Gravity Techniques Research Articles

Characterization and Evolution of the Professor Valley Salt Body, Paradox Basin, Utah Using Integrated Geological, Geochemcial and Geophysical (Gravity) Techniques

Characterization and Evolution of the Professor Valley Salt Body, Paradox Basin, Utah Using Integrated Geological, Geochemcial and Geophysical (Gravity) Techniques

Statistical physics modelling of adsorption isotherms of water vapour on shale: Stereographic, energetic and thermodynamic investigations

AbstractUnderstanding the mechanisms of shale–water interaction by water vapour adsorption is crucial for predicting shale gas productivity. In this study, equilibrium adsorption data of water vapour on four different shales of the Sichuan Basin at three temperatures (298, 308, and 318 K) were measured using static gravity techniques. The water vapour adsorption isotherms were simulated by three statistical physics models. Steric parameters, including the number of water vapour molecules adsorbed per site (n), monolayer adsorption amount (q0), and adsorption energy (ΔEa), and thermodynamic parameters such as configuration entropy (Sa), internal energy (Eint), and free energy (Ga) derived from the selected model were used to explain the adsorption mechanism. The model analyses suggest that the adsorbed water vapour molecules are attached to the shale surface in a multi‐anchorage manner. The adsorption of the first layer shows a Type I characteristics, while the adsorption of the subsequent layer is of Type III. The calculated adsorption energies indicate that the physical adsorption takes place on the water vapour molecules on the shale, and the main interaction forces are hydrophilic bonding forces and van der Waals forces. Negative Eint and Ga values indicate that the spontaneous properties are for water vapour adsorption and that the system requires the release of energy to capture the water vapour molecules.

Physicochemical concentration of heavy minerals - a treatise on wet process media: gravity, centrifugal and flotation techniques

Physicochemical concentration of heavy minerals - a treatise on wet process media: gravity, centrifugal and flotation techniques

New insights into crustal and geological structures beneath the Southern Benue trough of Nigeria and parts of Cameroon Volcanic Line from tailored gravity data

We utilized a high-resolution tailored gravity dataset to investigate the geological structure beneath the Southern Benue Trough of Nigeria and along the Cameroon Volcanic Line (CVL). The tailored gravity data was obtained by applying a stochastic combination technique to integrate global gravity field model, terrestrial gravity data, and residual gravity data over the study area. We then carried out gravity techniques to compile the Bouguer gravity map and to estimate the crustal thickness. To obtain suitable estimates of the reference depth and density contrast of the Moho interface, we fitted the gravimetrically determined Moho geometry to the seismic estimates by minimizing the Root-Mean-Square of their differences. A minimum RMS of 3.6 km at a reference depth of 26 km and a density contrast of 450 kgm−3 was achieved over the study area. Our results reveal a dense magmatic feature criss-crossing the central portion of the study area. This phenomenon led to a thinning of the crust and formation of various geological structures, mainly at the southern end. We could see a very thick sedimentary cover within some of these structures possibly occasioned by compressional and extensional tectonic forces acting at the southwest end. Our study reveals that these compacted sedimentary covers could be important habitats for mineralization. We have also been able to refine and depict the lateral extent of the crustal architecture at a fine scale using our tailored gravity dataset. We concluded that the tectonic events beneath the study area are complex and point to several geophysical factors earlier revealed in published studies. However, a narrowing of two or more conjugate plates (margins) propelled by an upward force may have primarily led to the upward displacement of some of the magmas in-between those plates forming the intrusive rocks.

