Określenie możliwości zastosowania symulacji komputerowej do przewidywania kierunku przebiegu reakcji podczas zatłaczania wód złożowych

Abstract

Currently, practically the entire volume of water extracted in the process of hydrocarbon exploitation is utilized by injection into deposits. Changes in the physico-chemical parameters (pH, red-ox potential, temperature, etc.) of the water during extraction and the contact of the injected water with the native water and deposit rock may result in the precipitation of sediment particles and suspensions. It causes clogging of the near-wellbore zone and limits the amount of water that can be injected with the injection well. Due to the high complexity of the system: the injected water–reservoir rock, and a wide range of interactions between individual components, the analytical data does not always allow for the correct interpretation of the course of the processes and determination of their impact on the permeability of the near-well zone. Using the results of physico-chemical analyses of the composition of separator water samples with different properties – two samples with low mineralization S1K (575 mg/dm3) and S4K (551 mg/dm3), a sample with high S2K (306 428 mg/dm3) and medium mineralization S3K (79 858 mg/dm3) – calculations were performed using the PHREEQC program for the three databases: phreeqc.dat, wateq4f.dat and pitzer.dat. It was found that in the case of low mineralization waters, the results obtained in each of the databases are similar for the minerals present in all the databases. However, in the case of solutions with high mineralization, there are significant differences in the obtained results. The calculated solubility indices allowed to determine the direction of the precipitation/dissolution reaction of individual minerals in the deposit and to indicate the risks, mainly with the formation of iron compounds deposits, for the operation of the injection well. Laboratory tests of water mixing were also carried out. The formation of iron oxide deposits that could damage the near-well zone was observed, which confirmed the results obtained during computer simulations.