A method and system for estimating the status of a production well using a probability calculator and for developing such a probability calculator. The method includes developing a probability calculator, which may be a Bayesian network, utilizing the Bayesian network in a production well event detection system, which may include real-time well measurements, historical measurements, engineering judgment, and facilities data. The system also includes a display to show possible events in descending priority and/or may trigger an alarm in certain cases.