- Home
- Conferences
- Conference Proceedings
- Conferences
68th EAGE Conference and Exhibition incorporating SPE EUROPEC 2006
- Conference date: 12 Jun 2006 - 15 Jun 2006
- Location: Vienna, Austria
- ISBN: 978-90-73781-00-9
- Published: 12 June 2006
21 - 40 of 462 results
-
-
Finding the Edge of Salt Via a Dual-Velocity Flood
Authors J.E. Anderson and C.M. MarcinkovichImaging an overturned salt edge with turning waves often requires large apertures, long recording times and a sediment velocity profile that appropriately increases with depth and that is unobstructed by other salt bodies within the aperture of interest, conditions that may not always be available in practice. In some situations, data that may not meet all of the turning-wave-image criteria can be used to find the salt face via a dual-velocity-model flood technique similar to a vertical-seismic-profile (VSP) proximity survey. In this case, the reflectors that truncate against salt are imaged at their truncation point in the correct position, helping to define the salt face.
-
-
-
How Many Angles Do We Really Need for Delayed-Shot Migration
By J.T. EtgenWhether you can use a sparse set of source angles in delayed-shot migration, or not, depends on how well your actual set of sources approximates (or can be made to approximate) an unaliased “antenna”. If you have a well sampled source antenna, then sparse angles can be used to create high-quality images since you can transform your data into the equivalent delayed-line-source experiment. If your collection of sources does not satisfy this requirement, then you may have to use a large number of angles to construct artifact-free images.
-
-
-
Measuring Reservoir Compaction Using Time-Lapse Timeshifts
Authors P.J. Hatchell and S.J. BourneTime-lapse timeshifts refer to the differences in two-way seismic travel times that are frequently observed in the analysis of time-lapse seismic surveys. One source of timeshifts originates inside the reservoir interval as a result of changes in the pore-fluid properties that alter the seismic velocity. Another is from changes in seismic velocity and layer thickness that occur both inside and outside of the reservoir as a result of reservoir compaction and stress and strain redistribution in the surrounding formations. Timeshifts induced by changes in fluid properties are always zero above the top reservoir reflection event and constant below the base of the reservoir. These fluidinduced timeshifts can be significant (for example, when gas is released as an oil passes through bubble point) and are routinely calculated using Gassmann or similar theories and are not the focus of this paper. The compaction-induced timeshifts have opposite gradients on the inside and outside of the reservoir. Within the reservoir, the reduction in layer thickness and the expected increase in seismic velocity will reduce the seismic travel time across these layers. Outside the reservoir, the decrease in reservoir thickness is exactly balanced by surface subsidence and rock expansion. The expanding overburden produces increased layer thickness and slower seismic velocities that increase the seismic travel times. Observations on real time-lapse seismic data over compacting reservoirs show that the positive timeshifts that accrue in the overburden are larger than the negative timeshifts that accrue inside the reservoir (the sign convention chosen is that positive timeshifts result when the seismic travel time increases). The amount of overburden elongation cannot exceed the amount of reservoir compaction. So if the change in velocity were simply proportional to the change in vertical strain, the reduction in travel time through the reservoir would exceed the increase in travel time though the overburden. The net effect would be a negative timeshift below the reservoir. Instead positive timeshifts are observed below compacting reservoir indicting velocity reduction per unit elongation strain significantly exceeds the velocity increase per unit contraction strain. Using simple models of the velocity-strain response it is shown that time-lapse timeshifts are proportional to the stretching of the overburden layers and that this is highly correlated with the reservoir compaction. The net result is that time-lapse timeshifts are a good measurement of the reservoir compaction.
-
-
-
Definition of Depositional Geological Elements in Deep-Water Minibasins of the Gulf of Mexico Using Spectral Decomposition in Depth Domain
Authors R.H. Tatham, P. Montoya, W. Fisher, R. Steel and M. HudecSubmarine channels, large scours, distributary channel-lobe complexes, turbidite fan complexes and many other components of deep water depositional systems in the central Gulf of Mexico were successfully imaged and mapped using spectral decomposition in the depth domain. When this powerful tool is applied along an interpreted seismic horizon, a better definition of stratigraphic architecture is obtained.
