Abstract Although drilling has slowed substantially from its peak in 2010, steadily improving natural gas prices coupled with the promise of demand from liquefied natural gas and gas to liquids facilities have renewed interest in the prolific Haynesville shale gas play in NW Louisiana. A consensus of opinion among operators in the field will agree that only a fraction of the Haynesville potential has been developed to date. As is the case in most shale plays, production from wells has been highly variable, leading to the use of 3D seismic reservoir characterization studies for the determination of sweet spots, well placement and completion strategies where seismic anisotropy has been proven to be an important factor in understanding the shale plays. This paper illustrates a workflow (Figure 1) integrating reservoir and geomechanical properties obtained from pre-stack seismic inversion and incorporating stress and fracture information extracted from azimuthal analysis of the seismic data. Eight wells in the area targeting the Haynesville and mid-Bossier reservoirs were used for calibration of surface seismic measurements of reservoir and geomechanical properties. A variety of seismically derived attributes are used to estimate production potential in the field. This paper shows the application of global azimuthal inversion, a technology for extracting the azimuthal anisotropy. Above all, the workflow makes quantitative use of microseismic and SEM (Scanning Electron Microscope) derived mineralogy data to validate the seismic-derived attributes. Figure 1 Integrated geoscience workflow for a shale play, incorporating numerous discipline to high-grade the survey area to identify ‘sweet spots’ and optimize drilling locations and completions.

Abstract CGG recently acquired the Tabasco multi-client, high-resolution 3D seismic survey on the North Slope of Alaska. It covers 133 sq. mi (Figure 1) and was designed for optimum imaging of the faulting and onlaps in the Cretaceous and Jurassic hydrocarbon-bearing sequences. The survey was the first multi-client survey performed in the area in over a decade. It was acquired in separate northern and southern parts, both of which were processed independently, and saw the first use of many high-end acquisition techniques in the region. It was the first-ever, high-productivity, extended slip-sweep vibroseis program acquired on the North Slope, breaking previously-established records and setting a new standard at 5,000 records gathered in a 24-hr period. It also introduced the proprietary EmphaSeis broadband vibroseis technique, providing a frequency range of 4-80Hz. Thus, the survey delivered a number of innovative solutions in this challenging environment.

Over the last two decades 3D reflection seismic has been applied for mine planning in South Africa. For coal exploration, the mining targets are at shallower depths of less than 400 m. The challenge set by the mining companies is to obtain high-resolution seismic data with maximum vertical resolution at this depth of investigation. The cost of geophysics must also be more attractive than that of the ‘total drilling’ alternative. Seismic source trials were therefore conducted at one mine site. The ICIS (Internal Combustion Impulse Source) has been developed by CGG to provide a solution for shallow target surveys and for in-fills where access for conventional sources is restricted. The ICIS and Mini-vibrator performance were tested in shallow coal prospects, where existing 2D data have been acquired by Nomad 65 heavy vibrator. The tests demonstrated that ICIS is well suited to image target depths less than 500 m with frequencies up to 100 Hz. The comparison with the vibroseis sources showed that ICIS I) Delivered very good near offset data (> 50 m) and for up-hole/low velocity layer survey ii) Required more shots per shot point in the medium offset range (1000 m) due to its low energy iii) Not designed for far offset data (3000 m). ICIS was found to be a viable geophysical and logistic solution for certain high-resolution mineral surveys.

PreviousNext No AccessInternational Geophysical Conference and Oil & Gas Exhibition, Istanbul, Turkey, 17-19 September 2012Imaging drilling hazards in the Forties oilfield using nodal ocean-bottom seismicAuthors: K. KosterD. MonkA. RokkanS. RonenR. BouralyE. BathellierK. Koster1 ApacheSearch for more papers by this author, D. Monk1 ApacheSearch for more papers by this author, A. Rokkan2 CGGVeritasSearch for more papers by this author, S. Ronen2 CGGVeritasSearch for more papers by this author, R. Bouraly2 CGGVeritasSearch for more papers by this author, and E. Bathellier2 CGGVeritasSearch for more papers by this authorhttps://doi.org/10.1190/IST092012-001.156 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract Reliable seismic images of gas accumulations in the shallow subsurface underneath the production platforms in the Forties oilfield are mitigating drilling risks and reducing drilling costs. Ocean Bottom Nodes were selected to record the seismic data for the ability to operate safely and efficiently in obstructed and busy oilfields. The resulting seismic images allow extra care to be taken during drilling of wells where gas is likely to be encountered. The resulting operations are therefore optimized in terms of both safety and costs. Permalink: https://doi.org/10.1190/IST092012-001.156FiguresReferencesRelatedDetailsCited ByReferences11 February 2020 International Geophysical Conference and Oil & Gas Exhibition, Istanbul, Turkey, 17-19 September 2012ISSN (online):2159-6832Copyright: 2012 Pages: publication data© 2012 Published in electronic format with permission by the Society of Exploration Geophysicists and The Chamber of Geophysical Engineers of TurkeyPublisher:Society of Exploration Geophysicists HistoryPublished: 13 Jan 2013 CITATION INFORMATION K. Koster, D. Monk, A. Rokkan, S. Ronen, R. Bouraly, and E. Bathellier, (2012), "Imaging drilling hazards in the Forties oilfield using nodal ocean-bottom seismic," SEG Global Meeting Abstracts : 1-4. https://doi.org/10.1190/IST092012-001.156 Plain-Language Summary PDF DownloadLoading ...

