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EAGE/SEG Research Workshop on Reservoir Rocks - Understanding reservoir rock and fluid property distributions - measurement, modelling and applications
- Conference date: 30 Apr 2001 - 03 May 2001
- Location: Pau, France
- ISBN: 978-94-6282-123-1
- Published: 30 April 2001
47 results
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On the rocks - questions of scale and physical processes related to heterogeneity
By R. CalvertThis paper is a speculative treatment of widely differing dynamic phenomena which might be more influenced by property variability rather than property averages.
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Stable extraction of fundamental rock properties from seismic data
By F. D. GrayA new method for the extraction of the fundamental rock properties expressed by Lamé's parameters, Lamé's constant (λ) and shear rigidity (μ), from pre-stack seismic data is proposed. This new method should be more stable and less ambiguous than the method currently used to extract these parameters.
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The use of VSP and modelling techniques in the definition of salt structures and pre-salt lithologies - examples from the Kashagan field, North Caspian basin, Kazakhstan
Authors A. R. Verdel, C. T. A. M. Leo, K. van Ojik, W. Zempolich and T. ter BurgDrilling for sub-salt Paleozoic carbonate reservoirs in the North Caspian sea, offshore Kazakhstan, presents numerous subsurface and surface challenges. The goal of such drilling is to safely penetrate carbonate reservoirs that range in depth from 4 to 5 km, which are likely to contain over-pressured H2S-rich hydrocarbons.
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High precision fluid mapping in compacting reservoirs
By L. SonnelandThe aim of this paper is to demonstrate the successful application of the technology to increase the precision in the reservoir description, and thereby lower the risk, reduce the cost, improve production of existing fields and to better assess future hydrocarbon field developments.
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Shale compaction and geopressure - an attempt to develop a unified model
By N. C. DuttaFluid transport in sedimentary basins is a well-known phenomenon. It happens due to stresses caused by tectonic events and/or gravitational force, due to sediment loading or erosion. Typically, if the loading process is rapid, fluid expulsion through compaction can be severely `retarded', especially, in fine-grained sediments with `low' permeabiliry, such as silts or clays. This results in stress re-distribution withm the column - a greater proportion of the overlying weight of the sediments is borne by the fluids than in the case had the sediments compacted normally, causing a decrease in the stress acting on the rock framework. This phenomenon is known to occur in most sedimentary, clastics basins (geopressure).
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Lithological-petrophysical discrimination of the Baltic Cambrian siliciclastics
Authors A. Shogenova, S. Sliaupa, V. Rasteniene, A. Jöeleht, K. Kirsimäe, L. Bitjukova, L. Lashkova, A. Zabele, A. Freimanis, P. Hoth and E. HuengesDiscrimination of siliciclastic lithologies traditionally is a complex problem essentially in terms of petrophysical parameters. The absence of the unified rocks classification only adds difficulties for lithology analysis by using physical properties and logging data.
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Interpreting the dry frame pressure dependence of Lochaline sandstone
By C. MacBethUltrasonic P and S wave travel-time measurements have made on Cretaceous sandstones from the Locahaline silica mine in West Scotland whilst being subjected to increasing pressure in a Hoek cell, The resulting dryframe P and S wave vebcities for a sequence of pressure values between 0 and 70MPa are then transformed into elastic modeli using density calculated from pore volume squeeze-out on a sister sample. Both the exces normal and the tangential compliance are calculated by using differential effective medium theory to compensate for host matrix softening due to evolution of the equant porosity.
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Attenuation in Carnarvon Basin sandstones subjected to varying confining and pore pressures
Authors A. F. Siggins, D. N. Dewhurst and P. R. TingateSandstone samples from the Carnarvon Basin in the Australian North West Shelf have been tested under triaxial loading conditions with independent control of pore pressure. Ultrasonic waveforms were recorded during these tests.
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Velocity and attenuation measurements during 2 phase core flooding
Authors C. Jones, J. M. Somerville and S. HamiltonReservoir saturation changes can be detected by repeat 3-D seismic surveys. These rely on some seismic attribute such as travel time, amplitude or velocity changing with saturation, either gas, oil or water. Rock physics measurements show that rocks with a high compliance or low stiffness have the greatest sensitivity of Vp to saturation changes. Stiff rocks may only exhibit small changes in Vp with saturation, which may be undetectable on repeat surveys. However other seismic attributes, such as signal amplitude may show large variations.
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How to determine when seismic monitoring in a HP HT context is worthwile
Authors S. Vernassa, Y. Painchaud, L. Pauget, S. Marec and J. MarrauldThe appraisal process entailed in determining whether or not seismic monitoring was worthwhile in the special context of an HP HT field involved working with different kinds of data from different sources and at different scales.
