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First EAGE International Conference on Fault and Top Seals - What do we know and where do we go?
- Conference date: 08 Sep 2003 - 11 Sep 2003
- Location: Montpellier, France
- ISBN: 978-90-73781-32-0
- Published: 08 September 2003
1 - 50 of 66 results
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Attempt at Correlation Study between Linear and Relative Permeability Data of Basis Types of Carbonate Rocks, Applying a Neural Network
Authors B. D. Darlak and M. W. WlodarczykThis paper deals with a new application of neural network in the study of relative permeability curves. This problem has particular significance since during these lengthy experiments the number of tested samples is fewer than it should be used to prepare main data base.
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Risking Accumulations and Sealing in Petroleum Systems Modeling - A Bayesian Approach
Authors A. Kauerauf and T. HantschelModeling the accumulation and loss of hydrocarbons in traps is one of the prirnary tasks in Petroleum Systems Modeling. Hydrocarbon column heights and accumulation sizes are in most cases determined by the physical properties of the top seals which can also obviously include faults and facies boundaries. The sealing capacity is usually quantified with capillary pressure values, and hydrocarbon break-through and loss from an accumulation occurs when the density contrast between the hydrocarbons and water times column height exceeds the capillary pressure. Accurate quantitative knowledge of the sealing capillary pressure is therefore required. Unfortunately, experimental values or theories for the derivation of capillary values from interfacial tensions, fluid properties and pore geometry are seldom available with the required degree of accuracy, especially as effective or bulk values are required.
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Is the Top of Overpressure Seal in the Gulf of Mexico a Result of Capillary Sealling?
Authors L. M. Cathles, C. Poyurs, J. Shosa and M. WizevichMost active basins generate and retain near-lithostatic fluid pressures a few kilometers below the sediment surface.
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Secondary Migration in a 2D Visual Laboratory Model
Authors F. Vassenden, Ø. Sylta and C. ZwachReservoirs and cap-rocks undergo burial dwing geological time. Hydrocarbons migrate into and fill traps during periods of active expulsion from source rocks. The supply of oil and gas can be abundant until deep burial stops the supply. Capillary leakage of oil and gas from the trap can then potentially decrease the size of the accumulation. A laboratory study of filling into and leakage out of a trap has been undertaken with a visual 2D laboratory model. The model defined a synthetic cap rock having a finite entry pressure overlying a permeable reservoir rock. The trap was formed by imbedding a pyramid-shaped layer of smaller glass beads in a pack of larger glass beads.
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Identifying and Assessing Seals Using Carbon Isitope Mud Gas Depth Profiles - Examples from the Western Canada Sedimentary Basin
Authors B. J. Tilley and K. MuehlenbachsThe regional integrity of hydrocarbon seals was investigated across the BC/Alberta edge of the Western Canada Sedimentary Basin by looking at the geochemistry of gases from three wells. We analyzed the carbon isotope and compositional geochemistry of hydrocarbon gases liberated by drilling.
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Accurate Assessment of Fill History - A Critical Element when Adressing Seal Potential
Authors M. Lisk, W. Bailey, M. Brincat and A. GartrellAccurate determination of hydrocarbon fill history is critical to the effective validation of predictive trap integrity models. In most instances, such models are validated using the distribution of hydrocarbon discoveries, thereby excluding the majority of the well results that are water wet. Interpreting the fill history of presently water-wet traps is desirable because it enlarges the footprint of investigation and helps produce a more statistically reliable predictive model. A reliance on conventional hydrocarbon shows, which are easily degraded over geological timeframes or during the drilling process and where there is uncertainty in the significance of oil show intensity, often makes reliable determination of the hydrocarbon charge history of water wet traps equivocal.
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Seal Assessment in the Context of Underground CO2 Storage - Challenges and Existing Methods
Authors P. Zweigel and E. G. B. LindebergCapture of C02 from large point sources and subsequent long-term underground storage is at present the most promising option to reduce greenhouse-gas emissions without major sudden changes of our energy system. Two main types of subsurface CO2 reservoirs exist: emptied hydrocarbon fields and (saline) aquifers. In addition, some minor quantities of CO2 can be stored in enhanced oil recovery (EOR) projects. In all these cases, the existente of a tight seal is mandatory, to restrict buoyancy-driven upward migration of the CO2 into the atmosphere.
