Academic literature on the topic 'Potential-field inversion modelling'
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Journal articles on the topic "Potential-field inversion modelling"
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Cordell, Lindrith. "Terrace-function inversion for three-dimensional modelling of potential-field data." Exploration Geophysics 19, no. 1-2 (March 1988): 32–34. http://dx.doi.org/10.1071/eg988032.
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Giraud, Jérémie, Vitaliy Ogarko, Roland Martin, Mark Jessell, and Mark Lindsay. "Structural, petrophysical, and geological constraints in potential field inversion using the Tomofast-x v1.0 open-source code." Geoscientific Model Development 14, no. 11 (November 2, 2021): 6681–709. http://dx.doi.org/10.5194/gmd-14-6681-2021.
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Abstract. The quantitative integration of geophysical measurements with data and information from other disciplines is becoming increasingly important in answering the challenges of undercover imaging and of the modelling of complex areas. We propose a review of the different techniques for the utilisation of structural, petrophysical, and geological information in single physics and joint inversion as implemented in the Tomofast-x open-source inversion platform. We detail the range of constraints that can be applied to the inversion of potential field data. The inversion examples we show illustrate a selection of scenarios using a realistic synthetic data set inspired by real-world geological measurements and petrophysical data from the Hamersley region (Western Australia). Using Tomofast-x's flexibility, we investigate inversions combining the utilisation of petrophysical, structural, and/or geological constraints while illustrating the utilisation of the L-curve principle to determine regularisation weights. Our results suggest that the utilisation of geological information to derive disjoint interval bound constraints is the most effective method to recover the true model. It is followed by model smoothness and smallness conditioned by geological uncertainty and cross-gradient minimisation.
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Kumar, Shashi, Himanshu Govil, Prashant K. Srivastava, Praveen K. Thakur, and Satya P. S. Kushwaha. "Spaceborne Multifrequency PolInSAR-Based Inversion Modelling for Forest Height Retrieval." Remote Sensing 12, no. 24 (December 10, 2020): 4042. http://dx.doi.org/10.3390/rs12244042.
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Spaceborne and airborne polarimetric synthetic-aperture radar interferometry (PolInSAR) data have been extensively used for forest parameter retrieval. The PolInSAR models have proven their potential in the accurate measurement of forest vegetation height. Spaceborne monostatic multifrequency data of different SAR missions and the Global Ecosystem Dynamics Investigation (GEDI)-derived forest canopy height map were used in this study for vegetation height retrieval. This study tested the performance of PolInSAR complex coherence-based inversion models for estimating the vegetation height of the forest ranges of Doon Valley, Uttarakhand, India. The inversion-based forest height obtained from the three-stage inversion (TSI) model had higher accuracy than the coherence amplitude inversion (CAI) model-based estimates. The vegetation height values of GEDI-derived canopy height map did not show good relation with field-measured forest height values. It was found that, at several locations, GEDI-derived forest height values underestimated the vegetation height. The statistical analysis of the GEDI-derived estimates with field-measured height showed a high root mean square error (RMSE; 5.82 m) and standard error (SE; 5.33 m) with a very low coefficient of determination (R2; 0.0022). An analysis of the spaceborne-mission-based forest height values suggested that the L-band SAR has great potential in forest height retrieval. TSI-model-based forest height values showed lower p-values, which indicates the significant relation between modelled and field-measured forest height values. A comparison of the results obtained from different SAR systems is discussed, and it is observed that the L-band-based PolInSAR inversion gives the most reliable result with low RMSE (2.87 m) and relatively higher R2 (0.53) for the linear regression analysis between the modelled tree height and the field data. These results indicate that higher wavelength PolInSAR datasets are more suitable for tree canopy height estimation using the PolInSAR inversion technique.
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Madsen, Line Meldgaard, Gianluca Fiandaca, and Esben Auken. "3-D time-domain spectral inversion of resistivity and full-decay induced polarization data—full solution of Poisson's equation and modelling of the current waveform." Geophysical Journal International 223, no. 3 (September 23, 2020): 2101–16. http://dx.doi.org/10.1093/gji/ggaa443.
