The well response for production at a constant rate for a composite system; pressure, , and the corresponding derivative, , responses, the top and bottom sets of curves, respectively, are shown. The intent is to demonstrate the influence of diffusivity ratio, , and the exponent, . The unbroken lines presume that the ’s are equal; the symbols denoted as circles and squares presume that . If the ’s are equal, then the influence of η_D is negligibly small; see Curves labelled B; the corresponding derivative curve shows that the analytical solution shown as a dashed line (marked AN) predicts values in excellent agreement. The circles and squares illustrate the influence of for . In general, solutions depend on both and .