Martin Landrø

Norwegian University of Science and Technology

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Lasse Amundsen

Equinor (United Kingdom)

Alexey Stovas

Norwegian University of Science and Technology

Kenneth Duffaut

Equinor (Norway)

Daniel Wehner

GEOMAR Helmholtz Centre for Ocean Research Kiel

Rune Mittet

Physical Sciences (United States)

Kittinat Taweesintananon

Norwegian University of Science and Technology

Ståle Emil Johansen

Norwegian University of Science and Technology

Jan Kristoffer Brenne

Norwegian University of Science and Technology

Robin André Rørstadbotnen

Norwegian University of Science and Technology

Kjetil E. Haavik

Equinor (Norway)

Cooperative Institutions

Norwegian University of Science and Technology

107

Equinor (Norway)

Equinor (United Kingdom)

Centre National de la Recherche Scientifique

NTNU Samfunnsforskning

SINTEF

Applied Petroleum Technology (Norway)

Acoustics (Norway)

Stanford University

Aker BP (Norway)

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4D gravity response of compacting reservoirs: Analytical approach

Geophysics (2012)

Pamela Tempone Martin Landrø Erling Fjær

Time-lapse gravity is a technique sensitive to subsurface change in mass and in mass distribution. We attempted to devise a method to predict gravity effects caused by redistribution of subsurface mass induced by reservoir compaction. First, displacements and strains due to compaction were modeled using a geomechanical model. Then, 4D gravity effects were derived from the displacements and the volumetric strains computed in and around the reservoir. A sensitivity study was carried out for geomechanical parameters, such as Poisson’s ratio, as well as for geometrical parameters, such as reservoir radius and depth. Finally, changes in gravity due to compaction were compared to changes induced by reservoir fluid substitution. Given a rigid basement close below a strongly compacting reservoir, our modeling case showed that the deformation itself could give gravity changes comparable to changes caused by reservoir fluid density changes, which are the changes traditionally targeted by gravity monitoring. For a homogeneous subsurface, the compaction gave negligible gravity changes for our modeling case.

Density contrast

10.1190/geo2010-0361.1

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Citations (7)

Pressure effects caused by CO2 injection in the Tubåen Fm., the Snøhvit field

International journal of greenhouse gas control (2014)

S. Grude Martin Landrø Jack Dvorkin

10.1016/j.ijggc.2014.05.013

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Citations (98)

Estimating source signatures from source-over-spread marine seismic data

Geophysics (2018)

K.S. Helgebostad Martin Landrø Vetle Vinje Carl-Inge Nilsen

Recent developments in marine seismic acquisition include deploying a source vessel above a towed-streamer spread. We have developed an inversion algorithm to estimate source signatures for such acquisition configurations, by minimizing the difference between the recorded and a modeled direct wave. The forward modeling is based upon a physical modeling of the air bubble created by each air gun in the source array, and a damped Gauss-Newton approach is used for the optimization. Typical inversion parameters are empirical damping factors for the bubble oscillations and firing time delays for each air gun. Variations in streamer depth are taken into account, and a constant sea-surface reflection coefficient is also estimated as a by-product of the inversion. For data acquired in shallow waters, we have developed an extension of the forward modeling to include reflections from the water bottom to stabilize the inversion. The algorithm is tested on synthetic- and field-data examples, and the estimated source signature for the field-data example is used in a designature processing flow.

Source field

10.1190/geo2017-0789.1

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Citations (1)

Attenuation of Long Offset Ground Roll Noise by Source Beam-Steering

75th EAGE Conference and Exhibition incorporating SPE EUROPEC 2013 (2006)

H. Mehdizadeh Martin Landrø

This paper demonstrates the use of plane-wave annihilator (PWA) filters, a powerful tool for estimating dips in seismic data. Compared to conventional dip scanning methods, the PWA technique provides a more accurate and robust dip field estimate without any dip limitation. It also provides a coherency measure, useful for QC, at each analyzed point. We compare the accuracy and efficiency of two PWA dip estimation algorithms with a conventional dip scanning method on the BP EAGE 2004 velocity benchmark dataset. The estimated dip fields produced with PWA filters are very high resolution and correlate well with the seismic data.

Benchmark (surveying)

10.3997/2214-4609.201402379

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Determining the dilation factor in 4D monitoring of compacting reservoirs by rock‐physics models

Geophysical Prospecting (2007)

José M. Carcione Martin Landrø Anthony F. Gangi F. Cavallini

ABSTRACT Hydrocarbon depletion and fluid injection cause compaction and stretching of the reservoir and overburden layers. 4D prestack seismic data can be used to detect these changes because compaction/stretching causes changes in traveltimes and seismic velocities. We show that, by using two different petro‐elastic models at varying effective pressures, a good approximation is to assume that the fractional changes in layer thickness, Δ L / L , and seismic velocity, Δ v / v , are related by a linear function of Δ L / L . The slope of this function (the dilation factor, α= (Δ v / v )/(Δ L / L ) ) is negative and its absolute value generally decreases (shale, low porosity) or increases (sandstone, high porosity) with increasing layer thickness and decreasing effective pressure. The analysis is mainly performed for isotropic deformations. The dilation factor for uniaxial deformations is smaller in absolute value. The dilation factor, which can be calculated from time‐lapse data, can be used to predict reservoir compaction/stretching as a function of depth and surface subsidence.

