Ahmed Salem

• Doctor of Engineering
• Saudi Aramco

The present study focuses on the geothermally prospective are of Wadi Al Lith (Western Saudi Arabia), which is expressed by the presence of hot springs. With a surface temperature that exceeds 80 °C, the Ain Al Harrah hot spring presents the most promising area for geothermal energy production. The Wadi Al Lith prospective geothermal field was gene...

Western Saudi Arabia is a promising area for geothermal energy exploration. Its geothermal wealth is attributed to the ongoing Red Sea rift evolution and crust thinning. Several hot springs in the region indicate the presence of potential geothermal resources. The present study aimed to characterize the geothermal system of a hot spring in the regi...

A new model of the thermal structure of the easternmost portion of the Arabian continental crust is presented. Detailed heat flow models based on more than 660 temperature measurements from 230 exploration wells have been performed over an area of 166,000 km2 in size, spanning from the Arabian Gulf to the Eastern Arabian Shield. Geothermal gradient...

The Axios-Thermaikos basin in northern Greece is a sedimentary composite depocenter that developed tectonically during the Neogene. It has been considered promising for hydrocarbon resources, with a proven offshore gas field. Several geological and geophysical surveys, including drilling, were conducted in previous decades. However, a complete mode...

This study focuses on a geothermal field of a hot spring in Western Saudi Arabia. The geothermal activity of the field is related to the tectonic processes connected with the evolution of the Red Sea Rift. The hot spring is geothermally promising as surface temperatures reach more than 80 οC. We conducted a gravity survey over the focused hot sprin...

Abstract Heat flow measurements in the Arabian Plate are inconsistent with anticipated heat flow levels and are not uniformly distributed. They originate mostly from shallow temperature measurements for geothermal surveys and are not specifically targeted for determining the thermal field at the lithosphere scale. We employed spectral analysis of...

Western Saudi Arabia is a promising area for geothermal energy exploration since it has many fields related to the ongoing evolution of the Red Sea Rift. Several hot springs indicate the presence of potential geothermal resources as the water reaches temperatures greater than 80 οC. The aim of the present study is to characterize the geothermal sys...

The Arabian plate has been known by its west-east asymmetric lithospheric structure, expressing itself in distinct topography and geological patterns. The western portion of the plate, consists of the Arabian Shield, exhibiting buoyant and exposed basement, while the eastern portion belongs to the wider Western Gulf Basin (Fig. 1), hosting a variet...

The onshore Axios-Thermaikos basin in northern Greece developed during the Neogene. An offshore gas field has been verified in the area, indicating significant potential for hydrocarbon resources. Although many surveys have been conducted, a complete model of its subsurface remains unpublished. The primary goal of this study is to increase the over...

The onshore Axios-Thermaikos basin in northern Greece is a sedimentary composite depocenter of 4km depth, that developed tectonically during the Cenozoic extending over the alpine basement of the Internal Hellenides. It consists of Lower Eocene to Quaternary sediments deposited unconformably over the Mesozoic emplaced ophiolite and sedimentary rock...

Geological features, such as faults, dikes and contacts appear as lineaments in gravity and magnetic data. The Automated Coherent Lineament Analysis and Selection (ACLAS) method is a new approach to automatically compare and combine sets of lineaments or edges derived from two or more existing enhancement techniques applied to the same gravity or m...

This paper presents a case study of mapping basement structures in the northwestern offshore of Abu Dhabi using high-resolution aeromagnetic data. Lineament analysis was carried out on the derivatives of the reduced-to-the-pole magnetic data, along with supporting information from published geologic data. The lineament analysis suggests three well-...

We have developed a simple iterative gravity-inversion approach to map the basement and Moho surfaces of a rift basin simultaneously. Gravity anomalies in rift basins commonly consist of interfering broad, positive crustal-thinning anomalies and narrow, negative sedimentary-basin anomalies. In our model, we assumed that the Moho and basement surfac...

Summary This paper presents a case study of integrated 2D forward modeling of seismic and gravity data over the offshore Guyana basin and Demerara Plateau. The aim of this study is to use gravity modeling to address uncertainties in the seismic velocity model and hence produce a more robust depth solution. This is done by modeling horizons for each...

This paper presents a case study of mapping basement structures in the northwestern offshore of Abu Dhabi using high-resolution aeromagnetic data. Lineaments analysis was carried out on the derivatives of the reduced to the pole (RTP) magnetic data, along with supporting information from published geologic data. The lineament analysis suggests thre...

