Causes of solvent slug decrease during oil displacement processes under miscible conditions, with a review of simulation aspects of such processes

U ovom radu ukratko su obrađeni efekti difuzije i disperzije i drugi efekti prisutni tijekom procesa istiskivanja nafte tekućinama podatljivim miješanju, odnosno otapalima. Prilikom tih procesa dolazi do značajnog povećanja iscrpka nafte, ali istovremeno i do smanjivanja, a moguće i potpunog gubljenja čepa otapala. Kod projektiranja ovakvih procesa od iznimne je važnosti određivanje optimalne veličine čepa otapala koji je u direktnom kontaktu s ležišnim fluidima i gdje je spomenute efekte potrebno uzeti u obzir. Pri tome primjena simulacije ležišta kao prognozne metode proračuna dodatnog iscrpka može biti od pomoći ukoliko je dovoljno kvalitetnih podataka, npr. na osnovi laboratorijskih mjerenja na jezgrama, zatim tzv. slim-tube testova i/ili pilot ispitivanja reprezentativnih dijelova ležišta, raspoloživo za pojedini simulacijski projekt, a osvrt na to je dat u završnom dijelu teksta.The paper briefly describes the effects of diffusion and dispersion and other effects present during the oil displacement processes with miscible fluids, i.e. solvents. Recovery of oil is significantly improved during the application of such processes, but at the same time accompanied with decrease or even total loss of solvent slug. When designing such processes, particular attention should be paid to determine optimum slug size that is in direct contact with reservoir fluids, and where the mentioned effects have to be taken into consideration. Thereby the application of reservoir simulation, as a prediction method for calculation of incremental recovery, can be useful if sufficient high-quality data, such as laboratory core analyses, slim-tube tests and/or pilot tests performed on representative parts of the reservoir, are available for a particular simulation project, and the review of that is given in the final part of the text