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Vertical Seal Efficiency of Conventional and Fault-Related Traps in Deepwater Clastic Environment
Authors D. Grauls, J. L. Montenat and M. LescanneIn deep offshore Tertiary basins the hydrocarbons trapped in turbiditic plays are very often found at shallow burial in different structural settings. These traps are also characterized by important 4 way or 3 way-dip closures sometimes exceeding 1000 meters especially in ultra deep imbricate fan system.
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Evaluation of Reservoir Fluid Behaviour, Compartmentalisation and Seal Efficiency through Gas While Drilling Data Analysis (GWDtm)
Authors P. Blanc, B. Barraud, D. Kandel, D. Levaché and G. SegaliniThe acquisition of gas data while drilling for geological-surveillance and safety is an almost universal. practice. Hence, mud logging services provide the earliest available data, along with LWD operations. A method has been developed by Total and Eni in order to use these gas data within the scope of reducing uncertainties in formation evaluation.
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A Methodology for Integrated Seal Assessment and Risking
Authors R. R. Hills, S. D. Mildren, R. Daniel and J. KaldiAn integrated workflow for seal assessment and risking is proposed. The methodology considers six key parameters that can be combined into a single value indicative of overall risk for the presence of a sealed trap.
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Fault Trap Analysis of the Lower Permian Rotliegend Gas Play in the Lauwerszee Trough, NE Netherlands
By F. V. CoronaThe Lauwerszee Trough is a northeast-trending sub-basin located within the Southem Permian Basin, and lies in the onshore area of northeast Netherlands. Referrred to as the "Golden Land" Trend, it is the classical Lower Permian Rotliegend gas play of the Netherlands, consisting here of the prolific, high net-to-gross sandstones of the Slochteren Formation trapped in tilted fault blocks and sourced from the Carboniferous.
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Reservoir Compartmentalisation, Approaches Based on the Fluids - An Examples in the UK North Sea
Authors G. Caillet, A. Noyau, D. Kandel and F. WalgenwitzThis paper is dedicated to an approach based on fluid analyses to investigate the possibility of either a fluid compartmentalisation or a fluid connectivity in complex oil and gas fields. This may have a major impact for the optimisation of the development and production of the fields.
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Prograding' Deltaic Tectonics in Brunei - Implications for Fault Sealing
Authors M. R. P. Tingray, R. R. Hillis, C. K. Morley, R. E. Swarbick and S. J. DrakeThe Baram Delta province of Brunei (northwest Borneo) is a Tertiary delta system built up upon an active margin. Hence, the structures observed in Brunei are the result of a complex interaction between gravity-driven deltaic tectonics and transpressive tectonics associated with the active margin.
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Large Strain Testing of Fault Seals - Laboratory Experiments and Development of Fault Seal Models
Authors F. D. E. Cuisiat, K. Bjørlykke, R. H. Gabrielsen and R. B. FærsethFaults that affect fluid flow in hydrocarbon reservoirs are produced by the deformation of a large variety of sediment types, under different stress conditions.
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Discrete Element Stress Modelling in the Timor Sea and Otway Basin, Australia
Authors S. P. Hunt, P. Boult and C. BronwynRock stress can only be measured at local points in space but determination of the state of stress in large rock masses is affected by heterogeneities, most significantly faults and horizon boundaries. Faults and horizon boundaries can greatly affect the magnitude and orientation of the in-situ rock stress state. The discrete element method is specifically designed to solve fracture problems.
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Predicting Brittle Failure of Faults and Caprocks
Authors S. D. Mildren and R. R. HillisIn the context of many Australian hydrocarbon provinces, brittle failure is considered to be the critical factor controlling trap integrity. Fault reactivation and cap rock integrity are assessed for a fault-bound hydrocarbon trap in the Timor Sea, Australia, using a new approach to assessing brittle failure.
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Integrated Trap Integrity Analysis in a Reactivated Setting - Examples from the Northern Bonaparte Basin, Australia
Authors M. P. Brincat, W. R. Bailey, S. D. Mildren and M. LiskConventional fault seal analyses that utilise empirical relationships are frequently used to constrain the hydrocarbon column height that a fault can support. However, this type of approach comprises a static treatment for assessing fault seal capacity and therefore may not be appropriate in tectonically active areas where fault reactivation can lead to seal breach.
