Abstract
This paper is based on a collection of studies, partly published partly unpublished, where the performance of multilateral wells is assessed from the viewpoint of reservoir drainage. The underlying studies range from case study of multilateral wells with production history, to feasibility studies of multilateral wells (in land, platform, and subsea fields), to generic studies by numerical methods and optimization techniques on reservoir drainage efficiency of multilateral wells. This paper will not reproduce a full account of those studies, rather it will highlight the key lessons latent in those studies which may serve as useful guiding principles for those contemplating or planning use of such wells. Specifically, the paper addresses how multilateral wells fare against the more conventional or traditional horizontal wells. The key concepts are summarized in four ‘lessons’ pertaining to high-drawdown, low-drawdown, multi-reservoir, and injection applications. Brief mention is made also of aspects other than reservoir drainage (or injection) efficiency that can influence the choice of well architecture.
