A GENERALIZED EQUATION FOR CALCULATING THE PRODUCTIVITY OF VERTICAL AND HORIZONTAL WELLS IN HOMOGENEOUS AND STRATIFIED RESERVOIRS

An equation for calculating the productivity of a horizontal well prod ucing under pseudo steady-state flow is presented. It is easy to use a nd is identical in form to that used for a vertical well. With the pro per changes in variables, the equation can be generalized to cover ver tical wells. The drainage volume is assumed to be box shaped, and perm eability anisotropy in the x, y and z-directions is accounted for. Thi s feature is novel to the Industry. The productivity of a horizontal w ell in a stratified reservoir with cross flow is also given in an equa tion form, similar in structure to that of a one layer reservoir. Thes e equations were derived from very complex general solutions. Example calculations illustrating the use of the equations are given.