Brad Artman

Stanford University | SU · Department of Geophysics

Most papers the readers find in this special section were presented at the First International Workshop on Microseismic Technology held in Asheville, North Carolina, USA, on 17–22 August 2014. The workshop’s organizing and technical program committee consisted of Werner Heigl (Apache Corporation), Vladimir Grechka (Marathon Oil), Leo Eisner (IRSM A...

We present location results for a group of similar to 200 microearthquakes that occurred in 2012 in a region of Oklahoma hosting ongoing exploration activities. Using a local passive surface seismic monitoring network of 15 broadband stations, we applied two modern location techniques that use fundamentally different approaches. The first is a pick...

It is commonly assumed that minimizing noise recorded in microseismic records leads to better data quality, which will then allow fewer station installations. The most obvious way to reduce noise levels on a record is by burying stations to capitalize on the exponential decay of surface wave amplitudes as a function of depth. Therefore, the logic g...

We applied seismic interferometry to data from an ocean-bottom survey offshore Norway and found that ambient seismic noise can be used to constrain subsurface attenuation on a reservoir scale. By crosscorrelating only a few days of recordings by broadband ocean bottom seismometers, we were able to retrieve empirical Green's functions associated wit...

Monitoring hydraulic fracture stimulations from the surface is a technique that, in the past, met with mixed success. One reason for this experience is that the measurement has often been treated as if it were only a minor variant of the reflection surveys our industry is most familiar with. While reflection seismic sources are designed to generate...

There is a common misconception in microseismic monitoring that shear arrivals are more difficult to detect at the surface than compressional arrivals. This is despite the fact that, for common fracture types, the energy released in the form of shear waves is greater than compressional energy. To reconcile such claims, it has been assumed that the...

A better approach to delivering more reliable information for optimizing production is full elastic wave-equation imaging of microseisimic data. This approach has the potential to help in performing accurate stimulated reservoir volume (SRV) calculations in shale plays. SRV is a key factor in resource plays and is used by engineers to assess the ef...

2D crooked-line profiles from the 2007 Flin Flon seismic survey are migrated into 3D volumes. The 3D migrated data allow confirmation of the earlier structural interpretations since comparison of the true subsurface location of the contacts in the deviated drillholes correspond with the 3D seismic reflection surface. 3D migration has proven effecti...

The study of wave attenuation in partially saturated porous rocks over a broad frequency range provides valuable information about the fluid system of reservoirs, which are inherently multiple phase fluid systems. Until now, not much laboratory data have been collected in the seismically relevant low frequency range and existing literature data on...

Imaging source locations is difficult when there are no evident arrivals and/or the signal-to-noise ratio is low. With minimal data filtering, time-reverse methods can locate these sources. Results, however, are greatly affected by noise in the data, incomplete sampling of the wave field, and the velocity model. To mitigate these effects, the data...

Locating subsurface sources from passive seismic recordings is difficult when attempted with data that have no observable arrivals and/or a low signal-to-noise ratio (S/N). Energy can be focused at its source using time-reversal techniques. However, when a focus cannot be matched to a particular event, it can be difficult to distinguish true focusi...

We have designed and set up a pressure vessel for 250 mm long and 76 mm in diameter cylindrical samples to measure seismic wave attenuation in rocks at frequencies between 0.01 and 100 Hz and to verify the occurrence of fluid-flow induced by stress field changes. A dynamic stress is applied at the top of the rock cylinder by a piezoelectric motor g...

Common techniques for locating fracture events, from large earthquakes to small fractures, are often hampered by the need to pick arrivals in the data domain, which can be onerous or impossible with low signal-to-noise data. Many methods require a significant amount of preprocessing and rigid assumptions about the source location and type. We use t...

Surface waves extracted from the ambient seismic wavefield via interferometry can be used for velocity inversion. In order to invert shear wave velocities at the reservoir scale, Bussat & Kugler (2009) adapted this approach to Scholte waves at frequencies up to 1 Hz. These waves were extracted from comparatively short OBS recordings, ranging from s...

ABSTRACT We present the chain of time-reverse modeling, image space wavefield decomposition and several imaging conditions as a migration-like algorithm called time-reverse imaging. The algorithm locates subsurface sources in passive seismic data and diffractors in active data. We use elastic propagators to capitalize on the full waveforms availabl...

