Gravity Interpretation Research Articles

Gravity interpretation of the Erzincan-Cayirli Basin its connection with the North Anatolian Fault Zone using quadratic density function

Gravity interpretation of the Erzincan-Cayirli Basin its connection with the North Anatolian Fault Zone using quadratic density function

Structural signatures of the Amazonian Craton in eastern Colombia from gravity and magnetometry data interpretation

Geophysical interpretation of potential field data plays an important role in the integration of geological data. Estimation of density and magnetic susceptibility variations within the upper crust helps evaluating the continuity of geological structures in the field. In the present study we use gravity and magnetic data in NW Amazonian Craton in Colombia. Total horizontal gradient of the reduction to magnetic pole were used to delineate magnetic lineaments and domains showing four zones, each with its own features. Multiscale edge detection (worming) of the data help delineate upper crustal structures that we interpret as tectonic boundaries that correlate with the four zones identified. 3D density and magnetic susceptibility inversion showed high density and/or high magnetic susceptibility sources correlated with these crustal structures. Zone (1) is located south of the Guaviare River, with predominant NW-SE and NE-SW magnetic lineaments; zone (2), located from south of the Guaviare River to the north, present nearly E-W magnetic lineaments and a deep E-W edge interpreted as a possible shear zone parallel to Guaviare, Orinoco and Ventuari rivers; zone (3) from south of the Vichada River to the north, with NE-SW and NW-SE lineaments; N-S zone (4) cuts the zones (2) and (3), characterized by high density/magnetic susceptibility source bounded by N-S deep edges. A more complete tectonic evolution interpretation requires further work, but we speculate that the zone (4) could indicate an aborted rift/collision suture and that the zone (2) is indicative of a younger deformation event. Shear direction at (2) is not clear: geological maps show NEE-SWW right-lateral faulting, but geophysical anomalies suggest left-lateral displacement, highlighted by left dislocation of the Orinoco River. We also speculate that a N-S edge located at the SE of the area can be related with the Atabapo Belt and the limit of Ventuari-Tapajós and Rionegro geochronological provinces.

Interpretation of Gravity and Magnetic Data in the Erbil Plain (Iraqi Kurdistan Region)

Interpretation of Gravity and Magnetic Data in the Erbil Plain (Iraqi Kurdistan Region)

Gravity interpretation for delineating subsurface structures and depth of basement at El Moghra area, North Western Desert, Egypt

ABSTRACT El Moghra area represents a vital part of the national reclamation area at the northern part of Western Desert, Egypt. Delineating subsurface structures (faults & basins) and depth to the basement is the base of planning the area. Basins can be water aquifers or oil traps. Gravity data has been used to tackle such aims. The gravity (Bouguer) anomaly map is separated into regional components (deep sources), and residual component (shallower sources). The residual gravity map was used to delineate subsurface structural features dissecting the investigated area. Also, Euler deconvolution and Tilt Derivative methods have been used for delineating the structural elements. The gravity interpretation indicates that the most main tectonic have E–W, ENE–WSW, and N–S trends for the major structures, while the minor structures are aligned in NNE–SSW, NE–SW, NNW–SSE, and NW–SE. The results of depth estimation using 2D and 3D modelling show that the eastern and southwestern parts of the area under study exhibit a deep basement structure, reaches more than 7000 m (basin). However, the central and northwestern parts of the investigated area show shallower depth of basement rocks (4100 m).

