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Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2012-ITN | Award Amount: 4.18M | Year: 2012

This training network focuses on the development of modern quantum sensors based on precision measurements of inertial forces, electro-magnetic fields, and time. Important ideas and major contributions to current research in this field have originated from atomic physics and quantum optics. The topics covered are gravitational probing, rotational sensing, field probes, and atomic clocks, with potential future applications ranging from fundamental science to geological exploration, navigation and medical diagnostics. The consortium will train a cohort of young researchers on the physics of atomic clocks and interferometers, which form the basis of quantum sensors, and several techniques to realise technologically relevant devices. The envisioned designs incorporate micro-structured components for trapping and guiding of atoms and photons. With this approach we aim for a high level of integration and advantageous parameter regimes, which will widen the range of possible applications by addressing aspects of sensitivity and bandwidth of measurements, alleviating access restrictions to points of interest, and improving mobility for field applications. We complement the range of topics by including surface probes, field sensitive microscopes, and molecular spectroscopy, deepening the connections to other scientific disciplines. The partner consortium is an exceptional combination of industrial and academic stakeholders, ranging from technology suppliers to users, supported by, e.g., the European Patent Office and the Research Policy Institute to assist the innovation process. The research training covers physical principles and technological aspects from development to implementation, with input from industrial partners on truly relevant needs. It is complemented by training on societal aspects, intellectual property rights, and transferable skills training, thus addressing a wide skill set that unites technical expertise with an innovative mindset.

When anomalous gravity gradient signals provide a large signal-to-noise ratio, airborne and marine surveys can be considered with wide line spacing. In these cases, spatial resolution and sampling requirements become the limiting factors for specifying the line spacing, rather than anomaly detectability. This situation is analysed by generating known signals from a geological model and then sub-sampling them using a simulated airborne gravity gradient survey with a line spacing much wider than the characteristic anomaly size. The data are processed using an equivalent source inversion, which is used subsequently to predict and grid the field in-between the survey lines by means of forward calculations. Spatial and spectral error analysis is used to quantify the accuracy and resolution of the processed data and the advantages of acquiring multiple gravity gradient components are demonstrated. With measurements of the full tensor along survey lines spaced at 4 × 4 km, it is shown that the vertical gravity gradient can be reconstructed accurately over a bandwidth of 2 km with spatial root-mean square errors less than 30%. A real airborne full-tensor gravity gradient survey is presented to confirm the synthetic analysis in a practical situation. © 2014 European Association of Geoscientists & Engineers.

Mazur S.,GETECH | Mazur S.,ARKeX Ltd. | Green C.,GETECH | Green C.,University of Leeds | And 6 more authors.
Tectonics | Year: 2012

Significant E-W extension and/or compression must have been generated by displacements along the Red River Fault (RRF) since its curvature does not match a small circle centered at the Euler pole for the Indochina-south China plate pair. The amount of extension perpendicular to the RRF offshore Vietnam depends on the magnitude of left-lateral displacement along the RRF. In general, the larger the left-lateral displacement along the fault, the smaller the amount of E-W extension. All purely strike-slip models of the opening of the South China Sea that assume large displacements (>250km) along the RRF encounter major problems because they imply little extension, or even considerable shortening, offshore east Vietnam. This is inconsistent with the presence of large elongated basins offshore Vietnam. Using a plate tectonic model, we compare continental extension values implied by different magnitudes of displacement along the RRF with crustal stretching estimates derived from 2-D profiles modeled from gravity data. We utilize 2-D gravity forward models to restore the extended continental margin crust to its original position prior to extension. We find that substantial amounts of extension for offshore Vietnam can only be modeled assuming moderate displacements along the RRF compatible with the presence of a southward subducting proto-South China Sea. The total amount of ENE-WSW extension offshore northern Vietnam constrained by our 2-D gravity profiles and gravity inversion increases southward from 36 to 89km along the Yinggehai Basin. These values of ENE-WSW extension are consistent with 250km of left-lateral displacement along the RRF. © 2012. American Geophysical Union. All Rights Reserved.

Barnes G.,ARKeX Ltd. | Barraud J.,ARKeX Ltd.
Geophysics | Year: 2012

The nonuniqueness problem that occurs when inverting potential field data is well known. It can, however, be surmounted by jointly inverting these data with independent data sets, incorporating depth information and regularizing the solution. The goal is to produce a geologic model that is compatible with all measured quantities, does not exceed any prescribed limits, and is geologically plausible. To achieve this, we have developed a spatially based surface inversion algorithm that solves for the geometric interface between geologic bodies. The bodies are constructed from grids of rectangular prisms that have their bottom depths adjusted by the algorithm to form the inverted surface. To solve large-scale inversions, approximations are used in the potential field calculations that allow internal matrices to be stored in sparse format with minimal loss of accuracy. The impetus for the work came from the need to combine airborne gravity gradient data with depth horizons estimated from interpreted 2D seismic profiles to form a high-resolution 3D inversion for imaging salt bodies. By treating the depth information as measurements rather than constraints, we accommodate uncertainties in these estimates. Total variation regularization is incorporated to support the sharp edges of the salt structures and to stabilize the solution. Inversions for near-surface structures also incorporate a high-pass filter to suppress the interference in the gravity gradient signal from deeper geology. The resulting optimization finds a surface that fits (in a least-squares sense) the depth information and the high-frequency content of the gravity gradient data. © 2012 Society of Exploration Geophysicists.