-
-
-
Natural Perturbations of Shared Earth Models
More LessNatural Perturbations of Shared Earth Models (SEMs) are introduced and demonstrated. SEMs, such as the Compound models developed at Norsk Hydro, contain representations of natural geological entities (compartments, formations, fluids, (geo)logical rules etc). Natural Perturbation of the entities (deformation, translation, rotation etc.) can be performed involving only very few degrees of freedom. Perturbations, exemplified in the paper, are run individually, in series or parallel. A special entity within the Compound model (the perturbation structure) holds the order of the Natural Perturbations to be evaluated and can therefore be used in (global and joint) automatic optimization.
-
-
-
Geostatistical Impedance Simulation after Prestack Depth Migration
Authors F. Schaub, A. Egreteau, P. Thierry and H. BeucherConventional reservoir characterization using geostatistical techniques to compute facies and porosity distribution usually begins from an estimation of the acoustic impedance. This impedance distribution is obtained using inversion technique as the stratigraphic inversion which works on prestack reflection seismic data [Tonellot & al., 2001]. The aim of this work is to take advantage of Amplitude versus Angle (AVA) inversion done after prestack depth migration to perform a depth domain impedance estimation constrained by AVA attributes. We propose to use geostatistical impedance simulation constrained by the migrated common image gather (CiG) and the skeleton of the structure obtained during the AVA inversion as well as the intercept and the slope sections.
-
-
-
Neural Modelling of Core Permeability Data
Authors R.K. Fruhwirth and G. MaierIn this paper we show a neural network based method to develop a relationship between core permeability data and a set of other well logs to complete permeability information in well areas that do not contain that information. As an alternative to the common multi layer perceptron we use a special network architecture that has several advantages in approaching the optimal network size. In combination with parallel learning, automatic network growing and sophisticated stopping criteria that architecture allows an efficient and robust estimation of the optimal network for a particular problem. We use resistivity, gamma-ray, density, neutron porosity and the p-wave sonic logs as model input yielding a heuristic permeability model that allows completion of information in the area of interest yielding a synthetic permeability log. In addition convolutional network input in combination with principal component transform enhances the quality of the resulting model.
-
-
-
Methodology for Integration of Small Scale 3D/4D Seismic Features in Reservoir Simulations
Authors N. Hadj Kacem, P. Berthet, F. Pivot and P. SamierGeological modelling of depositional facies and petrophysics is usually performed with a high vertical resolution and a low lateral resolution due to flow simulation constraints. The 3D/4D seismic may bring a high lateral resolution on reservoir characterization. To handle this fine scale information, the geological modelling requires a direct integration of well and seismic information. The lateral fine scale details of some good quality seismic attributes allow to locate small and meaningful reservoir connectivity. The deterministic method of integration, presented here, preserves seismic connectivity into the flow reservoir model. The method also offers a permanent link from seismic/geologic information to dynamic model. As soon as small heterogeneity is properly transferred into the flow model, the great benefit of this method is to reduce the history matching phase and to ensure more predictive dynamic model. In this paper, we illustrate a three step methodology allowing an automatic integration of geologically coherent seismic information within the reservoir model.
-
-
-
The EU Research Strategy for Zero Emission Fossil Fuel Conversion
By P. DechampThe research strategy put in place by the Directorate General for Research of the European Commission in the field of the mitigation of CO2 emissions is first placed in the general context of the Commission energy policies. These actions are addressing the climate change issue, the introduction of renewable energy sources, the security of energy supply, the promotion of energy efficiency and the opening of energy markets.
