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IOR 1991 - 6th European Symposium on Improved Oil Recovery
- Conference date: 21 May 1991 - 23 May 1991
- Location: Stavanger, Norway
- ISBN: 978-94-6282-133-0
- Published: 21 May 1991
1 - 20 of 100 results
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An analysis of composition and rate effects in gravity stabilised gas injection
Authors R. W. S. Foulser, S. G. Goodyear and P. H. TownsleyGravity stabilised gas flooding is believed to have considerable potential as an lOR process in North Sea fields, This paper considers the mechanisms affecting the displacement efficiency. A theoretical analysis of gas flooding using the method of characteristics is summarised. A major result of this analysis is that the process should not be thought of as oil draining into an oil bank, but rather in terms of oil being left bebind, An analytical expression for the process efficiency in secondary flooding is derived, which for a given oil relative permeability Corey exponent is a function of a single dimensionless variable.
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The effects of wettability and heterogeneities on the recovery of waterflood residual oil with low pressure inert gas injection, assisted by gravity drainage
Authors F. A. L. Dullien, I. Catalan, I. Chatzis and A. CollinsIt is shown that in the laboratory a very high percentage of the waterflood residual oil can be recovered with low pressure inert gas injection, assisted by gravity drainage, from both water-wet and oil-wet samples. A mixed wet semipermeable paste assures the production of both oil and water but it prevents gas production. Stacks of short core plugs can be produced equally as a single long core if a coarse version of the mixed wet paste is used between adjacent plugs. In water-wet cores displacement of waterflood residual oil requires a positive spreading coefficient of oil on water in air. Parallel-type macroscopic heterogeneities in the formation may have relatively little effect on the course of oil recovery, but they prevent a uniform saturation to be established in the core cross-section. Microscopic pore scale heterogeneities decrease the recovery efficiency.
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The effect of film-flow on the mobilization of waterflood residual oil by gas flooding
Authors P. E. Øren and W. V. PinczewskiThe importance of film flow in the displacement of waterflood residual oil by gas flooding in glass micromodels under strongly water wet conditions was studied both experimentally and theoretically. Measured oil and water film thicknesses are presented and compared with film thicknesses computed from a solution of the augmented Young-Laplace equation. Both the computed water and oil film thicknesses are shown to be in good agreement with those observed in micromodel displacement experiments. The conductivity of oil and water films was determined from computed film velocity profiles and these are shown to provide good first order estimates of the time scales associated with pore scale displacement events observed in the micromodel experiments. It is concluded that film flow plays an important role in determining the nature of the displacement processes on the pore scale.
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A Numerical and analytical study of off-shore oil rim depletion during tertiary gas injection
Authors L. J. Roberts and G. HulbertThis paper considers the optimisation of tertiary gas injection projects in the off-shore environment. It is shown that the best depletion strategy is to produce fluids from within the watered out zone with wells being recompleted downwards as the flood front advances. The production behaviour is dominated by the coning of oil and gas.
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Evaluation of the potential application on the WAG process in a North Sea reservoir
Authors G. Olsen, A. Skauge and J. A. StensenThe paper discusses the potential increase in oil recovery due to injection of water alternating gas (WAG). The WAG process is compared to waterflooding and gas injection. The mechanisms of the WAG process which makes the process interesting for a North Sea reservoir are discussed. The application of a WAG scheme is discussed with regard to the field restrictions and possibilities of Norwegian reservoirs. The WAG process is found to improve the oil recovery primarily due to improved vertical sweep efficiency. Cross-sectional models have been used to study the sensitivity to variations in vertical permeability.
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Surfactant flooding uncertainty analysis
Authors T. Bu and S. I. AanonsenSurfactant flooding is a process that is sensitive to a number of process and field related parameters. Even if core flooding at reservoir conditions has demonstrated an efficient recovery process with a certain chemical system a high degree of uncertainty remains regarding the field performance.
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Dilute surfactant flooding for North Sea applications - Technical and economic considerations
By P. L. BondorThe North Sea contains a considerable target for surfactant flooding. A dilute surfactant flooding concept which utilises a low (1%) concentration of active surfactant, applied during waterflooding, was developed in the laboratory and evaluated for fullscale application. The technical evaluation revealed an unacceptably high risk related to lack of detailed understanding of the process mechanisms operating in the reservoir. Economic studies showed that the method developed, if successful, would result in a technical cost per incremental barrel of, some $90 (at 15% discount ratel, and thus is not viable for North Sea applications in the foreseeable future.
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Well test verification of the technical potential for improved oil recovery by surfactant flooding in the Gullfaks Field
Authors E. Gilje, R. Kristensen, T. Maldal and O. VikaneThe residual oil saturation of 0.35-0.40 after waterflooding in high quality Brent sands in the Gullfaks Field constitutes an excellent opportunity for improving the oil recovery by surfactant flooding. In order to assess the technical potential for improved oil recovery, Statoil decided in 1989 to initiate a surfactant flooding development program for Gullfaks application comprising: surfactant production, characterization, screening and optimization.
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Improved oil recovery surfactants based on lignin
Authors F. E. DeBons and L. E. WhittingtonThe limited supply and increasing cost of petroleum-based surfactants for chemical enhanced oil recovery have led Texaco to study renewable resources as sources of improved oil recovery (lOR) surfactants. The starting material of choice is lignin, the second most abundant organic chemical on earth. Lignins are produced in large quantities as waste in pulp and paper mills and are very inexpensive.
