Geoelectrical Exploration of Groundwater by Using Vertical Electrical Sounding Technique at Wadi Morra, South Sinai, Egypt

Wadi Morra area is one of the most important areas targeted by the government for sustainable development. This development depends mainly on groundwater occurrences. This research aims to explore groundwater in this region, which depends on groundwater for its needs. To achieve this aim, the geoelectrical resistivity method was used, represented by Schlumberger Vertical Electrical Soundings (VESs). Seventeen VESs have been carried out with a maximum half current electrode spacing (AB/2) of 700m. The measured VESs are interpreted qualitatively and quantitatively to construct a geoelectrical model. To detect the water-bearing layers and their extensions, three geoelectric cross-sections in addition to a one-panel diagram were constructed using all the available data. Also, both true resistivity and isopach contour maps of waterbearing layers were created based on these data. The interpretation results indicate that there are five geoelectric layers (A, B, C, D, and E), two of them (C and D) are water-bearing layers. The first water-bearing layer is layer C, which represents the Nubian sandstone aquifer, and the second layer is layer D, which represents the fractured basement aquifer. These two aquifers were observed along the northern part of the Saint Catherine - Nuweiba road that dissects the Wadi Morra basin, while it is absent at the southern part of this road. It is due to the presence of a few faults. According to groundwater occurrences, the study area was divided into two zones. The first zone is zone (A) where the groundwater is present, either in the Nubian sandstone aquifer or in the fractured basement aquifer and the second zone is zone (B) where there is no groundwater at all due to the presence of basement rocks at a few depths. This research also recommends that the best places for drilling productive wells be at zone A.

Evaluation of Soil Foundation by Integration of Geophysical and Geotechnical Methods at West Kom Umbo Area, Aswan, Egypt

This research includes combining a geophysical study with a geotechnical study to explore different soil types in the western Kom Umbo area. First: The geophysical study, which includes Electrical Resistivity and Ground Penetrating Radar were conducted to determine the subsurface layers, and to identify “gaps and soil heterogeneity, if any.” Fifty Vertical Electrical Soundings (VESs) were made to determine the layers and the electrical resistivity of the layers. Twelve Ground Penetrating Radar profiles (GPR) have also been created to identify soil homogeneity, gaps, geotechnical properties and to identify “existing cracks or faults. Second: the geotechnical study, which includes the study of a different boreholes in all areas of the study to determine the different layers and geotechnical properties. And field tests (standard penetration test) were done and laboratory tests (such as sieves analysis). And how to determine the degree of soil quality and the ability to build on it. From the above, we can combine the results of geophysics with the results of the geotechnical study to evaluate of soil foundation and to obtain confirmed and accurate information about the nature of the soil in the study area and its homogeneity and determine the possibility of exploiting and benefiting from it in industrial facilities, large, small, residential buildings, green spaces. According to this research the study area is generally divided into two layers, the first layer consists of gravel sand which has a resistivity range from 4189 to 38033 and the second layer is sand which has a resistivity value ranging from 1224 to 9682 ohm/m. and in the present study we have achieved the next procedure on the processed GPR data, displaying 2D profiles that contain the expected anomalies. Because the study area is saturated with silty sand and gravel, part of radar waves is attenuated and the reflections from the subsurface materials are weak. Results with the 100 MHz antennae are the resistive sand, gravel is a very good GPR target, and horizontal layering and stratification are evident throughout the deposit. Engineering studies on samples which collected from different sites in the study area reveal that, the results of uniformity coefficient (Cu) ranging between 3.15 (Very uniform) to 35.56 (Non-uniform). The results of coefficient of gradation range between 0.61 (poorly graded) to 2.41 (Well graded).

Extended Elastic Impedance Inversion for Better Delineation of Gasbearing Sand Reservoir, Saffron Gas Field, Offshore Nile Delta, Egypt

Extended Elastic Impedance (EEI) is a very useful seismic reconnaissance attribute. EEI logs can directly correspond to the petrophysical properties of the reservoir and the seismic. EEI reflectivity volumes can be obtained directly from the pre-stack seismic data. Better discrimination between the seismic anomaly caused by either lithology or fluid content can be utilized by applying this approach. The concept of extended elastic impedance is used to derive the petrophysical properties and distribute the reservoir facies. The study area was a Pliocene gas field, that lies in the deep marine, Offshore Nile Delta, Egypt. The workflow is simple, efficient, and uses very few inputs. We started with the fluid/ lithology logs and investigated the optimum projection in the intercept/gradient domain. Then, we used the conditioned angle stacks, to calculate the intercept/ gradient volumes, using Shuey’s two-term Approximation. The intercept and gradient volumes are converted directly to the fluid and lithology 3D volumes, without any of the pre-stack inversion constraints. The outputs were tested using a blind well and the correlation exceeds 80%. The results show that the EEI is a worthy effort to highlight the difference between the reservoir and nonreservoir sections, to identify the hydrocarbon area.