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Coal permeability is usually anisotropic and the permeability anisotropy ratio along the face cleats to the butt cleats can be up to 17:1 for some coals. The characteristic of the anisotropic coal permeability and its impact on the optimal well design for coalbed methane (CBM) production are important, but have not been well studied. This paper investigates this issue through numerical modeling and reservoir simulations. Various case studies are performed on the two commonly used multi-lateral well patterns including the quad-lateral well and the pinnate lateral well to investigate the impact of permeability anisotropy ratio on the layout of the multi-lateral well. The results demonstrate that the optimal well direction of the quad-lateral well is parallel to the butt cleat direction as expected. However, the optimal main well angle of the pinnate lateral well is significantly affected by the permeability anisotropy ratio. The …