Abstract In this paper we present the application of the technique of artificial neural networks to the thermodynamic characterization of reservoir fluids. The development of a demarcation system that allows the prediction of reservoir fluid type, (black oil, volatile oil or gas condensate) based on field information from production tests and validated PVT analysis is described.
Neural networks are coarse models of the human neural system an they have been used successfully in solving practical problems of pattern recognition. In this work, a carefully selected data set of eighty (80) gas-oil ratios API gravity and percentage of C7+ composition values, corresponding to black oil, gas condensate and volatile oil were used for training the neural network. The training objective was the recognition of fluid type. The trained system, was validated with two hundred and fifty (250) PVT laboratory test from eastern Venezuela showing an excellent performance in fluid type characterization. The reservoir fluid type forecasts obtained with this approach were found to be outstanding when compared to those made through the application of classifying criteria proposed by other authors. It is concluded that the proposed demarcation system is superior to the previously reported techniques.
Introduction In recent years, the characterization of the phase behavior starting from production data of fluids originally "in place" has emerged as a challenging problem in the study of oil reservoirs, the determination of fluid type in a reservoirs is a very important and decisive step in reservoir engineering. Many of the decisions which must be made regarding the reservoir depend on fluid type. For instance, the method of fluid sampling, the types and sizes of surface equipment, the calculation procedures for determining oil and gas in place, the techniques of predicting oil and gas reserves, the plan of depletion, and the selection of enhanced recovery method are all dependent on the fluid type classification. Not less important is the fact that in some countries the fiscal treatment depends on the type of produced liquid, hence a forecast of this characterization can be helpful in the marketing process. In the case of the Eastern Venezuela reservoirs the first issue to be resolved is to classify the type of fluid (black oil, volatile oil or gas condensate).