An Oil and Gas Play Turns Into a Prime Helium Prospect

Black Exploration, LLC drilled a wildcat oil and gas test on a large structure on the Zia Pueblo in early 2023. The primary objectives were oil and gas. However, helium potential was also recognized as a possible secondary objective. This large structure sits adjacent to some of the largest reported air corrected mantle, He and CO2 degassing carbonic and geothermal springs in the Rocky Mountain region. The prospect overlies a classic Synthetic Overlapping Transfer Zone between the northern Albuquerque Basin and the southern Espanola Basin in the Rio Grande rift in Northern New Mexico. Recognition of possible deep crustal and upper mantel faulting as well as surface geologic mapping, gravity, seismic and geo-microbial techniques helped delineated the prospect. A possible explanation for why high mantle derived helium is concentrated in this area is the intersection of the ancient Jemez Lineament and the more recent Rio Grande rift. This wildcat has now discovered helium and white hydrogen in the Abo formation. If economically productive the well will be the first helium discovery in the Rio Grande Rift. This could open the rift and its sub basins into a large, new oil, gas and helium and hydrogen producing province.

Integrative Analysis of the Geothermal Structure in Kepahiang: Insights from Magnetotelluric, Gravity, and Remote Sensing Techniques

This research was conducted to determine the structure and depth of the reservoir using remote sensing as an initial survey to assess the geological alignment direction, employing ALOS PALSAR radar imagery. Subsequently, further surveys were conducted using the magnetotelluric and gravity methods to analyze the structure and depth of the geothermal reservoir. The magnetotelluric data were processed using Phoenix software, where the data was transformed from the time domain to the frequency domain using Fourier transformation, and processed to obtain apparent resistivity and phase. The MT data was integrated with gravity data, and the gravity data underwent standard correction procedures to obtain the Complete Bouguer Anomaly (CBA) map. Two-dimensional (2D) inversion using the NLCG algorithm and 2D forward modeling of the gravity data were performed. The dominant alignment pattern obtained was northwest-southeast, with an orientation of 320° NW or 140° SE. Based on the results of geological alignment, a profile is produced that is perpendicular to the straightness. The results from the 2D inversion and gravity forward modeling indicated that the geothermal reservoir is likely located beneath the caprock at an estimated depth of approximately 1800 m, with resistivity values ranging from 32 to 256 Ohm-m and a density value of 2.6 gr/cc.

Integrated application of gravity, aeromagnetic, and electromagnetic methods in exploring the Ganzi geothermal field, Sichuan Province, China

The Ganzi geothermal field is located in the Songpan-Ganzi orogenic belt in Sichuan Province. Many hot springs are exposed along the Yalahe valley in Ganzi geothermal field, which is a favorable area for high-temperature geothermal resource exploration. However, the geological model of heat exchange, the regional structure controlling hydrothermal convection and the development model of geothermal reservoirs are still unclear. Therefore, further studies are necessary to meet the geothermal exploration requirements in the middle and deep strata of this geothermal field. In this study, a geological model of the geothermal system of Ganzi geothermal field is proposed. We are convinced that there exists a hydrothermal convection system in the Ganzi geothermal field, the heat transfer of which is accomplished through deep-rooted major faults. Therefore, the identification of deep-rooted major faults and the description of geothermal reservoirs are the research objects of the integrated geophysical methods. The main factors controlling the geothermal reservoirs in the deep-rooted Xianshuihe major fault and Yalahe fault zones are analyzed by using gravity, aeromagnetic, and electromagnetic methods and techniques. The analysis results of regional gravity and aeromagnetic anomalies show that the Xianshuihe major fault has produced obvious gravity and aeromagnetic anomalies on the surface, and thus the position and strike of this fault can be accurately predicted by inversion of the aeromagnetic anomalies. Geothermal reservoirs show low-resistivity anomalies in the electromagnetic profile. The inversion results of the controlled source audio-frequency magnetotelluric (CSAMT) data show that geothermal reservoirs are mainly developed along the Yalahe valley, and the west side of the valley is more favorable for geothermal exploration. This study is of guiding significance to the efficient exploitation and utilization of the Ganzi geothermal field.

