Multilateral wells with smart completions controlled by different flow-control technologies offer great operational flexibility, with each lateral able to be operated and optimized independently. Understanding the contribution of each lateral in the complexity of the system was a major objective of this study. In order to optimize the system and predict results under different operational conditions, a multilateral-well-modeling methodology was developed. This methodology covers two main factors affecting multilateral productivity—a flow-dependent gas/oil ratio (GOR) and interference between the laterals.
The study was based on multilateral wells complete with inflow control valves (ICVs). As a general description, the wells are completed with three to seven laterals and each lateral is isolated by packers and controlled by an ICV, as shown in Fig. 1.
A multiphase surface system flow simulator that is able to optimize production from wells and networks as an integrated system was adapted to generate and optimize the subsurface multilateral-well flow behavior. This simulator is used mainly for surface network modeling and optimization, but the complex subsurface well system was modeled with this application. This complex simulation model resolves and finds the optimal ICV pressure drop and diameter for each lateral for different inflow-performance conditions, such as different rate-dependent GOR curves at different operational conditions. The model was created as a black-oil model. In each lateral, the flow and pressure drop through the reservoir are determined in the horizontal section, as well as the annular flow between the casing and tubing. Each ICV is represented with a choke model....
A Methodology for Multilateral-Well Optimization
01 May 2017