A framework for 3-D joint inversion of MT, gravity and seismic refraction data

Moorkamp, Max; Heincke, Björn; Jegen, Marion; Roberts, A. W.; Hobbs, R. W.

doi:10.1111/j.1365-246x.2010.04856.x

Cited by 252 publications

(171 citation statements)

References 54 publications

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“…Further improvements in models of mineral deposits can be obtained by including resistivity borehole logs as local prior information (e.g., Yan et al 2017a), by transferring structural boundaries observed in reflection seismic images or seismic velocity models to 2D or 3D inversion models of MT data (e.g., Le et al 2016b;Yan et al 2017b;Moorkamp 2017) or by performing joint inversions of MT, seismic and potential field data using petrophysical or structural coupling (e.g., Moorkamp et al 2011;Gallardo and Meju 2011;Haber and Gazit 2013;Takam Takougang et al 2015;Moorkamp 2017). Strictly speaking, well logs only represent the resistivity structure up to a few metres off the borehole and may be affected by borehole fluids and the invaded zone around the borehole.…”

Section: Resultsmentioning

confidence: 99%

Two-Dimensional Magnetotelluric Modelling of Ore Deposits: Improvements in Model Constraints by Inclusion of Borehole Measurements

Kalscheuer

Juhojuntti

Vaittinen³

2017

Surv Geophys

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A combination of magnetotelluric (MT) measurements on the surface and in boreholes (without metal casing) can be expected to enhance resolution and reduce the ambiguity in models of electrical resistivity derived from MT surface measurements alone. In order to quantify potential improvement in inversion models and to aid design of electromagnetic (EM) borehole sensors, we considered two synthetic 2D models containing ore bodies down to 3000 m depth (the first with two dipping conductors in resistive crystalline host rock and the second with three mineralisation zones in a sedimentary succession exhibiting only moderate resistivity contrasts). We computed 2D inversion models from the forward responses based on combinations of surface impedance measurements and borehole measurements such as (1) skin-effect transfer functions relating horizontal magnetic fields at depth to those on the surface, (2) vertical magnetic transfer functions relating vertical magnetic fields at depth to horizontal magnetic fields on the surface and (3) vertical electric transfer functions relating vertical electric fields at depth to horizontal magnetic fields on the surface. Whereas skin-effect transfer functions are sensitive to the resistivity of the background medium and 2D anomalies, the vertical magnetic and electric field transfer functions have the disadvantage that they are comparatively insensitive to the resistivity of the layered background medium. This insensitivity introduces convergence problems in the inversion of data from structures with strong 2D resistivity contrasts. Hence, we adjusted the inversion approach to a three-step procedure, where (1) (2) this inversion model from surface impedances is used as the initial model for a joint inversion of surface impedances and skin-effect transfer functions and (3) the joint inversion model derived from the surface impedances and skin-effect transfer functions is used as the initial model for the inversion of the surface impedances, skin-effect transfer functions and vertical magnetic and electric transfer functions. For both synthetic examples, the inversion models resulting from surface and borehole measurements have higher similarity to the true models than models computed exclusively from surface measurements. However, the most prominent improvements were obtained for the first example, in which a deep small-sized ore body is more easily distinguished from a shallow main ore body penetrated by a borehole and the extent of the shadow zone (a conductive artefact) underneath the main conductor is strongly reduced. Formal model error and resolution analysis demonstrated that predominantly the skin-effect transfer functions improve model resolution at depth below the sensors and at distance of $ 300-1000 m laterally off a borehole, whereas the vertical electric and magnetic transfer functions improve resolution along the borehole and in its immediate vicinity. Furthermore, we studied the signal levels at depth and provided specifications of borehole magnetic and elect...

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Section: Resultsmentioning

confidence: 99%

Two-Dimensional Magnetotelluric Modelling of Ore Deposits: Improvements in Model Constraints by Inclusion of Borehole Measurements

Kalscheuer

Juhojuntti

Vaittinen³

2017

Surv Geophys

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“…As is noted in Roberts et al (2012), the simulators, particularly the seismic simulator (Heincke et al, 2006), are more sophisticated than required for the problem at hand; however, to facilitate future development and allow integration and direct comparison with other work (Heincke et al, 2006;Moorkamp et al, 2011Moorkamp et al, , 2013, we use these simulators.…”

Section: Methods and Model Spacementioning

confidence: 99%

“…Similarly, there are also conceptual intricacies associated with properly and quantitatively including most kinds of uncertainty associated with the problem, for example, uncertainty in the data measurements and model discrepancy (due to the fact that a model is not a complete representation of nature). Recently however, a few authors such as Roy et al (2005), Heincke et al (2006), and Moorkamp et al (2011Moorkamp et al ( , 2013) make considerable progress in developing structural coupling-based joint inversion methodologies through crossgradient and other coupling schemes. Bodin et al (2012) also develop hierarchical Bayes approaches for joint inversion.…”