Integrated Geophysical Approach of Groundwater Potential in Wadi Ranyah, Saudi Arabia, Using Gravity, Electrical Resistivity, and Remote-Sensing Techniques

In order to cope with the rise in human-caused demands, Saudi Arabia is exploring new groundwater sources. The groundwater potential of Wadi Ranyah was studied using a multi-dataset-integrated approach that included time-variable gravity data from the Gravity Recovery and Climate Experiment (GRACE), vertical electrical sounding (VES), and time-domain-electromagnetic (TDEM) data with other related datasets to examine the variations and occurrence of groundwater storage and to define the controlling factors affecting the groundwater potential in Wadi Ranyah in southwestern Saudi Arabia. Between April 2002 and December 2021, the estimated variation in groundwater resources was −3.85 ± 0.15 mm/yr. From 2002 to 2019, the area observed an average yearly precipitation rate of 100 mm. The sedimentary succession and the underlying fractured basement rocks are influenced by the structural patterns that run mainly in three different trends (NW, NE, and NS). The sedimentary cover varies from 0 to 27 m in thickness. The outputs of the electrical sounding revealed four primary geoelectric units in the study area: on top, a highly resistant geoelectrical unit with a resistivity of 235–1020 Ω.m, composed of unsorted, loose, recent sediments; this is followed by a layer of gravel and coarse-grained sands with a resistivity of 225–980 Ω.m; then, a water-bearing unit of saturated sediments and weathered, fractured, basement crystalline rocks with a resistivity of 40–105 Ω.m, its depth varying from 4 to ~9 m; and then the lowest fourth unit composed of massive basement rocks with higher resistivity values varying from 4780 to 7850 Ω.m. The seven built dams store surface-water runoff in the southwestern part of the wadi, close to the upstream section, in addition to the Ranyah dam, as the eighth one is located in the middle of the wadi. The subsurface NW- and NS-trending fault lines impede the groundwater from flowing downstream of the wadi, forming isolated water-bearing grabens. Minimal surface runoff might occur in the northern part of the wadi. The combined findings are beneficial because they provide a complete picture of the groundwater potential of Wadi Ranyah and the controlling structural patterns. Using this integrated technique, the groundwater potential in arid and semiarid regions can now be accurately assessed.

Loop quantum gravity of a spherically symmetric scalar field coupled to gravity with a clock

The inclusion of matter fields in spherically symmetric loop quantum gravity has proved problematic at the level of implementing the constraint algebra including the Hamiltonian constraint. Here we consider the system with the introduction of a clock. Using the abelianizaton technique we introduced in previous papers in the case of gravity coupled to matter, the system can be gauge fixed and rewritten in terms of a restricted set of dynamical variables that satisfy simple Poisson bracket relations. This creates a true Hamiltonian and therefore one bypasses the issue of the constraint algebra. We show how loop quantum gravity techniques may be applied for the vacuum case and show that the Hamiltonian system reproduces previous results for the physical space of states and the observables of a Schwarzchild black hole.

Application of gravity and magnetic techniques to model the geometry of the northern margin of the Onion Creek salt diapir, Paradox Basin, Utah

The Onion Creek salt diapir lies within the Paradox Basin of southeast Utah where it forms part of a group of salt structures that separate the Paradox Basin into smaller sub-basins. A series of anomalous, tight folds occur on the northern side of the Onion Creek diapir within the Permian Cutler Group. These folds are thought to be associated with a shallow detachment horizon with three possible origins: 1) a weak shale layer within the Cutler Group; 2) a salt namakier; or 3) a salt shoulder. We collected and analyzed gravity and magnetics data across a portion of the concealed Onion Creek salt body. Since the salt is less dense and less magnetic than the Cutler Group siliciclastics, these geophysical data aid in defining the extent of subsurface salt. Our gravity data show a free-air anomaly low over the diapir with a gradual increase in values as more of the Cutler Group covers the subsurface salt. Magnetic data display a similar trend, but also suggest more complicated 3-D structure exists beneath the study area. Forward and inverse modeling indicated a salt shoulder model best fit the geophysical data. These results suggest gravity and magnetic methods are a low-cost method to evaluate plausible subsurface salt structure for oil and gas exploration studies.