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SUMMARY We present a new algorithm for 3-D forward modelling and spectral inversion of resistivity and time-domain full-decay induced polarization (IP) data. To our knowledge, all algorithms available for handling 3-D spectral inversion of full-decay IP data use a time-domain approximation to Poisson's equation in the forward response. To avoid this approximation, we compute the response in the frequency domain solving the full version of Poisson's equation for a range of frequencies (10–8–104 Hz) and then transform the response into the time domain, where we account for the transmitted current waveform. Solving Poisson's equation in 3-D is computationally expensive and in order to balance accuracy, time, and memory usage we introduce the following: (1) We use two separate meshes for the forward response and the model update, respectively. The forward mesh is an unstructured tetrahedral mesh allowing for local refinements whereas the model (inversion) mesh is a node-based structured mesh, where roughness constraints are easily implemented. By decoupling the two meshes, they can be tuned for optimizing the forward accuracy and the inversion resolution, independently. (2) A singularity removal method known from resistivity modelling has been adapted to the complex IP case and is applied to minimize the numerical errors caused by the fast changing potential close to the source electrodes. The method includes splitting the potential field into a primary part (response of a homogenous background) and a secondary part (from the anomalies). Two different forward meshes are then used to compute the forward response: a dense mesh for the primary potential field (only computed once for each frequency) and a coarser mesh for the secondary potential field (computed in each iteration step of the inversion). With this method, the singularity is minimized and the memory usages is decreased significantly at the same time. (3) Finally, we are sparsing (downsampling) the Jacobian matrix based on a threshold value of the normalized sensitivity. The Jacobian computation is performed by time-transforming the frequency-domain Jacobian obtained through the adjoint method. The Jacobian downsampling is carried out before the time-transform in the frequency domain, thus avoiding the time-transformation of the Jacobian elements with negligible sensitivity. We invert resistivity data and all IP time-gates simultaneously and use the Gauss–Newton model update to minimize the L2 misfit function. We invert the resistivity data and all IP time-gates simultaneously and use the Gauss–Newton model update to minimize the L2 misfit function. We demonstrate the performance of our inversion approach with a synthetic data example with 3-D anomalies and a field example, where lithology logs verify the results. The data sets contain 1256 quadrupole measurements with 33 IP time-gates each. The inversions results show good data fits and model retrieval. The inversion takes approximately one hour per iteration using four CPUs. With this speed and accuracy, we believe this modelling and inversion approach will be a strong tool for 3-D spectral inversion of resistivity and full-decay IP field data for both surface and borehole applications.
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Corbo-Camargo, Fernando, Jorge Arzate, Emilia Fregoso, Gianluca Norini, Gerardo Carrasco-Núñez, Vsevolod Yutsis, Juan Herrera, and Javier Hernández. "Shallow structure of Los Humeros (LH) caldera and geothermal reservoir from magnetotellurics and potential field data." Geophysical Journal International 223, no. 1 (July 14, 2020): 666–75. http://dx.doi.org/10.1093/gji/ggaa338.
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SUMMARY This study focuses in the analysis of the internal structure of the upper 3 km of Los Humeros (LH) caldera and the relation of electrical and hydrothermal anomalies. For this purpose, we measured, processed and interpreted 78 broad-band magnetotelluric (MT) soundings. We performed a 3-D inversion of the data set (ModEM) using all MT soundings, although only half of the available frequencies per sounding due to limited computed power. We also carried out the 2-D inversions (NLCG) of the invariant determinant along two orthogonal profiles (EW and NS) crossing the caldera structure; their comparison yields similar resistivity and structural models results. The resistivity modelling is complemented with the results of a joint 3-D inversion of an accurate gravity database of 720 stations, and total field aeromagnetic data (SGM) from the caldera crater. The combined results provide novel details about the structure of the shallow geothermal reservoir of the resurgence caldera complex hosting the active hydrothermal system. Density and resistivity models show the existence of a composed crater basin structure separated by an EW high-density structure; the northern basin is associated to the LH crater, whereas the southern basin associates to the emergent Los Potreros (LP) caldera basin. The magnetization model indicates that there is a common source for the magnetic volcanic products observed at the caldera surface, and that the LP fault is the more magnetized fault of the geothermal system. The propylic zoning under the geothermal field, which according to the MT model results has resistivities above ∼100 Ω-m, was extrapolated using this and additional criteria to obtain the distribution of other hypothetical propylitic zones of hydrothermal potential.
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Fedi, Maurizio, and Mark Pilkington. "Understanding imaging methods for potential field data." GEOPHYSICS 77, no. 1 (January 2012): G13—G24. http://dx.doi.org/10.1190/geo2011-0078.1.
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Several noniterative, imaging methods for potential field data have been proposed that provide an estimate of the 3D magnetization/density distribution within the subsurface or that produce images of quantities related or proportional to such distributions. They have been derived in various ways, using generalized linear inversion, Wiener filtering, wavelet and depth from extreme points (DEXP) transformations, crosscorrelation, and migration. We demonstrated that the resulting images from each of these approaches are equivalent to an upward continuation of the data, weighted by a (possibly) depth-dependent function. Source distributions or related quantities imaged by all of these methods are smeared, diffuse versions of the true distributions; but owing to the stability of upward continuation, resolution may be substantially increased by coupling derivative and upward continuation operators. These imaging techniques appeared most effective in the case of isolated, compact, and depth-limited sources. Because all the approaches were noniterative, computationally fast, and in some cases, produced a fit to the data, they did provide a quick, but approximate picture of physical property distributions. We have found that inherent or explicit depth-weighting is necessary to image sources at their correct depths, and that the best scaling law or weighting function has to be physically based, for instance, using the theory of homogeneous fields. A major advantage of these techniques was their speed, efficiently providing a basis for further detailed, follow-up modelling.