Structural characteristics of the KPR-CBR triple-junction inferred from gravity and magnetic interpretations, Philippine Sea Plate

The intersection of the Kyushu-Palau Ridge (KPR) and the Central Basin Rift (CBR) of the West Philippine Basin (WPB) is a relic of a trench-trench-rift (TTR) type triple-junction, which preserves some pivotal information on the cessation of the seafloor spreading of the WPB, the emplacement and disintegration of the proto-Izu-Bonin-Mariana (IBM) Arc, and the transition from initial rifting to steady-state spreading of the Parece Vela Basin (PVB). However, the structural characteristics of this triple-junction have not been thoroughly understood. In this paper, using the newly acquired multi-beam bathymetric, gravity, and magnetic data obtained by the Qingdao Institute of Marine Geology, China Geological Survey, the authors depict the topographic, gravity, and magnetic characteristics of the triple-junction and adjacent region. Calculations including the upward continuations and total horizontal derivatives of gravity anomaly are also performed to highlight the major structural features and discontinuities. Based on these works, the morphological and structural features and their formation mechanisms are analyzed. The results show that the last episode amagmatic extension along the CBR led to the formation of a deep rift valley, which extends eastward and incised the KPR. The morphological and structural fabrics of the KPR near and to the south of the triple-junction are consistent with those of the western PVB, manifesting as a series of NNE-SSW- and N-S-trending ridges and troughs, which were produced by the extensional faults associated with the initial rifting of the PVB. The superposition of the above two reasons induced the prominent discontinuity of the KPR in deep and shallow crustal structures between 15°N–15°30′N and 13°30′N–14°N. Combined with previous authors’ results, we propose that the stress produced by the early spreading of the PVB transmitted westward and promoted the final stage amagmatic extension of the CBR. The eastward propagation of the CBR destroyed the KPR, of which the magmatism had decayed or ceased at that time. The destruction mechanism of the KPR associated with the rifting of the PVB varies along strike the KPR. Adjacent to the triple-junction, the KPR was destroyed mainly due to the oblique intersection of the PVB rifting center. Whereas south of the triple-junction, the KPR was destroyed by the E-W-directional extensional faulting on its whole width.©2021 China Geology Editorial Office.

The Cooperation Between Loop Quantum Gravity and Entropic Gravity

The so-called new interpretation of the entropy of gravity belongs to a non-mainstream branch of gravity research for a long time. The core idea is that gravity is a statistical phenomenon; it is not fundamental, like the other three basic interactions. The statistical origin of gravity first came from the hint of black hole thermodynamics. For example, the famous Bekenstein-Hawking entropy formula in the early 1970s. The more famous work followed was that in the mid-1990s, T. Jacobson derived Einstein's equations based on the thermodynamics of black holes-the basic equations of general relativity. That is, Einstein's equation is actually the state equation of the space-time thermodynamic system. The most recent development is the entropy interpretation of gravity mentioned by the subject, which was proposed by E. Verlinde in early 2010. At that time, it attracted considerable attention. is a macroscopic force that describes the system's response to changes in entropy. A typical example is the elasticity of rubber bands. The entropy of Verlinde can be roughly explained as: there is a (hypothetical) holographic surface between two objects. When the distance between the two objects changes, the entropy on this holographic surface will also change, resulting in a change in system energy. The system always tends to increase in entropy, so gravity is reacted in the response to this change. In this explanation, the holographic principle is the basic principle, while the general theory of relativity is presented layer by layer. Entropy belongs to the so-called emergent phenomena in condensed matter physics, that is, a phenomenon that only appears on a certain level.

Using Kiefer Density Matrix for Time Flow Analysis and How This Links to a Proof of Production of Planck Mass BHs during Inflation and Their Resulting Breakup, Leading to a DE Candidate

