Cerro Dragón, is the largest oil field in terms of oil production in Argentina. The field is operated by Pan American Energy and is a typical brownfield from Golfo San Jorge basin with multi-layered fluvial sandstones with different degree of depletion, many supported by injection water. Casing drilling has been used in numerous difficult wells where drilling through troublesome well sections would not have been possible with conventional drilling techniques. This technique has verified the ability to complete the drilling of high risk wells with problems of nonproductive time due to lost circulation and highly damaged reservoirs. Nevertheless, this technology prevented openhole logging. This set up a new scenario of applications that challenged the multidisciplinary areas of field management and their workflows to characterize reservoirs. After evaluating alternatives, Panamerican Energy chose the application of a unique methodology that involves wireline operations of openhole and casedhole pulsed neutron logging training and the application of neural network modeling.This paper details the methodology used, planning, technologies, and logistic used for acquisition and data processing as well as the results obtained in recent years of application of the technique in the Cerro Dragón field. The application of neural networks resulted an effective solution to the absence of data from openhole logging for development projects with wells drilled while casing. For its part, the teamwork between the operator and the service company was the key to obtain results that were proven in several successful well completions.