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Elastic attribute analysis using rock physics and seismic modelling in gas storage monitoring
More LessSeismic measurements acquired at different stages in the life of a reservoir are a key in reducing operating colts and maximizing recovery. Changes in saturation, pore pressure and stresses, induced by reservoir production may influence the process of wave propagation in rocks. This paper looks at this issue through geomechanical and rock physics modelmg. The stresses which result from the geomechanical modelling and saturation can be used to generate elastic attributes and seismic responses at well location that reveal the patterns of seismic monitoring results expected under various production schemes. The integrated procedure applied on both real and synthetic data for monitoring an underground gas storage leads to demonstrate the play of S wave data to differentiate pressure effects from saturation ones.
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Error propagation in Gassman modelling for 4-D feasibility studies
By F. EngelmarkTree elastic parameters necessary for Gassman fluid replacement modeling, namely the velocity of the pressure wave (Vp), velocity of the shear wave (Vs) and bulk density (Rhob). These can be estimated from seismic data through inversion, using direct wireline log measurements or by conducting laboratory measurements on dry cores using ultra sonic frequencies. Whereas the three elastic parameters are measured directly on cores and in wells, seismic is unique in the sense that we can most accurately invert for acoustic impedance (Z-p) and with 4-C seismic also quite accurately estimate gamma, or Vp/Vs ratio, for a sufficiently thick reservoir interval.
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Improved reservoir characterization using pseude-wells and massive seismic modelling
Authors F. Pivot and A. DouillardSeismic reservoir characterization consists in deriving reservoir properties from 3D seismic data. The crucial point in this is to determine a relationship between a set of seismic attributes and the reservoir properties i.e. to onderstand how sensitive the seismic response is to the petrophysical parameters. Here, we propose a new methodology that can provide direct answers to this question.
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Time-lapse AVOA analysis at Teal South
Authors S. A. Hall and C. MacBethSummary not available
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Mapping net pay and channel facies using P- and S-impedance inversion of 3D seismic in deepwater GOM
More Less3D seismic data over the Horn Mountain field, deegwater Gulf of Mexico, were transformed to net /gross volume by combining P-impedance and S-impedance inversions calibrated with log and core data. The net pay volume transformation has excellent agreement with wireline log data and is being used for detailed reservoir description and Field development planning.
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Rock properties from longer seismic offsets
Authors K. Hawkins, G. Roberts, R. Leggott and G. WilliamsSeismic recording offsets have historically been restricted for the following reasons: expense, operation difticulty, and the good use of longer offsets is technically more difficult. For current ocean bottom acquisition technology the rost and operational difficulty of acquiring Jonger offsets quickly becomes prohibitive but in the case of conventional marine streamer and onshore acquisition these issues are relatively trivial leaving only the extra technical difficulty as an obstacle. While the longer offsets do present a challenge to the seismic processor, the information gained in unraveling their kinematic and amplitude behaviour provides us with the opportunity to team much more about the subsurface than just the usual structural image.
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Establishing confidence in the physical basis of seismic attributes
Authors W. D. Pennington, A. Minaeva, J. Haataja, D. Xie, S. Len, A. Green, A. Matelski and D. ForelAs part of a study to determine the physical basis of seismic attributes for use in reservoir characterization and monitoring, we have worked with seismic data from four different fields, representing a range of rock types and data quality. In all of these gelds, there veere significant challenges to the interpretation of seismic data for useful purposes.
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Static reservoir properties and uncertainties from seismic inversion and sedimentary modelling
Authors D. Marion, P. Rowbotham, E. Insalaco, P. Swaby and B. MichelThe prediction of the spatial distribution of petrophysical properties within a heterogeneous reservoir is affected by significant uncertainties when based only on well information. However, integrating additional constraints such as 3D seismic data and sedimentary concepts can significantly improve the accuracy of reservoir models and help reduce uncertainties on predictions away from wells.
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From 2D sedimentary model to synthetic seismic section - a case study
Authors T. Cadoret, J. Marrauld and L. Jacquelin-ValleThe aim of this study is to obtain a synthetic seismic image of a 2 dimension medium defined in terms of sedimentary architectural elements (AE) and describing the most likely geological setting between two nearby wells of a deep offshore field. To reach this goal, several work steps are performed.
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Can seismo-electromagnetic wave conversions be used as an exploration tool?
Authors S. Garambois and M. DietrichWe present field experiments and numerical simulations of conversions between seismic and electromagnetic waves propagating through porous media.