We are using the book “Towards Quantum Gravity” with an article by Claus Kiefer as to a quantum gravity interpretation of the density matrix in the early universe. The density matrix we are using is a one loop approximation, with inflaton value and potential terms, like V (phi) using the Padmanabhan values one can expect if the scale factor is a ~a (Initial) times t ^ gamma. In doing so, we identify two time steps and presume a very small initial time step candidates initial time values which are from a polynomial for time values. A gravity wave analysis concludes our article with inflaton decay, which is finally linked to BHs. And then finally we show using work done by Hawking, et al. how this may give us Planck Sized Black Holes, in the onset of Inflation, with resulting consequences so outlined. A vastly simplified proof of BH masses of Planck mass is presented which ties in directly with issues of the mass of the inflaton initially generated by the 2nd derivative of the effective potential V (phi) at a time t ~4 times Planck time. And we include at the close questions as to DE, and data sets which may give credence to speculation as to different time flow rates at the start and then the conclusion later on, of expansion of our universe. The DE would be created by the breakup of the black holes due to a mechanism brought up by Dr. Freeze in 2012, and we also are using the future works section 8 to define the contours of our DE model which builds upon quite directly the sequence of material from pages 1 to 9 which are cited as to making connection between early universe conditions and the ideas of primordial DE models.

Gravitational Analysis in Regional Science and Spatial Economics: A Vector Gradient Approach to Trade

For decades, gravitational analysis has been a key instrument in analyzing spatial flows. Time and again, it has prompted new and challenging research questions. This paper provides a concise overview of the foundation, the conceptualization and empirical relevance of gravitational principles in regional science and spatial economics. Attention is also given to general “social physics” interpretations of gravity in spatial interaction models and to the impact of intangible distance frictions. The main emphasis in the study is placed on the significance of spatial impedance functions and gravity potential analysis. In particular, the paper focuses on cross-border trade and has three main goals: (i) to address the robustness of distance friction parameters related to trade borders, employing, inter alia, quantitative results from meta-analyses on trade models in spatial economics; (ii) to present a promising methodology based on gravity potential and the related gravitational gradient models that include directional intensities of flows; (iii) to test the validity of the latter approach on the basis of a vector gradient analysis of export patterns of the Netherlands. The paper argues that—despite the space-reducing impact of the modern digital technologies—gravitational principles still have an uncontested relevance in an analysis of spatial flows in regional science.

Lithospheric model along transect HT-1 across Western Carpathians and Pannonian Basin based on 2D integrated modelling

2D integrated modelling approach was applied to determine the lithospheric structure along transect HT-1 located in the Carpathian-Pannonian Basin–European platform region. Our approach combines simultaneous interpretation of surface heat flow, topography, gravity and geoid data. All available geophysical and geological data were used to create an initial model that has been afterwards modified by trial and error method until reasonable fit was obtained between input data and model predictions. The main focus of our study was the position and shape of the lithosphere-asthenosphere boundary (LAB). In the Pannonian Basin the modelled LAB is at depths of about 80–90 km and rapidly dips towards the Western Carpathians where its depth reaches values 145 to 150 km. Beneath the European platform the LAB depth is about 135–140 km. We can observe a slight lithospheric root under the Western Carpathians. This lithospheric thickening is interpreted as a small remnant of a subducted slab. This result is in a good agreement with the previous lithospheric models in the Carpathian-Pannonian Basin.

Implications of new phase transitions approach onto specific black holes

Among many open questions in theoretical physics, consistent quantum gravity theory is still a major issue to be solved. Recent major works in phase transitions of black holes (BH) can be helpful for quantum interpretation of classical gravity. We study the new effective method to discuss the thermodynamic phase transitions onto well renowned regular BHs. Ordinary approaches of phase transitions depend upon equation of state and it is impossible to obtain all critical points with ordinary approaches. This study is derived from the slope of temperature versus entropy and it provides the possibility of finding all the critical points analytically. This technique provides pressure, which is different from standard relation of pressure and independent of other thermodynamical relations. We discuss some issues in ordinary methods and provide an easy approach to investigate the critical behavior of thermodynamical quantities. We find out the phase transitions points and horizon radii of non-physical range for BHs. We also use the new thermodynamical relations to briefly study well-known Joule–Thomson (JT) effect on regular BH.