The central Red Sea rift is considered to be an embryonic ocean. It is characterised by high heat flow, with more than 90% of the heat flow measurements exceeding the world mean and high values extending to the coasts - providing good prospects for geothermal energy resources. In this study, we aim to map the depth to the Curie isotherm (580. °C) i...

Magnetic depth estimation methods are routinely used to map the depth of sedimentary basins by assuming that the sediments are nonmagnetic and underlain by magnetic basement rocks. Most of these methods generate basement depth estimates at discrete points. Converting these depth estimates into a grid or map form often requires the application of qu...

In this paper, two infinite classes of inequalities for the q-gamma and the q-digamma functions are established by means of using the Taylor theorem. The bounds appeared in these inequalities are in terms of the Hurwitz and Riemann q-zeta functions.

We incorporate a temperature-depth constraint derived from magnetic Curie depths directly into the solution of the one-dimensional heat flow conduction equation to anchor geotherms deep within the crust. In this study, Curie depths are carefully derived from magnetic power spectra using a recently devised Defractal Spectral Depth Determination appr...

The local-wavenumber method estimates the depth to a magnetic source based on the spectral content of a single anomaly assuming that the base of the magnetic body is at infinite depth. However, the "infinite-depth" assumption can lead to significant underestimation of the depth to the top of magnetic bodies, especially in areas where the depth to t...

The southern Sudan rift basins form part of the Mesozoic Central African Rift System (CARS) and span an area 1000 km wide and 800 km along strike. They consist of two major NW-SE trending rift basins; the Muglad and the Melut. Following a series of gravity, magnetic and seismic related studies (Fairhead et al., 2012) most of the rift system’s kinem...

Full Tensor Gravity Gradiometry (FTG) data are routinely used in exploration programmes to evaluate and explore geological complexities hosting hydrocarbon and mineral resources. FTG data are typically used to map a host structure and locate target responses of interest using a myriad of imaging techniques. Identified anomalies of interest are then...

We sought to map the depth and density contrast of the Mohorovicic discontinuity (Moho) across the Red Sea area and to model sedimentary thickness from gravity data. The gravity data that are used are a combination of satellite and terrestrial gravity data processed into a Bouguer anomaly grid. A 200-km low-pass filter was used to separate this gri...

Depth to basement estimation methods using various components of the spectral content of magnetic anomalies are in common use by geophysicists. Most simple models used for this purpose have the base of the magnetic body at infinity. Recent publications have shown that this ‘infinite depth’ assumption is responsible for generating anomalously shallo...

The SLUTH method requires first-order derivatives at two or more different heights above the ground and can estimate the location and depth of source bodies from magnetic data. Results of this method are independent of a specific model type and can be used to estimate the most appropriate model (structural index). This paper presents a grid impleme...

The major use of magnetic data in hydrocarbon exploration is in mapping depth to basement. The available magnetic interpretation methods are generally good at mapping basement lineaments and structures, but generally less good at mapping the morphology of the deeper parts of the basement surface. This is due to the dominance of the magnetic respons...

SUMMARY Iraq has a long history of hydrocarbon exploration which included the regional gravity surveying of Iraq using land gravity and aeromagnetic methods. These exploration data sets have now been fully compiled into digital products which provide a wealth of new structural and sub surface information for the shallow parts of the basins (main se...

This paper interprets aeromagnetic data for a deep basin section of the Karroo rift in south-east Tanzania. We use a novel integrated approach involving the application of advanced derivatives to define structure and the tilt-depth method to determine and map the depth to basement. In the latter case we use the result of both reduced to pole and re...

This paper presents a procedure for interpreting magnetic data over tilted basement blocks. The objective of this procedure is to estimate source parameters of a tilted basement block from first- order derivatives of magnetic profile data. The method uses a model consisting of two superimposed infinite contacts with opposite dip. The procedure esti...

This paper presents a multi-deconvolution method for interpretation of potential-field data. The multi-deconvolution method used information from isolated anomalies and data transformations to produce functions forming a peak or a through above the center of a potential-field source. The proposed method can be applied to a wide range of potential f...

The Lotikipi Basin is a rift basin lying within the East African Rift System, west of Lake Turkana in north west Kenya. The basin is filled with a 4km sequence of volcanic derived sediment, stacked rhyolite flows and olivine basalts, underlain by supposed reservoir potential sediments at least 500m thick. 2D Seismic imaging is observed to be degrad...

We compute the depth to the top of magnetic basement using the Tilt-Depth method from the best available magnetic anomaly grids covering the continental USA and Australia. For the USA, the Tilt-Depth estimates were compared with sediment thicknesses based on drilling data and show a correlation of 0.86 between the datasets. If random data were used...