The objective of this study is to evaluate which production information can be deduced from a 4D seismic survey during the Steam-Assisted Gravity Drainage (SAGD) recovery process. Superimposed on reservoir heterogeneities of geological origin, many factors interact during thermal production of heavy oil and bitumen reservoirs, which complicate the interpretation of 4D seismic data: changes in oil viscosity, in fluid saturations, in pore pressure and so on. This study is based on the real Hangingstone field case of the McMurray formation in the Athabasca region (Canada). In previous works, an initial static model (geology, petroacoustic and geomechanical) has been constructed and a thermal production of heavy oil with two coupled fluid-flow and geomechanical models has been simulated. Seismic parameters (density, compression velocity and shear velocity) of the saturated rocks have then been computed from mechanical and reservoir parameters at several stages of the production. A repeated acquisition survey is modelled at different stages of SAGD production. This is performed using a 3D seismic modelling approach. To focus on the reflections generated within the reservoir zone, a target-oriented modelling is chosen. It is based on the ray+Born approach which permits to compute the P-wave elastic response by correctly handling the seismic amplitudes as a function of source-receiver offset. Real incoherent noise is added to the zero-phase synthetic data to produce a more realistic result. The noise-free and the noisy synthetic data are processed to get stacked and time migrated images. A simple processing workflow leads to image the steam chamber development, in particular its V-shape in radial section, and to observe time-lapse in the reservoir zone. An interpretation work is then carried out. Some seismic attributes like RMS values of amplitude changes between stages, energy, time differences of reservoir bottom between stages, etc. are computed from the synthetic (noise-free and noisy) seismic data. Some of these attributes prove to be robust to the noise and to show some production effect. Possible trends between these attributes and the modelled reservoir/geomechanical properties (lithofacies, pressure, temperature, steam saturation, etc.) are also evaluated. Finally, geobodies are extracted from the seismic attributes.

SummaryWith the advent of high-channel count recording systems, one of the major hurdles for increasing spatial sampling density has been overcome. We are able to deploy dense receiver geometries with small group intervals and compact arrays or even point receivers. This allows us to record unaliased signal and noise and therefore do a much better job with noise attenuation during processing. We can then reap the full benefits of long offsets and wide azimuths for processing, imaging and reservoir. There is a need to match the increase in receiver density on the source side. To accomplish this in 3D land seismic we need a significant increase in source productivity while decreasing the source array size. Such productivity improvements can be created by spending less time per source point and by utilizing alternative source methodologies such as slip-sweep and blended acquisition.The following challenge to deliver a clearer image and improved reservoir characterization is to emit and record broadband signals which offer better penetration and resolution. Our solution is to “performance-tune” the sweep to the vibrator’s mechanical and hydraulic limits. It extends bandwidth for a desired target output spectrum where low frequencies are enhanced, mid frequencies are unaffected and high frequencies retained or extended. In this presentation, we describe our successive technological leaps towards point source-point receiver seismic acquisition and illustrate it with recording and processing case studies from different regions of the world.

