“…For example, at any point in Ω the partial differential equation and/or the boundary conditions may contains integrals of the unknown u over parts of Ω, values of u elsewhere in D or, generally speaking, some non-local operator on u. Beside the mathematical interest of nonlocal conditions, it seems that this type of boundary condition appears in petroleum engineering model for well modeling in a 3D stratified petroleum reservoir with arbitrary geometry (see [12] and [15]). A lot of papers ( see [34], [24], [25], [2], [19], [1]) on problems like (1.1) considered cases of generally boundary value condition. In [6], Bonzi et al studied the following problems.…”