Papers by Ahmed al-benna'a
Iraqi geological journal, Mar 31, 2024
The upward continuation was used to obtain central Iraq's residual gravity and RTP magnetic maps ... more The upward continuation was used to obtain central Iraq's residual gravity and RTP magnetic maps at elevations 2, 12, 16, and 22 km. These maps are processed by the Total Horizontal Derivative (THD) technique to detect the main lineaments that represent the boundary of subsurface sources or faults. The obtained lineaments trends represented on the rose diagram and the main trends in the study area were found. The lineaments (faults) orders from the main trend descending, from gravity data, are N55W, N45W, N35W, N-S, and N65W, respectively, for the four considered upward elevations. The length of the faults obtained from gravity data ranges from 40-250km, while the length of faults obtained from magnetic data ranges from 20-100km. The lineament from the main trend descending, from magnetic data, are NS, N55W, N35W, N45W, N45E, N35E, N65W and N55E, respectively. The lineaments obtained from magnetic data indicate that the main trend in shallow sources is NW-SE, while for deep sources; the main trend is N-S. The NW-SE fault trends obtained from gravity data are related to the Najd faults system, while the N-S fault trends are related to the Nabitah system. Generally, it is indicated from the analysis of lineaments of gravity and magnetic data that the NW-SE is the main trend of shallow structures in most areas of central Iraq.
Iraqi journal of science, Mar 27, 2019
The gravity and magnetic data of Tikrit-Kirkuk area in central Iraq were considered to study the ... more The gravity and magnetic data of Tikrit-Kirkuk area in central Iraq were considered to study the tectonic situation in the area. The residual anomalies were separated from regional using space windows method with space of about 24, 12 and 10km to delineate the source level of the residual anomalies. The Total Horizontal Derivative (THD) is used to identify the fault trends in the basement and sedimentary rocks depending upon gravity and magnetic data. The identified faults in the study area show (NW-SE), less common (NE-SW) and rare (N-S) trends. Some of these faults extending from the basement to the upper most layer of the sedimentary rocks. It was found that the depth of some gravity and magnetic source range 12-13Km, which confirm the basement depth obtained by C.G.G. 1974. While the depth of shallow gravity source of about 4Km, this depth of the shallow source may be lay with sedimentary cover in Triassic age. A comparison of the residual gravity and magnetic anomalies of the relatively shallow depths showed a general coincidence. The obtained tectonic boundaries divided the study area to many blocks. The tectonic boundaries in general control the river running in the area, at the same time the longitudinal faults control the main oil fields in the study area.
Iraqi geological journal, Oct 31, 2022
The 2D seismic reflection data were used to study the structure of Shurau and Sheikh Alas formati... more The 2D seismic reflection data were used to study the structure of Shurau and Sheikh Alas formations (Oligocene) in the Ismail area, northern Iraq. The horizons of Shurau and Sheikh Alas reflectors were identified based on seismic data and well logs through a synthetic seismogram construction. The Two-Way Time, velocity and depth maps of two coinciding formations were obtained. A Great coincidence was noticed between two identical maps of the two formations. The Main closure (syncline) trending NE-SE was detected at the southwestern part of the study area, the syncline is associated with many anticlines in the same trend. The northern part of Bai Hassan structure was appeared at the southeast part of the study area, while some northeastern part of Qara chauq structure was detected in the southwestern part of the study area. The structure features of the two formations mostly trending NW-SE with some local variations may be due to transversal faults.
IntechOpen eBooks, Dec 14, 2022
Gravity keep all things on the earth surface on the ground. Gravity method is one of the oldest g... more Gravity keep all things on the earth surface on the ground. Gravity method is one of the oldest geophysical methods. It is used to solve many geological problems. This method can be integrated with the other geophysical methods to prepare more accepted geophysical model. Understanding the theory and the principles concepts considered as an important step to improve the method. Chapter one attempt to discuss Newton's law, potential and attraction gravitational field, Geoid, Spheroid and geodetically figure of the earth, the gravity difference between equator and poles of the earth and some facts about gravity field.