The objective of this study is to evaluate which production information can be deduced from a 4D seismic survey during the Steam-Assisted Gravity Drainage (SAGD) recovery process. Superimposed on reservoir heterogeneities of geological origin, many factors interact during thermal production of heavy oil and bitumen reservoirs, which complicate the interpretation of 4D seismic data: changes in oil viscosity, in fluid saturations, in pore pressure and so on. This study is based on the real Hangingstone field case of the McMurray formation in the Athabasca region (Canada). In previous works, an initial static model (geology, petroacoustic and geomechanical) has been constructed and a thermal production of heavy oil with two coupled fluid-flow and geomechanical models has been simulated. Seismic parameters (density, compression velocity and shear velocity) of the saturated rocks have then been computed from mechanical and reservoir parameters at several stages of the production. A repeated acquisition survey is modelled at different stages of SAGD production. This is performed using a 3D seismic modelling approach. To focus on the reflections generated within the reservoir zone, a target-oriented modelling is chosen. It is based on the ray+Born approach which permits to compute the P-wave elastic response by correctly handling the seismic amplitudes as a function of source-receiver offset. Real incoherent noise is added to the zero-phase synthetic data to produce a more realistic result. The noise-free and the noisy synthetic data are processed to get stacked and time migrated images. A simple processing workflow leads to image the steam chamber development, in particular its V-shape in radial section, and to observe time-lapse in the reservoir zone. An interpretation work is then carried out. Some seismic attributes like RMS values of amplitude changes between stages, energy, time differences of reservoir bottom between stages, etc. are computed from the synthetic (noise-free and noisy) seismic data. Some of these attributes prove to be robust to the noise and to show some production effect. Possible trends between these attributes and the modelled reservoir/geomechanical properties (lithofacies, pressure, temperature, steam saturation, etc.) are also evaluated. Finally, geobodies are extracted from the seismic attributes. L’objectif de cette étude est d’évaluer quelle information de production peut être déduite d’une campagne sismique 4D durant le procédé de récupération par injection de vapeur SAGD (Steam- Assisted Gravity Drainage). En plus des hétérogénéités réservoir d’origine géologique, de nombreux facteurs interagissent pendant la production thermique d’huile lourde et de bitume, ce qui complique l’interprétation des données sismiques 4D : variation de la viscosité de l’huile, des saturations en fluide, de la pression de pore, etc. Cette étude est basée sur le champ pétrolier Hangingstone de la formation McMurray en Athabasca (Canada). Dans des travaux antérieurs, un modèle statique initial (géologique, pétroacoustique et géomécanique) avait été construit. Puis la production thermique d’huile lourde avait été simulée en mettant en oeuvre le couplage d’un modèle d’écoulement de réservoir et d’un modèle géomécanique. Les paramètres sismiques des roches saturées (densité, vitesses de compression et de cisaillement) avaient alors été calculés à plusieurs étapes de la production à partir des paramètres mécaniques et de réservoir. À partir de ces résultats, une acquisition sismique est simulée à quatre états de production SAGD. Comme on s’intéresse aux réflexions sismiques en ondes de compression générées dans le réservoir, une modélisation sismique orientée cible est choisie. Cette modélisation est basée sur une approche ray+Born et permet de calculer la réponse sismique en estimant correctement les amplitudes sismiques en fonction de l’offset (distance source-récepteur). Pour obtenir des données plus réalistes, du bruit réel incohérent est ajouté aux données sismiques synthétiques. Les jeux de données synthétiques non bruitées et bruitées sont ensuite traités afin d’obtenir des images sismiques temps sommées et migrées. Une séquence simple de traitement sismique permet d’imager le développement de la chambre de vapeur, en particulier sa forme en V dans le plan perpendiculaire aux drains horizontaux, et d’observer des différences de temps de trajet dans la zone réservoir. Un travail d’interprétation est alors mené sur ces données sismiques synthétiques à différents états de production. Plusieurs attributs sismiques, comme les valeurs RMS des variations d’amplitude entre états, les variations de temps de trajet à la base du réservoir entre états, ou l’énergie des images sismiques à chaque état, sont calculés sur les données synthétiques non bruitées et bruitées. Quelques attributs sismiques apparaissent robustes au bruit et impactés par la production. Les relations entre ces attributs sismiques et les propriétés réservoir/géomécaniques (lithofaciès, pression, température, saturation en vapeur d’eau, etc.) sont aussi évaluées. Enfin, concernant l’interprétation sismique, des corps réservoir connectés (geobodies) sont extraits des attributs sismiques.

Within the past decade, new developments in seismic azimuthal anisotropy have identified a link between fracture density and orientation observed in well logs and the intensity and orientation of the actual anisotropy. Recent studies have shown a correlation between these measurements that provide quantitative estimations of fracture density from 3D wide-azimuth seismic data in tight-gas sand reservoirs. Recent research shows the significance of advanced seismic processing in the successful recovery of reliable fracture estimations, which directly correlates to borehole observations. These quantitative estimations of fracture density provide valuable insight that helps optimise drilling and completion programs, particularly in tight reservoirs. Extending this analysis to CSG reservoirs needs to consider additional reservoir quality parameters while implementing a similar quantitative approach on the interpretation of seismic data and correlation with borehole logging observations. The characterisation of CSG plays involves the understanding of the reservoir matrix properties as well as the in-situ stresses and fracturing that will determine optimal production zones. Pre-stack seismic data can assist with identifying the sweet spots—productive areas—in CSG resource plays by detailed reservoir-oriented gather conditioning followed by pre-stack seismic inversion and multi-attribute analysis. This analysis provides rock property estimations such as Poisson's ratio and Young's modulus, among others, which in turn relate to quantitative reservoir properties such as porosity and brittleness. This study shows an integrated workflow based on pre-stack azimuthal seismic data analysis and well log information to identify sweet spots, estimate geo-mechanical properties, and quantify in-situ principal stresses.

