Event-based risk management (EBRM) is an improved way of describing subsurface uncertainties and their possible business impacts in a manner that facilitates specific actions to improve business performance. In EBRM, uncertainties are viewed as potential causes of risk events that could in turn lead to consequences that affect the attainment of objectives. This “causes–event–consequences” syntax aids the design of prevention measures to inhibit the causes turning into the event and mitigation measures to reduce the potential consequences should the risk event occur, and it also facilitates construction of a risk taxonomy scheme based on risk consequences, events, and causes.

Using a data set of 1456 subsurface risks, each risk was described in this manner and placed in the taxonomy, and the proportion of risks in each taxonomic group was analyzed. This revealed clear trends in the relative frequency of risk groups with type of field: for example, risks related to hydrocarbon-in-place volumes are more frequently identified in deep-water oil fields and gas fields feeding liquefied natural gas plants, situations in which resource volumes are critical to support the large project capital costs. Trends were also evident with field maturity: for example, risks related to hydrocarbon-in-place volumes are more frequently identified before the field sanction decision than afterward.

Several benefits have yielded from EBRM: the risk description syntax encourages the creation of meaningful risk-management actions, the taxonomy and associated risk identification frequencies assist the identification of relevant risks so that key risk areas are not overlooked and also help to anticipate future risks, and the focus on risks (rather than uncertainties) helps to focus resources (data acquisition, technical studies) onto those aspects of the subsurface that are likely to impact business outcomes.