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IOR 1997 - 9th European Symposium on Improved Oil Recovery
- Conference date: 20 Oct 1997 - 22 Oct 1997
- Location: The Hague, Netherlands
- ISBN: 978-90-73781-08-5
- Published: 20 October 1997
1 - 50 of 72 results
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Production Experience Boosts Further Oil Development on the Troll Field
Authors S. E. Wenneko, Ø. Bøe and G. OlsenThe Troll oil and gas field is located in 340 m water depth offshore Norway, about 80km west of Bergen, and covers an area of 700 km2. It contains an up to 27m thick oil rim sandwiched between a large gas cap and an active aquifer.
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Simulation of Hydraulically Fractured Wells
More LessThe technique of fracturing the wells is frequently used in petroleum engineering to improve the oil production. This technique is applied not only to vertical wells, but also to horizontal wells or multi-lateral wells. However, there are no efficient numerical methods to simulate these kinds of wells, especially for the fractured horizontal or multi-lateral wells. The handling of such a well by a reservoir simulator is particularly discussed in this paper.
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Managing Uncertainties in Resources Evaluation and Field Development Planning
More LessApplication of improved oil recovery methods requires considerable resources which advocates for sound evaluation of field development scenarios. Uncertainty in reservoir characterization makes an overall estimation more subjective and, therefore, less reliable.
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Improving Hydrocarbon Recovery Efficiency Utilising Horizontal Production and/or Injection Wells
Authors L. P. Dake, P. G. Sutcliffe and A. A. P. TweedieHorizontal wells have seen a dramatic rise in the range of applications and the number of wells completed during the past decade. However, horizontal wells have been primarily drilled as producers maximising the benefit from the large reservoir contact which such boreholes allow. To date there have been only a handful of reported applications of horizontal wells as injectors. The potential benefit of horizontal injectors could lie in improving the sweep efficiency and enhancing the degree of pressure maintenance characteristics of reservoirs as they enter an advanced stage of depletion in redevelopment projects.
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Layered Reservoirs with Crossflow and Gravity Effects - Numerical Studies
Authors G. B. Savioli, M. S. Bidner, P. M. Jacovkis and M. J. CoccoThe two dimensional flow of oil through heterogeneous and bounded reservoirs, including gravity effects, is rigorously solved by finite differences.
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Identification and Reduction on Uncertainties in Automatic History Matching and Forecasting
Authors T. Yi and T. Sezgin DaltabanThis paper presents novel applications of the Bayesian inversion approach and the simulated annealing method (SAM) for identifying and reducing uncertainties involved in automatic history matching and forecasting processes which are of paramount importance for optimisation of hydrocarbon recovery. The Bayesian inversion approach enables the priori knowledge about the inversion parameters to be incorporated into the objective function to form a posteriori, in conjunction with the likelihood function reflecting the mismatch between the history data and the data predicted from the numerical model. The simulated annealing method (SAM) bas been applied to escape local optima which may still exist in the posteriori objective function, in order to further reduce the nonuniqueness of the inversion solutions.
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Predicting Productivity of the Horizontal Well Inside Limited Reservoirs
Authors A. I. Ibragimov, M. N. Baganova and A. NekrasovIn the present paper new flow rate formulas for horrzontal and slanting well in isotropic and anisotropic reservoirs are presented. These formulas accurately approxímate dependenties of the well productivíty on geometric and hydrodynamic parameters of the system «reservoir + well» such as length, radius, and slanting angle of the well, distance to the external reservoir boundary, thickness of the lager, permeability, and anisotropy degree of the reservoir.
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Towards an Optimal Corporate Appraisal Strategy - a Global View
By F. DemirmenSubsurface appraisal is a key activity in exploration and production. Large sums of money, an estimated US$ 1 billion a year at least, are being spent by the industry to appraise new discoveries as well as fields that are candidates tor development.
