Integration of magnetic, gravity, and well-logging data interpretation to delineate the structural framework and formation evaluation of Bahariya Formation, North Diyur area, northern Western Desert, Egypt

2021 ◽  
Vol 40 (10) ◽  
pp. 724-733
Author(s):  
Walaa Araby ◽  
Samy H. Abd ◽  
Alaa E. Aref ◽  
Ibrahim Al-Alfy ◽  
M. M. Abdullah ◽  
...  
Keyword(s):  
Structural Control ◽  
Water Saturation ◽  
Gravity Data ◽  
Depth Estimation ◽  
Well Logging ◽  
Western Desert ◽  
Gravity Modeling ◽  
Potential Field Data ◽  
Lithology Identification ◽  
Bahariya Formation

The Bahariya Formation in Egypt's Western Desert is a major source for minerals and hydrocarbon accumulation. It is also characterized by a relatively high radiation content because it contains iron oxide deposits that attract radioactive elements. The main objectives of our study are to establish depth to basement, basement configuration and related structural elements, and thickness and configuration of the overlain sedimentary section. In addition to the analysis of well-logging data, many advanced techniques have been applied to analyze magnetic and gravity data, including depth estimation, 2D magnetic and gravity modeling, and 3D inversion of potential field data. By integrating all available data, we can determine the structural control of the study area and evaluate the subsurface parameters. Well logging has been used for interpretation of porous and permeable zones, water saturation calculation, and basic lithology identification. The depth to basement in our study ranges from −1700 to −4500 m. The basement is shallow in the northern parts of the study area and deeper in the southern parts. The main clay minerals of the formation are montmorillonite, chlorite, and a mixed clay layer. The Bahariya Formation is composed mainly of sandy clay and sandstone, and therefore it is considered an excellent reservoir.

scholarly journals Geophysical assessment and hydrocarbon potential of the Cenomanian Bahariya reservoir in the Abu Gharadig Field, Western Desert, Egypt

2021 ◽  
Author(s):  
Mohammad Abdelfattah Sarhan
Keyword(s):  
Visual Analysis ◽  
Water Saturation ◽  
Effective Porosity ◽  
Western Desert ◽  
Absolute Permeability ◽  
Normal Faults ◽  
Potential Zone ◽  
Bulk Volume ◽  
Water Cut ◽  
Bahariya Formation

AbstractIn this study, the sandstones of the Bahariya Formation in the Abu Gharadig Field, which is a promising oil reservoir in the Abu Gharadig Basin, Western Desert, Egypt, were assessed. The wireline logs from three wells (Abu Gharadig-2, Abu Gharadig-6, and Abu Gharadig-15) were studied using seismic and petrophysical analyses. Based on seismic data, the study area contains an ENE–WSW anticlinal structure, which is divided by a set of NW–SE normal faults, reflecting the effect of Late Cretaceous dextral wrench tectonics on the northern Western Desert. The visual analysis of the well logs reveals a potential zone within well Abu Gharadig-2 located between depths of 10,551 and 10,568 ft (zone A). In contrast, potential zones were detected between depths of 11,593–11,623 ft (zone B) and 11,652–11,673 ft (zone C) in well Abu Gharadig-6. In well Abu Gharadig-15, potential zones are located between depths of 11,244–11251ft (zone D) and 11,459–11,467 ft (zone E). The quantitative evaluation shows that the intervals B and C in well AG-6 are the zones with the highest oil-bearing potential in the Abu Gharadig Field in terms of the reservoir quality. They exhibit the lowest shale volume (0.06–0.09), highest effective porosity (0.13), minimum water saturation (0.11–0.16), lowest bulk volume of water (0.01–0.02), high absolute permeability (10.92–13.93 mD), high relative oil permeability (~ 1.0), and low water cut (~ 0). The apex of the mapped fold represents that the topmost Bahariya Formation in the Abu Gharadig Field for which the drilling of additional wells close to well AG-6 is highly recommended.

scholarly journals Space-frequency analysis and reduction of potential field ambiguity

1997 ◽  
Vol 40 (5) ◽  
Author(s):  
M. Fedi ◽  
A. Rapolla
Keyword(s):  
Potential Field ◽  
Phase Plane ◽  
Gravity Data ◽  
Depth Resolution ◽  
Depth Estimation ◽  
Vertical Axis ◽  
Local Power ◽  
Potential Field Data ◽  
Space Frequency ◽  
Inherent Ambiguity