Geologic interpretation is best realized by joint interpretation of multiple geophysical techniques. After recording a 25 station. 7.5km linear passive array for over 48h. we divide the data into four time subsets characterized by total energy content. We investigate the 4 volumes with methods where the subsets satisfy the assumptions underlying th...

Locating subsurface sources from passive seismic recordings is difficult when attempted with data that has no observable arrivals or a low signal‐to‐noise ratio. Using time‐reversal techniques recorded energy can be focused at its source depth. However, when a focus cannot be matched to a particular event, it can be difficult to distinguish true fo...

Since the Earth is elastic, it is worth the computational burden to process multicomponent data for elastic phenomena with fully coupled time-domain wave-equation propagators. At every time sample in the back-propagated model domain, the complete wave field is decomposed exactly into compressional and shear wave components by simple spatial derivat...

Active seismic processing is concerned with two-way travel times, down and up, through the subsurface. In contrast, passive seismic methods are predicated on 3+ travel paths in the case of interferometry, and one-way travel path wave fields in the case of source location. Secondary sources and diffractions maintain the same kinematics as primary so...

Anthropogenic noise effects have always been a great concern for passive seismic because they are usually strong and difficult to remove. The problem is addressed by analysis of 2D (time-space) attribute sections derived from the recorded data. On the att

Since the Earth is elastic, it is worth the computational burden to process multicomponent data for elastic phenomena with fully coupled time-domain wave-equation propagators. At every time sample in the back-propagated model domain, the complete wave fie

Low frequency (~1-6Hz) microtremor signals have been measured at the surface in many locations around the world over hydrocarbon reservoirs (multiphase fluid systems in porous media). These low frequency microtremors are observable as modifications of the frequency domain character of passive seismic records. The anomalies in the data spectra posse...

In this paper, we predict microseismicity for a series of simple rectangular reservoir geometries using results from coupled fluid-flow and geomechanical simulation. The results are analysed in terms of their spatial and temporal variations in distribution. We also evaluate the associated failure mechanisms to characterise the type of brittle failu...

Since the Earth is elastic, it is worth the computational burden to process multicomponent data for elastic phenomena with fully coupled time-domain wave-equation propagators. At every time sample in the back-propagated model domain, the complete wave field is decomposed exactly into compressional and shear wave components by simple spatial derivat...

Since the Earth is elastic, it is worth the computational burden to process multicomponent data for elastic phenomena with fully coupled time-domain wave-equation propagators. At every time sample in the back-propagated model domain, the complete wave field is decomposed exactly into compressional and shear wave components by simple spatial derivat...

We present results from a passive seismic survey carried out with broadband seismometers over an oil field in southern Germany. The aim was to analyze the ambient seismic noise spectrum in order to test for spectral signatures that may be indicative of variations in the subsurface. Variations in the naturally occurring background noise level happen...

We analyse the effects of an earthquake on the spectra of ground motion signals measured above and nearby a known oil and gas reservoir in the vicinity of Voitsdorf, Austria. The comparison of spectra of passive seismic data recorded before, during and after the earthquake indicates that a hydrocarbon reservoir can be stimulated by an earthquake. T...

Introduction One of the most significant pioneering directions of work that inspired researchers in what was to become the field of seismic interferometry was experimental work in the mid- to late 1990s by Mathias Fink and coworkers on time-reversed acoustics. In particular, the group conducted experiments with piezoelectric transducers surrounding...

A very important aspect of removing multiples from seismic data is accurate prediction of their kinematics. We cast the multiple prediction problem as an operation in the image space parallel to the conventional surface-related multiple-prediction methodology. Though developed in the image domain, the technique shares the data-driven strengths of d...

Passive seismic imaging is the process of synthesizing the wealth of subsurface informa-tion available from reflection seismic experiments by recording ambient sound with an array of geophones distributed at the surface. Cross-correlating the traces of such a pas-sive experiment can synthesize data that is immediately useful for analysis by the var...

The shot-profile migration approach of wave-equation migration generates subsurface images using the interferometric principle of crosscorrelating two passive wavefields. These wavefields are typically a source wavefield containing energy from an excited source and a receiver wavefield comprised of scattered-source wavefield energy by the discontin...

The Center for Subsurface Sensing & Imaging Systems (CenSSIS, www.censsis.neu.edu) has been advancing the concept of ‘‘Diverse Problems‐Similar Solutions,’’ whereby imaging, inversion, and tomography (IIT) algorithms developed for one field or physical regime are applied to another. Following this philosophy, algorithms developed for geophysical im...

