A method and system for estimating reservoir pressure in a hydrocarbon reservoir from downhole pressure measurements of producing wells is disclosed. Pressure measurements are obtained from wells in the production field over time, and communicated to a server that applies the pressure measurements for a well to a model of that well. The server operates the model using the pressure measurements to determine an operating mode of the well, such as producing or shut-in. Upon detection of a change in operating mode indicative of an abrupt change in flow at the well, such as corresponding to a shut-in event, additional downhole pressure measurement data is acquired until a steady-state condition is reached. The pressure measurements are used to determine a reservoir pressure, which is transmitted to a responsible reservoir engineer or other user. Modification of the determined reservoir pressure value by the user can be received, and the stored reservoir pressure and well model are updated accordingly.