Ambiguity of depth estimation of magnetic sources via spectral analysis can be reduced representing its field via a set of space-frequency atoms. This is obtained throughout a continuous wavelet transform using a Morlet analyzing wavelet. In the phase-plane representation even a weak contribution related to deep-seated sources is clearly distinguished with respect a more intense effect of a shallow source, also in the presence of a strong noise. Furthermore, a new concept of local power spectrum allows the depth to both the sources to be correctly interpreted. Neither result can be provided by standard Fourier analysis. Another method is proposed to reduce ambiguity by inversion of potential field data lying along the vertical axis. This method allows a depth resolution to gravity or the magnetic methods and below some conditions helps to reduce their inherent ambiguity. Unlike the case of monopoles, inversion of a vertical profile of gravity data above a cubic source gives correct results for the cube side and density.

scholarly journals 3D Gravity Modeling of Complex Salt Features in the Southern Gulf of Mexico

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Mauricio Nava-Flores ◽  
Carlos Ortiz-Aleman ◽  
Mauricio G. Orozco-del-Castillo ◽  
Jaime Urrutia-Fucugauchi ◽  
Alejandro Rodriguez-Castellanos ◽  
...  
Keyword(s):  
Gravity Data ◽  
Three Dimensional ◽  
Complex Salt ◽  
Gravity Modeling ◽  
Gravity Inversion ◽  
Inversion Method ◽  
Oil Exploration ◽  
Potential Field Data ◽  
Estimation Algorithms ◽  
3D Gravity

We present a three-dimensional (3D) gravity modeling and inversion approach and its application to complex geological settings characterized by several allochthonous salt bodies embedded in terrigenous sediments. Synthetic gravity data were computed for 3D forward modeling of salt bodies interpreted from Prestack Depth Migration (PSDM) seismic images. Density contrasts for the salt bodies surrounded by sedimentary units are derived from density-compaction curves for the northern Gulf of Mexico’s oil exploration surveys. By integrating results from different shape- and depth-source estimation algorithms, we built an initial model for the gravity anomaly inversion. We then applied a numerically optimized 3D simulated annealing gravity inversion method. The inverted 3D density model successfully retrieves the synthetic salt body ensemble. Results highlight the significance of integrating high-resolution potential field data for salt and subsalt imaging in oil exploration.

scholarly journals Gravity Analysis for Subsurface Characterization and Depth Estimation of Muda River Basin, Kedah, Peninsular Malaysia

2021 ◽  
Vol 11 (14) ◽  
pp. 6363
Author(s):  
Muhammad Noor Amin Zakariah ◽  
Norsyafina Roslan ◽  
Norasiah Sulaiman ◽  
Sean Cheong Heng Lee ◽  
Umar Hamzah ◽  
...  
Keyword(s):  
River Basin ◽  
Rock Type ◽  
Gravity Data ◽  
Power Spectral Analysis ◽  
Depth Estimation ◽  
Structural Features ◽  
Peninsular Malaysia ◽  
Gravity Survey ◽  
Basement Rock ◽  
Geophysical Techniques

Gravity survey is one of the passive geophysical techniques commonly used to delineate geological formations, especially in determining basement rock and the overlying deposit. Geologically, the study area is made up of thick quaternary alluvium deposited on top of the older basement rock. The Muda River basin constitutes, approximately, of more than 300 m of thick quaternary alluvium overlying the unknown basement rock type. Previous studies, including drilling and geo-electrical resistivity surveys, were conducted in the area but none of them managed to conclusively determine the basement rock type and depth precisely. Hence, a regional gravity survey was conducted to determine the thickness of the quaternary sediments prior to assessing the sustainability of the Muda River basin. Gravity readings were made at 347 gravity stations spaced at 3–5 km intervals using Scintrex CG-3 covering an area and a perimeter of 9000 km2 and 730 km, respectively. The gravity data were then conventionally reduced for drift, free air, latitude, Bouguer, and terrain corrections. These data were then consequently analyzed to generate Bouguer, regional and total horizontal derivative (THD) anomaly maps for qualitative and quantitative interpretations. The Bouguer gravity anomaly map shows low gravity values in the north-eastern part of the study area interpreted as representing the Main Range granitic body, while relatively higher gravity values observed in the south-western part are interpreted as representing sedimentary rocks of Semanggol and Mahang formations. Patterns observed in the THD anomaly and Euler deconvolution maps closely resembled the presence of structural features such as fault lineaments dominantly trending along NW-SE and NE-SW like the trends of topographic lineaments in the study area. Based on power spectral analysis of the gravity data, the average depth of shallow body, representing alluvium, and deep body, representing underlying rock formations, are 0.5 km and 1.2 km, respectively. The thickness of Quaternary sediment and the depth of sedimentary formation can be more precisely estimated by other geophysical techniques such as the seismic reflection survey.