Cross-correlating up-coming and down-going wavefields inh erently applies a spatial mul- tiplication. This multiplication could be performed in the wave-number domain as a con- volution. However, the full imaging condition, including subsurface offset, transforms to a Fourier domain equivalent that is also a lagged multiplication. This fact allows...

Correlating transmission wavefields to produce reflection w avefields contains in its rigor- ous definition the mandate of processing data due to only a sin gle source. If more than one source is contained in the wavefield, crosstalk between t he sources will produce a data volume that is not the same as shot gathers with impulsive sources at each...

Images of the lithosphere from three-component seismic arrays recording wavefields gen-erated by teleseismic earthquakes (30 • -90 • epicentral distance) reveal important aspects of lithospheric structure. Unfortunately, interpretation of these images remains ambigu-ous due to improper reflector mapping and amplitude restoration. We introduce the s...

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Passive seismic imaging is based on the fact that by cross-correlating the transmission responses of a medium, one can reconstruct its reflection response. Here, we show a method to directly migrate the transmission responses measured at the surface, based on the shot-profile migration. We also show that the results from direct migration of passive...

Historically, characterization of the lithosphere with information in teleseismic body-wave coda has been realized with collections of 1-D receiver functions. However, the promise of larger, fully 3-D teleseismic data sets with finer spatial sampling (e.g. the US-ARRAY project) motivates the investigation of industry-oriented imaging algorithms in...

Traditionally, passive seismology connotes the use of earthquake signals from continuously recording receivers. Small time windows around the arrivals of earthquakes are then analyzed in myriad fashion. I will distinguish from this body of work, the notion of passive seismic imaging, which requires no knowledge of the time or characteristics of a s...

Rekindling the passive seismic imaging effort at Stanford, I have acquired grants with Simon Klemperer of the Stanford Crustal Research Group from both the Petroleum Re- search Fund and the National Science Foundation to pursue two- and three-dimensional imaging efforts of the subsurface in a passive listening methodology. Utilizing the out- standi...

With the widespread adoption of wavefield continuation methods for prestack migration, the concept of operator aliasing warrants revisiting. While zero-offset migration is unaffected , prestack migrations reintroduce the issue of operator aliasing. Some situations where this problem arises include subsampling the shot-axes to save shot-profile migr...

Because the shot-profile migration algorithm largely mimic s the data acquisition process, simple thought experiments may extend its utility to image the subsurface with less con- ventional geometries and/or sources. Imaging with the forward- and backward-scattered wavefields in an elastically modeled earth from buried sourc es is easily implemente...

We explore the classic signal and noise separation problem of removing linear events from shot-gathers through several inversion schemes using a combined modeling operator composed of both hyperbolic and linear radon transforms. Data are inverted simultane- ously for both linear and hyperbolic moveout which provides two model-space outputs. These a...

We extend the 2-D theory of angle-domain common-image gathers (ADCIGs) to forward- scattered wavefields, and present a method for extracting re flectivity as a function of either the reflected or converted-wave receiver-side scattering a ngle. We use the shot-profile con- figuration of wave-equation migration along with planar sou rce and receiver...

Accepting an inversion principle, it is possible to design an algorithm to meet any re-quirements or constraints. Given the context of representing a signal with an arbitrary overcomplete dictionary of waveforms within the signal, one can design an inversion al-gorithm that will focus energy into a small number of model space coefficients. With thi...

With the widespread adoption of wavefield continuation methods for prestack migration, the concept of operator aliasing warrants revisiting. While zero-offset migration is unaf-fected by spatial aliasing due to the migration operator, this is not the case for prestack migration. This problem arises in any situation where sources and receivers are n...

Passive recordings from an array of 2500 four component receiver stations at the Val-hall reservoir in the Norwegian North Sea were made available from February 2004 and January 2005 by BP. Analysis of some of the raw hydrophone records shows that the bulk of the records do not yield obvious, crisp events. Some noise trains that look like approxima...

One of the major concerns in the passive seismic imaging experiment as outlined in by Claerbout et al. (1988) is touched on by the title: Why a big 2D array to record micro-seisms? My question is: Will a linear array produce sufficient results? I answer this question in the affirmative with anecdotal and modeling evidence as well as note a recent s...