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Role of Geomechanical Simulations in Understanding the Evolution of Structural Damage
Authors G. D. Couples, H. Lewis, N. G. Higgs, P. E. Olden, S. Uehara and J. MaAs structural features develop, they acquire a wide range of imposed material discontinuities and surfaces onto which strain becomes localised. Each such localisation feature acquires a distribution (in time and space) of petrophysical properties as a direct consequente of its structural history, with an obvious dependency on the host rock types. Because the evolved petrophysical properties will often be considerably different from those of the "undeformed" host rocks, fluid flow simulations need to account for the presence of the localisation features. Predicting their properties, and especially their flow effects at a variety of scales, is one of the big challenges of today.
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Compartmentalisation in Rotliegend Gas Fields, Examples from Offshore and Onshore the Netherlands
Authors I. van der Molen, E. Zijlstra, J. Okkerman and P. ReemstInitiaily a single gas field is characterised by a single GWC, a single pressure system (on the geological timescale), a single gas composition and one GIIP. Spatially bounded subvolumes that need to be accessed individually to ensure their adequate depletion on the production timescale are called "compartments". There is no strictly physical definition for compartmentalisation. The time value of money and limitations of present-day well technology combine with natural, ofien complicated, internal reservoir architecture and associated geologic distributions of physical properties to make a field compartmentalised.
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Sub-Seismic Faults and Their Possible Influence on Overpressure and Hydraulic Leakage - Examples from Offshore Norway
Authors A. E. Lothe, H. Borge and R. H. GabrielsenThe sealing properties of the major fault in a sedimentary basin are potentially important, timevariable parameters in the evaluation of lateral fluid flow. The sealing capacity of fault depends on lithology, burial depth, diagenesis and throw. Though, large uncertainties are associated with the intepretation of hardly detectable faults where such occur in the continuation of larger fault zones on seismic. Such sub-seismic faults can contribute to the establishment of pressure compartments in sedimentary basin.
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The Oseberg Field (Northern North Sea) - Sealing Potential of Faults
Authors J. A. Clausen, S. Thibeau. J. -P. Rolando, R. H. Gabrielsen, M. Green and T. RivesThe Oseberg Field, which is the one of the largest hydrocarbon field in the Norwegian North Sea, is located approximately 140 km WNW of Bergen, Norway. This study concentrates on the northem parts of the Oseberg Field, namely the Alpha North Structure and the northem parts of the Alpha Main Structure.
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The Use of Critical State Mechanics to Predict the Deformation within the Reservoir Setting
Authors R. J. Cuss and S. HorsemanCritical state soil mechanics shows that complex deformation can be described by a series of surfaces in the effective mean stress (p¹), differential stress (q¹) and void ratio (v) pararnetric space.
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Experimental Approach to Asses Fault-Seal Potential of Shale Smear
By M. TakahashiTo quantify the fault-seal potential of shale smear, a series of laboratory experiments of Takahashi [2003] has been performed on permeability change during deformation of simulated shale smear. Accompanying the field observation, the author tried to apply the experimental methodology to natural sandstone-shale successions. This shows preliminary results of experimentally shale smear reproducing with continuous permeability monitoring, using natural sandstone-shale interbedded specimens obtained from Miri oil field (Upper Miri Formation, Miri, Sarawak, Malaysia), and the results of field observations at Airport Road outcrop in the same oil field.
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Fault Zones as Heterogeneous Volumes - What Do They Consist of and How Should We Treat Them in Fault Seal Evaluation?
Authors S. S. Berg, R. H. Gabrielsen, T. Skar and E. ØianAs part of a multi-disciplinary project, where one of the main goals is to improve the description of fault zones in fluid flow modeling, detailed analyses of the architecture of fault zones have been carried out. This contribution focuses on common architectural characteristics of normal fault zones based on selected outcrop studies, and emphasizes important aspects of fault zone components, which largely have been excluded in modeling of subsurface faults.
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A Comparison of Two Fault Seal Analysis Techniques, Case Study from Eastern Venezuela
Authors M. A. Pachell, C. Rankin and P. FarfanAnalysis of an extensional fault array in a siliciclastic sequence from eastern Venezuela provides insight into the effectiveness of two fault seal analysis techniques: juxtaposition and the shale gouge ratio (SGR, Yielding et al., 1997).