The research policy of the Commission is mainly the European Research Area concept and its number one instrument, the Framework Programmes for research and technological development. The rational and the analysis supporting the ERA will be covered, as well as the structure and the new implementation modalities of the Framework Programme. Initial ideas for the 7th framework programme covering the years 2006-2013 will be debated.
CO2 capture and sequestration projects are organised to fit into the above-mentioned research policy, while contributing to the successful deployment of the Commission energy policies. These projects represent a portfolio of the order of 140 m€ of research and technological development.
Future perspectives, in particular in view of initiatives in the international arena and the Zero Emission Power Technology Platform, are finally outlined, addressing the need for an integrated European approach to develop and demonstrate CO2 capture and storage technologies for the benefit of the European citizens, industry and society.
-
-
-
The ReMoVe project; Can We Guarantee Long Term Safety of Geological Storage of CO2
By E. ElewautSince 1990, Europe and the European Commission have invested a huge amount of research in the geological storage of CO2, The aim was initially to create an inventory of potential storage sites and volumes, later to build models to study the subsurface behavior of CO2 and the storage matrix and to forecast possible problems, later still to perform risks analysis at all relevant time scales.
Since Statoil started injecting CO2 on an industrial scale off-shore Norway in 1996, the focus has shifted to the monitoring of geological storage. Over the last ten years, experience has been acquired with both large scale projects (Sleipner, Norway; Weyburn, Canada) and more limited in scope, so called “subsurface laboratories” in Germany, The Netherlands and Poland. Two new geological storage projects (In Salah, Algeria and Snøhvit, Norway) now provide the opportunity to build on this work.
The CO2ReMoVe project started on 1 March 2006. It is being carried out under the umbrella and with the support of the European Commission’s Sixth Framework Programme for Research and Technology Development.
For five years, 30 partners from 12 different countries all over the world will invest EUR 15 million in an effort to bring together all relevant research and industry experience and know how in the field of underground storage of carbon dioxide.
The consortium of industrial, research and service organizations proposes a range of monitoring techniques, applied over an integrated portfolio of storage sites in order to develop:
1. methods for base-line site evaluation;
2. new tools for monitoring storage and possible well and surface leakage;
3. new tools to predict and model long term storage behavior and risks;
4. a rigorous risk assessment methodology for a variety of sites and time scales;
5. Guidelines for best practice for the industry, policy makers and regulators.
The recommendations from these international efforts will form an important step towards a worldwide consensus in licensing and certification of the storage activities in a number of geological media. These will include oil and gas reservoirs, coal seams and aquifers.
It can be expected that the project will achieve a better understanding with the policy makers and the public that CO2 can be safely transported and stored in the subsurface and that this storage can at all times be safely monitored. The project will also provide the assurance required for geologically stored CO2 to qualify for credits under the emissions trading mechanism.
It can be expected that the project will lead to greater understanding among policy-makers and the public that CO2 can be safely transported and stored in the subsurface, and that this storage can be safely monitored at all times the project will also provide the assurance required for geologically stored CO2 to qualify for credits under the emissions trading mechanism.
