Assessing Combination Traps - Using Risk to Define Uncertainty

Probabilistic assessment of exploration prospects comprises two processes: estimation of the range of success case volumes, and estimation of the chance of success. The range of success case volumes is referred to as the prospect’s “uncertainty.” The chance of success is often incorrectly referred to as the prospect’s “risk.” Risk is actually the chance of failure, rather than the chance of success. Assessors typically consider the evaluation of “uncertainty” and “risk” to be completely separate activities. Combination traps (both fault-independent and fault-dependent) require a blurring of the distinction between uncertainty and risk. The chance of success for each trap type is used to define the uncertainty within the success case. In order to create the success case distribution of potential contacts in a combination trap, one must consider the chance of success for each individual trap type. This blurs the distinction between “risk” and “uncertainty.” Geologists who do not consider risk when assessing uncertainty may create success case distributions that cannot be technically supported.