Abstract: Muddy interbeds are extremely developed and widely distributed in the terrestrial heavy oil reservoirs in Fengcheng oilfield, Xinjiang. The muddy interbeds exhibit serious heterogeneous and discontinuous distribution with distinct differences between intervals, which significantly impacts the effective development of the heavy oil reservoirs by SAGD technology. In order to evaluate the quality and reconstruction effect of the reservoirs, the reservoir heterogeneity caused by the muddy interbeds needs to be quantitatively analyzed. By using the Lorenz curve method, the paper establishes an evaluation model to characterize the muddy interbed distribution in oil sands; and presents several concepts about geometrical heterogeneity coefficient, numerical heterogeneity coefficient and composite heterogeneity coefficient and their calculation methods. With this method, the permeability profiles of 3 SAGD wells are evaluated in Wellblock Zhong-18 of Fengcheng oilfield, and their correlations with the recovery after 14 years of stable production which is predicted by CMG numerical simulation software are analyzed. The results show that the method can distinguish the heterogeneity differences between different profiles and the composite heterogeneity coefficient exhibits a good negative correlation with the recovery, which could guide block optimization for SAGD and reservoir reconstruction effect evaluation