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Chmiel, M., A. Mordret, P. Boué, F. Brenguier, T. Lecocq, R. Courbis, D. Hollis, X. Campman, R. Romijn, and W. Van der Veen. "Ambient noise multimode Rayleigh and Love wave tomography to determine the shear velocity structure above the Groningen gas field." Geophysical Journal International 218, no. 3 (May 24, 2019): 1781–95. http://dx.doi.org/10.1093/gji/ggz237.
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SUMMARY The Groningen gas field is one of the largest gas fields in Europe. The continuous gas extraction led to an induced seismic activity in the area. In order to monitor the seismic activity and study the gas field many permanent and temporary seismic arrays were deployed. In particular, the extraction of the shear wave velocity model is crucial in seismic hazard assessment. Local S-wave velocity-depth profiles allow us the estimation of a potential amplification due to soft sediments. Ambient seismic noise tomography is an interesting alternative to traditional methods that were used in modelling the S-wave velocity. The ambient noise field consists mostly of surface waves, which are sensitive to the Swave and if inverted, they reveal the corresponding S-wave structures. In this study, we present results of a depth inversion of surface waves obtained from the cross-correlation of 1 month of ambient noise data from four flexible networks located in the Groningen area. Each block consisted of about 400 3-C stations. We compute group velocity maps of Rayleigh and Love waves using a straight-ray surface wave tomography. We also extract clear higher modes of Love and Rayleigh waves. The S-wave velocity model is obtained with a joint inversion of Love and Rayleigh waves using the Neighbourhood Algorithm. In order to improve the depth inversion, we use the mean phase velocity curves and the higher modes of Rayleigh and Love waves. Moreover, we use the depth of the base of the North Sea formation as a hard constraint. This information provides an additional constraint for depth inversion, which reduces the S-wave velocity uncertainties. The final S-wave velocity models reflect the geological structures up to 1 km depth and in perspective can be used in seismic risk modelling.
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Lawrence, Sophie, Mark Thompson, Adrian Rankin, Joanna Alexander, Daniel Bishop, and Ben Boterhoven. "A new structural analysis of the Browse Basin, Australian North West Margin." APPEA Journal 54, no. 1 (2014): 1. http://dx.doi.org/10.1071/aj13001.
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A new structural analysis is presented for the Browse Basin of the Australian North West Margin, integrating new observations based on a regional 2D seismic data-set and potential field data. Previously published plate reconstructions and gravity inversion modelling were used to understand the mega-regional context of this interpretation and propose a new history of basin evolution. Key basin-forming northeast to southwest structural elements were developed during Carboniferous to Permian rifting, inherited fabrics from relaxed Proterozoic fold belts. Long-lived highs formed during this time delineated the structure of the basin through later Mesozoic rifting. Rifting was accommodated initially by inheritance of large basin-bounding Paleozoic listric faults and then development of new planar faults in the basin. This led to the formation of both rotated syn-rift sediment wedges and tilted fault block geometries. Structures related to several phases of inversion have been mapped, including a previously little-documented Early Cretaceous event. The influence of inherited structural trends and location of inversion structures is discussed. This work provides a new understanding of structural inheritance and rift architecture, and highlights the complexity of the inversion history of the Browse Basin. It has implications for petroleum systems development and the timing of potential hydrocarbon trap formation.
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Vu, M. T., A. Jardani, A. Revil, and M. Jessop. "Magnetometric resistivity tomography using chaos polynomial expansion." Geophysical Journal International 221, no. 3 (February 14, 2020): 1469–83. http://dx.doi.org/10.1093/gji/ggaa082.
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SUMMARY We present an inversion algorithm to reconstruct the spatial distribution of the electrical conductivity from the analysis of magnetometric resistivity (MMR) data acquired at the ground surface. We first review the theoretical background of MMR connecting the generation of a magnetic field in response to the injection of a low-frequency current source and sink in the ground given a known distribution of electrical conductivity in the subsurface of the Earth. The forward modelling is based on sequentially solving the Poisson equation for the electrical potential distribution and the magnetostatic (Biot and Savart) equation for the magnetic field. Then, we introduce a Gauss–Newton inversion algorithm in which the logarithm of the electrical conductivity field is parametrized by using the chaos polynomial expansion in order to reduce the number of model parameters. To illustrate how the method works, the algorithm is successfully applied on four synthetic models with 3-D heterogeneous distribution of the electrical conductivity. Finally, we apply our algorithm to a field case study in which seepage was known to be occurring along an embankment of a headrace channel to a power station.