-
-
-
Climate Change – The Challenge of the 21st Century
By K. RadunskyIssues to be addressed by the presentation:
- Energy scenarios by the International Energy Agency: Business as usual scenario, scenario with enhanced energy efficiency, scenario with additional carbon capture and storage;
- Possible impacts of climate change, worldwide and in Austria: temperature change, cryosphere, hydrology and water resources, terrestrial biological systems (including agriculture and forestry), human health, disasters and hazards;
- Policy responses
· The UNFCCC: its ultimate objective
· The Kyoto Protocol: its added value
· The European Union: its current position on climate change as reflected in council conclusions
· Processes started in Montreal in 2005
o Process linked to Article 3.9 Kyoto Protocol
o Dialogue under the Convention
- Elements of a possible future architecture: Outcome of the Climate Dialogue at Pocantico
- Carbon capture and storage
· Potential contribution: based on the Special report of the IPCC
· Issues for further consideration: based on the outcome of SBSTA24
- The timing challenge: based on recent scientific results (PIK)
-
-
-
Controlled Source Electromagnetic Imaging in Shallow Water - A Case Study
Authors D. Andreis, L. MacGregor, J. Tomlinson and N. BarkerCSEM surveys have been used successfully in a variety of settings including West Africa, Southeast Asia, The Gulf of Mexico and the North Atlantic. Early surveys concentrated on deepwater areas. However they represent only a small proportion of potential exploration targets. In particular to date the method has been limited to relatively deep water (300m or more). This is because in shallow water, signals that have interacted with the air can have a severe impact on the recorded signals and can dominate the response. This noise (known as the 'airwave') dominates the CSEM response at source-receiver offsets which are sensitive to resistivity structure at the likely range of depths of hydrocarbon reservoirs. Researchers at OHM have been working on extending the operating envelope of the CSEM method into progressively shallower water. The approach adopted centres on characterising the physics behind the airwave phenomenon, and then using this knowledge to design approaches to data acquisition and processing that mitigate its effect. As with many geophysical problems, there is unlikely to be one silver bullet that will solve the 'airwave' problem in all circumstances, and so a range of concepts were investigated.
-
-
-
Shell's Controlled Source EM Results Show Positive Impact
Authors D.J. Smit, S. Saleh, M. Costello, J. Voon and J. MoserIn this paper an overview will presented of the use of so-called Controlled Source Electro-Magnetic (CSEM) data acquired in deep water areas. Various results in different geologiocal settings will be used to illustrate its impact on a global exploration portfolio. We conlclude with a discussion on some future developments.
-
-
-
A Fast and Rigorous 3D Inversion of the Marine CSEM Data
Authors M.S. Zhdanov and A. GribenkoMarine controlled source electromagnetic (MCSEM) surveys have become an important part of the offshore petroleum exploration. However, due to enormous computational difficulties of the full 3-D inversion, the practical interpretation of the MCSEM data is still based on qualitative analysis and relatively simple 2-D geoelectrical models of the sea-bottom structures. In this paper we present a new approach to 3-D inversion of the MCSEM data. It is based on the rigorous integral equation (IE) forward modeling and a new IE representation of the sensitivity (Frechet derivative matrix) of the observed data to the variations of the sea-bottom conductivity. This approach requires just one forward modeling on every iteration of the regularized gradient type inversion algorithm, which speeds up the computations significantly. We also use a regularized focusing inversion method, which provides a sharp boundary image of the petroleum reservoir. The methodology is tested on a 3-D inversion of the synthetic EM data representing a typical MCSEM survey conducted for offshore petroleum exploration.
-
-
-
Anisotropic Depth Migration of Marine Controlled-Source Electromagnetic Data
Authors K. Hokstad and T. RøstenWe present a transversely isotropic depth migration scheme for marine controlled-source electromagnetic (MCSEM) data, based on Claerbout's well-known 45 degree equation from seismic imaging. The proposed scheme is applicable to MCSEM data acquired with a 2-D geometry, and is numerically very efficient. We show examples from field data acquired offshore Norway.
-
-
-
Contribution to Oil Exploration and Development - A Successful Inductive Multi-Frequency EM Survey On-Shore Brazil
Authors C.A. Dias, O.A.L. de Lima, H.K. Sato and J.A.C. MoraesIn this work we discuss the results of an experimental study performed using a multi-frequency electromagnetic method over a mature oil field in Recôncavo basin, Bahia-Brazil. Five 1.8 km transects, 200 m apart, were surveyed over a selected oil reservoir block. The processed EM data are represented as cross-sections and maps of apparent resistivity and induced polarization parameter, using a consistent plotting procedure. All the sections, controlled by well logging data, allow to recognize the following geological features: (i) the oil sandstone horizons and their trapping shales; (ii) the oil-water interface and some zones of water invasion; and (iii) lateral electric contrasts representing fault zones. These results suggest the real possibility of the use of the spectral EM method in the direct detection of hydrocarbons, as well as for monitoring the efficiency of the artificial fluid injection used for secondary recovery. Also, this experiment brings about a further development in the inductive measurement of IP and introduces, for the first time, the use of this property in oil reservoir exploration and characterization.
