ارزیابی ریسک اکتشاف هیدروکربن از طریق عدم اطمینان و روش های تجزیه و تحلیل حساسیت

The evaluation of the exploration risk in the oil industry is a fundamental component of the decision process related to the exploratory phase. In this paper the two basic components of the exploratory risk: trap geometry and trapped hydrocarbon quantities (fluid), are compounded in a single coherent uncertainty and sensitivity approach. The results clarify that the model geometry influences each Petroleum System Modeling step and that the geometric uncertainty is correlated with the fluid uncertainty. The geometric uncertainty evaluation makes use of geostatistical techniques that produce a number of possible realizations of the trap geometry, all compatible with available data. The evaluation of the fluid uncertainty, through a Monte Carlo methodology, allows us to compute the possible quantities of oil and gas, generated in a basin and migrated from the hydrocarbon source location to each single trap. The final result is the probability distribution of oil and gas for each trap in the basin, together with other useful indicators like: the hydrocarbon filling probability map, the closure probability map, the drainage area probability map, the spilling paths probabilities, the trap-filling scenarios.

In the hydrocarbon exploration activities the main goal is to find traps where oil and/or gas were accumulated and retained in quantities that are greater than a variable economic threshold. Neglecting all the economical variables that come into play, the basis of any drilling decision is associated with the presence/absence of hydrocarbons (hydrocarbon risk) in the potential traps of the basin. This evaluation is the result of the joint efforts undertaken by a team of geologists, geochemists, geophysicists and engineers, in trying to get the best picture of the prospects that may be potentially drilled. This study can be schematically split into two components: the geometric one and the fluid one. The first one is the object of Basin Modeling (BM) 1 activity, that gives a 4D (in space and time) description of the basin status and evolution. The fluid one is the objective of the Petroleum System Modeling (PSM), that produces the history of the geologic processes that led to generation and accumulation of hydrocarbons in the current traps.