Crustal structure beneath the volcanic field in the Tihamat Plains, Saudi Arabia: An integrated model constrained by gravity modelling and receiver function results

• Structure of rift-related volcanic rocks in Tihamat Plains is constrained by gravity and receiver function results. • Two-layered-crustal-structure is envisaged in the Tihamat Plains, Saudi Arabia. • Moho uplift and magma underplating in the lower crust are visualized. The Tertiary Tihamat-Asir-Volcanic-Zone (TAVZ) in the Tihamat Plains (TP) at the Arabian Shield margin north of the southern Red Sea is largely obscured by Quaternary alluvium and salt deposits, but partly exposed. We integrate available gravity data in the TP which is represented by three semi-circular Bouguer Anomaly (B.A.) highs with peak values of 30 mgal, situated at distances of ~ 50 km. This feature suggests prevailing anomalous crustal masses under the TP and were investigated using: (i) Digital Elevation Model (DEM); (ii) radially averaged spectral estimates on the causative source body depths within the crust; (iii) tilt-angle derivatives with horizontal derivatives of the tilt-angle values; and (iv) a theta map to define the edge of the continental crust in offshore Jizan. 2D gravity models for two traverses, the Mansiyah-Baysh Traverse (MBT) and Suq-Al-Ahad Traverse (SAAT), were constructed across the TAVZ, constrained by Receiver Function (REF) results from ten broadband seismic stations. Additional constraints for gravity interpretation come from the physical properties derived from REF results for the upper and lower crust. Our integrated crustal model infers a zone of Moho uplift approximately ~ 40 km wide, with vertical relief of 10–12 km at depths of ~ 37–45 km, where the average density of the crust is appreciably higher. Gravity models indicate a large volcanic field beneath the TP extending along the coast of the Red Sea. We find that crustal modification is an outcome of crust–mantle interaction owing to an elevated thermal regime under the TP.

Subsurface basement, structure, stratigraphy, and timing of regional tectonic events affecting the Guajira margin of northern Colombia

We have combined previous data from Mesozoic-Cenozoic outcrops in the Guajira Peninsula of northern Colombia with regional gravity, bathymetric, and seismic interpretations to demonstrate the existence of a 280 km long western extension of the Great Arc of the Caribbean (GAC) along the continental margin of Colombia. Seismic data reveal an 80–100 km wide domal-shaped basement high that exhibits internal chaotic seismic facies. This elongate and domal-shaped structure extends 1800 km from the Aves Ridge in the Caribbean Sea to the study area in offshore Colombia. The western extension of the GAC in Colombia and western Venezuela is buried by 700–3000 m of continental margin sedimentary rocks as a result of the GAC colliding earlier with the Colombian margin (Cretaceous-early Paleogene collision) than its subaerially exposed eastern extension along the Leeward Antilles ridge (late Paleogene-Neogene). Our compilation of geologic information from the entire GAC reveals that GAC magmatism occurred from 128 to 74 Ma with magmatism ages progressively younger toward the east. Six upper Eocene to recent marine seismic sequences overlying the domal basement high of the GAC have been mapped by our analysis of 2400 km of seismic lines and 12 well logs. Based on subsurface mapping correlated with well-log information and onland geology in the Guajira Peninsula, these six sequences record four major deformational events: (1) late Eocene rifting in an east–west direction produced half-grabens in the northern part of the area, (2) Oligocene transtension in the southern part of the area expressed by right-lateral Oligocene strike-slip faulting and extensional basin formation, (3) early-middle Miocene transtension, and (4) late Miocene-early Pliocene Andean uplift accompanied by rapid erosion and clastic infilling of offshore basins by the Magdalena delta and deep-sea fan. The significance of this basin framework is discussed for known and inferred hydrocarbon systems.