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Permeability prediction from well logs and principal components
Authors P. M. Wong and S. ChoPermeability prediction from welf logs is a challenging problem for petrophysicists. In recent years, neural networks have shown consistently pramising results in field applications. This paper compares the performance of the use of welf logs and their principal components (PCs) as inputs to neural networks for permeability prediction. From the results in a SE Asian reservoir, the study shows that, white the overall performance remains similar, the complexity of the network reduces dramatically with the use of PCs. The findings offer significant insights into the importance of geophysical data preprocessing and selection of algorithmic parameters.
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Application of parallel neural networks in reservoir characterisation from well logs
Authors A. Bhatt, H. B. Helle and B. UrsinA new class of neural networks for quantitative analysis of reservoir properties from well logs is demonstrated in several practical applications. The parallel neural network consists of a number of identical networks (experts) trained on identical or overlapping patterns. We demonstrate that the new artificial neoral network approach is a pragmatic and accurate alternative for converting well data to common reservoir parameters such as porosity, permeability, fluid saturation and for identification of lithofacies. Application to measurement white drilling is feasible.
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Approximate transmission responses for a visco-elastic TIV medium
More LessTransmission effects in the overburden are important for amplitude-versus-offset studies and for tree-amplitude imaging of seismic data. Thin layers produce transmission effects which depend on frequency and slowness. O'Doherty and Anstey (1971) derived a remarkable formula for the transmission response for a plane wave at normal incidente in a stack of homogeneous layers taking into account the direct pulse and short-period multiples.
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Shear-wave splitting and fluid-driven deformation in a critical crust
Authors S. Crampin and S. ChastinAzimuthally varying seismic shear-waves splitting is seen with almost identical characteristics in almost all sedimentary, igneous, and metamorphic rocks below about 1 km-depth in the Earth's crost.
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Amplitude scattering phenomenon - is interface wave propagation guilty?
Authors N. Favretto-Cristini and E. de BazelaireAmplitude scattering, caused by the occurence of thin gaps between layers, is a fractal phenomenon that may generate visible events on seismic sections, correlated from trace to trace but different from usual reflections, although of equivalent energy.
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Poro-viscoelastic representation of shaley sandstones with partial saturation
Authors N. H. Pham, J. M. Carcione, H. B. Helle and B. UrsinBased on a Biot-type formulation of the wave equation we have obtained velocities and attenuation of shaley sandstones with partial saturation. In the limiting case for a pure sandstone the model reproduces the main features of published data on vetocity and attenuation versus saturation.
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Developing stress-monitoring sites
Authors S. Crampin, S. Chastin and P. LearyTheory, laboratory and field evidence reported elsewhere demonstrate that shear-wave splitting monitors the low-level pre-fracturing deformation of the crustal rock which is driven by the response of fluids in cracked rock.
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Shear waves in alternating solid and viscous fluid layers
By B. GurevichExplicit expressions for the frequency dependence of the velocity and attenuation of shear waves in a periodic system of flat solid and viscous fluid layers have been derived by solving exact Rytov's dispersion equation in the long-wavelength approximation. The dispersion and attenuation are related to the well known mechanisms of dissipation in porous media: viscoelastic mechanism (viscous shear relaxation) and visco-inertial Biot's mechanism. The expressions describing the effects of these two mechanisms in a broad frequency range have been derived from the same standpoint. The asymptotic expresslons for various limiting cases coincide with the results of previous studies.
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Hydrocarbon detection via fluid relaxation analysis
More LessIn this work I report on the progress of a novel approach used to determine the presence of hydrocarbons based upon seismic attenuation. By means of numerical modelling, I investigate the possibility of using the viscous fluid relaxation properties of heterogeneous reservoir porous rocks to detect hydrocarbons. The key ideas of this approach are to stimulate the reservoir rocks via a pilot signal and then to quantify the anelastic effects by rneans of tracking waves.
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An experimental and theoretical investigation of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material
Authors S. Barake, F. van der Bas, G. Ooms and P. PoesioAn experimental and theoretical investigation has been made of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material. The experiments have been performed on Berea Sandstone cores.
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The Renormgroup model for fluid flow through the fractal porous media
Authors G. A. Kuz‘min and O. N. SobolevaRocks have a developed porous structure that determines the fuid flows, waves and other proceses in them. It has been recognized that the scale invariant models may approximate the porous structure.
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Critical fractures in a 3km deep well at Soultz (FR) - stronger than friction?
By K. F. EvansWe perform a 'crirical fracture' analysis for the 850 m section of granitic basement exposed below 2.75 km in well GPKI at the Europe an Union's HDR site at Soultz in France.
