Abstract
Barite sag continues to be a recurring, potentially serious problem on many directional wells. Despite concerted efforts by the drilling industry and early progress, recent continued improvements in sag mitigation have been limited. Sag is a particular problem on HTHP wells and in deepwater wells where ECD management is required. These wells pose difficult drilling conditions where drilling practices may offset sag-management advancements.
The sag "magic bullet" has thus far been elusive. This is understandable since sag is affected by many parameters and their interactions are difficult to quantify. While the importance of mud rheology is well known, attempts to find the key rheological parameter have not been completely successful. Furthermore, lack of industry standards to measure and report barite sag has limited the availability of usable field data. Sound engineering strategies and guidelines have helped, but clearly more developments are needed.
The primary objectives of this paper are to (a) examine key barite-sag challenges, (b) characterize current best practices, and (c) discuss strategies, opportunities, and active programs for step improvements. Recent barite-sag case histories from the Gulf of Mexico, West Africa, and Atlantic Canada are included to set the proper perspectives.