Integrated interpretation of gravity, magnetic, seismic, and well data to image volcanic units for oil-gas exploration in the eastern Junggar Basin, northwest China

We carried out a multigeophysical data joint interpretation to image volcanic units in an area where seismic imaging is difficult due to complicated and variable volcanic lithology. The gravity and magnetic methods can be effective in imaging the volcanic units because volcanic rocks are often strongly magnetic and have large density contrasts. Gravity and magnetic data have good lateral resolution, but they are faced with challenges in defining the depth extent. Although seismic data make for poor imaging in volcanic rocks, they can provide a reliable stratigraphic structure above volcanic rocks to improve the vertical resolution of the gravity and magnetic method. We have developed an integrated interpretation method that combines the advantages of seismic, gravity, magnetic, and well data to generate a 3D quasigeology model to image volcanic units. We first use seismic data to obtain the stratigraphic boundaries, and then we apply an anomaly stripping method based on a seismic-derived structure to extract residual gravity and magnetic anomaly produced by volcanic rocks. We further perform the 3D gravity and magnetic amplitude inversion to recover the distribution of the density and effective susceptibility. We perform geology differentiation using the inverted density and effective magnetic susceptibility to identify the spatial distribution of four groups of volcanic units. The results show that the integrated interpretation of multigeophysical data can significantly decrease the uncertainty associated with any single data set and yield more reliable imaging of lateral and vertical distribution of volcanic rocks.

Integrating multigeophysical data to improve structural imaging in the Dayangshu Basin

We have used the integrated interpretation of gravity, magnetotelluric (MT) data, and seismic data to improve the structural imaging of the Dayangshu Basin. The Dayangshu Basin is mainly composed of clastic and volcanic rocks. The logging data in the basin show different degrees of direct hydrocarbon indication, suggesting that the Dayangshu Basin has good potential for exploration. However, the widely distributed volcanic rocks attenuate seismic waves and lead to poor seismic imaging. Thus, the seismic signal is weak in the Ganhe Formation (K1g) and reliable seismic images cannot be obtained below that formation. MT data can accurately obtain images of deep structures because the resistivity of volcanic rocks is significantly higher than that of sedimentary rocks. Therefore, to obtain a more reliable geologic model, we combine the traditional 3D MT inversion result with logging and seismic data to establish an initial model. The 3D MT fuzzy constrained inversion (FCI) produces a more reliable geophysical model and geologically meaningful results. The resistivity model inverted from FCI shows that volcanic rocks are widely distributed in the Ganhe Formation, and the resistivity value of the lower section of the Longjiang Formation is greater than that of the upper section of the Longjiang Formation. Finally, the 3D gravity inversion with structural constraints from 3D MT FCI method was performed to improve the model resolution in depth and to highlight the density variations within the Jiufengshan Formation, which can further optimize the geologic model. We have determined how the effective integration of gravity, MT, and seismic data can improve the structural imaging of the Dayangshu Basin.

Integrating time-lapse gravity, production, and geologic structure data in a gas reservoir study

Time-lapse gravity is most commonly used to monitor fluid movement and is especially useful when monitoring water encroachment in a gas reservoir. Although time-lapse gravity data are directly sensitive to density changes in reservoirs, it is still necessary to integrate multiple types of data with complementary information to enhance the time-lapse gravity interpretation. When monitoring water influx in a reservoir, the changes in water yield in production wells may directly indicate saturation changes with time and provide such complementary information about the areas of fluid movement. We have developed a workflow to invert a time-lapse gravity data set and production data to help monitor the edge-water encroachment through a case study at the Sebei gas field in western China. Three time-lapse gravity surveys were acquired between 2011 and 2013, resulting in three sets of time-lapse gravity difference data. Production data were also collected from 286 wells during the same period of time. We integrate the two data sets and the structural information in the reservoir through a framework of constrained time-lapse gravity inversion. In this workflow, we incorporate information from the production data into the inversion by converting the gas and water yield into a reference model. We also incorporate geologic structural information through spatially varying bound constraints. Through this approach, we construct a set of time-lapse density contrast models that are consistent with the time-lapse gravity data, production data, and structural information. The resultant density contrast models better delineate the regions of reservoir with increased water influx and also enable improved porosity estimation in the reservoir.