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Simulation Study of Sabah Field, Libya
Authors A. M. Reda, K. Sadikoglu, D. Twaddle and M. ArbiThis paper describes a field study of a faulted, fractured, and multi-layered carbonate reservoir with 17 years of production and pressure history from 59 Wells. The reservoir is supported by an extensive aquifer that bas been sweeping the hydrocarbon from both the bottom and the edge. Early water breakthrough and rapidly increasing water cut bas been a major problem in many of the wells. The major objective of this study is to understand fluid movement in this complex multi-layered reservoir system, to locate the hydrocarbon that is trapped or unswept, and to recover it in an optimum fashion. The field is currently producing at an average water cut of 84%. Three infill wells have been drilled on locations recommended by the simulation, and were found to be at their initial water saturation as predicted by the model.
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A Priori Prediction of Relative Permeability and Capillary Pressure from Pore-Scale Modelling
Authors P. -E. Øren, S. Bakke and O. J. ArntzenWe reconstruct 3-D sandstone models that give a realistic description of the complex microstructure observed in actual sandstones. Pore networks replicating the microstructure of the reconstructed samples are constructed and used as input to a two-phase network model. The network model simulates primary drainage and water injection for both water wet and mixed wet systems. Predicted transport properties for different reconstructed sandstones are found to be in good agreement with available experimental data. The agreement provides a strong hint that it is possible to a priori predict average transport properties from the associated pore-scale parameters.
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Laboratory and Field Measurements of Residual Oil Saturation from Gas Injection at the Oseberg Field
Authors A. Skauge, J. I. Kristiansen and S. SøgnesandUpdip gas injection has been the main drive mechanism in the oil production from the Oseberg Field since the start of production in December 1988. The oil field is located in the North Sea area, and is one of the larger oil reservoirs. The paper summarizes the available data giving information about the residual oil saturation after gas injection, and show how log interpretations have been applied for monitoring of the gas displacement process.
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Application of a Novel Gas Single-Well Tracer Test to Determine Remaining Oil in Gas Flooded Reservoirs
Authors A. Skauge, T. Lind and H. A. DeansAn approach have been tested to obtain a reservoir estimate of residual oil saturation after gas injection. The methodology is similar to the weIl-known Single-Well Tracer Test that has been used to measure water flood residual oil saturation in-sits in more than 200 field trials since 1968. The gas tracer test was performed at the Oseberg Field, well 30/9-B-03. The actual formation had been gas flooded and was assumed to be at residual oil saturation.
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An Innovative Procedure to Compute Equivalent Block Size in a Dual-Porosity Model
Authors S. Sarda, B. J. Bourbiaux, M. C. Cacas and J. C. SabathierIn recent years, new techniques and methods have been developed to characterize the natural fracturing at various field scale and integrate fractured reservoir characterization data into 3D geometrical models of fracture networks. However, 3D images of fractured reservoir are not directly usable as a reservoir simulation input. Representing the fracture network in reservoir flow simulators was always considered unrealistic because of the partial knowledge of this network and because of numerical limitations. Actually, the Warren & Root model remains the basis for any dual porosity simulator. In this model, the fractured reservoir is represented as an array of numerical parallelepipedic matrix blocks separated by uniform orthogonal fractures.
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Numerical Evaluation of the Combined Effect of Wettability and Heterogeneity on Waterflood Performance
Authors R. Lenormand, K. Li, M. Robin and D. Bossie CodreanuLaboratory experiments have shown that wettability affects fluid distribution at the pore scale and therefore has an important effect on the end-point saturations and the shapes of capillary pressure (Pc) and relative permeability (Kr) curves.
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The Effects of Wettability and Interfacial Forces on the Depressurisation of Waterflooded Reservoirs
Authors R. I. Hawes, R. A. Dawe and C. A. GrattoniThe criticaI gas saturation when gas released from solution first becomes mobile is an important parameter in determining the economic viability of depressurising a reservoir after it has been waterflooded. If the value of the critical gas saturation is high, some considerable time elapses before any gas is produced, so that its discounted value is reduced, whereas a low value of critical gas saturation producer an early return on the investment.