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Farzamian, Mohammad, Dario Autovino, Angelo Basile, Roberto De Mascellis, Giovanna Dragonetti, Fernando Monteiro Santos, Andrew Binley, and Antonio Coppola. "Assessing the dynamics of soil salinity with time-lapse inversion of electromagnetic data guided by hydrological modelling." Hydrology and Earth System Sciences 25, no. 3 (March 26, 2021): 1509–27. http://dx.doi.org/10.5194/hess-25-1509-2021.
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Abstract. Irrigated agriculture is threatened by soil salinity in numerous arid and semi-arid areas of the world, chiefly caused by the use of highly salinity irrigation water, compounded by excessive evapotranspiration. Given this threat, efficient field assessment methods are needed to monitor the dynamics of soil salinity in salt-affected irrigated lands and evaluate the performance of management strategies. In this study, we report on the results of an irrigation experiment with the main objective of evaluating time-lapse inversion of electromagnetic induction (EMI) data and hydrological modelling in field assessment of soil salinity dynamics. Four experimental plots were established and irrigated 12 times during a 2-month period, with water at four different salinity levels (1, 4, 8 and 12 dS m−1) using a drip irrigation system. Time-lapse apparent electrical conductivity (σa) data were collected four times during the experiment period using the CMD Mini-Explorer. Prior to inversion of time-lapse σa data, a numerical experiment was performed by 2D simulations of the water and solute infiltration and redistribution process in synthetic transects, generated by using the statistical distribution of the hydraulic properties in the study area. These simulations gave known spatio-temporal distribution of water contents and solute concentrations and thus of bulk electrical conductivity (σb), which in turn were used to obtain known structures of apparent electrical conductivity, σa. These synthetic distributions were used for a preliminary understanding of how the physical context may influence the EMI-based σa readings carried out in the monitored transects as well as being used to optimize the smoothing parameter to be used in the inversion of σa readings. With this prior information at hand, we inverted the time-lapse field σa data and interpreted the results in terms of concentration distributions over time. The proposed approach, using preliminary hydrological simulations to understand the potential role of the variability of the physical system to be monitored by EMI, may actually allow for a better choice of the inversion parameters and interpretation of EMI readings, thus increasing the potentiality of using the electromagnetic induction technique for rapid and non-invasive investigation of spatio-temporal variability in soil salinity over large areas.
Dissertations / Theses on the topic "Potential-field inversion modelling"
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Sheffer, Megan Rae. "Forward modelling and inversion of streaming potential for the interpretation of hydraulic conditions from self-potential data." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/235.
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The self-potential method responds to the electrokinetic phenomenon of streaming potential and has been applied in hydrogeologic and engineering investigations to aid in the evaluation of subsurface hydraulic conditions. Of specific interest is the application of the method to embankment dam seepage monitoring and detection. This demands a quantitative
interpretation of seepage conditions from the geophysical data.
To enable the study of variably saturated flow problems of complicated geometry, a three-dimensional finite volume algorithm
is developed to evaluate the self-potential distribution resulting from subsurface fluid flow. The algorithm explicitly calculates
the distribution of streaming current sources and solves for the self-potential given a model of hydraulic head and prescribed distributions of the streaming current cross-coupling conductivity and electrical resistivity. A new laboratory apparatus is developed to measure the streaming potential coupling coefficient
and resistivity in unconsolidated soil samples. Measuring both of these parameters on the same sample under the same conditions
enables us to properly characterize the streaming current cross-coupling conductivity coefficient. I present the results of a laboratory investigation to study the influence of soil and fluid parameters on the cross-coupling coefficient, and characterize this property for representative well-graded embankment soils. The streaming potential signals associated with preferential seepage through the core of a synthetic embankment dam model are studied using the forward modelling algorithm and measured electrical properties to assess the sensitivity of the self-potential method in detecting internal erosion. Maximum self-potential anomalies are shown to be linked to large localized
hydraulic gradients that develop in response to piping, prior to any detectable increase in seepage flow through the dam. A linear
inversion algorithm is developed to evaluate the three-dimensional distribution of hydraulic head from self-potential data, given a known distribution of the cross-coupling coefficient and electrical resistivity. The inverse problem is solved by
minimizing an objective function, which consists of a data misfit that accounts for measurement error and a model objective function that incorporates a priori information. The algorithm is suitable
for saturated flow problems or where the position of the phreatic surface is known.
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Heath, Philip John. "Analysis of potential field gradient tensor data : forward modelling, inversion and near - surface exploration." 2007. http://hdl.handle.net/2440/37869.
