Objectif The efficiency of polymer flooding in reservoirs with highly saline formation water depends to a large extent on the polymer's stability towards salt. Desalination or the use of a polymer that is efficient only at high concentrations may adversely affect the economics or technical feasibility of tertiary recovery.It is therefore necessary to develop a chemical system that can be applied in highly saline formation waters.Once a given field or part of a field has been selected for a pilot test, the data relating to it must be compiled.Anionic and nonionic synthetic polymers with different chemical characteristics show only a poor thickening behaviour in reservoir water of a high salinity. The effect exerted by polyacrylamides and acrylamide/acrylic copolymers in raising the viscosity is insufficient, even if their mol mass is extremely high. Using only nonionic monomers, e. g. vinyl pyrrolidone or acrylamide, results in a salt stable viscosity, but the absolute value of the viscosity is too low.However, polysaccharides are very effective thickeners in highly saline formation water. In contrast to xanthanes, glucanes have no anionic components and therefore show the largest viscosities. Classification of the glucane broth is possible by the combination of a centrifugation and a filtration process.Dueste-Valendis is selected as a field, where polymer flooding is suitable. Several geological and reservoir engineering data are obtained. Pulse tests have been performed, in order to see possible communication withwells in adjacent blocks.Tracer tests are necessary to determine sweep geometry and length of dispersion. Basic research work resulted in the development of a tracer system, which is suitable in Dueste-Valendis.A simulation study is intended to predict the optimum metering rate for the polymer and the production pattern. For this purpose, polymer-specific data for the field selected will be determined on samples of the reservoir rock.POLYMERS FOR ENHANCED OIL RECOVERY. Polymers produced in the laboratory have to be tested to determine whether they are suitable for use in reservoirs with highly saline formation water. If they are found to be suitable, their reproducibility must be checked on a pilot and a production scale.PRODUCT SCREENING. The conditions for dissolving and shearing on a technical scale are to be varied so that the optimum relationship between viscosity and filterability is obtained under the conditions in a reservoir with a salinity of about 150 g/l of total dissolved solids.DETERMINATION OF THE PROPERTIES RELATING TO FLOODING ON WATER-WET MODEL CORES. Flooding tests are performed on cores of different permeability in the range of intended injection and production rates. Adsorption and retention effects of the polymer are determined.OPTIMIZATION OF THE POLYMERS' LONG-TERM STABILITY. The effects exerted by various additives, additive concentrations and additive combinations on the polymers' long-term stability under the conditions in the reservoir.DETERMINATION OF THE PROPERTIES RELATING TO FLOODING ON OIL-WET MODEL CORES. The stability of the solutions in the presence of an oil phase and the chromatographic separation of the polymers are investigated.SELECTION OF THE RESERVOIR. A field must be selected that might appear suitable for polymer flooding in the light of its data, e. g. mobility ratio, average permeability, permeability variation, formation thickness, mineralogy, stage of depletion, and the maximum degree of depletion attainable by waterflood. The next step is the selection of a suitable, well-delineated reservoir block, for which purpose geological and reservoir engineering data must be reviewed. The possibility of communication with wells in adjacent blocks must be investigated by pulse tests and/or pressure measurements. PETROPHYSICAL INVESTIGATIONS. Coring in unconsolidated Valendis reservoir by special techniques and embedding the deep-frozen cores with inorganic solvent - resistant material allow determination of permeability, porosity, compressibility, capillary pressure, wettability, relative permeability, initial oil saturation, and residual oil saturation after waterflooding. In addition, mineralogical studies are performed.SIMULATION STUDY. A history match and feasibility tests to optimize flooding geometry and polymer slug volumes have to be carried out.DETERMINATION OF DATA RELATING TO THE POLYMER ON ORIGINAL CORES AT THE RESERVOIR TEMPERATURE. Mobility and permeability reduction are determined as well as retention and adsorption effects in large cores. Based on the injectivity of the polymer it has to be decided, whether a hydrofrac is necessary. Programme(s) ENG-HYDROCARB 1C - Programme (EEC) of Community projects in the hydrocarbons sector, 1973-1985 Thème(s) 1.5 - IMPROVED OIL RECOVERY Appel à propositions Data not available Régime de financement DEM - Demonstration contracts Coordinateur BASF AG UND WINTERSHALL AG Contribution de l’UE Aucune donnée Adresse 6700 LUDWIGSHAFEN Allemagne Voir sur la carte Coût total Aucune donnée
