Mohamed Abdel Zaher

Thickness variation of the sedimentary cover in the South Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data using neural network method

The Bouguer anomaly map of scale 1:500,000 and the lithological logs of more than 120 deep wells distributed in the Southern part of Western Desert of Egypt were used to determine the thickness of the sedimentary cover containing the main sandstone water formation. The predominant structures affecting both the basement rock and the sedimentary cover were also studied. Gravity stripping approach was applied to separate density anomalies within the sedimentary fill from the influence of deeper levels in the crystalline crust. The study indicated that the surface of the basement rock is highly rugged and mostly controlled by structures causing variation of the sedimentary cover thickness from location to other all over the area. Isopach maps were constructed based on the Artificial Neural Network (ANN) model which is considered a best method for that operation. The maximum thickness of sandstone formations is recorded at west Oweinat, southwest of Aswan, Dakhla oasis and west of Qena town. As this formation is the main water aquifer in the study area, therefore these locations are characterized by the presence of huge amount of ground water. Accordingly, these areas must be taking the priority in the programs of sustainable development in southern Egypt.

Geochemical and stable isotopic studies of Gulf of Suez’s hot springs,Egypt

The Gulf of Suez region is one of the most interesting geothermal areas in Egypt because of the high temperatures of its springs. The eastern and western shores of the Gulf of Suez are characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures. Variations of deuterium and oxygen-18 concentrations in thermal waters have been used to aid in describing the source of recharge in the Gulf of Suez hot springs. Isotope and geochemical data for the Gulf of Suez thermal waters suggest that recharge to the hot springs may not be entirely from the Gulf of Suez water, but possibly from the meteoric water that comes from areas of higher altitude surrounding the hot springs.

Geothermal studies in oilfield districts of Eastern Margin of the Gulf of Suez, Egypt

Abstract Results of geothermal studies carried out at 149 onshore oil wells have been used in evaluation of temperature gradient and heat flow values of the eastern shore of the Gulf of Suez. The investigations included temperature logs in boreholes, calculation of amplitude temperature, geothermal gradients and heat flow. The results obtained indicate that geothermal gradient values are in the ranges of 0.02–0.044 °C/m and regionally averaged mean heat flow values are found to fall in the interval of 45–120 mW/m2. Temperature gradients and heat flow values change from low values eastward to high values toward the axial of Gulf of Suez rift. The result of this research work has been highly successful in identifying new geothermal resources eastward of the Gulf of Suez. Additionally, this study shows that the areas with relatively higher temperature gradients have lower oil window, mature earlier, than those with low gradient values. Thus, high temperature gradients cause to expedite the formation of oil at relatively shallow depths and narrow oil windows. On the other hand, low temperature gradient makes the oil window to be quite broad when locate at high depths.

Subsurface investigation on Quarter 27 of May 15th city, Cairo, Egypt using electrical resistivity tomography and shallow seismic refraction techniques

Abstract Geophysical tools such as electrical resistivity tomography (ERT) and shallow seismic (both P-wave seismic refraction and Multi-channel Analysis of Surface Waves (MASW)) are interesting techniques for delineating the subsurface configurations as stratigraphy, structural elements, caves and water saturated zones. The ERT technique is used to delineate the contamination, to detect the buried objects, and to quantify some aquifer properties. Eight 2-D (two dimensional) electrical resistivity sections were measured using two different configurations (dipole–dipole and Wenner). The spread length is of 96 m and the electrodes spacing are 2, 4 and 6 m, respectively to reach a depth ranging from 13 to 17 m. The results indicate that, the subsurface section is divided into main three geo-electrical units, the first is fractured marl and limestone which exhibits high resistivity values ranging from 40 to 300 ohm m. The second unit is corresponding to marl of moderate resistivity values and the third unit, which is the deeper unit, exhibits very low resistivity values corresponding to clayey marl. The fourth layer is marly clay with water. The presence of clay causes the most geotechnical problems. Fourteen shallow seismic sections (both for P-wave and MASW) were carried out using spread of 94 m and geophone spacing of 2 m for each P-wave section. The results demonstrate that the deduced subsurface section consists of four layers, the first layer exhibits very low P-wave velocity ranging from 280 to 420 m/s, the second layer reveals P-wave velocity ranging from 400 to 1200 m/s, the third layer has P-wave velocity ranging from 970 to 2000 m/s and the fourth layer exhibits high velocity ranging from 1900 to 3600 m/s. The ERT and shallow seismic results, reflect the presence of two parallel faults passing through Quarter 27 and trending NW-SE.

Geophysical characterization of the role of fault and fracture systems for recharging groundwater aquifers from surface water of Lake Nasser

Abstract The role of the fracture system is important for enhancing the recharge or discharge of fluids in the subsurface reservoir. The Lake Nasser is consider one of the largest artificial lakes all over the world and contains huge bulk of storage water. In this study, the influence of fracture zones on subsurface fluid flow in groundwater reservoirs is investigated using geophysical techniques including seismicity, geoelectric and gravity data. These data have been utilized for exploring structural structure in south west Lake Nasser, and subsurface discontinuities (joints or faults) notwithstanding its related fracture systems. Seismicity investigation gave us the comprehension of the dynamic geological structure sets and proposing the main recharging paths for the Nubian aquifer from Lake Nasser surface water. Processing and modelling of aerogravity data show that the greater thickness of sedimentary cover (700 m) is located eastward and northward while basement outcrops occur at Umm Shaghir and Al Asr areas. Sixty-nine vertical electrical soundings (VES’s) were used to delineate the subsurface geoelectric layers along eight profiles that help to realize the subsurface geological structure behind the hydrogeological conditions of the studied area.

Structural control of hydrogeological aquifers in the Bahariya Oasis, Western Desert, Egypt

This work addresses the detection of aquifers and the delineation of subsurface structures predominant in the basement rocks and their relations with these aquifers at the Bahariya Oasis, Western Desert, Egypt, and the relationship between the subsurface structures and the aquifers. In this respect, land geomagnetic and geoelectric-reconnaissance surveys were carried out over the oasis. Additionally, wells and bore-hole logs were used to verify the results and to explore the distributions of the subsurface reservoirs and the geological sequences. The results illustrate that the main groundwater aquifers in the fractured limestone ranges from 40 m to 90 m in depth and in the saturated Nubian sandstone from 800 m to 1200 m in depth. The thickness of the Carbonate reservoir varies from 90 m to 160 m. The Nubian sandstone formation that unconformably overlies the basement rocks has a thickness of approximately 250 m. In general, the depth to the basement rocks ranges from 1.2 km and 2.9 km in certain local areas according to the magnetic data. The structure trend analyses show that the dominant tectonic trends are northeastward and northwestward. These structures play an important role in controlling the aquifer depths and most probably supply water from the deeper Nubian aquifer to the shallower Carbonate aquifer.