Abstract: There is greater error in steady productivity prediction of horizontal well,it is found out that,through semianalytic coupling model calculation correlation,under the condition of different oil drainage shape and anisotropy of horizontal permeability,the error changing law of Joshi formula is that the expected value is 30% smaller under the condition of thick pay zone,low vertical permeability or short horizontal section,and the value will be 30% greater under the condition of thin pay zone,long horizontal section or elongated drainage area.Furthermore,the semianalytic coupling model is employed to calculate the productivity index of horizontal well in different elliptic drainage area,nonlinear regression is carried out by SPSS software,the nondimentional productivity index prediction relation of horizontal well is obtained,the relative error is within ±1.5%,the prediction precise is enhanced considerably.

Key words: horizontal well, productivity prediction, relational equation