Modelling Inflow Performance of Multilateral Wells by Integration of Numerical and Analytical Approach

Multilateral wells have emerged as a new means, alternative to vertical and horizontal wells for optimal reservoir exploitation. The single wellbore requires fewer production well slots hence reduces cost of rig time, tools, services and equipment together with increased and accelerated reserves. The main objective of this project is to develop a swift novel approach to predict and assess inflow performance of multilateral wells. Two modelling techniques are applied that is by using numerical and analytical approach. Numerical approach implements production optimization software tools to model the multilateral well inflow performance and perform sensitivity analysis against varying reservoir condition. Analytical approach employs horizontal inflow performance models to determine the multilateral well deliverability and perform sensitivity analysis against different well configuration. The single phase inflow performance models considered in this project are Joshi’s model (1988), Butler model (1994) Furui et al., model (2003), Babu and Odeh model (1989) and Helmy and Wattenbarger model (1998). The analysis is done under two different conditions: Steady-state and pseudo-steady state condition, for dual-lateral and tri-lateral well. Hypothetical reservoir and well data is used to generate similar inflow performance models for numerical and analytical approach. The models from two different approaches are compared and the analytical model that give the least percentage of difference from PROSPER model is selected to perform the sensitivity study. The inflow performance models simulated by both approaches show a combination of straight line and Vogel inflow performance model. For dual-lateral and tri-lateral well under steady-state condition the analytical model that gives the closest match to PROSPER model is Butler model (1994). For dual-lateral and tri-lateral well under pseudo-steady state condition the model that gives the least percentage of difference with PROSPER model is Helmy and Wattenbarger model (1998) and Babu and Odeh model (1989) respectively. The significance of this study is because prediction of well performance is one of the key factors in deciding the economic viability of a project. Estimates of well performance assist petroleum engineers to decide the optimum production and reservoir management plan.