Play risk evaluation for hydrocarbon exploration

Risk and uncertainty are coherent attributes in hydrocarbon play exploration, and comprehensive exploration strategy requires a deliberate consideration of risk aversion and an faithful understanding of uncertainty. According to the characteristics of SINOPEC oversea oil and gas exploration projects, as well as the exploration project evaluation criteria of international oil companies, this paper describes the establishment of value-determined standards and hydrocarbon play risk workflow by quantitative assessment of hydrocarbon generation and charge capability, reservoir quality, preservation condition, and trap validity of a play. According to data density, coverage and geological understanding, in accordance with bucket theory, the probabilities of occurrence of four risk factors were determined, and the chance of geologic success (COGS) of a play was obtained by multiplying the probabilities of each risk factor. This workflow provided a method for transferring qualitative geological understanding and exploration data to quantitatively assess the risk probability of each factors and overall COGS. The COGS values determine the play risk, which is a comprehensive reflection of the exploration phase and geological characteristics of the study block. The play risk workflow facilitates high grading areas, allows a focus on the exploratory and appraisal aspects, and provides a scientific basis for exploration investment decision.