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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
61 - 80 of 100 results
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Selective penetration of biopolymer profile-control gels: Experiment and model
Authors M. I. Hoefner, R. V. Seetharam, P. Shu and C. H. PhelpsProfile control treatments using polymer gels can improve waterflood performance by reducing fluid channeling through higher-permeability "thief" zones. The success of such treatments often depends on placing the gel preferentially in the thief interval. Laboratory coreflood data presented in this work clearly shows that certain xanthanbased profile control gels exhibit tbe property of "selective penetration." Selective gels flow preferentially into higher-permeability media and resist penetration into tighter media. These gels could tbereforeeliminate the need for mechanical zone isolation and thus reduce the cost of profile control treattnents significantly.
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Effect of CR³+ on the rheology of xanthan formulations in porous media: Before and after gelation
Authors R. S. Seright and F. D. MartinExperiments were performed to probe the rheology of chromium(III)-xanthan gels and gelants in porous media. For a large portion of the time before gelation, the presence of 90-ppm Cr³+ did not significantly affect the rheology of a 3000-ppm xanthan solution in Berea sandstone. After gelation, residual resistance factors were not much greater than those for xanthan solutions without Cr³+. Clay and carbonate minerals in Berea may have inhibited gelation by forcing the reaction to occur near neutral pH rather than at the injection pH of 3.8.
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Preparation of a water control polymer treatment at high temperature and salinity conditions
Authors A. Zaitoun, N. Kohler, B. K. Maitin and M. ZettlitzerThe reservoir conditions in the northern Germany oilfield of Ploen-Ost on which RWE DEA is the operator are well-suited for the application of water control polymer technology in production wells. Polymers are expected to improve reservoir conformance around the wellbore and thus to stimulate oil production from the lowest permeability layers while reducing water influx from the highest permeability ones. The high temperature (95°C) and salinity (130 giL TDS) of the reservoir led us to test two new polymers, namely HST and Polysaccharide G, which have a better stability than polyacrylamides. Both polymers can selectively reduce the relative permeability to water of Ploen sandstone cores, with little effect on the relative permeability to oil and can thus be considered as valuablewatercontrol agents. Because of its higher shear resistance and its stronger shear-thinning behavior, Polysaccharide Gis expected to be easier to handle than HST.
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New biopolymer for EOR Moscow
Authors L. A. Starukhina, V. V. Deriabin and V. J. TitovA new biopolymer has been produced that can satisfy demands to enhance oil recovery for it has a high viscosity of diluted solutions in formation waters. Biopolymer solutions are stable in a wide range of pH values and temperatures, possess pseudoplastic behaviour and steadiness to thermal degradation at temperatures above 100°C. This biopolymer called simusan is an exopolysaccharide (EPS) produced by Acinetobacter species capable to utilize ethanol as a carbon and energy source. An estimation of chemical and rheological properties, its emulsion activity and filterability of simusan solutions as wen as fermentation broth has been performed. A technique to improve filterability of the simusan fermentation broth has been developed. New compositions on the base of simusan possessing thickenning and gelation properties have been produced and tested in the oil fields.
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Restriction of gas coning by polymer/silicate well treatment
Authors I. Lakatos, M. Kristof, S. Tromboczky, M. Bodola, I. Munkacsi and J. Lakatos-SzaboThe laboratory and field studies were focussed on development of a well treatment technology which can be used for restriction of gas coning in te Algyo reservoir. The chemical system is a modified version of an earlier method based on simultaneous gelation of polymers and silicates.
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A New approach to pseudofunctions for multiphase flow in stratified porous media
Authors P. Ingøy, R. Gauchet and L. W. LakeConsidering flooding of stratified reservoirs, this paper focus on the case with significant gravity effects. Assuming the fluids are incompressible, we develop a new VerticaI Equilibrium (VE) theory, and introduce pseudo-functions to describe the displacement problem. From the form of the pseudorized equations we conclude that previously proposed analytical methods for assessing flood performance may lead to erroneous results due to incorrect treatment of gravity. We derive travelling wave solutions for the pseudorized problem and compare an example case with numerical simulations. We show that the travelling wave solution can be formulated as a new generalized Dietz solution which accounts for reservoir stratifications and capillary effects. Previously published interface models are obtained in the limit of zero capillary pressure. We derive several results for stationary displacement, and introduce a graphical method for assessing the vertical sweep efficiency under these circumstances.
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The effect of fracture permeability distribution on waterflood efficiency in naturally fractured reservoirs
By G. HamonThis paper discusses the influence of the vertical distribution of horizontal fracture penneability on the waterflood efficiency. The first part presents the analysis of weIl test pressure data from a vertical weIl completed in a naturally fractured reservoir. A dual-porosity simulator, based on a finite difference discretization of the formation is used to generate pressure versus shut-in time during a build-up. It is found that nested fracture networks with different spacings and penneabilities may reconcile the pressure response and core observations, Field examples are presented. In the second part of the paper, dual-porosity simulations of a water injection are run. The main thrust of this paper is to point out that a very different watercut performance may be obtained depending on whether the matrix block size is derived from core observation only, weIl test analysis only, or takes into account both sourees of infonnation. Guidelines are provided to take into account the effect of nested fracture networks in coarse grid. waterflood simulations with dual-porosity simulators.