-
-
-
A 3D Near-Wellbore Imaging Algorithm for Triaxial Induction Data
Authors A. Abubakar and T.M. HabashyWe present a rigorous nonlinear inversion method for the three-dimensional (3D) imaging of the near-wellbore region employing multi-array triaxial induction data. The method used is the so-called Multiplicative-Regularized Contrast Source Inversion
(MR-CSI) method. There are two main features of this method. The first is that the method does not require the explicit solution of the full forward problem at each iteration step. The second is that the regularizer is included as a multiplicative constraint that allows the automatic and adaptive determination of the regularization parameter. These two features enable us to robustly solve an inverse problem with 65,536 unknowns using a single-processor present-day computer power.
-
-
-
Inversion of Multi-Transient Electromagnetic (MTEM) Data
Authors B.A. Hobbs, G. Li, C. Clarke and J. LinfootThe multi-transient electromagnetic (MTEM) technique, for detecting and monitoring hydrocarbons, works by injecting a transient current into the ground (a source) and recording the potential difference between two receiver electrodes (the receiver) some distance, or offset, from the source. Field layout is similar to that of seismics, with many receivers per source and many sources per profile. After processing, the data for each source-receiver pair consist of the earth’s impulse response function and step response function. Two methods of inversion are described in this paper. The first uses a single value from each step response (the late time value) and transforms this to an apparent resistivity. These apparent resistivities are inverted in a 2D scheme to give a cross-section of resistivity versus depth. In the second method the full waveforms of either the step or the impulse response functions, are inverted simultaneously for several offsets at each common mid-point position. The resulting 1D resistivity models are collated to form a 2D resistivity image of the subsurface. The methods are illustrated with data from a demonstration survey over a gas storage reservoir.
-
-
-
Fracture Imaging in Weathered Granitic Quarries Using GPR Data
Authors M.A.B.B. Barsottelli-Botelho and M.H. HeimerWe study a granite rock quarry, partially covered by a weathering cap, situated at the State of Bahia (Brazil). The aim was to understand the spatial distribution of fracture surfaces inside the rock and distinguish quickly intact marketable granite areas in order to improve quarry management. To interpret the real data, we use a finite-difference scheme to simulate 2D ground penetrating radar data by solving the damped wave equation. The synthetic GPR sections reveals how a conductive clayey overburden (20 mS/m) masks the real position of the fractures in the granite. The algorithm shows clearly the increase in attenuation with the increase of the frequency, and also with the thickness increase of the weathering cover; which is also responsible for the pull-down effect on reflectors below. The results of the modeling have a good agreement with the actual data.
-
-
-
Normalized ElectroMagnetic Imaging (NEMI) for Controlled Source EM Evaluation of Hydrocarbon Prospects
Authors E.C. Morris, M.C. Sinha, L.M. MacGregor and D.W. OldenburgMarine Controlled Source ElectroMagnetic (CSEM) surveying is a powerful tool for mapping offshore electrical resistivity structure and in recent years has been developed as a DHI tool. Geophysical inversion and forward modeling are currently the standard methods of CSEM data analysis. However, due to non-linearity of the problem, these methods are computationally time intensive. We present a technique for fast imaging of thin resistive layers within a conductive background that enables a ‘first look’ at full CSEM datasets before imaging. The non-linear properties of the electromagnetic fields are used to determine the existence and lateral extent of thin resistive layers that may be associated with hydrocarbon-bearing layers. We present the results of synthetic datasets that show the imaging algorithm is successful at identifying the existence and lateral extent of a hydrocarbon bearing layer.
-