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In this thesis the mathematics of the potential field gradient tensor is thoroughly reviewed and the inter - relationships between the various components and quantities are established. Numerical forward modelling of 3D regolith scenarios is undertaken, showing that current instrumentation for measuring magnetic gradients is useful for near - surface exploration. Gravity gradiometry is only able to detect relatively large contrasts in density, and does not offer the same small - scale resolution as magnetic gradiometry. I examine the magnetic case further by incorporating surface measurements of magnetic susceptibility. These data are highly variable, and forward modelling shows while gradiometry is useful for regolith exploration, interpretation is difficult due to the high level of geological noise. I have tested new and standard filters as tools for extracting information from gradient tensor data. This includes boundaries between geological units and possible mineralisation positions. New techniques developed involve calculating an Analytic Signal for the entire gradient tensor, and forming multiplicative combinations of the individual gradient tensor components. The determinant and inverse of the gradient tensor 3 x 3 matrix can also yield useful information pertaining to source position and geological boundaries. These are illustrated by means of synthetic data examples. Examination of inversion techniques on gradient tensor data illustrates that single component inversion is comparable in the quality of the final result to a multi - component inversion, albeit much faster. Eigenvalues and eigenvectors of the full tensor produce information about depth and direction, although interpretation must be taken with care. I have developed an inversion routine to locate magnetic dipole sources, and illustrate how it produces multiple solutions to a problem, and how it is not possible to unambiguously determine which of these is correct. A new inversion routine was therefore developed. This new hybrid global inversion routine is an automated technique to locate a generalised magnetic multipole. It can locate dipole and quadrupole ( and some octupole ) sources successfully, and be used either in real time as data is being collected, or as post - processing on an entire data set.Philip Heath
Thesis (Ph.D.)--School of Chemistry and Physics, 2007.
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Heath, Philip John. "Analysis of potential field gradient tensor data : forward modelling, inversion and near - surface exploration." Thesis, 2007. http://hdl.handle.net/2440/37869.
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In this thesis the mathematics of the potential field gradient tensor is thoroughly reviewed and
the inter - relationships between the various components and quantities are established.
Numerical forward modelling of 3D regolith scenarios is undertaken, showing that current
instrumentation for measuring magnetic gradients is useful for near - surface exploration.
Gravity gradiometry is only able to detect relatively large contrasts in density, and does not offer the same small - scale resolution as magnetic gradiometry. I examine the magnetic case
further by incorporating surface measurements of magnetic susceptibility. These data are highly variable, and forward modelling shows while gradiometry is useful for regolith exploration, interpretation is difficult due to the high level of geological noise.
I have tested new and standard filters as tools for extracting information from gradient tensor
data. This includes boundaries between geological units and possible mineralisation positions. New techniques developed involve calculating an Analytic Signal for the entire gradient tensor, and forming multiplicative combinations of the individual gradient tensor components. The determinant and inverse of the gradient tensor 3 x 3 matrix can also yield useful information pertaining to source position and geological boundaries. These are illustrated by means of synthetic data examples.
Examination of inversion techniques on gradient tensor data illustrates that single component
inversion is comparable in the quality of the final result to a multi - component inversion, albeit much faster. Eigenvalues and eigenvectors of the full tensor produce information about depth
and direction, although interpretation must be taken with care. I have developed an inversion
routine to locate magnetic dipole sources, and illustrate how it produces multiple solutions to
a problem, and how it is not possible to unambiguously determine which of these is correct.
A new inversion routine was therefore developed.
This new hybrid global inversion routine is an automated technique to locate a generalised
magnetic multipole. It can locate dipole and quadrupole ( and some octupole ) sources
successfully, and be used either in real time as data is being collected, or as post - processing on an entire data set.Philip Heath
Thesis (Ph.D.)--School of Chemistry and Physics, 2007.
Conference papers on the topic "Potential-field inversion modelling"
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Alvers, M. R., H. J. Götze, S. Schmidt, L. Barrio-Alvers, C. Plonka, C. Bodor, and B. Lahmeyer. "Practical Aspects of 3D Interactive Potential Field Modelling and Inversion." In 77th EAGE Conference and Exhibition 2015. Netherlands: EAGE Publications BV, 2015. http://dx.doi.org/10.3997/2214-4609.201412988.
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Witter, Jeffrey B. "3D GEOPHYSICAL INVERSION MODELLING OF POTENTIAL FIELD DATA APPLIED TO THE INVESTIGATION OF FOUR GEOTHERMAL RESOURCE AREAS." In 113th Annual GSA Cordilleran Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017cd-292435.