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The Three-Dimensional Architecture of Small-Scale Faults in Unconsolidated Sediments
Authors M. B. Kristensen and J. A. KorstgårdPrediction of fluid flow in hydrocarbon reservoirs is complicated by the presence of faults, which may act as barriers to fluid flow, as conduits for flow, or be partially transmissive. Seismically resolvable faults can be mapped and incorporated explicitly into reservoir evaluation studies, but understanding the influence of sub-seismic faults, which may be important over production timescales, is more problematic. Understanding the development and geometry of small-scale faults in addition to their microstructures and internal fault zone architecture is therefore vital for optimizing fluid flow models. Faults in unconsolidated sediments described here provide a unique opportunity to study both fault zone structure in relation to fault offset and the geometrical interactions between faults
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Risking the Impact of Sub-Seismic Relay Zones on Fault Seal Capacity
Authors C. Childs, T. Manzocchi, J. Imber, C. G. Bonson and J. J. WalshFaults are frequently segmented both in map view and in cross-section. Displacement is transferred between adjacent fault segments with high displacement gradients via a zone of high strain, often referred to as a relay zone.
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Fluid Flow in Faults - Modelling with the Athena Reservoir Simulator
Authors T. Skar, S. S. Berg, A. Braathen, R. H. Gabrielsen, I. Garrido and E. ØianThe architecture of faults has significant influence on fluid flow behaviour in deformed reservoirs. The internal architecture and geometry of fault zones may vary from those with a simple geometry and structure to those with multiple fault strands within a complex architecture.
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Sand and Shale Smear in Soft-Sediments
Authors R. K. Davies, R. J. Knipe, H. Lickorish and A. LiFaults that develop in recently deposited sediments, especially those in water-logged submarine sediments, are mechanically different fiom those in more deeply buried cemented rock. Many of these faults form due to gravity flow processes such as the instability at the toes of prograding delta fronts. In a heterolithic sand and clay-rich section both sands and shales smear into the fault zone with fault displacement. Predictive methods for determining the distribution of fault rocks across the fault surface in soft sediments must consider the effects of both the clay and sand smear in the fault zone.
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Fault Gouge Evolution in Highly Overconsolidated Mudrocks - A Field Study
Authors M. Holland, J. L. Urai, W. van der Zee and J. KonstantyFaults in brittle lithologies can form highly conductive fluid pathways at small displacements. At increasing displacement the transport properties of the fault zone are more complex. In sandstones and carbonates cataclastic gouges are formed which remain rather permeable but may be re-cemented by diagenetic fluids.
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Experimental Investigation of Clay Smear Processes in a Geotechnical Direct Shear Apparatus
Authors J. L. Urai, R. Schmitz, W. van der Zee and P. VrolijkClay smear is an important process in siliciclastic sequences, but the details of the evolution of fault zones in sand-clay layered sequences are poorly understood. This project presents the results of an experimental investigation of clay smear processes, using a geotechnical direct shear apparatus.
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Fault Conduit/Fault Seal Behavior, South Eugene Island Block 330 Field, Offshore Louisiana
Authors S. Losh and L. Cathles IIIFaults commonly serve a dual purpose in the petroleum system: as conduits of hydrocarbon to reservoirs, and as seals for those same reservoirs.
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Fault Seal Based on Fault Throw and Fault Geometry from Seismic Data - How Reliable is It, and How Can It Be Improved?
Authors L. T. W. Sigemes and S. OttesenIn most fault seal analyzing methodology like the use of; Shale Gouge Ratio and Clay Smear Factor, fault throw and fault geometry are two of the most critical parameters. The value of these parameters very often comes from interpretation of seismic data, and very often these data are used as if they are "hard facts.
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On the Use of Multi-Carrier Hydrocarbon Migration Modelling with Clay-Smearing in Faults
Authors Ø. Sylta, C. Childs, S. Sperrevik and A. TømmeråsComplex scenarios for the trapping of oil and gas against faults can often be observed in multi-pay (multi-carrier) fields. Understanding hydrocarbon migration in such systems can be extremely dificult due to complex spatial variations in the sealing and conductive capacity of faults separating carriers of different ages. The analysis of multi-pay migration systems therefore requires the use of computerised simulation techniques. Here we describe such a technique which incorporates fault sealing properties due to the effects of clay smearing which is widely recognised as one of the main processes controlling fault sed capacity in clastic sequences.