Geophysical interpretation for delineating groundwater and subsurface structure in the East of Cairo City, Egypt

This study aimed to delineate groundwater and the structural trends in the East of Cairo City. For this aim, we carried out different geophysical approaches such as gravity, magnetic, and electric methods. For the gravity and magnetic data analysis, we used filtering, Euler deconvolution, and radially power spectrum techniques. In addition, 3-D modeling was performed on the magnetic data only. The radial power spectrum technique shows that the depths of the surface anomalies corresponding to the short wavelength are 0.48 and 0.5 km. While, the depths of the surface anomalies corresponding to the long wavelength are ranging from 2.74 to 2.33 km from gravity and magnetic interpretation, respectively. The Euler deconvolution revealed that the investigation area was under the effect of several fault trends; a major NW-SE trend and NE-SW and NW-SE as minor trends for gravity data. While the fault trends are in N-S and NE-SW directions for RTP magnetic data. The 3-D modeling results show that the basement depth was fluctuating between 1.186 to 1.657 Km. The principal tectonic deformations of the investigating area are towards the E-W, N-S, and NE-SW trends. The gravity and magnetic techniques in this study revealed that different faults dissect the area of trends NE-SW matching the Gulf of Aqaba direction, NW-SE matching the Gulf of Suez, N-S matching the River Nile system, and E-W matching the Mediterranean tectonics. The geo-electrical method was used to investigate groundwater presence. Regarding the seismicity, the area can be considered moderate to highly active. Most of the area faults are active except in the area's southern part. So, this part can be considered the most suitable and safe part for construction.

Time-lapse electromagnetic and gravity methods in carbon storage monitoring

For geologic carbon storage (GCS), monitoring of the storage reservoir and detection of secondary plumes if they accumulate outside of the reservoir are important to confirm that the injected CO2 stays where intended. Seismic methods are most often applied but are expensive. Due to cost considerations, especially for long-term monitoring, less expensive techniques play a role when designing monitoring networks. In this article, the merits of gravity and electromagnetic (EM) methods as monitoring tools for GCS are presented. Many of the technologies are well established, and several new technologies are on the horizon. EM and gravity techniques are complementary to seismic methods and together provide better subsurface monitoring. Time-lapse multiphysics joint inversion, including seismic, EM, and gravity, could be a game changer for carbon storage monitoring. The trade-off between the sensitivity or resolution to a given plume size and the associated costs will be an important factor in selecting efficient and reliable monitoring arrays at GCS sites. Complex digital models representing geology encountered at storage sites can be used for this purpose and present another cost savings.

Engineering entanglement Hamiltonians with strongly interacting cold atoms in optical traps

We present a proposal for the realization of entanglement Hamiltonians in one-dimensional critical spin systems with strongly interacting cold atoms. Our approach is based on the notion that the entanglement spectrum of such systems can be realized with a physical Hamiltonian containing a set of position-dependent couplings. We focus on reproducing the universal ratios of the entanglement spectrum for systems in two different geometries: a harmonic trap, which corresponds to a partition embedded in an infinite system, and a linear potential, which reproduces the properties of a half-partition with open boundary conditions. Our results demonstrate the possibility of measuring the entanglement spectra of the Heisenberg and XX models in a realistic cold-atom experimental setting by simply using gravity and standard trapping techniques.

Effective LQC model for k=+1 isotropic cosmologies from spatial discretizations

The closed, spatially isotropic FLRW universe (k=+1) is endowed with modifications due to a discrete underlying space-structure. Motivated from Loop Quantum Gravity techniques, a full Thiemann regularisation is performed. The impact of these modifications of the single-graph-sector appearing in the scalar constraint are interpreted as physical quantum gravity effects. We investigate the form of the modified scalar constraint and its analytical approximations for k=+1 spacetimes and assume this effective constraint as the generator of dynamics on the reduced isotropic phase space. It transpires that the system still features a classical recollapse with only marginal discreteness corrections. Moreover, the initial and final singularities are resolved and we present an effective model mirroring the qualitative features of system.

