Pressure-transient behavior of horizontal wells with and without gas cap or aquifer

New analytic solutions are presented in real time and as Laplace transforms for horizontal wells in reservoirs bounded at the top and bottom by horizontal planes. Two types of boundary conditions are considered at these planes, and the Laplace-transform pressure solutions are used to include wellbore-storage and skin effects. Solutions are based on the uniform-flux, line-source solution, but differ from most existing solutions owing to the use of pressure averaging to approximate the infinite-conductivity wellbore condition and use of the correct equivalent wellbore radius for an anisotropic reservoir. New flow periods (regimes) are identified, and simple equations and existence criteria are presented for the various flow periods that can occur during a transient test.