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Coreflood experiments with surfactant systems for lOR: Computer tomography studies and numerical modelling
Authors J. Alvestad, E. Gilje, A. O. Hove, O. Langeland, T. Maldal and B. E. R. SchillingThis paper addresses the dynamic behaviour of surfactant systems for IOR-applications in terms of phase behavior and coreflood recovery processes. Extensive measurcments of phase behaviour have provided a good characterization of the phase diagram of abrine, surfactant and heptane system. The surfactarit system does not require any cosurfactant to obtain middle phase microemulsions. Tertiary recovery surfactant coreflood experiments have been perforrned and the dynamic process in the core have been studied using computer tomography (CT). Effluent analysis have also been performed. A new phase-behavior-model based on direct interpolation of experiment al data combined with correlations has been developed and used for the modelling of the phase bchaviour of this overall three-cornponent system (brine, heptane and surfactant). A tertiary coreflood recovery test have been simulated using a compositional chemical flooding simulator with the new phase-behaviour model.
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Miscible displacement in fractured-porous media (theory and experiments)
Authors K. Basniev and P. BedrikovetskiiThe hydrodynamical theory of the miscible displacement in fractured-porous media (FPM) that describes convective, gravitational, diffusive mechanisms of the recovery from blocks and hydraulic interaction between blocks and cracks is developed. The solution of the inverse problem is obtained to determine FPM properties from data from laboratory displacement.
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Dispersion and distribution of singel comounds in real oil/CO2-transition zones
Authors V. Meyn, S. Kerschbaum and R. KramerThe mass transport of definite oil components within transition zones between live oil and CO2 was studied. The major topic was to investigate the dispersion under steady state conditions using phases produced by single and dual contact procedure, representing phases occurring in transition zones.
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An experimental study of waterflooding and depressurisation relevant to gas condensate reservoirs
Authors P. Naylor and N. C. SargentDevelopment options for gas condensate reservoirs are to depressurise the reservoir, maintain the pressure by water injection or to maintain the pressure by gas injection. The depressurisation option may itself allow water to flood the reservoir from any attached aquifer. Thus, evaluation of the options depends critically on the interaction between the condensate and water. This paper describes a series of low pressure core flooding experiments carried out to investigate these interactions.
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Discrete element modelling of borehole mechanics
Authors S. Thallak, M. Dussenault and L. RothenburgWe present two-dimensional discrete element method (DEM) analyses to simulate a borehole in granular material. This simulation is two-dimensional plane strain, and we have succeeded in developing an approach for flow coupling to steady-state flow conditions. Results of these simulations suggest a number of behavioral features and deformation mechanisms. The stress distribution around the borehole clearly reflects a type of non-linear elastic behaviour with elasto-plastic dilatant mechanisms. In anisotropic stress fields, the simulated borehole demonstrates the development of breakouts at 90° to the direction of application of the principal stress. An outwardly directed fluid-flow has a dramatic stabilizing effect on the material in the borehole wall; conversely, if fluidflow is inwardly directed, the pore fluid gradient has a destabilizing effect on the borehole. We also discuss some implications of pore-fluid injection on in-situ hydraulic fracturing in unconsolidated reservoirs. It is evident that DEM methods have great power in emulating realistic behaviour of granular or fractured geomaterials in complex conditions. Whereas they are not a design tool at the present time, they provide more insight into mechanisms, and this insight helps guide other numerical analysis approaches.
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Oil field development using in-situ combustion in combination with foam systems and alkaline solutions
Authors M. T. Abasov and T. V. KhismetovIn this paper the results of experimental and field investigations of EOR methods combining in-situ combustion with foam systems injection and alkaline flooding are generalized.
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In situ combustion (lSC) in fractured heavy oil reservoirs
Authors M. Greaves, G. Javanmardi and R. W. FieldIn situ combustion of heavy and also light crude oil was successfully propagated in a cylindrical sandstone core, with an adjacent 1mm surrounding simulated fracture, during a series of dry combustion testing using air and 35% oxygen. Combustion peak temperatures up to 830'C were achieved with air, but oxygen utilisation was less efficient than with enriched air. The combustion front was cone shaped as first observed by Schulte and de Vries. The extent of the front tended to increase with increasing combustion peak temperature.
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Water of condensation and the steam condensation front during steamdrive
Authors C. T. S. Palmgren, J. Bruining, H. J. de Haan and E. N. J. BiezenThis study concentrates on process parameters affecting the behaviour of the steam condensation front (SCF) in slightly dipping reservoirs during displacement of low and medium viscosity oils.
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Validation and application of probabilistic simulation for fluid flow through porous media
Authors D. W. van Batenburg, H. Bakken, J. Bruining and C. T. S. PalmgrenThe non-linear partial differential equations describing oil- water displacement in porous media can be solved using a probabilistic simulation technique. Results have been presented by various authors. However, an elaborate proof of the technique has as yet not been presented. The results of a probabilistic simulator, are validated using a one dimensional solution in closed of the Buckley-Leverett problem including capillary forces. Subsequently the simulator is applied to study the effect of permeability heterogeneity on displacement characteristics. Both one and two dimensional examples are presented.
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A Heuristic approach to reservoir homogenization
Authors T. Johansen, K. Fundingsrud and J. AlvestadIn conventional reservoir simulation, the reservoir parameters needed must be entered as point values representing rock and rock/fluid interaction properties over finite volumes. Because of CPU and storage limitations, these volumes normally must be defined larger than a scale at which they for practical purposes can be considered as homogeneous.
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On the inverse problem application to reservoir characterisation
Authors G. B. Savioly, C. A. Grattoni and M. S. BidnerReservoir parameters are estimated by adjusting simulation models to match field or laboratory data. Multivariate optimization techniques with physically realistic constraints on the parameters are used in order to obtain these estimates. Two examples are presented.
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