The Canadian foothills are situated in a challenging drilling environment with deep wells in hard, abrasive formations that lead to extended drilling times. There is a real concern of casing wear in the upper sections and special care must be taken to ensure the integrity of the casing throughout the life of the well. Studies have shown that even slight doglegs in this vertical section lead to localized "hot spots" where erosion of the casing is focused. Keeping the well straight in this highly dipping formation has been a priority for directional drilling companies and operators.
Rotary Steerable Systems (RSSs) have greatly assisted in drilling these wells. From a "closed loop" feature, which automatically seeks a vertical profile in an openhole sidetrack with a carefully controlled dogleg severity (DLS), the rotary steerable tool is proving invaluable in drilling these complex wells and in reducing risks.
This paper describes the use of the RSS in different drilling applications and the procedures that have been developed in Western Canada. Case studies illustrate the benefits now being realized.