A semi-analytical method for the multilateral well design in different reservoirs based on the drainage area

The determination of the optimal multilateral well configuration for different kinds of reservoirs is extremely challenging due to the wide varieties of possible well type. In this paper, we propose a novel method to determine the number of laterals, lateral length and lateral spacing in the multilateral well. The objective in the design is to fully exploit the entire reservoir within a certain period of development time. A geological map is constructed based on the reservoir properties. The fast marching method is used to calculate the drainage area of each lateral in the development time. The drainage area of the designed multilateral well configuration can cover the entire reservoir. The results have been validated by analytical method and specific steps of the method are presented. The applications in both homogeneous and heterogeneous cases are studied. Longer development time can lead to less number of laterals, shorter lateral length and larger lateral spacing. The drainage area is irregular in the heterogeneous case. The algorithm can automatically determine the number of laterals, lateral length and lateral spacing based on the geological characteristics to exploit the reservoir efficiently. The proposed method is appropriate for the field application due to the short computational time.