Section: Joint Inversionmentioning

confidence: 99%

“…This may be with a view to, for example, determining where appropriate drilling locations might lie to maximize the possibility of hydrocarbon extraction. There are many approaches used to constrain the proxy models, ranging from deterministic inverse approaches to Markov chain Monte Carlo (MCMC) search schemes (Press, 1970;Sambridge and Mosegaard, 2002;Shapiro and Ritzwoller, 2002;Hobro et al, 2003;Gallardo and Meju, 2004;Roy et al, 2005;Heincke et al, 2006;Meier et al, 2007;Moorkamp et al, 2011). Deterministic inverse schemes are optimal when the uncertainties in the data and physical system are small, and the aim is to find the optimum model as fast as possible.…”

Section: Introductionmentioning

confidence: 99%

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Joint stochastic constraint of a large data set from a salt dome

et al. 2016

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'Joint stochastic constraint of a large data set from a salt dome.', Geophysics., 81 (2). ID1-ID24.Further information on publisher's website:http://dx.doi.org/10.1190/geo2015-0127.1Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTUnderstanding the uncertainty associated with large joint geophysical surveys, such as 3D seismic, gravity, and magnetotelluric (MT) studies, is a challenge, conceptually and practically. By demonstrating the use of emulators, we have adopted a Monte Carlo forward screening scheme to globally test a prior model space for plausibility. This methodology means that the incorporation of all types of uncertainty is made conceptually straightforward, by designing an appropriate prior model space, upon which the results are dependent, from which to draw candidate models. We have tested the approach on a salt dome target, over which three data sets had been obtained; wide-angle seismic refraction, MT and gravity data. We have considered the data sets together using an empirically measured uncertain physical relationship connecting the three different model parameters: seismic velocity, density, and resistivity, and we have indicated the value of a joint approach, rather than considering individual parameter models. The results were probability density functions over the model parameters, together with a halite probability map. The emulators give a considerable speed advantage over running the full simulator codes, and we consider their use to have great potential in the development of geophysical statistical constraint methods.

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“…1, and enhance formation-fluid tracking (Rector III 1995;Hoversten et al 2003;MacGregor et al 2007;Chen et al 2007;Hu et al 2009;Newman et al 2010;Moorkamp et al 2011;Abubakar et al 2012;Gao et al 2012;Lien 2013).…”

Section: Introductionunclassified

Synergizing Crosswell Seismic and Electromagnetic Techniques for Enhancing Reservoir Characterization

2016

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SummaryIncreasing complexity of hydrocarbon projects and the request for higher recovery rates have driven the oil-and-gas industry to look for a more-detailed understanding of the subsurface formation to optimize recovery of oil and profitability. Despite the significant successes of geophysical techniques in determining changes within the reservoir, the benefits from individually mapping the information are limited. Although seismic techniques have been the main approach for imaging the subsurface, the weak density contrast between water and oil has made electromagnetic (EM) technology an attractive complement to improve fluid distinction, especially for high-saline water. This crosswell technology assumes greater importance for obtaining higher-resolution images of the interwell regions to more accurately characterize the reservoir and track fluid-front developments. In this study, an ensemble-Kalman-based history-matching framework is proposed for directly incorporating crosswell time-lapse seismic and EM data into the history-matching process. The direct incorporation of the time-lapse seismic and EM data into the history-matching process exploits the complementarity of these data to enhance subsurface characterization, to incorporate interwell information, and to avoid biases that may be incurred from separate inversions of the geophysical data for attributes. An extensive analysis with 2D and realistic 3D reservoirs illustrates the robustness and enhanced forecastability of critical reservoir variables. The 2D reservoir provides a better understanding of the connection between fluid discrimination and enhanced history matches, and the 3D reservoir demonstrates its applicability to a realistic reservoir. Historymatching enhancements (in terms of reduction in the historymatching error) when incorporating both seismic and EM data averaged approximately 50% for the 2D case, and approximately 30% for the 3D case, and permeability estimates were approximately 25% better compared with a standard history matching with only production data.

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A framework for 3-D joint inversion of MT, gravity and seismic refraction data

Cited by 252 publications

References 54 publications

Two-Dimensional Magnetotelluric Modelling of Ore Deposits: Improvements in Model Constraints by Inclusion of Borehole Measurements

Two-Dimensional Magnetotelluric Modelling of Ore Deposits: Improvements in Model Constraints by Inclusion of Borehole Measurements

Joint stochastic constraint of a large data set from a salt dome

Synergizing Crosswell Seismic and Electromagnetic Techniques for Enhancing Reservoir Characterization

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