A method may include obtaining well activity data regarding various wells in a reservoir region of interest. The method may further include determining a predetermined well assignment for various parallel processing stages using a bin-packing problem algorithm and the well activity data. The predetermined well assignment may assign the wells to the parallel processing stages. A respective parallel processing stage among the parallel processing stages may perform a portion of a reservoir simulation using a respective computer processor and a well among the wells. The method may further include simulating the reservoir region of interest based on the wells being simulated according the predetermined well assignment for the parallel processing stages.