Objectif Many reservoirs have long been subjected to water drive. Hydrocarbon gas injection in conditions of multiple contact miscibility is one of the most promising processes for recovering "tertiary oil" (i. e. residual oil after waterflooding or water drive).The aim of this research project is to specify the conditions of optimization of injecting dynamically miscible gas injection into a reservoir already waterflooded, through experimental, numerical and economical approaches.A detailed knowledge of the mechanisms (involved in the creation of growth of the oil bank) is first needed to obtain reliable predictions from numerical simulation of this process. Once the numerical model is validated, it will be used to study the feasibility of a pilot injection project (including both reservoir engineering and economical aspects).This new tertiary enhanced oil recovery process should enable 25 to 30 % of the residual oil to be recovered.Phase 1 :Both frontal and rear miscibility, as tertiary recovery process, were proven to be very promising in terms of their efficiency to displace the oil trapped during the water drive.The effect of the swelling of the oil by the injection gas was brought into evidence in vaporizing and condensing gas drives. From the comparison of the results of two experiments corresponding to tertiary condensing gas drive, the swelling effect being much more considerable in the second experiment, it arises that the swelling mechanism contributes largely to stabilize the advance of the injection gas. In case of vaporizing gas drive, the effect of swelling mechanism is less considerable, since the type of miscibility developed is "self-stabilizing".Results of the numerical simulation are satisfactory.Phase 2 :Physical simulation of various cases of applications led to the same type of production histories as those obtained in the phenomenological study using synthetic fluids.The tertiarymultiple contact miscible process is demonstrated to be highly efficient for recovering waterflood residual oil in the various cases of application simulated physically. Water-alternating gas injection experiments (condensing and vaporizing gas drive), indicated clearly effects of slug size and slug ratio. The numerical simulation gave satisfactory match of lab experiments, confirming that SIMCO model can be considered as a reliable predictive tool for field application studies.Phase 3 :The Alwyn North field was selected for the pilot feasibility study.- A first screening study performed on 2D cross-section, allowed to select the best reservoir/gas couple (associated gas to be injected in the BRENT NW reservoir as pilot project).- Complementary laboratory experiments have been performed on the actual selected rock-fluid system. The confirmed the feasibility of the tertiary miscible gas injection, Triphasic relative permeability experiments have also been performed. The oil PVTwas adjusted on several lab results, including oil swelling by different gases.- A 3D model was then set up to define the optimum conditions of miscibles gas injection : Additional oil recovery is evaluated to be 13. 2% with total recovery of the injected gas with definition of the OOIP.- Results on the pilot project have been extrapolated to the whole ALWYN NORTH field. Reservoir performances (gas injection/production, oil production, water injection/production versus time) have been defined.-.- A preliminary pre-project study has been done, to describe the equipments and to evaluate technical costs of the work programme necessary to implement the project on ALWYN. Results are positive.The efficiency of miscible gas injection under tertiary conditions is related to the formation of an oil bank by remobilization followed by coalescence of the drops of oil trapped in dispersed fashion.The following questions arise :- how do the mechanisms of diffusion, dispersion, mass transfers implement the creation and the growth of the oil bank?- what is the influence of the petrophysical properties of the reservoir?- what procedures must be complied with so that the laboratory results can be considered as usable for the following reservoir simualtion?The project is to take place as follows :- PHASE 1 : Study of the mechanisms.The purpose is to identify for each type of dynamic miscibility ( frontal, rear, partial) the critical parameters playing the major role to implement the creation and the growth of the oil bank :. mechanisms of dispersion, diffusion. polyphasic flow mechanisms The experimental part of the work consists mainly in displacement experiments using synthetic fluids in order to facilitate the interpretation of the results. The numerical simulation of these experiments is to show if adaptations of the available numerical simulators are necesary to match their history.- PHASE 2 : Extension to actual cases.This phase consists of verifying the statements obtained in phase 1 by studying the sentivity of the tertiary recovery process on actual field conditions (displacemnet experiments with fluids and rocks from different types of reservoir). - PHASE 3 : Feasibility of a pilot injection project.The choice of the reservoir for this feasibility study. will be done according to the results of the preceding steps.Much attention will be devoted in order to select the best candidate among the different fields preferentially situated in the European zone where the contractor, through participations or operations, has already got a good preliminary information.This phase will consist of a complementary laboratory study, on the selected couple reservoir engineering study, the pre-development study and the economical aspects. /injection gas, the reservoir -engineering studies, the pre-development study and the economical analysis. 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 GERTH Contribution de l’UE Aucune donnée Adresse 232 AV. NAPOLEON BONAPARTE 92500 Rueil Malmaison France Voir sur la carte Coût total Aucune donnée