Overburden

Groundwater-related subsidence

Dilation (metric space)

Anelastic attenuation factor

Transverse isotropy

10.1111/j.1365-2478.2007.00633.x

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Citations (14)

An Experimental Comparison of Three Direct Methods of Marine Source Signature Estimation

Proceedings (1995)

Robert Laws Martin Landrø Lasse Amundsen

Three, published methods for estimating the source signature of a marine seismic array are compared experimentally. The methods each use measurements of the pressure-field near to the array to predict the pressure-field at arbitrary positions further from the array. All three methods offer the possibility of computing the far-field signature, in absolute amplitude, as a function of radiation angle on a shot by shot basis during the acquisition. Such an estimate is of great value in acquisition quality-control and in data-processing.

Signature (topology)

Basis (linear algebra)

10.3997/2214-4609.201409276

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Citations (1)

Implementing measured source signatures in a coarse‐grid, finite‐difference modeling scheme

Geophysics (1993)

Martin Landrø Rune Mittet R. Sollie

In a marine seismic air‐gun array, each gun location does not necessarily coincide with a node in a finite‐difference grid. Especially for coarse‐grid, finite‐difference modeling, this problem must be handled with care since there might be up to three or four air guns between adjacent grid points. The real sources are represented by fictitious monopole‐ and dipole source functions located at grid nodes. The effective sources are estimated from the extrapolated pressure field at a horizontal surface located below the sources. We find that an array consisting of eight guns separated by a distance of 3 m and located at 7.5 m depth can be approximated by six monopole‐ and dipole source functions distributed on a finite‐difference grid with 10 m spatial sampling. The residual error energy norm between the actual wavefield and the corresponding finite‐difference wavefield observed on a fictitious streamer placed at 95 m depth is less than 0.5 percent.

Finite difference

Regular grid

10.1190/1.1443400

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Citations (12)

Improved Low Frequency Output from Seismic Air Guns by Firing at Shallow Depths?

Martin Landrø L. Amundsen

Summary Based on a field test in the Trondheimsfjord performed some years ago, we study the effect of changing the source depth on the low frequency content in the source spectrum. We find that extremely shallow source depths will increase the low frequency signal generated by air guns. Further, we conclude that there is a qualitative difference between enhancing the low frequency content by repeated bubble oscillations and by creating a broadband single peak signal. A single peak gives a relatively flat spectrum also for low frequencies, while a bubble tuned signature will cause notches and higher amplitudes for some frequencies. For processing and analysis purposes it is better to use a single peak compared to repeated bubbles that are hard to fully exploit at the processing step. A short source signal is preferred prior to a long bubbly source signal for several causes: non-repeatable effects for the bubble oscillations, need to estimate a relatively precise source signature for designature purposes. It our view a cheap and efficient way to avoid bubbles and increase both high and low frequencies from single air guns is to fire the air gun close to the surface, which is of interest for high-resolution and ultra-high resolution surveys for wind farm projects, marine mineral exploration and CO2 monitoring.

SIGNAL (programming language)

Signature (topology)

10.3997/2214-4609.202242001

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Citations (0)

Frequency Effects at Pre-, Near- and Post-critical Offsets Observed on Water-plexiglas Interface

Proceedings (2011)

Л. В. Скопинцева Tariq Alkhalifah Martin Landrø

In time-lapse seismic surveys, changes in the medium properties are anticipated only in specific locations of the subsurface. These locations are usually limited to reservoir layers where fluid substitution occurs. Elsewhere, the seismic response is expected to remain the same over time. We introduce an impedance anamorphosis to correct for unlikely seismic impedance changes that may appear in 4D seismic inversion as a result of the "zero-mean" property of the reconstructed model. Results obtained with a simple synthetic example and with real seismic data acquired over the Sleipner CO2 storage demonstrate the effectiveness of the method.

Acoustic impedance

10.3997/2214-4609.20149617

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Citations (0)

Source signature determination by inversion

Geophysics (1992)

Martin Landrø R. Sollie

A new method for estimating the pressure wavefield generated by a marine air‐gun array is presented. It is assumed that data is acquired at a ministreamer located below the source array. Effective source signatures for each air gun are estimated by an inversion algorithm. The forward modeling scheme used in the inversion algorithm is based upon a physical modeling of the air bubble generated by each air gun. This means that typical inversion parameters are: gun depths, empirical damping coefficients, and reflection coefficient of the sea surface. Variations in streamer depth are also taken into account by the inversion scheme. The algorithm has been successfully tested on examples with unknown streamer positions, gun parameters, reflection coefficient of sea surface, and ministreamer data contaminated with white noise.

Reflection coefficient

10.1190/1.1443230

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Citations (52)