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Evidence for a critical crust
Authors S. Chastin and S. CrampinWe present evidente that the Earth's trust is a critical system caused by the organisation of fluid-saturated stress-aligned microcracks. A critical crust has profound implications for low-level rock deformation and phenomena such as reservoir description and the build up of stress before earthquakes. Following papers will discuss particular implications and applications.
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Hydrologically-significant structures imaged by induced microseismicity in a 3km deep well in granite at Soultz (FR)
Authors K. F. Evans and R. H. JonesDuring 1993, 25,000m³ of water was injected at a peak overpressure of 9 MPa into a 550 m section of granitic basement exposed below 2.75 km in well GPK1 at the EU's HDR site at Soultz (Rhinegraben) in France.
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Improving reservoir engineering with microseismics
Authors S. Maxwell and T. UrbancicThe efficiency of hydraulic fractures largely determines the economics of tight gas sand reservoirs. Having a reliable method to directly measure hydraulic fracture geometry / orientation and to assess the quality of the created fractures as permeable pathways, allows field engineers to improve cornpletion designs and development strategies for effectave drainage of these reservoirs.
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New data - new models? Downhole microseismic monitoring of a hydraulically fractured reservoir
Authors M. Hartung, M. R. G. Bell, J. F. B. Kraaijevanger and C. MaisonsThis paper discusses the microseismic data recorded during and after a hydrofrac stimulation of a silicilite, oil-bearing reservoir using permanently deployed downhole sensors.
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Time-dependent creep in unconsolidated reservoirs sands above a threshold viscous compaction pressure
Authors P. N. Hagin and M. D. ZobackLaboratory studies of room-dry unconsolidated reservoir sands reveal a time-dependent or viscous component of deformation.
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Permanent passive seismic monitoring for reservoir management - the µSICS™ approach
Authors J. -P. Deflandre, P. Delaplace and F. HuguetPermanent passive seismic monitoring bas been performed since 1993 on the underground gas storage facility located at Céré-la-Ronde (France). This 7-year survey experiment represents a fruitfut experience for the development of equipment and software and for the elaboration of a methodology for both short term and permanent passive seismic survey.
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Pore pressure and fluid detection from compressional - and shear-wave data
By J. DvorkinBy analyzing experimental data we show that in many room-dry rocks, the Poisson' s ratio (PR) decreases with decreasing differential pressure (confining minus pore pressure).
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Wave propagation in multiscale porous media
More LessWe consider a fractured porous medium, i.e. a dual-porosity medium which consists of two interacting porous systems whose permeabilities are very different.
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Upscaling poroelastic media
Authors B. Gurevich and S. A. ShapiroUpscaling of heterogeneous porous reservoirs differs from the upscaling in elastic media due to the effect of the wave-induced fluid flow that may occur between areas of different compliance.
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Simple hereditary media models with singular memory kernels for transient waves in lossy media
By V. E. RokThe macroscopic wave dispersion relations of an inhomogeneous porous media are strongly affected by scattering and absorption energy by grams, boundaries of micro-pores, and vissous boundary layer in the pore fluid flow.
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Upscaling in reservoir engineering and geophysics
Authors L. Paterson and J. GunningThe word upscaling is loosely used to mean averaging fine-scale information to give the same effective properties at the coarse-scale. However, a precise definition is usually user and purpose specific, and more particularly dependent on the physical model used to define the notion of "effective ". This deserves some discussion.
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Integrating effective flow and seismic properties
Authors G. E. Pickup and C. D. MacBethMany reservoirs (bath hydrocarbon-hearing and aquifers) are fractured, and mach work has been carried to characterize their proporties and to simulate tluid flow through them. Due to stress fields, fractures are frequentty aligned, giving rise to anisotropic proporties. In particular, for a reservoir with parallel fractures, fluid flow will be much stronger in one direction than in another. One method of detecting fracture orientation, is using seismic measurements. In this abstract, we show how seismic anisotropy depends on microscopic proporties, such as the elastic compliance within a fracture, and how seismic anisotropy can be used to predict permeability anisotropy.
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Power-law behavior of well log spectra
Authors J. P. Stefani and G. S. DeThis talk contains two notable observations: 1) the spatial spectra of well logs follow a powerlaw behavior, and 2) the value of the power is only weakly dependent on log type and basin type.
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Pore-scale modelling of multiphase flow in rocks
Authors L. Paterson, M. A. Knackstedt and W. V. PinczewskiThe seismic response of multiphase flow through reservoirs is a key component of quantitatively interpreting 4D seismic. It is known that the seismic response does not fust depend on the fractions of fluids present, but also on the way that the phases are distributed. Various patchy saturation distributions can arise degending on whether the fluid displacements are dominated by capillary, viscosity or gravity.
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