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Al-Subaihi, Meshari, Tahani Al-Rashidi, Raj Kishore Prasad, Dipankar Dutta, Atul Kshirsagar, Tushar Patil, Malvika Nagarkoti, Christopher Burns, and Colin Bertrand Cranfield. "Integrated Field Development Modelling to Improve Recovery from a Complex Fractured Carbonate Reservoir with Potential for Low Salinity Waterflooding EOR." In SPE EuropEC - Europe Energy Conference featured at the 83rd EAGE Annual Conference & Exhibition. SPE, 2022. http://dx.doi.org/10.2118/209669-ms.
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Abstract Integrated field development studies were performed to increase oil recovery from the Marrat reservoir in the Umm Gudair field, a large, low permeability, complex, naturally fractured and highly faulted carbonate reservoir. The studies involved rebuilding the static model, creating and history matching a new dynamic model and using it to examine redevelopment scenarios. These included well interventions and workovers under primary depletion, secondary waterflood and, following a screening exercise, low salinity flooding (LSF). A new structural interpretation of 3D seismic data provided a revised static geological model and yielded insight into the number, geometry and origin of the many faults intersecting the reservoir. Rock types defined from core analysis were distributed in the static geological model using trends from Bayesian lithofacies classification based on pre-stack inversion of seismic data. Porosity and permeability were modelled by rock type. Saturation-height functions for each rock type were developed from mercury injection capillary pressure (MICP) data; and the reservoir free water level was varied so that these functions honoured the log-based water saturation interpretation. The dynamic model input description was based on available and interpreted data for the assumed oil wet reservoir. The history matching was aided by sophisticated application of decline curve analysis (DCA) and used an Opportunity Index approach to optimise well placement. The history matching led to a simplified and effective solution for characterising the locally naturally fractured reservoir nature. The effect of high permeabilities associated with increased fracture density was accommodated by introducing facies-based and distance from fault-related permeability modifiers, while maintaining geological rigour. The dynamic model was used to examine a range of field redevelopment scenarios. This showed that LSF could enhance field recovery and achieve a three-fold increase in estimated ultimate recovery, in conjunction with other improved reservoir management strategies. The results provided support for specialised laboratory and dynamic modelling investigations as a precursor to LSF pilot trials. A low cost source of LSF injectant was identified which could contribute to lowering the overall carbon footprint.
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Al-Subaihi, Meshari, Tahani Al-Rashidi, Raj Kishore Prasad, Dipankar Dutta, Atul Kshirsagar, Tushar Patil, Malvika Nagarkoti, Christopher Burns, and Colin Bertrand Cranfield. "Integrated Field Development Modelling to Improve Recovery from a Complex Fractured Carbonate Reservoir with Potential for Low Salinity Waterflooding EOR." In SPE EuropEC - Europe Energy Conference featured at the 83rd EAGE Annual Conference & Exhibition. SPE, 2022. http://dx.doi.org/10.2118/209669-ms.
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Abstract Integrated field development studies were performed to increase oil recovery from the Marrat reservoir in the Umm Gudair field, a large, low permeability, complex, naturally fractured and highly faulted carbonate reservoir. The studies involved rebuilding the static model, creating and history matching a new dynamic model and using it to examine redevelopment scenarios. These included well interventions and workovers under primary depletion, secondary waterflood and, following a screening exercise, low salinity flooding (LSF). A new structural interpretation of 3D seismic data provided a revised static geological model and yielded insight into the number, geometry and origin of the many faults intersecting the reservoir. Rock types defined from core analysis were distributed in the static geological model using trends from Bayesian lithofacies classification based on pre-stack inversion of seismic data. Porosity and permeability were modelled by rock type. Saturation-height functions for each rock type were developed from mercury injection capillary pressure (MICP) data; and the reservoir free water level was varied so that these functions honoured the log-based water saturation interpretation. The dynamic model input description was based on available and interpreted data for the assumed oil wet reservoir. The history matching was aided by sophisticated application of decline curve analysis (DCA) and used an Opportunity Index approach to optimise well placement. The history matching led to a simplified and effective solution for characterising the locally naturally fractured reservoir nature. The effect of high permeabilities associated with increased fracture density was accommodated by introducing facies-based and distance from fault-related permeability modifiers, while maintaining geological rigour. The dynamic model was used to examine a range of field redevelopment scenarios. This showed that LSF could enhance field recovery and achieve a three-fold increase in estimated ultimate recovery, in conjunction with other improved reservoir management strategies. The results provided support for specialised laboratory and dynamic modelling investigations as a precursor to LSF pilot trials. A low cost source of LSF injectant was identified which could contribute to lowering the overall carbon footprint.
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Noufal, Abdelwahab, Gaisoni Nasreldin, Faisal Al-Jenaibi, Joel Wesley Martin, Julian Guerra, Hani Al Sahn, Eudes S. Muniz, Safdar Khan, and Abdulla M. Shehab. "Integrating Laboratory Testing and Numerical Modelling for a Giant Maturing Carbonate Field in UAE — II. Coupled Geomechanical Modelling of Stacked Reservoir Intervals." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207729-ms.
