Computation of regional gravity anomaly — A novel approach

Khah²,

et al. 2023

Preprint

Geophysical studies are utilized as one of the main steps in exploration that must be performed before exploratory drilling due to the high cost of excavation and its related heavy machinery and reduction of the exploration cost. One of the most critical geophysical issues in estimating the physical and geometric parameters is the store carrying out using the residual magnetic anomaly reduction. These parameters include depth, volume, shape factor, and type of storage. The present geophysical study aims to prepare and model magnetic data for proposed drilling sites in the Baba Ali Iron ore deposit in the Hamedan province of Iran. Inverse modeling is one of the most efficient interpretive methods of potential field data. In this study, the Bhattacharya method in MATLAB software is used to minimize the target function and potential field data to create the best fit for magnetic data. In this modeling, the graphs of the residual anomaly and model showed an excellent conformation two-dimensionally. Also, 3D modeling reconstructs the properties of the productive resources of anomalies correctly. After preparation of total magnetic maps, it was found out that the magnetic lens in four anomalies with surface depths of 20, 50, and 50 meters is estimated for this zone. Their specific gravity was 4.77 t / m3, and their initial storage capacity was 95,400 tones at most. Also, exploratory excavation is proposed to complete the preliminary explorations of the specified region by inverse modeling for the three points.

Section: Modeling Of Arti Cial Magnetic Datamentioning

confidence: 81%

Estimation of Depth, Physical Parameters, and Location using Nonlinear Inverse Modeling of Magnetic Data by Bhattacharya Method in a field of NW Iran

Khah²,

et al. 2023

Preprint

“…The angle of inclination varies sharply for different slopes. For slopes 0 and 90 degrees, the diagram's meeting point of the angle of inclination with the x-axes (x = 0) is close to the edges of the 2D model (Mallick & Sharma, 1997;Stocco et al, 2009). Fig.…”

Section: Modeling Of Artificial Magnetic Datamentioning

confidence: 82%

Geobody Estimation by Bhattacharyya Method Utilizing Nonlinear Inverse Modeling of Magnetic Data in Baba-Ali Iron Deposit, NW Iran

Khah²,

et al. 2023

Preprint

Geophysical investigations are one of the leading efforts in any exploration project that must be performed ahead of time due to the high excavation expenditures, heavy machinery, and cost reduction. One of the essential geophysical concerns is the estimation of the physical and geometrical parameters of the reserve (geobody), which is done by exploiting the nonlinear inverse modeling of magnetic data. These parameters include depth, volume, shape factor, and type of storage. The present investigation aims to prepare and model magnetic data for proposed drilling sites in the Baba Ali Iron ore deposit in the Hamedan province of Iran. The areal and depth extent of the iron ore geobody was unknown. The Bhattacharyya method by MATLAB software coding was used to minimize the target function and potential field data and create the best fit for the magnetic data. The residual anomaly and model graphs exhibited an excellent two-dimensional conformation in this modeling. Also, 3D modeling correctly reconstructs the properties of the productive resources of anomalies. After preparing full magnetic maps, the magnetic lenses distinguished in four anomalies of surface depths, 20, 50, and deeper than 50 meters for this zone. This magnetite lens for the first zone was estimated based on filters applied on the entire magnetic map so that the lens's depth is trivial and almost zero. Their specific gravity is calculated as 4.77 t/m3, and their initial storage capacity is suggested to be about 95,400 tones at most. Finally, to complete the preliminary explorations of the specified area, exploratory drilling is suggested for three points by inverse modeling.

“…Nevertheless, other filters detect the anomaly masses' horizontal boundaries. Also, due to fitting to data and their flexibility using the lateral anomalies separation and edges' position (the estimation of the boundary of geological structures such as a fault or dyke), considered as analytical signal filters and derivatives (Blakely, 1995;Blakely & Simpson, 1986;Griffin, 1949;Hinze, 1990;Hosseini et al, 2014;Kaufman & Keller, 1981;Loke & Barker, 1996;Mallick & Sharma, 1997;Miller & Singh, 1994;Paterson & Reeves, 1985;Roest et al, 1992;Talwani & Ewing, 1960;Talwani et al, 1959;Telford et al, 1990;Wijns et al, 2005). Since the 1970s, various semiautomatic methods have been developed using gradients (derivatives) of the magnetic field anomalies to determine geometric parameters such as boundaries' locations and the causative sources' depths.…”

Section: Introductionmentioning

confidence: 99%

Boundaries Determination in Potential Field Anomaly Utilizing Analytical Signal Filtering and its Vertical Derivative in Qeshm Island SE Iran

Khah²,

et al. 2023

Preprint

The analytical signal method and its derivatives can be explicitly calculated and assessed for analyzing and estimating the boundary of geological structures, such as faults or dikes, from potential field anomalies. Gravity field of the east of Qeshm Island and its north coast from Sarkhun to Latidan in SE Iran has been measured in one-kilometer regular network. The regional anomaly effects are deducted from the Bouguer anomaly, where it can get the residual anomalies which is the considered dataset used in this study. The Bouguer range is -297 to -330 milligals (mGal) applying filters and modeling. It was revealed that there are five negative anomalies caused by salt penetration in the region. Regional anomalies expectedly have a low spatial frequency and long wavelengths, while the residual anomalies associated with shallow sub-surface potentials have high spatial frequencies and short-wave wavelengths. Two different fault trends were observed comparing the artificial model using MATLAB coding, the real one, and the filtered residual anomaly map of the Qeshm region. Also, another fault trend is suggested in the east height of Oman, which is a possible place of salt penetration. Due to the limited dimensions (120 * 100 km) and the information obtained from the existing drillings, the depth of the anomaly resources can be examined up to 8 km. Due to the gravitational condition between the two domes of Qeshm saline and the bridge located in the Hara saline area, it is suggested to be considered as an area for further oil exploration routines.