Inflow Performance of a Stacked Multilateral Well

The use of multilateral well is becoming an emerging method to improve oil recovery efficiently. A stacked multilateral well can produce fluids from two or more separate productive zones. Unlike a commingled vertical well, inflow performance relationship (IPR) of a multilateral system is influenced by wellbore hydraulics of the horizontal boreholes. As a rock and fluid properties may vary considerably from one zone to another, construction of the composite IPR would become a necessity in an effort to evaluate and optimize the production performance. The purpose of the present study is to investigate the effect of pressure losses along the horizontal wellbores on inflow performance of a multilateral well system. A mathematical model is used here to calculate pressure losses within the wellbores and the productivity indices as well. A procedure to construct the composite IPR of a multilateral well and a method to predict the production decline are presented. A parametric study of wellbore hydraulics of a multilateral well system has been conducted. In general, results obtained show that increasing pressure losses in the lateral holes leads to the IPR curve shifting downward and reduced daily oil production. These demonstrate that production rate estimation for a given multilateral well would be too optimistic when pressure losses are omitted. No such work on stacked multilateral wells has been reported in the pertinent literature. Overall, this paper provides some information to better understand the application of multilateral well technology and to improve our knowledge of the importance of wellbore hydraulics evaluation in the performance prediction. It is particularly important to production engineers in an attempt to optimize and design the production equipments.