New constraints on the tectonosedimentary evolution of the offshore San Pedro Basin (southeastern Dominican Republic): implications for its hydrocarbon potential

Abstract The San Pedro Basin (SPB) is located at the southeastern margin of Hispaniola Island (Dominican Republic and Haiti). It is the largest offshore basin of the Dominican Republic with an extension of 6000 km 2 . The basin has a maximum water depth of 1600 m and is positioned to the rear of the Muertos Thrust Belt (MTB). The SPB is bounded to the west by the Azua Basin which has a proven petroleum system and small oil production has been recovered from the Maleno and Higuerito fields. While in the scientific literature the SPB and the Azua basins have been considered as disconnected sedimentary systems, our current study suggests both that shared a common tectonic evolution and therefore the presence of an untested petroleum system in the SPB can be expected. We have carried out a detailed review and synthesis of the onshore systematic geological mapping (the SYSMIN I and II programmes) together with the integration of a large volume of subsurface geophysical data. This includes analysis of 60 exploration wells provided by Banco Nacional de Datos de Hidrocarburos (BNDH) of the Dominican Republic, processing of new 2D multi-channel seismic data from the Spanish Research Project NORCARIBE, reprocessing of legacy seismic profiles, and interpretation of gravity and magnetic data. Our results have led us to propose a new evolution model for the SPB. The basement of both basins consists of Cretaceous sedimentary and volcanic rocks of intra- and back-arc settings. A change in the stress regime in the Campanian led to partial inversion of the basement units favouring the deposition of two main sequences of Campanian–Maastrichtian and Paleocene?–Eocene age in a submarine foreland setting. Due to collision between the Carbonate Bahamas Province and Hispaniola in the middle Eocene, compressional stresses were transferred to the south where Cretaceous and Paleogene sediments were deformed, forming the current configuration of the MTB and generating a new accommodation space where the SPB has developed since upper Eocene–Oligocene until Present. While the Azua Basin was finally exhumed after the Miocene–Pliocene, most of the SPB continued as an actively subsiding basin. This new model has allowed identification of the main elements of the petroleum system in the SPB: a mature Upper Cretaceous source rock; and Oligocene–Miocene carbonate and clastic reservoirs interbedded with sealing shales and marls. Main traps (structural and stratigraphic) are of Oligocene–Miocene age and their formation seems to be synchronous to oil generation. While the main elements of the petroleum system seem to be present in the basin, timing is a key issue that must be addressed and assessed in any future exploration in the basin.

Interpretation of gravity and magnetic data on the hot dry rocks (HDR) delineation for the enhanced geothermal system (EGS) in Gonghe town, China

As a new kind of renewable and environmental-friendly energy to generate electricity, hot dry rocks (HDR) geothermal reservoirs have been studied, along with the enhanced geothermal system (EGS). Geophysical methods have been used for the geological characterisation in different scales. The small-scale geophysical data are required for the local geological analysis so as to provide prior information for HDR modelling. Gonghe basin is in the northeast margin of the Qinghai–Tibet Plateau. Several drilling records indicate that this basin is a potential HDR prospecting area with high geothermal gradient, high heat flow and widespread igneous rock distribution, especially the Gonghe town (Qiabuqia) along with its neighbouring area. Gravity and magnetic surveys were carried out here. To better understand the areal and vertical distribution of the HDR, the gravity and magnetic data were inverted using 2D manual inversion and 3D cross-gradient joint inversion based on the smooth $${l}^{0}$$ norm constraint of minimum support functional stabiliser. The 2D model showed the sedimentary cap with a thickness of around 1000–1500 m. Granites of different periods and intrusion process were widely distributed and underlined the sediments accompanied by some deep faults. As for the HDR delineation, 3D models showed a potential area along Gonghe town and Dongba. The density and susceptibility were estimated at over 2.6 g/cm3 and 4 × 10–3 SI separately, when referred with exiting HDR distribution along the geological profile of DR4–QR1–DR3–DR2 wells. The upper boundary of HDR was outlined at the depth of around 2000 m, and the volume of HDR was then estimated around 6100 km3 above 3500 m depth. The appearance of the density and susceptibility models was affected by the lithology, stress and hydrothermal alteration. More precise geophysical methods including the microgravity, seismic and MT (magnetotelluric) surveys would be more applicable at the HDR exploitation stage.