Summary This paper presents an integrated workflow for the interpretation of 4D seismic data to monitor steam chamber growth during the steam-assisted gravity drainage recovery process (SAGD). Superimposed on reservoir heterogeneities of geological origin, many factors interact during thermal production of heavy oil and bitumen reservoirs, which complicate the interpretation of 4D seismic data: changes in oil viscosity, fluid saturations, pore pressure, and so on. The workflow is based on the generation of a geological model inspired by a real field case of the McMurray formation in the Athabasca region. The approach consists of three steps: the construction of an initial static model, the simulation of thermal production of heavy oil with two coupled fluid-flow and geomechanical models and the production of synthetic seismic maps at different stages of steam injection. The distribution of geological facies is simulated on a fine grid using a geostatistical approach, which honours all available well data. The reservoir's geomechanical and elastic properties are characterized by logs and literature at an initial stage before the start of production. Production scenarios are run to obtain pore pressure, temperature, steam and oil saturations on a detailed reservoir grid around a well pair at several stages of production. Direct coupling with a geomechanical model produces volumetric strain and mean effective stress maps as additional properties. These physical parameters are used to compute new seismic velocities and density for each stage of production according to Hertz and Gassmann formulas. Reflectivity is then computed, and a new synthetic seismic image of the reservoir is generated for each stage of production. The impacts of heterogeneities, production conditions and reservoir properties are evaluated for several simulation scenarios from the beginning of steam injection to 3 years of production. Results show that short-term seismic monitoring can help in anticipating early changes in steam injection strategy. In return, long-term periods allow the behaviour of the steam chamber to be monitored laterally and in the upper part of the reservoir. This study demonstrates the added value of 4D seismic data in the context of steam-assisted heavy oil production.

The performance of heavy-oil production by Steam-Assisted Gravity Drainage (SAGD) can be affected by near-well reservoir heterogeneities. However, as many factors interact during thermal production such as changes in oil viscosity, fluid saturations, pore pressure, stresses..., the monitoring of the steam chamber growth by 4D seismic data is not direct. An integrated workflow is presented. Based on a Canadian heavy oil field, the approach consists of three steps: 1/ the construction of an initial static model, 2/ the simulation of the thermal production of heavy oil with two coupled fluid-flow and geomechanical models, 3/ the production of synthetic seismic cubes at different stages of steam injection. The impacts of heterogeneities, production conditions and reservoir properties are evaluated for several production stages. Results show that heterogeneity distribution has a strong impact on mechanical results and then on the synthetic 4D seismic data. This study also highlights the impact of the shale mechanical behaviour on the steam chamber development during thermal production. Finally, this study demonstrates the added value of 4D seismic data in the context of steam-assisted heavy oil production.

In partnership with Gaz de France (GDF) and Institut Français du Pétrole (IFP), CGGVeritasdeveloped SeisMovieTM, an extremely flexible, non-stop monitoring system based on a network ofstationary low-energy piezoelectric seismic sources and multi-component receiver arrays, eithervertical or horizontal.

The performance of heavy-oil production by Steam-Assisted Gravity Drainage process (SAGD) can beaffected by near-well reservoir heterogeneities. However, as many factors interact during thermalproduction such as changes in oil viscosity, fluid saturations, pore pressure, stresses,... the interpretation of4D seismic data in terms of steam chamber geometry is not direct nor unique.

Compressional tectonics in the Eastern Cordillera foothills are investigated using a large strain, two-dimensional finite clement method. The main purpose is to calculate the stress regimes within the Cusiana field and to compare the results with field data. In the foothills, the NW-SE tectonic push is clearly confirmed by borehole breakouts. The present-day state of stress in the Cusiana field, is investigated through a footwall-hanging wall model with a detachment/ramp thrust fault. The tectonic push was simulated by applying horizontal displacement to the vertical boundary of the model. Simulations with both elastic and elastoplastic rheologies were performed. To obtain a realistic horizontal stress gradient (in the range of 1.25 to 1.5 psi/fi) at depth, the stiffness of the hanging wall block has to be sufficiently low to accomodate the thrust geometry. With a perfectly sliding fault (zero friction), the tectonic push localizes the plastic deformation into a shear band which can be interpreted as the backthrust observed on the seismic section. Moreover, in the vicinity of the Cusiana thrust, the major principal stress rotates. This rotation is in good agreement with orientation found by core DSCA measurements. P. 41