Barnes G.,ARKeX Ltd. | Lumley J.,ARKeX Ltd.
Geophysics | Year: 2011

As the demand for high-resolution gravity gradient data increases and surveys are undertaken over larger areas, new challenges for data processing have emerged. In the case of full-tensor gradiometry, the processor is faced with multiple derivative measurements of the gravity field with useful signal content down to a few hundred meters' wavelength. Ideally, all measurement data should be processed together in a joint scheme to exploit the fact that all components derive from a common source. We have investigated two methods used in commercial practice to process airborne full-tensor gravity gradient data; the methods result in enhanced, noise-reduced estimates of the tensor. The first is based around Fourier operators that perform integration and differentiation in the spatial frequency domain. By transforming the tensor measurements to a common component, the data can be combined in a way that reduces noise. The second method is based on the equivalent-source technique, where all measurements are inverted into a single density distribution. This technique incorporates a model that accommodates low-order drift in the measurements, thereby making the inversion less susceptible to correlated time-domain noise. A leveling stage is therefore not required in processing. In our work, using data generated from a geologic model along with noise and survey patterns taken from a real survey, we have analyzed the difference between the processed data and the known signal to show that, when considering the Gzz component, the modified equivalent-source processing method can reduce the noise level by a factor of 2.4. The technique has proven useful for processing data from airborne gradiometer surveys over mountainous terrain where the flight lines tend to be flown at vastly differing heights. © 2011 Society of Exploration Geophysicists.

Barnes G.J.,ARKeX Ltd | Lumley J.M.,ARKeX Ltd | Houghton P.I.,ARKeX Ltd | Gleave R.J.,ARKeX Ltd
Geophysical Prospecting | Year: 2011

Noise levels in marine and airborne full tensor gravity gradiometer surveys together with conventional land, marine and airborne gravity surveys are estimated and analysed in gridded form, resulting in relations that detail how these different survey systems can be compared analytically. After defining survey parameters including line spacing, speed and instrument bandwidth, the relations estimate the noise levels that result on either grids of gravity (gz) or gravity gradient (Gzz) as a function of the spatial filtering often applied during geological interpretation. Such comparisons are believed to be a useful preliminary guide for survey selection and planning. © 2010 European Association of Geoscientists & Engineers.

Barraud J.,ARKeX Ltd
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

The depth of isolated gravity and magnetic sources can be calculated with the curvature of special functions applied to the gravity or magnetic anomalies. This "curvature method" has been published by several authors and this paper investigates two ways to improve the validity of the results. The first way is to assess the local 2D conditions by evaluating the local shape of the special function. The proposed Shape Angle is calculated with the curvatures of the special function in two orthogonal directions. It is well suited to infer the quality of depth estimates because non-ideal sources will distort the ideal cylindrical shape of the special function. The second approach to discriminate between reliable depth estimates and spurious ones is to calculate source parameters associated with the estimate. Since the result is attached to a specific type of source, the application of the curvature method to the wrong type returns abnormal values of these parameters that can be easily discarded when compared with expected values. These discrimination techniques are tested on synthetic models and to gravity gradiometry data acquired in Pennsylvania, USA. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.

Davies M.A.,ARKeX Ltd | Martin J.,CGG Veritas
KazGeo 2010 - 1st International Geosciences Conference for Kazakhstan: Where Geoscience Meets the Silk Road | Year: 2010

This paper demonstrates the use of Full Tensor Gravity Gradient Imaging (GGI) as an exploration tool within a salt basin province. In May 2010 Gravity Gradient data was acquired over 9000 km2 of the Gabon Atlantic Margin to; (1) compare and contrast GGI with 'conventional' gravity observations, (2) better image carbonate / salt structures, (3) demonstrate the ability of GGI to image structures in ultra deepwater and (4), demonstrate the shelf life of a GGI dataset by incorporating the data into a joint Seismic Velocity Modelling workflow, thus providing a better image of the subsalt structure. This paper will report on the outcome of the study and draw parallels between the Gabon dataset and areas in Kazakhstan where GGI would aid salt basin modelling. This will be done using a GGI feasibility study approach, where the 3D input model is based on seismic data acquired by CGGV over the Northern Caspian area.

ARKeX Ltd | Date: 2011-07-20

A method of processing geophysical data from a survey of a surveyed region of the earth to provide a representation of the underlying geology of said surveyed region, the method comprising inputting 2-D seismic data for said surveyed region, generating a first representation depicting a plurality of reflection interfaces of said underlying geology of said surveyed region using said input seismic data, inputting potential field data for said surveyed region, generating a second representation depicting a plurality of density interfaces of said underlying geology of said surveyed region using said input potential field data; combining said representation of said plurality of density interfaces with said representation of said plurality of reflection interfaces to reposition at least one of said plurality of reflection interfaces and generating a final representation depicting said underlying geology of said surveyed region using said combined first and second representations.

ARKeX Ltd | Date: 2012-03-12

We describe improved techniques for airborne gravity gradiometer surveys. In particular we describe a method and system for performing a gravity gradiometer survey of a surveyed region of terrain, the method comprising: providing an aircraft with a gravity gradiometer; flying said aircraft over said terrain at a speed of at least 100 m/s and at an average height above said terrain of above said terrain of at least 300 m; and collecting gravity gradient data for said surveyed region of terrain from said gravity gradiometer, said gravity gradient data comprising data for at least one component of the gravity gradient tensor.

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