Patent ID: 8898017

Claim:
A method of estimating reservoir pressure in a subsurface hydrocarbon reservoir, comprising: receiving, during normal operations of the well producing hydrocarbons, data corresponding to pressure measurements at a wellbore of a well, corresponding to temperature measurements at the wellbore of the well, corresponding to rate history of flow rates for each or any of phases of gas, oil, and water at the well, and corresponding to a state of valves in the wellbore of the well; applying, by a computer, the received data to a model of the well to determine an operating mode of the well over time, wherein the model determines the operating mode based on the pressure measurements, the temperature measurements, and the state of the valves and wherein the operating mode comprises one of steady-state shut-in, steady-state producing, steady-state injecting, transient shutting-in, transient start-up, and slugging; applying, by the computer, the rate history to remove event-related pressure transients from a pressure history at or near the well; determining, by the computer during normal operations of the well producing hydrocarbons, a change in the determined operating mode of the well that indicates a change in the flow at the well, wherein the change in the determined operating mode is determined by the application of the received data and the rate history to remove event-related pressure transients from a pressure history at or near the well to the model; upon the change in the determined operating mode of the well that indicates the change in the flow at the well, receiving additional data corresponding to pressure measurements at the wellbore of the well over a transient period following the change in the determined operating mode until a steady state is reached or upon another change in the determined operating mode; determining, by the computer, an estimate of reservoir pressure at the well from the received additional data corresponding to the pressure measurements at the wellbore of the well over the transient period following a change to transient shut-in and/or shut-in mode; and notifying a user of the change in operating mode at the well and of the estimated reservoir pressure.