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The Impact of Carbonate-Carbonate Sealing Faults in Oilfields of NW Oman
Authors K. Harris, J. Filbrandt, M. Hossain and H. ShuailyThere are several late Cretaceous oilfields in northwest Oman which are characterised by low permeability, chalky reservoirs with long entry heights (5-40m) and long transition zones (5- 20m). Two of these fields are considered to be combined structural-stratigraphic traps, in which faults provide the lateral seal in the up-dip direction.
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Mechanics of Top Seal Leakage in the Carnarvon Basin, Australian Northwest Shelf
Authors D. N. Dewhurst, A. L. Henning and G. E. KovackThe Muderong Shale is the regional top seal in the Camarvon Basin on the Northwest Shelf of Australia. Evidence for top seal breach in this area comes from post-Muderong plays and hydrocarbon shows.
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Deepwater North West Borneo - Hydrocarbon Retention in an Active Fold and Thrust Belt
Authors T. J. Chrisholm and G. M. IngramIn the deepwater acreage of East Malaysia, compressional deformation of the Oligocene to Recent sediment pile has resulted in an extensive fold and thrust belt stretching more than 800 km dong the southem margin of the North West'Borneo Basin. The basin remains relatively under-explored until now and recent oil and gas discoveries in the main Toe Thrust play have proven that considerable upside potential is yet to be realised in addition to existing fields. The upside oil potential is the main driver for ongoing exploration campaigns in NW Borneo, but considerable risks remain and one of the most important of these is top seal integrity.
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Basin Modeling Approach to the Prediction of Fault Rock Properties in High Net-to-Gross Reservoirs
Authors F. Dula and E. McAllisterPrediction of fault rock properties is critical where exploration prospects involve reservoir-reservoir juxtaposition (static seals) and during field production when faults may baffle or enhance (dynamic response) the flow of hydrocarbons. Traditional approaches to the estimation of fault rock properties (e.g., gouge porosity, permeability, etc.) have concentrated upon the present day reservoir conditions (depth, juxtaposition, core observations, and permeability contrasts) and do not typically take into account the evolution of these properties. This contribution describes a basin modeling approach for predicting the paleo and present day properties of fault rocks formed at different depths and temperatures in clean (clay content < 20%), high net-to-gross sandstones.
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Fault-Plane Reflections as a Diagnostic of Pressure Differences in Reservoirs - South Eugene Island, Offshore Louisiana
Authors M. Haney, J. Sheiman, R. Snieder, S. Naruk, J. Busch and S. WilkinsSeismic data taken at Blocks 314, 315, 330, and 331 of the South Eugene Island field contain reflections from a major growth fault. Out of a list of possible causes, we find that differences in pore pressure across the fault give rise to the fault-plane reflections over a large portion of the fault. The pressure differences are detectable since pore pressures that exceed the hydrostatic pressure, or overpressures, lower the seismic velocity. Thus, the presence of the fault-plane reflections point to the fault providing a significant lateral seal. We develop a processing scheme to highlight the fault-plane reflections while simultaneously removing the reflections from the layered structure. Using this processed data set, we extract the amplitude of the fault-plane reflections on the fault-plane. The areas of strong reflection amplitude correlate well with the geology and known zones of overpressure. Over a limited area on the fault, we observe reflectivity originating fiom elevated pore pressures in the fault zone itself.
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Sensitivity Analysis of the Influence of Faults on Oil Production from Shallow Marine Reservoirs
Authors T. Manzocchi, J. A. Strand, J. Matthews, A. Skorstad, J. Carter, J. Howell and K. D. StephenWe describe results fiom the multi-partner, EU-supported SAIGUP project, the principal purpose of which is to quantify objectively the influence of geological complexity on production forecasts in progradational shallow marine reservoirs. The approch used has been to build realistic synthetic reservoirs with combinations of geological factors and to flow-simulate a 30-year production history using four different production plans on each. Formal statistical as well as more physically or geologically based, often curiosity-driven, analyses of the 20,000 sets of simulation results are used to determine the influence of geological characteristics on total oil production, recovery factor, and discounted reservoir value.
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