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Experimental Determination of the Mobility of Hydrocarbon Liquids in Gas Condensate Reservoirs - Three Actual Cases
Authors D. C. Morel, A. Nectoux and J. DanguignyThe experimental results of three long core, low rate, reservoir condition gas condensate depletion tests are presented in this paper. The three cases exhibited very different PVT and rock properties. Early production of the condensed phase was observed, with CCS in the range of 0 to 11 %. Condensed phase recoveries varied from a few percent to 25% during these experiments.
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Simulated and Analytical Solutions for Fractured Reservoirs with Double Porosity Model
Authors Q. H. Liao, S. R. Hencher and J. H. BlackThis paper presents the results from research to validate discrete fracture network modelling simulations of fractured reservoirs by comparison with conventional analytical solutions. Model rock masses containing layered formations and regular orthogonal fracture systems have been generated using the program FracMan.
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Key Characteristics of Three-Phase Oil Relative Permeability Formulations for Improved Oil Recovery Predictions
Authors E. F. Balbinski, T. P. Fishlock, S. G. Goodyear and P. I. R. JonesSome IOR techniques create regions of three-phase flow. However, three-phase oil relative permeabilities are not generally well characterized and so there may be considerable uncertainty in the estimation of incremental recoveries. None of the many three-phase oil relative permeability formulations appear to fit the data outstandingly over the whole range [1]. Agreement is unfortunately worst in the low oil saturation regime, which is the most important for IOR. In the absence of a good physical model, and as a preliminary step, key characteristics of threephase oil relative permeabilty formulations which interpolate between given two-phase data are considered. In this way we hope to encourage best practice by avoiding those with undesirable or unlikely characteristics. In order to illustrate these conclusions a numerical sensitivity study of the effect of different formulations on the incremental oil recovery from immiscible WAG is presented.
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Estimation of Critical Gas Saturation During Pressure Depletion in Virgin and Waterflooded Reservoirs
Authors S. R. McDougall and K. S. SorbieOne of the most important issues in petroleum engineering concerns the prediction of gas production during reservoir depletion - either following conventional waterflooding operations or, increasingly, in the early stages of hydrocarbon production.
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Finding a Regular Geometry for an Irregular Reservoir Shape for Well Performance Calculations
Authors D. H. Tehrani, G. Chen and J. M. PedenThe shape and geometry of the reservoir play an important rule in well pressure performance calculations by analytical methods. Dietz (1965) reported analytical solutions for a variety of regular shape reservoirs.
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Measurement of Gas-Oil Contact Angle at Reservoir Conditions
Authors Z. K. Al-Siyabi, A. Danesh, B. Tohidi and A. C. ToddSurface forces between rock and fluid system play a major role in the flow characteristics of fluids in hydrocarbon reservoirs, hence, the recovery of hydrocarbons in such media. In petroleum engineering, these forces are indexed by the interfacial tension (IFT) between different phases, and the contact angle between the reservoir rock and the fluids. The evaluation and alteration of these forces are essentul in planning, management and operation of reservoirs for optimum recovery.
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Effect of Fractional Flow Heterogeneity on Compositional and Immiscible Displacements
Authors S. K. Subramanian, R. T. Johns and B. DindorukThe scale of heterogeneities in reservoirs is often smaller than the grid size used in large scale reservoir simulations. Relative permeabilities have the foremost effect on fluid flow and small scale fractional flow must be upscaled to the grid size in flow simulations.
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The Design of a Miscible Gas Flood for the Wytch Farm Sherwood Reservoir
Authors P. F. Harrison, A. P. Cockin and R. C. SkinnerA miscible gas injection project has recently been sanctioned for the Wytch Farm Sherwood reservoir. Commencing during the second half of 1997, a total of 23mmscfpd of miscible gas will be injected into five wells in a Water AIternating Gas cycle, sweeping the reservoir through inverted nine-spot patterns. The project will be extended to a further five patterns over a ten year period to cover almost 50% of the reservoir. It is predicted that an incremental 12.6mmstb of oil reserves will be produced, but losing 10.6Bscf of sales gas and 443mtn of LPG to the reservoir.
