Effective Wellbore Length (Le)

In horizontal well test analysis, the length of the wellbore that is contributing to flow is called the effective wellbore length. It is almost always smaller than the actual horizontal wellbore length (L). For example, a well may be drilled for 5,000 ft horizontally, but only 3,000 ft may be contributing to flow, either because the rest of the wellbore is damaged, or it may even be outside the reservoir. In this case, effective wellbore length would be 3,000 ft and horizontal wellbore length would be 5,000 ft.