This contribution has two aims - to present a new high resolution 1 km grid magnetic field solution for the European area that includes the Atlantic continental margins and the Mediterranean and to map the regional variation in the depth to magnetic basement using the Tilt-Depth and Local wavenumber interpretation methods. Special focus is given to...

High-resolution aeromagnetic surveys are commonly used to locate subtle anomalies that are important in mineral and oil exploration. However, such anomalies, especially in highly populated areas, are often masked by undesirable magnetic signals from near surface man-made objects - known as `cultural noise' - making post processing and interpretatio...

We provide a rationale for rapidly assessing the depth and structure of sedimentary basins from magnetic anomaly data. Our methodology is based on "tilt-depth" calculated strictly from first-order derivatives of the total magnetic field. We assume a simple buried vertical contact model such that the 0 degree contour of the tilt derivative closely f...

We have developed a new method for interpretation of gridded magnetic data which, based on derivatives of the tilt angle, provides a simple linear equation, similar to the 3D Euler equation. Our method estimates both the horizontal lo-cation and the depth of magnetic bodies, but without specify-ing prior information about the nature of the sources...

Aeromagnetic data are routinely presented as contour or color-shaded maps of the total magnetic intensity (TMI). An interpreter's task is to identify features (anomalies) contained within the map and qualitatively and/or quantitatively interpret them into geologic structures at depth. If the map contains anomalies that have large magnetic intensiti...

Airborne electromagnetic (AEM) moment data are transformed to two depth sections that display the properties of a spherical conductor (the conductivity-radius-squared (CRS) and the dip of the current flow respectively). When the measured data look like model data, bright colors are used to indicate the properties of the discrete conductor; when the...

We have developed a method for imaging magnetic data collected for mineral exploration to yield the following structural information: depth, model type (structural index) and susceptibility. The active nature of mineral exploration data requires we derive the structural information from a robust quantity: we propose that the first- or second-order...

The Gebel El-Zeit area is located on the western coast of the Gulf of Suez, Egypt. The areas in/and around the Gulf of Suez are generally important due to their hydrocarbon resources. In this study, we have applied gradient interpretation techniques (Euler deconvolution and analytic signal) to the aeromagnetic data of the Gebel El-Zeit area. The ma...

Exploration in the northern Red Sea of Egypt has had little success in locating hydrocarbon accumulation. The main exploration problems in this region are the complex block faulting and Miocene salt structures. The complex basement block structure arises from the different ages of faults and the difficulty of determining the exact age relations. In...

An important problem in the interpretation of magnetic data is quantifying the source parameters that describe the anomalous structure. We present a new method that uses various combinations of the local wavenumbers for estimating the depth and shape (structural index) of the structure. Because the estimates are derived from third derivatives of th...

This paper presents an enhancement of the local-wa- venumber method (named ELW for "enhanced local wavenumber") for interpretation of profile magnetic data. This method uses the traditional and phase-rotat- ed local wavenumbers to produce a linear equation as a function of the model parameters. The equation can be solved to determine the horizontal...

Recent development of marine magnetic gradient systems, using arrays of sensors, has made it possible to survey large contaminated areas very quickly. However, underwater Unexploded Ordnances (UXO) can be moved by water currents. Because of this mobility, the cleanup process in such situations becomes dynamic rather than static. This implies that d...

Hohi area is located in central Kyushu island of Japan and is known as a volcano-tectonic depression region. The area is characterized by its potential geothermal resources. In this study, we attempt to delineate the subsurface structures of the area using integrated interpretation of existing gravity data. The gravity survey of Hohi area is about...

This paper develops an automatic method for interpretation of magnetic data using derivatives of the analytic signal. A linear equation is derived to provide source location parameters of a 2D magnetic body without a priori information about the nature of the source. Then using the source location parameters, the nature of the source can be ascerta...

Recent improvements in the local wavenumber approach have made it possible to estimate both the depth and model type of buried bodies from magnetic data. However, these improvements require calculation of third-order derivatives of the magnetic field, which greatly enhances noise. As a result, the improvements are restricted to data of high quality...

The Gebel El-Zeit area is located on the western coast of the Gulf of Suez, Egypt. The areas in/and around the Gulf of Suez are generally important due to their hydrocarbon resources. In this study, we have applied gradient interpretation techniques (Euler deconvolution and analytic signal) to the aeromagnetic data of the Gebel El-Zeit area. The ma...

A map of radioactive heat production was constructed from airborne spectral gamma-ray data of Gebel Duwi area, Egypt. The study area possesses a range of radioactive heat production varying from 0.21 μ Wm^<-3> to 3.09 μWm^<-3>. Sedimentary rocks in the Gebel Duwi area have higher heat production values (0.25 μWm^<-3> to 3.09 μWm^<-3>) than the crus...