Computer Application in Geosciences: Imaging of the Subsurface by Structural Coupled Inversion of Potential Field Data

2014 ◽  
Vol 644-650 ◽  
pp. 2670-2673
Author(s):  
Jun Wang ◽  
Xiao Hong Meng ◽  
Fang Li ◽  
Jun Jie Zhou
Keyword(s):  
Potential Field ◽  
Field Data ◽  
Gravity Data ◽  
Computer Application ◽  
Magnetic Data ◽  
Imaging Method ◽  
Inversion Algorithm ◽  
Constant Property ◽  
Near Surface ◽  
Potential Field Data

With the continuing growth in influence of near surface geophysics, the research of the subsurface structure is of great significance. Geophysical imaging is one of the efficient computer tools that can be applied. This paper utilize the inversion of potential field data to do the subsurface imaging. Here, gravity data and magnetic data are inverted together with structural coupled inversion algorithm. The subspace (model space) is divided into a set of rectangular cells by an orthogonal 2D mesh and assume a constant property (density and magnetic susceptibility) value within each cell. The inversion matrix equation is solved as an unconstrained optimization problem with conjugate gradient method (CG). This imaging method is applied to synthetic data for typical models of gravity and magnetic anomalies and is tested on field data.

scholarly journals Basement Mapping of the Fucino Basin in Central Italy by ITRESC Modeling of Gravity Data

Geosciences ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 398
Author(s):  
Federico Cella ◽  
Rosa Nappi ◽  
Valeria Paoletti ◽  
Giovanni Florio
Keyword(s):  
Seismic Activity ◽  
Site Response ◽  
Gravity Data ◽  
A Priori ◽  
Central Italy ◽  
Gravity Anomalies ◽  
Gravity Modeling ◽  
Ground Shaking ◽  
Sedimentary Evolution ◽  
Fucino Basin

Sediments infilling in intermontane basins in areas with high seismic activity can strongly affect ground-shaking phenomena at the surface. Estimates of thickness and density distribution within these basin infills are crucial for ground motion amplification analysis, especially where demographic growth in human settlements has implied increasing seismic risk. We employed a 3D gravity modeling technique (ITerative RESCaling—ITRESC) to investigate the Fucino Basin (Apennines, central Italy), a half-graben basin in which intense seismic activity has recently occurred. For the first time in this region, a 3D model of the Meso-Cenozoic carbonate basement morphology was retrieved through the inversion of gravity data. Taking advantage of the ITRESC technique, (1) we were able to (1) perform an integration of geophysical and geological data constraints and (2) determine a density contrast function through a data-driven process. Thus, we avoided assuming a priori information. Finally, we provided a model that honored the gravity anomalies field by integrating many different kinds of depth constraints. Our results confirmed evidence from previous studies concerning the overall shape of the basin; however, we also highlighted several local discrepancies, such as: (a) the position of several fault lines, (b) the position of the main depocenter, and (c) the isopach map. We also pointed out the existence of a new, unknown fault, and of new features concerning known faults. All of these elements provided useful contributions to the study of the tectono-sedimentary evolution of the basin, as well as key information for assessing the local site-response effects, in terms of seismic hazards.

scholarly journals Improve The Efficiency Of The Study Of Complex Reservoirs And Hydrocarbon Deposits - East Baghdad Field

2020 ◽  
Author(s):  
Sudad H Al-Obaidi
Keyword(s):  
Oil And Gas ◽  
Water Saturation ◽  
Well Logging ◽  
Well Testing ◽  
Petrophysical Parameters ◽  
Oil And Gas Fields ◽  
Hydrocarbon Fields ◽  
Gas Fields ◽  
Hydrocarbon Deposits

Practical value of this work consists in increasing the efficiency of exploration for oil and gas fields in Eastern Baghdad by optimizing and reducing the complex of well logging, coring, sampling and well testing of the formation beds and computerizing the data of interpretation to ensure the required accuracy and reliability of the determination of petrophysical parameters that will clarify and increase proven reserves of hydrocarbon fields in Eastern Baghdad. In order to calculate the most accurate water saturation values for each interval of Zubair formation, a specific modified form of Archie equation corresponding to this formation was developed.

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