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An experimental investigation of waterflooding of gas condensate reservoirs and their subsequent blowdown
Authors G. D. Henderson, A. Danesh and J. M. PedenThe phase and flow behaviour of water, gas and condensate in pores at reservoir conditions have been visually investigated using glass micromodels with realistic pore pattems and geometry. The displacement of hydrocarbons, both above and below the dew point, by the advancing water was studied. The model at residual hydrocarbon saturation was depleted and the remobilisation behaviour of the trapped gascondensate phases was investigated. Preliminary core flooding results obtained at conditions similar to the micromodel tests confirm the observed phenomena.
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Waterflooding strategy design using optimal control theory
More LessOne of the main problems that arise when designing the development of an oil or a gas-oil field is to find the distribution of wells and to fix the hydrodynamical conditions on them such that the oil recovery can be maximized.
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The Gullfaks Lower Brent waterflood performance
Authors H. M. Anes, O. Haga, R. Instefjord and K. G. JakobsenThis paper summarizes the main experiences within reservoir performance after 4 years (1987-1990) of production from the Etive and Rannoch Formations in the Gullfaks Field.
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Lean gas injection in a fractured reservoir: Compared performance of nitrogen and methane injection
Authors B. Thiebot and S. SakthikumarA laboratory technique has been developed to perform. natural gas/oil gravity drainage experiments under reservoir conditions, in one or three dimensions, that is on cores having or not the lateral faces open to flow. As an application to the EKOFISK reservoir, a series of experiments has been performed on outerop cores (limestone, chalk) of various permeabilities and capillary hold-up heights, in order to compare the efficiency of methane or nitrogen injection.
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Lean gas injection as means for maximizing the recovery on Eldfisk Field (Norway)
Authors M. Durandeau, S. Sakthikumar and P. PoucleeELDFISK field, located in Block 2/7 of Norwegian offshore 20 km South of EKOFISK field, is producing from fractured chalk formations called EKOFISK,TOR and HOD. The paper presents the successive modelling methodology used from 1982 to estimate its performance under natural depletion as well as improved oil recovery processes as a function of the available field information and the improvement of the simulators.
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Improved formulation for gravity segregation in naturally fractured reservoirs
Authors F. V. da Vilva and B. MeyerThis paper proposes improved dual-porosity formulations for gas-oil pseudo-capillary pressure and equilibrium gas saturation. These förmulations take account of the effect of oil reinfiltration. fracture slope and capillary continuity across fractures. For most of the highly fractured reservoirs encountered in the North-Sea and in Middle-Eas,. current numerical simulators may not adequately predict long term performances, due to improper treatment of gravity segregation. even though they are tuned to satisfy early history.
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An overview of the lOR projects in Turkey
Authors A. Bayrak and R. Ü. GüvenThis paper presents an overview of the improved oil recovery projects under planning, design or application stages by Turkish Petroleum Corporation (TPAO). These are two field wide inmiscible CO2 injection and a field wide waterflood projects.
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Compositional study of gravity stable immiscible nitrogen displacement of a black oil
Authors M. D. Frørup, E. H. Stenby and N. BechGravity stable injection of immiscible Nitrogen into steeply dipping, high permeable reservoirs can recover substantial quantities of oil which are not recoverable by water flooding. Gravity stable gas displacement presents a complicated problem in reservoir engineering.
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A Study of recovery mechanisms in a nitrogen diffusion experiment
Authors H. Hu, C. H. Whitson and Y. QiTo understand the peculiar recovery phenomenon in a core nitrogen diffusion experiment, anumerical study has been carried out to investigate various governing forces and their interactions. The mathematical model used to simulate the experiment combines the analytical solution in the fracture (open space) and numerical solutions in the core. The analytical solution of the composition distribution in the fracture includes both molecular diffusion and bulk velocity of the gas stream. The numerical solution in the core includes molecular diffusion, capillary pressure, gravity, and Darcy flow. The fully implicit compositional formulation used in the numerical model is necessary because of the large capillarity and composition effects, and the small pressure gradients in the system.
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Diffusion and gravity drainage tests to support the development of a dual porosity simulator
Authors F. E. Suffridge and T. A. RennerThis paper presents the results of seven gravity drainage and diffusion- gravity drainage core tests. Tests were performed on a single 4.99 cm diameter by 243.8 cm long Berea core using laboratory fluids representing a range of capillary to gravity force ratios. The objective was to provide a validation database for the gravity function applied in a dual porosity simulator for use in developing optimum depletion strategies for fractured reservoirs.
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Relative permeability hysteresis in micellar flooding
Authors E. Eikje, S. R. Jakobsen, A. Lohne and S. M. SkjævelandThis paper presents two-phase relative permeability curves for drainage and imbibition measured by the displacement method for (1) excess water-microemulsion, and (2) excess oil-microemulsion, The results show that the relative permeability curves are process dependent, even at the low interfacial tension of 0.1 mN/m for microemulsion-water, and 0.005 mN /m for microemulsion-oil.
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Three-phase microemulsion relative permeabilities experimental and theoretical considerations
Authors B. A. Kvanvik, A. Skauge, B. Matre and K. KolltveitTwo and three-phase unsteady-state relative permeabilities have been measured on Berea cores, using a brine-microemulsion-oil system with low interfacial tension (IFT).
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Investigation of the mechanism of chemical destruction of surfactants applied for EOR
Chemical destruction of nonionic surfactants occurs under the action of elements in catalytic amounts, involved in the reservoir medium. In some oil fields the destruction can be as high as 80% (OΠ-10). Main products resulted from the chemical destruction are alkylphenols, paraffins, residuals of polyoxyethylene fragments followed by interetherification to form sulphide and sulphoxide compounds.
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