Objective The objectives of the project was the development and pilot application of a high-salinity surfactant/polymer flood system which is able to achieve a higher ultimate recovery than zith conventional water flooding. The chemical system had to be designed for application in a reservoir of extremely high brine salinity of 195 g/l TDS without preconditioning of the reservoir (Loudon Pilot -Project : 104 g/l). The reservoir simulation study should establish a numerical model in order to simulate the flood process, support and optimize the process design for field scale-up, enable economic evaluation and study extended field applicability of the process. Engineering of the technical facilities for preparation of the flood solutions in a continuous in-line mixing process with supervision and automatic control equipment had to be planned and constructed.Laboratory workA surfactant/polymer system in reservoir brine was optimized in several flood experiments on Berea sandstone models and Leiferde core material of varying geometry. The microemulsion system consists of : 1. 5 % surfactant mixture (alkyl ether sulfate /alkylxylene sulfonate), 1. 5 % polyethyleneglycol (sacrificial agent), 0. 8 % white oil and 750 ppm polysaccharide in a brine /fresh water mixture of 160 kg/m3 TDS.In laboratory flood experiments the residual oil of about 40 % pore volume after water flood could be reduced to values below 10 % by chemical flooding (0. 2 PV microemulsion, 0. 8 PV mobility control ). Laboratory activities covered optimization of chemical system and flood sequence, selection of polymer (viscosity yield, injectivity), selection and analysis of tracers (ROH, NaSCN), development of a continuous mixing process for preparation of chemical solutions, treatment of clarification brine (coalescer), specifications of chemicals, test procedures forquality control and assistance in numerical simulation (measurement of input parameters).Reservoir Engineering and SimulationReinterpretation of logs of the Leiferde field wells resulted in a modified structure map of the pilot area in the south block.The flood concept was optimized as follows : history match of the south block, simulation of laboratory flood experiments and development of a field model for the chemical flood.The history match (water flood) used the 3-phase, 3D blackoil -simulator ECLIPSE. The calculated OOIP, cumulative oil and water production, water cut development and pressure agreed fairly well with field performance.The laboratory chemical flood experiments were matched with the simulator UTCHEM (University of Texas, Austin), the final data set being able to match all six linear and two areal floods with acceptable accuracy.With a selectional model of the pilot area, transferred to UTCHEM, a sensitivity study was carried out for final flood design.The result of the simulation of the pilot area led to an additional oil recovery of 14% PV over waterflooding.Engineering work for the required surface facilities for storage, blending and control units for the preparation of the chemical solutions and all injection facilities have been completed.Bids for construction of new and modification of available equipment have been obtained. The surfactant unit allows continuous in-line preparation of the solution. A heating unit and double -walled, insulated containers guarantee required temperature for storage and operation throughout the year. The polymer unit allows continuous preparation of the polysaccharide solution in a two-step dilution and shear treatment.The chemical flood process will be pilot-tested in the Leiferde oilfield (Gifhorn Trough, West Germany).During the Laboratory Phase a chemical system which can effectively mobilize residual oil had to be tested in laboratory flood experiment. For the numerical simulation of the chemical flood process the required input parameters had to be established, properties of the solutions determined, suitable tracers selected, analytical methods for control measurements developed and specifications worked out.In the Reservoir Simulation Study a numerical model of the reservoir had to be developed (history match). With this model the surfactant flood process has to be simulated using process data from laboratory measurement (surfactant flood prediction) in order to determine flood concept (slug sizes, injection and production rates etc. . ) and incremental oil recovery. A comparison of actual production performance with the prediction will furnish information to justify future applicability of the system.The Project Evaluation and Assessment will be based on following observations and measurements :- quality of delivered chemicals and solutions prepared by the surface facilities. Most important factors are compliance with specifications and injectability of the solutions.- development of displacement processThe chemical concentrations and the oil cut in the produced fluids will be measured.These data will indicate the displacement efficiency of the process and have to be compared to the predicted values of the model study . If required, the input data will be adjusted to update the model . For final evaluation the following investigations were planned : - technical and economical evaluation of the pilot- studies with larger reservoir models in order to gain information for future applicability in other parts of the oilfield- economic analysis for a commercial field project- investigate applicability to other oil reservoirs. Programme(s) ENG-HYDROCARB 1C - Programme (EEC) of Community projects in the hydrocarbons sector, 1973-1985 Topic(s) 1.5 - IMPROVED OIL RECOVERY Call for proposal Data not available Funding Scheme DEM - Demonstration contracts Coordinator DEA AG für Mineralöl und Chemie EU contribution No data Address Überseering 40 22297 Hamburg Germany See on map Total cost No data