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Wettability Heterogeneities in Gas Injection - Experiments and Modelling
Authors C. Laroche-Jaffrennou, O. Vizika and F. KalaydjianThe objective of the present work is to study the effect of wettability heterogeneities on: (1) displacement mechanisme, (2) sweep efficiency, and (3) trapped oil quantities and fluid distribution in three-phase gas injection.
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Sweep Efficiency in a Waterflooding Pattern Processed by Horizontal Wells
Authors C. G. Popa, F. Simion-Constantinescu and G. I. MarcuJoshi [1] derived an equation to compute the horizontal well production considering that the flow is symmetrical and similar to the flow into a pipe-like radial fracture. However this is a rode approximation especially for long and very long horiwntal well sections where the pressure loss along the well pipe shell be taken into consideration. Some results [2,3] have shown that the pressure loss can play a significant role on the horizontal well performances. On the other hand the pressure loss along the horizontal section generate a non uniform flux and potential distribution along the well. This well influence the front displacement in a waterflooding process.
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Water Quality and Well Injectivity
Authors L. Nabzar, J. -P. Coste and G. ChauveteauSmall particles suspended in injection waters may cause more severe permeability damages than larger ones. In addition, the deposition kinetics increases as velocity decreases so that substantial permeability damages are expected at large distances from injection wells where remediation is questionnable.
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A Production Well Foam Pilot in the North Sea Snorre Field - Application of Foam to Control Premature Gas Breakthrough
Authors I. Svorstøl, T. Blaker, M. J. Tham and A. HjellenThis paper discuses the design, field operatien, data acquisition and the performance of a foam pilot conducted in the North Sea Snorre field in mid-1996.
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Foams for GOR Control - Improved Stability by Polymer Additives
Authors M. G. Aarra, P. A. Ormehaug and A. SkaugeDisplacement tests in sandstone cores have been applied to quantify formation of foam and the gas blocking ability of water continuous foams with polymer additives. The different chemical properties of polymers and their interactions with surfactants made it intergisting to test both biopolymers and syrithetic polymers. Love mobility foams were generated both in Berea and reservoir core material with AOS based foams. The formation of foam with alphaolefinsulfonate surfactant was little influenced by polymer additives as indicated by similar foam properties throughout the core. The gas blocking ability of the foams was improved with polymer.
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Immiscible WAG Injection in the Fensfjord Formation of the Brage Oil Field
Authors A. Skauge and E. A. BergAn immiscible gas, WAG injection was initiated in the Fensfjord reservoir of the Brage Field late 1994. Two injection wells initially applied cyclic injection of gas and water. The pulse length of gas injection was about three months, and the W/G ratio has been close to 1:1. Gas breakthrough was observed after three months, according to expected breakthrough time from simulation studies. The WAG injection has later been expanded to six injection wells.
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Simulation Studies of WAG Using Three-Phase Relative Permeability Hysterises Models
By A. SkaugeA novel three-phase relative permeability hysteresis model has earlier been developed from experimental results. This paper has applied the three-phase hysteresis approach in simulations of three-phase flow situation and especially immiscible WAG.
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A Detailed Simulation Study of WAG Injection in a Heterogeneous Fluvial Reservoir Zone
Authors D. Kjønsvik, J. A. Stensen and J. AlvestadThe WAG performance in a water flooded high net-to-gross fluvial reservoir zone is compared to continoued water injection and tertiary gas injection. The reservoir model is a realistic, stochastic and detailed representation of a zone in a North Sea reservoir. The WAG process is studied in detail, with respect to fluid distributions in the inter-well volume and the attic volume for different production scenarios. A special focus is put on the influence of hysteresis in the gas relative permeability.
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Reduced Gas - Water Segregation by Use of Foam
Authors T. Holt and T. VassendenTwo dimensional laboratory experiments bas been performed in order to study the segregation of gas and water, and foam. The observed gas/water segregation was in good agreement with segregation theory, whereas foam segregation appears to be slower than predicted from theory, indicating an improved sweep efficiency by injection of foam. The latter observation is not conclusive, however, as all aspects of the foam experiments are not presently understood.
