The results of the study show that the proportion of porosity in the formation is relatively high, that there are multiple types of primary and secondary porosities, and that the effective porosity is close to the total porosity due to the low percentage of shale in the formation. The results of the study also show that there are some limited areas that may contain gas.

The goal of the research is an estimation of meteorological drought indices and their impact on desertification and land degradation. The climatic data for the time series from 1990-2021 are used, which involves precipitation, temperature, humidity and evapotranspiration, depending on the aims of the paper. The precipitation-based drought indices SPI (Standardized Precipitation Index), RDI (Reconnaissance Drought Index), PNI (Percent of Normal Index), RAI (Rainfall Anomaly Index), and ZSI (Z-Score Index) and PPA (Percentage of Precipitation Anomaly) are calculated. Analysis correlation and regression coefficient are also calculated between them. The results show that all indices point to a severe drought for the periods from 1990-1993 and 1998- 2000, as well as, the highest humid years in 2015 to 2018 (15 to17 years less than zero and 14-16 years above zero according to index) Also, that drought was continuous for years 2020, 2021 and till now. The results indicate a positive linear regression relationship between the SPI and RDI, RAI, ZSI, PNI, and PPA in range (R2 = 0.99, 0.96, 0.95, 0.95 and 0.95). While the correlation relationship between the SPI and other indices is strongly positive (r > 0.97).

Thirty-seven water samples are collected from the study area between Karbala and Najaf between longitudes (43°90´-44°25´) and latitudes (31°95´-32°40´) to study the physicochemical properties including concentrations of the major and minor ions and heavy metals. The electrical conductivity range between (2670-13270 µ/cm), total dissolved solids (1709-8489 ppm), calcium (188-798 ppm), magnesium (81-563 ppm), potassium (3-128 ppm), sodium (235-1200 ppm), chloride (355-1710 ppm), sulphate (582-2740 ppm), bicarbonate (114-1358 ppm), nitrates (0.2-2.1 ppm), the concentration of iron, lead, and cobalt are less than (0.05 ppm), manganese (0.05-0.23 ppm), copper (0.143-0.157 ppm), and nickel (0-0.21 ppm). The hydro-chemical variables show that salinity concentrations and the major ions increase in the direction of groundwater flow. The water type in the study area is sulphate. The groundwater is polluted with heavy metals in some places of the study area, as it is higher than the permissible standard limits, especially for (Mn, Ni, Pb). As for the evaluation of groundwater in the study area for human drinking purposes, it is found that it is not suitable in most of the wells. With regard to its use for animals, it is suitable for livestock and unsuitable for poultry. Indicators (SAR, Na%, PI, KI) are used to evaluate water for irrigation purposes and it is found to be good.

The current study is an attempt to identify possible subsurface structural features such as voids and cavities in the Galala area, Northwestern part of the Gulf of Suez, Egypt using shallow seismic refraction (SSR), electric resistivity tomography (ERT), and ground penetrating radar (GPR) data for assessment of the geotechnical seismic factors and their appropriateness to the local governing building code. For detecting voids & cavities features in subsurface rock, ERT and GPR are the best choices due to the high resistivity/dielectric contrast that exists between the fractures and cavities and the surrounding formation. Also, shallow seismic refraction (SSR) is used in foundation studies, civil engineering projects & geotechnical investigation (imaging the subsurface structure).
The field measurements include six ERT profiles using Dipole-Dipole (DD) arrays measured across the expected fracture. Accordingly, two seismic profiles with different directions are done to detect the common fracture trends in the area. In addition, 7 GPR profiles are carried out for the detection of fracture and cavities. The combined results interpreted from the ERT and SSR records obtained over the suspected site in the study area could be divided lithologically into three zones. They are the main geological zones based on variation in resistivity and seismic velocities according to the competence of bed with slight thickness variation from one profile to another. The first zone is the upper layer of weathered limestone, gravel fragments, and fractured marl, which is distinguished by poor to somewhat fair rock quality. The zone is overlaid by the second zone, which has a lithology of fractured argillaceous limestone of intermediate quality. The third zone is the hardest layer because it contains the toughest layer of limestone and is distinguished by a high competent rock. The bedrock at the site has a velocity range is about 1652 to 1720 m/sec for S-wave and 2570 to 2640 m/sec with average 2605 m/sec for P-wave, which is related to very compact and hard limestone. All of the GPR profiles reflect the existence of cracks and discontinuity/weak zones, about 2-4 m from the surface level of the area, especially in the western part.

