Purpose: The ability to monitor and detect anomalous changes in an oil well is a fundamental aspect of an offshore driller's job, so as to maintain well control, the safety of the surrounding rig and minimize risk. Drillers are required to have a high level of situation awareness in order to recognise and interpret indicators that suggest that hazardous hydrocarbons may have entered the well bore (referred to as kick detection), allowing them to take the best actions to deal with the situation. The aim was to use cognitive task analysis methods to identify the expert SA skills required for the complex task of kick detection. Method: An Applied Cognitive Task Analysis (ACTA) of the SA components required for kick detection was conducted. 1. A technical task description was produced, using material extracted from well control manuals and a five day training course. 2. The SA components required for the kick detection task using the preliminary Drillers' SA model. 3. The ACTA data were validated by three drilling experts. Results: The specific cognitive skills associated with maintaining SA that were required for accurate kick detection were: attending to and recognizing changes in the drilling parameters, understanding their significance as kick indicators in the context of a mental picture of the well state, and anticipating what could result in a kick, necessitating flow checking and/or shutting in actions. Limitations: ACTA methods are prone to research bias however actions were taken to minimize this. Practical implications: Training and work design recommendations based on the ACTA are outlined for supporting driller SA for effective well control and consequently to improve process safety. The study also illustrates how ACTA methods can be used to examine and support cognition in the workplace. (C) 2016 Elsevier Ltd. All rights reserved.