Mineralogical characterization and physical upgrading of radioactive and rare metal minerals from Wadi Al-Baroud granitic pegmatite at the Central Eastern Desert of Egypt

Granitic pegmatites of Wadi Al-Baroud area in the Central Eastern Desert of Egypt have appreciated amounts of radioactive (U, Th) and rare metal- (Nb, Ta, Y, Zr, Hf, and rare earth elements—REEs) bearing minerals. A combination of both geochemical and physical methods has been used for investigation of Wadi Al-Baroud granitic pegmatites. The identification, imaging, and chemistry of rare metal-bearing minerals were conducted using the optical microscope, X-ray diffraction (XRD), scanning electron microscope (SEM), and electron microprobe analyzer (EMPA). The pegmatites host Nb-Ta oxides (euxenite-Y, fergusonite-Y, and yttrocolumbite-Y), REE minerals (xenotime-Y, monazite-Ce and allanite-Ce), U-Th minerals (thorite and uranothorite), and Hf-rich zircon. In addition, muscovite, quartz, feldspars, and some iron oxide minerals such as magnetite, goethite, and lepidocrocite represent the essential, gangue, and associated minerals. Physical upgrading of Wadi Al-Baroud-mineralized pegmatites was carried out using gravity and magnetic separation techniques. Applying the optimum conditions for both separation techniques, it is possible to attain a good concentrate with an acceptable recovery. Accordingly, the final concentrate contains ~ 0.25% U, 0.46% Th, and 0.31% REE with recovery of 91.17% U, 96.56% Th, and 86.19% REE in a weight of 6.58% out of the original sample assays 0.02% U, 0.04% Th, and 0.03% REE. Therefore, it is well-recommended that the final concentrate should subject to proper hydrometallurgical treatment to extract their valuable metal contents.

Gauge-invariant bounce from loop quantum gravity

We present a gauge-invariant treatment of singularity resolution using loop quantum gravity techniques with respect to local SU(2) transformations. Our analysis reveals many novel features of quantum geometry which were till now hidden in models based on non-gauge-invariant discretizations. Quantum geometric effects resolve the big bang singularity replacing it with a non-singular bounce when spacetime curvature reaches Planckian value. The bounce is found to be generically asymmetric in the sense that pre-bounce and post-bounce branches are not mirrored to each other and effective constants, such as Newton’s constant, are rescaled across the bounce. Furthermore, in the vicinity of the bounce, minimally coupled matter behaves as non-minimally coupled. These ramifications of quantum geometry open a rich avenue for potential phenomenological signatures.

Evaluation of Nile Delta-Mediterranean Sea Conjunction Using GPS, Satellite-Based Gravity and Altimetry Datasets

Sinking of the Nile Delta region of Egypt is one of urgent issues to be investigated due to its vital importance to numerous perspectives such as economic, environmental and social impact on the whole Egyptian territory. This contribution represents one of the project outcomes entitled “Evaluation of Nile Delta Sinking Hypothesis Using the Global Positioning System (GPS), Tide Gauge and Satellite Altimetry and Gravity Techniques” that has been funded by the Science & Technology Development FUND (STDF), Egypt in the period from 2013 till 2017. To detect the rates of the horizontal and vertical movements, three main geodetic techniques; Global Positioning System (GPS) measurements of Delta region, time-varying gravity models of the Gravity Recovery and Climate Experiment (GRACE) mission to monitor the temporal changes over the delta regions and satellite altimetry time series have been used. Our findings regarding the GPS technique show that the northern part of the Nile Delta region suffers from clear subsidence especially at the eastern and western side as represented by Port Said, Mansoura, Gamalyia, Alexandria and Edfena stations. The central part as well as the surrounding areas of Nile Delta suffers from clear uplift as represented by Tanta, Damnhour and Hamoul stations. Satellite gravity results show erosion rates of the conjunction part of Nile Delta and Mediterranean contact, especially at its eastern (Port Said surrounding areas) and western (Alexandria surrounding areas) parts. As we go inland to the southern part of the Nile Delta, the temporal gravity variations pattern decreases showing that the Delta subsidence follows the regular subsidence pattern, except that for the northern contact part of the Delta to the Mediterranean Sea. This is also supported by satellite altimetry missions which shows a continuously rising rate of the Mediterranean Sea level as detected from the Saral/AltiKa mission.

