Abstract: To improve water flooding results in low permeability reservoirs,a new approach used to identify heterogeneous formations for well pattern adjustment was proposed in this paper.The coupling effect of permeability heterogeneity and the geometry of water flooding well pattern had been studied by using reservoir engineering method.In the research,two new factors,seepage factor and variable coefficient of seepage factor,were introduced,then the new method for well pattern adjustment and injector offset were derived from the analysis of the seepage process,its adaptability was evaluated by black oil numerical simulation.The variable coefficient of seepage factor decreases as the increase of injector offset from the orientation of well row.Furthermore,the distance of injector offset is going to be longer as the crosscutting ratio of well pattern goes down and the permeability difference of sand body rises.The production of the well group increased 5.6% and water cut decreased 3.7% after the optimal distance of injector offset,resulting in a significant improvement in water flooding.The proposed approach for heterogeneity evaluation and the formula calculating optimal injector offset provide new ways for well pattern adjustment in heterogeneous and low permeability reservoirs.