A fuzzy evaluation approach to oil/gas reserves analysis

It has been observed that reservoir stochastic modeling technology, which makes uses of the reserve´s parameters in stochastic model, solves the problem that the parameters are difficult to determine in complex reservoirs using traditional volumetric method. The approach, yet, without considering the inherent uncertainty of porosity, oil saturation and net gross ratio, can not determine the factors that play a leading role and evaluate the scale of influences on reserve calculation. In this paper, several sets of reserve calculation scenarios are presented based on the geological attributes of wells of X Oil Field. Using gray association analysis method to determine the reasonable petrophysical parameters, the optimal combinations of the influential factors involved in the calculation are used to compare relevance degrees of different programs. This paper resolves the ambiguity in the process of reserves estimation, following the quantitative assessment of effect of parameters uncertainty on reserve calculation. All we have attempted to achieve is to reduce risks and provide reliable basis in the decision-making of oil reservoir exploration and development.