Maximum Utilization of Energy Source Minerals Using Mineral Processing Techniques: A Review

The mineral is one of the most important energy resources. Indirect energy derived from Sun as Biomass. Organic byproducts were converted to fossil fuels through photosynthesis on Earth. Coal is a sedimentary rock that contains the accumulation of organic matter from plants. Coal is upgraded using gravity and flotation techniques. In many countries, SO2 is being removed from flue gases by different methods. Oil shale is shale that contains organic matter of incomplete conversion to oil. Oil shale can be burned directly to generate electricity. It can be upgraded to increase its organic content. It can be converted to oil or gas through pyrolysis. Nuclear fuel is a material that contains fissionable elements such as Uranium, Plutonium, and Thorium. Uranium is widely distributed in mineral ores. Natural uranium contains 0.7% U235 (fissile isotope) and 99.3% U238. The U235 must be increased up to 8% to be a fuel for energy reactor while the weapon-grade must contain at least 90% U235.

Multistage Gravity Beneficiation of Rutile in a Tar-Free Sand Residue

This study reports on the concentration of rutile in the sand recovered from tar sand in Ondo State in Nigeria. The tar-free sand residue, approximately 90 % of which passes through a sieve with a pore size of 355 µm, was subjected to sieve analysis as well as sequences of panning gravity pre-concentration and shaking-table concentration at a slurry density of 25 % solids to improve the rutile content. The sand residue recovered in addition to the panned pre-concentrate and shaking table concentrates were also subjected to reflected light microscopy as well as transmitted light microscopy, counting using ImageJ software and X-ray fluorescence spectroscopy. The micrographs obtained showed that the samples contain rutile, dark-brown in color, interlocked with the major silica content and the content of rutile estimated by ImageJ software increased in the pre-concentrate from 7.90 % to 19.23 % in the final concentrate. X-ray fluorescence spectroscopy also showed that the rutile content increased in the pre-concentrate from 1.43 % to 31.02 % in the final concentrate. Therefore, the rutile content was successfully increased by the cheap gravity techniques of panning and shaking tables.

Modelling subsurface geologic structures at the Ikogosi geothermal field, southwestern Nigeria, using gravity, magnetics and seismic interferometry techniques

Abstract We present results and a technique for imaging the subsurface structures of a geothermal field with particular focus on the Ikogosi geothermal field in Nigeria. The intent was to provide an understanding of the subsurface structural setup in the region and assess its viability for further geothermal resources exploitation. High-resolution aeromagnetic and gravity data were used for the study. A constrained 2D forward modelling technique was applied to these datasets to map the shape and corresponding depths of geologic structures in the region. This study has gone deeper to ascertain the basement structure and configurations and how it influences the heat source of the Ikogosi Warm Spring (IWS) region. The dominant host quartzite rock unit at the IWS location reaches average depths of 2.5–3.0 km and is located directly on an intruded high-density geologic formation in the subsurface. Fault structures traversing the IWS source have also been uncovered. We infer that these structural setups are central to the geothermal system of the IWS. Valid reflection responses from the profile model have been retrieved from randomly induced noise sources, using a passive seismic interferometry technique. Pre-stack depth migration of the reflected responses suitably imaged the reflectors within the subsurface of the IWS region, tracing fault boundaries and delineating intruded geological structures. This has provided pre-survey insights into the subsurface seismic imagery of the region. Results derived from this study could assist informed decision making regarding geothermal exploration and exploitation in the region.