Iraqi geological journal, Feb 29, 2024
A regional seismic section was constructed from fourteen local seismic lines from different surve... more A regional seismic section was constructed from fourteen local seismic lines from different surveys crossing the central part of Iraq from west to east. The seismic lines' surveys were performed during the period [1974][1975][1976][1977][1978][1979][1980][1981][1982][1983][1984][1985][1986][1987][1988][1989][1990]. The length of the regional seismic section is 662.5 km. The considered seismic lines are unified to the sea level datum. The quality of seismic lines is relatively poor in the western part of the regional seismic section, but it is of good quality in the central and eastern parts. Seven reflectors were identified along the regional seismic section, corresponding to ages from the Ordovician to the Miocene. The formations are Khabour (Mid-Ordovician), Akkas (Upper Silurian), Kurra Chine (Upper Triassic), Najmah (Upper Jurassic), Mauddud (Mid-Cretaceous), Shiranish (Upper Cretaceous) and Fatha (Lower Fars) (Mid-Miocene). The Two-way times for these seismic reflectors from the west to the east are 1691 -4000 ms, 750-4000 ms, 0-4000 ms, 208-4000 ms, 206 -3310 ms, 205 -2700 ms, and 216-2500 ms for the seven formations; starting from the oldest formation (Khabour Formation to the youngest one (Fath Formation ), respectively. The top depth values of the considered formations were defined from west to east for each formation (0-4.189) km, (0.456-4.880) km, (0.708-5.936) km, (0.802-8.5) km, (0-8.977) km, (0.5-9) km, and (1.8-9) km from the oldest to the youngest formation, respectively. The horizon generally dips towards the east. Two sedimentary basins were identified, the first in the western part of Iraq within the Paleozoic formation, while the eastern basin was within the Cenozoic and Mesozoic formations. These two basins are separated by an uplift at the central part of the regional seismic section. This uplift region was confirmed by gravity and magnetic high anomaly. Many faults were detected along the regional seismic profile. Most of these faults extend from the deeper to the shallower formations.
Iraqi journal of science, Mar 4, 2018
A new gravity and seismic survey along a profile length (70 Km) carried out at the area of explor... more A new gravity and seismic survey along a profile length (70 Km) carried out at the area of exploration Block-11 in Al-Najaf desert, southwest Iraq. The obtained gravity and seismic value compared with the previous available data that achieved by IPC and OEC for gravity and seismic data respectively. The difference between the new gravity profile and the old one is mainly in small anomaly not more than (14 %) that related to shallow depth levels and presents through power spectrum analysis. Previously, Ghulaissan-1 well which drilled in (1960) depend on a positive gravity and magnetic anomaly interpret, which is considered as an anticline structure in sub surface. It did not indicate any hydrocarbon shows after drilling, the integration study shows, that the positive anomaly appear in gravity record may be results from extension of presence thick Ophiolites and syn-tectonic gabbro.
Iraqi journal of science, Jan 30, 2018
A new derivative applied to the old gravity Bouguer map (served in 1940 s and 1950s), taking regi... more A new derivative applied to the old gravity Bouguer map (served in 1940 s and 1950s), taking regional study area covered the mid and south of Iraq. The gravity anomaly reflects a density contrast variation; therefore it is possible to use gravity inversion to the density and velocity model through layers (615m, 1100m, 1910m, 2750m and 5290m), the depth layers according to the power spectrum analysis of gravity Bouguer. The inversion is according to the integration of gravity anomalies of the each depth layer with the same depth of wells data, considered to the estimations and analysis of density and velocity scatters of the oil wells distribution with depth at the regional area. Taking the relation curve of density and velocity by presenting the function of (8 logs), which obtained the main relation to Seismic velocity and density of the study area, which is confirm with (Nafe and Drake curve). The result of the gravity inversion is on the anomalies behavior in density and velocity domain, taking in seismic stack processing of seismic reflection records and time to depth conversion, as the geophysical integration data is addition to the well data distribution in the regional area of Iraq. Good results obtained on comparing the interpretation of the considered seismic section in the study area.
Iraqi Journal of Science
Six ERI profiles using Wenner Schlumberger array were carried out at Baghdad University (ALJ... more Six ERI profiles using Wenner Schlumberger array were carried out at Baghdad University (ALJadiriya campus) to investigate soil at two sites. The spacing between electrodes of four profiles surrounding the new building in the Campus at the first site is 1 m, and the profile length ranges from 50 to 90 m. In comparison, two across profiles in the garden to detect water seepage in the site. The inverted model of the studied profiles shows many high and low resistivity zone. The sedimentology and mineralogy of the soil samples analysis from a depth range of 15 to 100 cm from three pits confirm the high homogeneity of the soil in the studied site composed of (silt and clay). The low resistivity values coincided with the moisture and amount of vegetable and herbs growth. Therefore, the authors believe the main factor causing variation in the resistivity value in the study area is the moisture Factor.