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Abstract A mature field located in a gently dipping structure onshore Abu Dhabi has multiple stacked oil and gas reservoirs experiencing different levels of depletion. The average reservoir pressure in some of these intervals had declined from the early production years to the present day by more than 2000 psi. Coupled geomechanical modelling is, therefore, of the greatest value to predict the stress paths in producing reservoir units, using the concept of effective stress. This paper examines the implications for long-term field management—focusing primarily on estimating the potential for reservoir compaction and predicting field subsidence. This paper takes the work reported in Noufal et al. (2020) one step further by integrating the results of a comprehensive geomechanical laboratory characterization study designed to assess the potential geomechanical changes in the stacked reservoirs from pre-production conditions to abandonment. This paper adopts a geomechanical modelling approach integrating a wide array of data—including prestack seismic inversion outputs and dynamic reservoir simulation results. This study comprised four phases. After the completion of rock mechanics testing, the first modelling phase examined geomechanics on a fine scale around individual wells. The goal of the second phase was to build 4D mechanical earth models (4D MEMs) by incorporating 14 reservoir models—resulting in one of the largest 4D MEMs ever built worldwide. The third phase involved determining the present-day stress state—matching calibrated post-production 1D MEMs and interpreted stress features. Lastly, the resulting model was used for field management and formation stimulation applications. The 4D geomechanical modelling results indicated stress changes in the order of several MPa in magnitude compared with the pre-production stress state, and some changes in stress orientations, especially in the vicinity of faults. This was validated using well images and direct stress measurements, indicating the ability of the 4D MEM to capture the changes in stress magnitudes and orientations caused by depletion. In the computed results, the 4D MEM captures the onset of pore collapse and its accelerating response as observed in the laboratory tests conducted on cores taken from different reservoir units. Pore collapse is predicted in later production years in areas with high porosity, and it is localized. The model highlights the influence of stress changes on porosity and permeability changes over time, thus providing insights into the planning of infill drilling and water injection. Qualitatively, the results provide invaluable insights into delineating potential sweet spots for stimulation by hydraulic fracturing.
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Xin, Chen, Li Jianlin, Zhao Min, Qi Qunli, Li Xiaoliang, Li Dongyang, Yu Wenwen, et al. "A New Fault Sealing Analysis Method Based on PSDM Seismic, Well Logging and Reservoir Performance and its Application in K Mature Oilfield." In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211153-ms.
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Abstract Accurate modelling of fault seal is crucial in understanding fluid flow and connectivity in mature fields. Numerous methods of modelling the sealing capacity of faults have been developed, such as lithological juxtapositions, SGR and PSSF. However, due to the uncertainty of structure, throw and lithology prediction, conventional methods are difficult to meet the needs of reservoir development. In order to improve the accuracy of fault seal analysis, a new method was proposed in this abstract. Integrated PSDM seismic data, well logging, and reservoir dynamic data, this new fault seal analysis method include 4 steps: 1) Horizons and faults update based on PSDM seismic data. In this step, more accurate structure model would be generated; 2) Integrated well logging and seismic motion inversion (SMI) for reservoir lithology modelling. In this step, the accuracy of lithology prediction results on both sides of the fault will be improved; 3) Fault seal analysis was ran efficiently in 3D geological model by lithology juxtaposition and SGR. 4) Fault seal analysis QC and optimization by using reservoir dynamic data. This method has been successfully applied to the K mature oilfield in Central Asia. The detailed faults interpretation was done based on new PSDM seismic data. The number of faults increased from 18 to 44, and the new structural model was improved obviously. The reservoir model based on the combination of well logging interpretation and seismic motion inversion (SMI) is not only consistent with drilled well, but also consistent with seismic inversion trend, which improves the accuracy of lithology prediction. Automatic fault seal analysis algorithm based on 3D geological model can efficiently generate the fault seal analysis results, and find potential areas. Fault seal analysis results can be validated and optimized by dynamic data from drilled wells. 6 potential faulted seal traps below conventional oil-water contract (OWC) were found in the slope area of oilfield. 3 wells have been drilled and confirmed 3 fault seal reservoirs with high oil production and much lower water-cut (6%) than conventional water-cut (96%) in the slope of K mature oilfield. It is proved that the method is beneficial for development in mature oil field. This new fault seal analysis method integrated the information from PSDM seismic data, well logging, and reservoir performance data to improve the accuracy of faults model and lithology model, and generated a more reasonable fault seal analysis result. This allows more confidence in estimating the sealing or leaking capacity of faults and reduces risk of re-exploration and development in mature oil field.
