Abstract: It is difficult to be put into production using common development mode and technique for W11-1E marginal field of Weixi' nan depression, making full use of available platform, and development of the extended reach well is an effective way to solve this problem.There is no much study on enhancing oil recovery of ordinary heavy oil reservoir with calcareous layer at present.The main conflicts are that the oil production raised as much as possible and the water breakthrough won't occur when the energy of water drive is utilized rationally.On the basis of optimization of horizontal well parameters and avoiding risk of formation crude viscosity, the conflicts was solved making full use of the elimination of top and bottom calcareous layer to edge water coning.3 drilled extended-reach horizontal wells is comparatively good, showing a high initial productivity and low water cut, reserves and production increased and high-efficiency development were operated simultaneously in the end.