Journal of University of Anbar for Pure Science
Iraqi Geological Journal, 2022
The most important characters of the rock formations are shear and compression velocities, which ... more The most important characters of the rock formations are shear and compression velocities, which are used to calculate elastic moduli. The geomechanical properties can be used to evaluate reservoir stability or to calibrate velocity and time/depth conversion, synthetic seismogram and other important applications. The aim of this study is to use the first order least square method to obtain an empirical equation to determine the shear velocity from compressional velocity for Mishrif, Rumaila, Ahmadi, and Mauddud formations in Hf-2 well. The obtained equations depend on sonic log and dipole shear sonic imager data of Hf-2 well and use Techlog software. The results from the obtained equations in comparison with those results of Green Castagna equation and measured data of dipole shear sonic imager of shear velocity for Mishrif, Rumiala and Mauddud formations. It is found from the comparison that the result is consistent each other’s. The consistent reflect the reality of shear waves va...
IRAQI JOURNAL OF SCIENCE, 2018
The changes of the tectonic boundary locations between the stable and unstable shelf on different... more The changes of the tectonic boundary locations between the stable and unstable shelf on different version of the tectonic maps of Iraq is discussed. It is found that the location of the boundary varies due to philosophy and the type of the geological parameters. It is used the stratigraphic, geophysical, structural, geochemical, hydrological and others information in delineating the boundary. The deep crustal structures obtained by using gravity data show that the boundary shifted toward the west by about 100 km in southern Iraq. According to the review, and when taking in consideration all the geological and geophysical parameters from the lower crust to the earth surface, it is believed that the boundary is not a line but it is a tectonic crustal zone. This zone represents a transition zone between the main two regions of the platform in Iraq, and it is segmented to many subzones by transverse faults. In addition, it is believed that the data of the parameters of shallow geology confirm the eastern side of the main zone, while the lower crustal structures confirm the western side of the main zone.
IRAQI JOURNAL OF SCIENCE, Oct 28, 2017
The seismic reflection and gravity data were used to detect the tectonic boundaries in Kut-Hai-Fa... more The seismic reflection and gravity data were used to detect the tectonic boundaries in Kut-Hai-Fajir and surrounding areas, central Iraq. The depth maps of Dammam, Nhr Umr, and Sulaiy, formations were constructed and used to detect some boundareis in the study area. The residual gravity map and Total Horizantal derivative (THDR) also used to detected the tectonic boundaries. It is obtained that most boundaries or faults found in the deep formations; while some of them showen in the shallow fomations. The faults or boundaries obtained from gravity intrpretation mostly coincied with the deepest formation boundaries. Generally, the grvity anomalies conform the morphological feature locations within the depth maps of the formations. Many longitudinal and transverse faults were traced from the seismic and gravity interpretation. It is concluded that the oil fields in the study area lying within certain tectonic zones and coincide with the positive residual gervity anomalies of spacing window of 8 km; mostly near the zero line values. It is believed that the integrated interpretation of residual gravity anomalies with the depth maps of some formations, that inferred from seismic data, gives good results for evaluation of an area for oil exploration.
IRAQI JOURNAL OF SCIENCE, 2017
Gravity and magnetic data are used to study the tectonic situation of Al-Kut-Al-Hai and surroundi... more Gravity and magnetic data are used to study the tectonic situation of Al-Kut-Al-Hai and surrounding areas in central Iraq. The study included application of many processing and interpretation programs. The window method with different spacing was used to separate the residual from regional anomalies for gravity and magnetic data. The Total Horizontal Derivative (THDR) techniques used to identify the fault trends in the basement and sedimentary cover rocks depending upon gravity and magnetic data. The identified faults in the study area show (NW-SE), (NE-SW) (N-S) and (E-W) trends. It is believed that these faults extending from the basement to the upper most layer of the sedimentary cover rocks.
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Papers by Ahmed al-benna'a