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Clegg, Nigel, Alban Duriez, Vladimir Kiselev, Supriya Sinha, Tim Parker, Fredrik Jakobsen, Erik Jakobsen, David Marchant, and Christoph Schwarzbach. "DETECTION OF OFFSET WELLS AHEAD OF AND AROUND AN LWD ULTRA-DEEP ELECTROMAGNETIC TOOL." In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0039.
Full textAbstract:
Mature fields contain wells drilled over decades, resulting in a complex distribution of cased hole from active producers, injectors, and abandoned wells. Continued field development requires access to bypassed pay and the drilling of new wells that must be threaded between the existing subterranean infrastructure. It is therefore important to know the position of any offset wells relative to a well being drilled so collision can be avoided. A well’s position is determined by directional survey points, for which the measurement error accumulates along the length of the well, increasing the uncertainty associated with the well position. The positional uncertainty is greater in wells drilled with older generations of surveying tools. Thus, a new well may be required to enter the ellipse of uncertainty representing the potential position of an older well, risking collision, to be able to reach desired targets in more distal parts of the reservoir. A potential solution to reduce collision risks is ultra-deep electromagnetic (EM) logging-while-drilling (LWD) tools, whose measurements are strongly influenced by proximity to metal casing and liners. This paper presents 3D inversion results of ultra-deep EM data from a development well in a mature field, which were used to identify a nearby cased well. Due to the large effect of casing on the measured EM field, it is important to validate the 3D results; this has been achieved using a synthetic modelling approach and assessment of azimuthal EM measurements. Models were created with casing positioned within resistive media with similar properties to those seen in the studied cases. Inverting these models allows testing of the inversion algorithm to show that it is providing a good representation of the cased well’s position relative to the newly drilled well. Further analysis of recorded and synthetic data showed that the raw EM field is strongly influenced as the casing is approached. The casing can be seen to clearly affect the EM field measurements when it is in the region of 10 to 15 m ahead of the EM transmitter, with the effect increasing in magnitude as this distance diminishes. Modelling shows that the EM field measurements behave in a predictable manner. As the ultra-deep EM tool approaches a cased well, it is possible to determine whether the casing is above, below, or critically, directly in line with the planned trajectory of the new well. Existing subterranean infrastructure can pose a major hazard to the drilling of new wells. Being able to identify an old well ahead of the bit using ultra-deep EM measurements would allow a new well to be steered away from the hazard or drilling stopped, preventing a collision. In addition, this may also allow the drilling of well paths that would otherwise be impossible to drill, due to the limitations imposed by positional uncertainty of the new and offset wells. This use of ultra-deep resistivity technology takes it beyond its more traditional benefits in well placement and formation evaluation, making it useful for improving well drilling safety.
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Valiakhmetov, Rustem, Andrea Murineddu, Murat Zhiyenkulov, Viktor Maliar, Viktor Bugriy, Grigori Kashuba, Valentyn Loktiev, et al. "Geophysical Aspects of Reservoir Characterization of Tight Gas Play in the Dnieper-Donets Basin." In SPE Eastern Europe Subsurface Conference. SPE, 2021. http://dx.doi.org/10.2118/208501-ms.
Full textAbstract:
Abstract The objective of this work is to describe a comprehensive approach integrating seismic data processing and sets of wireline logs for reservoir characterization of one of the tight gas plays of the Dnieper-Donets basin. This paper intends to discuss a case study from seismic data processing, integrating seismic attributes with formation properties from logs in a geocellular model for sweet spot selection and risk analysis. The workflow during the project included the following steps. Seismic data 3D processing, including 5D interpolation and PSTM migration. Interpretation of limited log data from 4 exploration and appraisal wells. Seismic interpretation and inversion. Building a static model of the field. Recommendations for drilling locations. Evaluation of the drilled well to verify input parameters of the initial model. The static model integrated all available subsurface data and used inverted seismic attributes calibrated to the available logs to constrain the property modelling. Then various deterministic and stochastic approaches were used for facies modeling and estimation of gas-in-place volume. Integrating all the available data provides insights for better understating the reservoir distribution and provided recommendations for drilling locations. Based on the combination of the geocellular model, seismic attributes and seismic inversion results, the operator drilled an exploration well. The modern set of petrophysical logs acquired in the recently drilled well enforced prior knowledge and delivered a robust picture of the tight gas reservoir. The results from the drilled well matched predicted formation properties very closely, which added confidence in the technical approach applied in this study and similar studies that followed later. It is the fork in the road moment for the Dnieper-Donetsk basin with huge tight gas potential in the region that inspires for exploration of other prospects and plays. A synergy of analytical methods with a combination of seismic processing, geomodeling, and reservoir characterization approaches allowed accurate selection of the drilling targets with minimum risk of "dry hole" that has been vindicated by successful drilling outcome in a new exploration well.