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Laboratory and Field Studies on Gravitational Effect in Low-Tension Waterflooding
Authors G. Gesztesi, M. Bodola, J. Török, J. Toth and B. MatingTheoretical considerations indicate the dominant role of gravitational force when emulsified oil flows in low-tension environment. Spontaneous segregation observed in vertically oriented sand columns suggests the gravity underride of the mobilizing micellar solution.
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Thin Under Gas Oil Rims - New Technology for Efficient Oil Production Using Foam Generating Oil/Water Polymers
Authors G. S. Stepanova, Y. G. Mamedov, I. A. Babayeva, A. A. Mosina, T. L. Nenartovich and A. A. LiWorldwide experience shows that oil production from thin onder gas cup zones with active aquifer is not efficient doe to quick gas/water breakthrough and depends on oil column thickness and the ratio between gas cap and oil part thickness. New WAG Technology based on injection of water solution of oil/water soluble polymers for efficient oil production from thin (5-15m) oil rims have been developed. Results of lab studies and simulation are discuseed. New WAG technology can be used for production of both, light and heavy oils. For heavy oils this technology can be considered to be as altemative to thermal EOR.
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Foam Propagation in Snorre Reservoir Core - Effects of Oil Saturation and Ageing
Authors K. Mannhardt and I. SvorstølA series of foam floods was conducted in Snorre reservoir core at 90°C and 300 bar, at different oil saturations. The rate of foam propagation and the time required to reach the maximum attainable apparent foam viscosity depended strongly on oil saturation. Apparent foam viscosity decreased steeply at a "critical " oil saturation of 13 to 15%. Extremely high apparent foam viscosities, up to 1000 cP, were generated at miscible gas flood residual oil saturation (13%). Above the critical oil saturation, strong foam with apparent viscosities of about 200 cP were still formed, compared to apparent gas viscosities in the absence of surfactant of 0 .5 to 0. 7 cP. The effect of gas composition (Snorre field gas, methane, nitrogen) on foam performance was minor. Significant residual gas mobility reduction was observed during gas injection into the foam-filled core.
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Role of Interfacial Rheological Properties of Oil/Water Systems in Mechanism and Design of EOR/IOR Technologies
Authors J. Lakatos-Szabó, I. Lakatos and B. KosztinInterfacial rheological properties of different Hungarian crude oil/water systems were determined in wide temperature and shear rate range and in the presence of inorganic electrolytes, tensides, alkaline materials and polymers. The detailed laboratory study definitely proved that the interfacial rheological properties are extremely sensitive parameters towards the chemical composition of immiscible liquids. Therefore, comparison and interpretation of the interfaciel rheological properties may contribute significantly to extension of the spectrum of the reservoir characterization, better understanding of the displacement mechanism, development of more profitable EOR/IOR methods, intensification of the surface technologies, optimization of the pipe line transportation and improvement of the refinery operations.
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Selective Fluid Shut-Off Treatments at the Algyõ Field, Hungary
Authors I. Lakatos, J. Lakatos-Szabó, S. Trömböcky, M. Bodola and G. PalásthyThe paper analyzes the field results of different selective fluid shut-off treatments carried out at the largest Hungarian oil field during the past decade. The polymer/silicate method was routinely and profitably used for water shut-off in oil producing wells. Recently a novel method based on is-site hydrolysis and flocculation of inorganic compounds is tested with the same goal. A complex foam/gel double injection technique was developed and used for restriction of gas conning in oil producing wells. Restriction of water conning and side invasion by injection of alcoholic polymer solutions into gas producing wells is also in the centre of field management. Although diverse experiences were obtained, the positive results and the substantial oil production entourage the experts to continue the laboratory and the field studies and to implement prospectful methods.
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Optimisation and Risk Assessment of a Water Shut-Off Treatment in a Wytch Farm Horizontal Well
Authors D. J. Franklin, J. R. Todd, C. L. Woods and B. R. GaneLimitations on water handling capacity at Wytch Farm mean high water-cuts from horizontal wells could lead to toss of oil production. To avoid this, a pilot study has been undertaken on a single horizontal well, to investigate the potential for a water shut-off treatment and estimate the associated risk. The study has shown that a water shut-off treatment early in 1997 should be economically beneficial to the performance of the field as a whole. Conditions that would reduce the return on the treatment have been identified and can be avoided by optimising the strategy, increasing the robustness of the project.