The research aims to show the validity of limestone rocks of Pila Spi Formation in the fold of Duhok, northern Iraq for Riprap purposes. The formations of Pila Spi, Fatha and Injana in addition to the Quaternary sediments are mainly exposed in the study area. Five stations are selected in the northeastern limb of Duhok anticline, in which the limestone rocks belonging to Pila Spi Formation are exposed. The petrophysical tests show that the dry density ranges between (2.46-2.08) g/cm3, the absorption ratio ranges between (3.15-10.90%) and the specific weight values range between (2.66-2.74). While the mechanical tests show that the percentage of mechanical abrasion ranges between (20.06-58.42%) and the percentage of chemical abrasion ranges between (6.87-21.25%), and when comparing the properties with the specification Florida standard, it is found that is the Pila Spi rocks are valid for Riprap purposes in stations (1 and 2) and invalid in stations (3, 4, and 5) because the values of absorption ratio and mechanical abrasion are beyond the limits of the specification. By conducting a comparison between the properties of the rock samples and the specifications Iraqi standard, it is believed that they are valid for riprap purposes in stations (1, 2, and 3) and not valid in stations (4 and 5) because the percentage of mechanical abrasion is beyond the boundaries of the specification. In comparison with the properties with the specification American standard, it is found to be valid for riprap purposes at stations (1 and 2) and not valid at stations (3, 4, and 5) because the absorption ratio values are out of specification limits.

Anticipating pore pressures are essential for the operation of drilling success for oil and gas wells in particular that may anticipate encounter abnormal pressure, i.e. higher than normal pressure. Drilling problems such as blow out or kick due to not considering the abnormal pressure where the formation pressure become greater than hydrostatic pressure, and vice versa in the case of differential pipe sticking because of sub normal pressure. Thus, drilling cost can be significantly reduced by early recognition the abnormal high pore pressures. The normal range for pressures attain to 0.433 and 0.50 psi/ft. The usual muds density is about 9 ppg. (pounds per gallon) which exerts a bottom hole pressure of about 0.47 psi/ft. Meanwhile, a well is in the process of being drilled, there are several parameters that indicate the presence of abnormal pressure, such as a sudden increase in penetration rate (ROP), a sudden increase in the temperature of the drilling mud, and a decrease in the density of the shale fragment. The producing wells which are used in this study are (AAm-5, AAm-4, AAm-3, AAm-2, and AAm-1.) There are many methods for predicting the abnormal pore pressures. The current study focuses on three methods, which are used: the ratio (d- exponent) method; acoustic probes method; and the shale density method. This study is conducted in Abu Amoud oil field located in the northwestern part of DhiQar Governorate. This oil field includes five oil wells, each well production is from four units. More than one method was used to find intervals of abnormal pressure for the Zubair Formation, Nahr Omar and other formations. Stratigraphic and lithological colum of the study area had the greatest influence on the pressure values. The results show that the ratio (d-exponent) method is considered as the best method for indication of the abnormal pressure intervals. The abnormal pressure intervals are (2875-4022) m. Up to this end, this study can mitigate so many problems while drilling new wells at selected formations within Abu Amoud oil field.

Self-Potential (SP) geophysical method is conducted in Seikanian suburban area which is situated at about (5 km) north of Kirkuk City. The study area suffers from deficiency of water supply. To acquire SP data, two survey lines of gradient layout are achieved, one in northern part near the foothill, another is perpendicular to the former, addition 22 grid points of SP measurements spreading over the whole studied area. Water pumping test is carried out in a well with SP reading monitoring the water table drawdown operation by sounder. The aim of study is to delineate underground water accumulation and sensitivity of SP signal to water hydraulic head in the well. The acquired data are interpreted qualitatively and quantitatively after profiling curves and drawing SP contour maps using Surfer 8 Software. The results showed that there is streaming electric potential condition in the subsurface of the studied area indicating groundwater existence and the pumping test procedures with accordance by monitoring SP device proved that SP reading is sensitive to hydraulic head which is a good tool to estimate some hydraulic properties namely water transmissivity and conductivity of the aquifer. The water table depth is about 7 m in the study area.