Numerical simulation of engineered water injection: Effect of Oil Composition and Rock Charge Distribution

Resumo

Oil production demands Enhanced Oil Recovery (EOR) techniques. Numerical simulation can simulate
recovery techniques such as injecting low salinity water into offshore carbonate reservoirs. However, numerical
modeling of LSWI has not been done mechanistically and needs solid scientific foundations. A numerical model
based on these foundations was created, using the PHREEQC program and the Python programming language as
a tool, to understand the effect of the presence of acidic and basic groups in the oil, positive and negative sites of
calcite (typical carbonate rock in Brazilian pre salt reservoirs), in the change of wettability, due to changes in the
composition of the injection water. For the development of the algorithm, the Complexation Surface Model (SCM)
and the Bond Product Sum (BPS) concepts were applied, aiming to predict the efficiency of the brine injection, to
increase the EOR. For oil, the acidic and basic numbers, when increasing, raise the BPS, when decaying, decrease
the BPS. But the acid influence is greater. For calcite, the influence of positive and negative sites have the same
proportion on BPS, following the same behavior of oil numbers. Because of that, wettability is changed, the higher
the BPS, the lower the EOR.