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Well Shut-Off Treatments - Near Well Simulation and Evaluation
More LessMany North Sea reservoirs are produced with waterflooding, gas or Water-Alternate-Gas (WAG) injection schemes. Non conformance of flooding, gravity override or underride, and the presente of the high permeable thief zones cause premature water or gas breakthrough problems in production wells.
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Placement Simulations Improve the Design of Water Shut-Off Treatments
Authors M. Hardy, D. van Batenburg and W. BotermansIn the past, high-volume water shutoff treatments have not been applied because of the economic burdens they incur. Today, many operators have reconsidered high-volume water shutoff treatments because these treatments make oil production from mature reservoirs more economically feasible. Many wells in mature North Sea reservoirs produce a large amount of water. Consequently, these wells often produce less oil than they potentially could.
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A Successful Immiscible CO2 Field Pilot in a Carbonate Heavy Oil Reservoir in the Ikiztepe Field, Turkey
Authors H. Ishii, H. K. Sarma, K. Ono and K. IsseverAn immiscible CO2 field pilot was completed successfully by Japan National Oil Corporation (JNOC) and Turkish Petroleum Corporation (TPAO) in a collaboration with the Japan EOR Research Association (JEORA) in the Sinan heavy oil reservoir in the Ikiztepe field, Turkey.
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Polymer Velocity Enhancement and Accumulation at Water Oil Interfaces
Authors G. A. Bartels, J. Bruining and P. ZithaAn important aspect in polymer flooding is the existence of inaccessible and excluded pore volume in the reservoir. This leads to velocity enhancement i.e. polymere move faster through the porous medium than the water in which they are dissolved. In the conventional description the velocity enhancement factor is taken to be constant. We derived new model equations based on a percolation model. It turns out that the velocity enhancement factor can be expressed in terms of relative permeabilities and is therefore saturation dependent. This results in an accumulation of polymers at the oil interface. We verified the the theoretical findings with two-phase polymer flow experiments. Our experimental results show indeed a considerable pile-up of polymers at the interface.
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An Experimental and Numerical Study of Polymer Action on Relative Permeability and Capillary Pressure
Authors P. Barreau, D. Lasseux, H. Bertin, P. Glénat and A. ZaitounInjection of polymer or gels in oiI or gas production wells is commonly used, among other techniques, to reduce the water cut when excessive water production occurs.
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Role of Polymer Adsorption and of Petrophysical Properties in Water-Cut Control Treatments by Polymer Injection in Gas Wells
Authors L. Chiappa, A. Mennalla and M. OrtolaniControlling water production is an increasing concern to oil companies as currently developed hydrocarbon fields mature. Reduced well productivity, increased costs associated to produced water treatment and premature well abandonment (in gas fields) are typical drawbacks caused by excessive water production.
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Water Shut-Off by Disproportional Reducing Gel - a Case Study
Authors K. O. Hettervik, S. R. Jakobsen, B. Schilling and A. StavlandApplications of disproportional permeability reducing (DPR) gel is discussed in this paper.
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Gravitation in Thermal EOR - How Disadvantage Can Be Used to Improve Efficiency of Thermal EOR
Authors D. G. Antoniady, A. A. Boxerman, A. R. Garushev and Y. I. StashokIt is a matter of general experience that gravitational effects arising during injection of air or steam most often affect adversely the efficiency of thermal EOR methods. Advantages of these methods are generally used where possibility exists of engineering a horizontal displacement.
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Laboratory R & D Leads to MEOR Field Pilot in Fuyu-Oilfield, China
Authors H. Yonebayashi, H. Enomoto, K. Fujiwara and C. -X. HongA MEOR field test is being conducted in Fuyu-oilfield, China to increase oil recovery from a mature reservoir through the waterflood for over 20 years.
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