We present a new method for interpreting isolated potential-field (gravity and magnetic) anomaly data. A linear equation, involving a symmetric anomalous field and its horizontal gradient, is derived to provide both the depth and nature of the buried sources. In many currently available methods, either higher order derivatives or postprocessing is...

This paper presents a case study on the subsurface structural imaging of Esh El Mallaha area. Esh EL Mallaha area is located on the western flank of the Gulf of Suez and it has a great importance due to its hydrocarbon resources. In 1994 the area was covered by aeromagnetic survey conducted by Aero Service Division, Western Geophysical Company of A...

A new method of interpretation of magnetic data, AN-EUL, is developed. The derivation is based on a combination of the analytic signal and the Euler deconvolution methods. With AN-EUL, both the location and the approximate geometry of a magnetic source can be deduced from high quality residual magnetic anomaly data. The method is tested using theor...

We present a new automatic method of interpretation of magnetic data, called AN-EUL (pronounced "an oil"). The derivation is based on a combination of the analytic signal and the Euler deconvolution methods. With AN-EUL, both the location and the approximate geometry of a magnetic source can be deduced. The method is tested using theoretical simula...

This paper documents results of an integrated interpretation technique of magnetic data over the onshore of Gebel EL-Zeit area, Gulf of Suez in Egypt. The objective of this study is to identify the possible subsurface structure of the area that may assist in delineation of promising prospects for hydrocarbon exploration. We have applied magnetic gr...

We investigate the analytic signal method and its applicability in obtaining source locations of compact environmental magnetic objects. Previous investigations have shown that, for two-dimensional magnetic sources, the shape and location of the maxima of the amplitude of the analytic signal (AAS) are independent of the magnetization direction. In...

Summary We present a new method for interpretation of potentialfield anomaly data. A linear equation, involving the anomaly and its horizontal gradient, is derived to provide both the depth and nature of the buried sources. The proposed method is similar to the Euler technique; however, it uses a shape factor (q) instead of a structural index (η) t...

Using pole-dipole array, electrical resistivity survey was conducted to investigate the subsurface under a subsiding building located in Kita Kyushu area, Japan. The resistivity measurements were acquired along two traverse lines and interpreted using a graphical procedure known as Bristow's method. Moreover, a vertical electrical sounding (VES) wa...

This paper investigates the ability of a supervised artificial neural network to estimate the location of buried steel drums from magnetic anomaly data. The neural network was trained using magnetic signatures of a magnetic dipole source, which experience shows to be equivalent to the field from a buried drum. It is demonstrated that for sources bu...

We have developed a simple approach to determine the depth and radius of subsurface cavities from microgravity data. The horizontal location of cavity centre is picked up as the projection of the minimum of gravity anomaly. Depth to the cavity centre is estimated using a back propagation neural network. The cavity radius can be then calculated usin...

Recent developments in airborne magnetic detection systems have made it possible to detect small ferro-metallic objects. However, airborne magnetic data can be really large and, therefore, there is an increasing need for a fully automatic interpretation technique that could be used to make decisions regarding the nature of the sources in the field...

Exploration in the Egyptian Red Sea has had little success in locating a hydrocarbon accumulation. The complex block faulting and Miocene salt structure are the main problems entailed the oil exploration. The complex basement block structure arises from the different ages of faults and the difficulty of determining the exact age relations. In an at...

Two adult sickle cell homozygotes from the eastern oases of the Kingdom of Saudi Arabia presented with severe persistent priapism. Each patient had a high Hb F of 24%, and their red cells were neither hypochromic nor microcytic. Priapism probably occurs more frequently in homozygous sickle cell disease than reported previously from this region. It...

Using pole-dipole array, electrical resistivity survey was conducted to investigate the subsurface under a subsiding building located in Kita Kyushu area, Japan. The resistivity measurements were acquired along two traverse lines and interpreted using a graphical procedure known as Bristow's method. Moreover, a vertical electrical sounding (VES) wa...

Sinai Peninsula is characterized by superficial thermal manifestations represented by a cluster of hot springs with varied temperatures (30-72°C). These springs are mostly issue out of fractures and distributed along the Eastern shore of the Gulf of Suez. In this work, we present a reconnaissance study to elucidate the geothermal resources and deli...

Dipolar aeromagnetic anomalies of the Quseir area and its extension to the offshore Red Sea have been interpreted to have a strong relation to the thermal sources of the Red Sea geothermal system. This interpretation is supported by field observations, which show that, most of these anomalies are found to be associated with diabase dyke intrusions....