Quantum chaos, thermodynamics and black hole microstates in the mass deformed SYK model

We study various aspects of the mass deformation of the SYK model which makes the black hole microstates escapable. SYK boundary states are given by a simple local boundary condition on the Majorana fermions and then evolved in Euclidean time in the SYK Hamiltonian. We study the ground state of this mass deformed SYK model in detail. We also use SYK boundary states as a variational approximation to the ground state of the mass deformed SYK model. We compare variational approximation with the exact ground state results and they showed a good agreement. We also study the time evolution of the mass deformed ground state under the SYK Hamiltonian. We give a gravity interpretation of the mass deformed ground state and its time evolutions. In gravity side, mass deformation gives a way to prepare black hole microstates that are similar to pure boundary state black holes. Escaping protocol on these ground states simply gives a global AdS2 with an IR end of the world brane. We also study the thermodynamics and quantum chaotic properties of this mass deformed SYK model. Interestingly, we do not observe the Hawking Page like phase transition in this model in spite of similarity of the Hamiltonian with eternal traversable wormhole model where we have the phase transition.

Geophysical investigation for sustainable development at Alamein Area, Northwestern Coast, Egypt

Alamein City is one of the recently established cities along the Mediterranean coast in Egypt. Nineteen vertical electrical soundings (VES's) were measured in the study area with maximum current electrode separation of 600 m to examine the depth to water bearing layer, subsurface succession and structures controlling the distribution of the groundwater aquifer. The interpretation results of the VES data revealed that the subsurface section in the area is subdivided into three geoelectrical layers. The uppermost layer covers the ground surface and consists of alluvial deposits with moderately high electrical resistivity values (10.5–291 Ω.m.), with thicknesses ranging from 0.8 to 12.2 m. The second layer consists of Limestone (L. St.) intercalated with clay (water bearing layer) with low electrical resistivity values (0.2–10 Ω.m); with thicknesses ranging from 1.4 to 34 m. The third layer consists of saturated oolitic limestone with moderate electrical resistivity values (5.5–120 Ω.m). Gravity data were retrieved, corrected and analyzed. Gravity interpretation reveals that the depth of the basement rocks varies from 3600 to 6400 m with basement faults extending mainly in NW-SE direction, which is corresponding to the major trend in the Northern Western Desert.

Subsalt imaging in northern Germany using multiphysics (magnetotellurics, gravity, and seismic)

Imaging subsalt is still a challenging task in oil and gas exploration. We have used magnetotellurics (MT) to improve the integration of seismic and gravity data to image the Wedehof salt dome, located in the Northern German Basin. High-density natural field source broadband MT data were acquired and enhanced the definition of the top and overhanging salt structures in addition to imaging the salt dome root. Salt boundaries show strong resistivity contrasts with the surrounding sediments and thus represent a good target for electromagnetic measurements, especially for top salt and salt flanks imaging. With integrated 3D gravity modeling focusing on the salt dome’s flanks at intermediate depths, an improved model was achieved. The new model provided sound input to a follow-up seismic depth migration that led to an improved imaging of the subsalt target proven by subsequent exploration drilling. The integrated interpretation of MT, gravity, and seismic combines the strengths of the different physics, thus increasing imaging reliability and reducing exploration drilling risks. Using a conservative workflow that included a feasibility study with field noise evaluation and careful acquisition parameter testing prior to survey start, a broadband array data acquisition, and advanced processing, the survey area's severe cultural noise issues could be overcome.