Patent ID: 7706980

Claim:
A method for testing a system comprising: a blowout preventer (BOP) having an upper end and a wellhead end, having a throughbore between the ends, and at least one means for closing the throughbore against a tubular located therein; a cementing unit (CU) for providing pressurized fluid; and piping for connecting the output of the CU to the BOP and into the throughbore of the BOP, the method comprising the steps of: a) shutting the closing means in the BOP against the exterior of said tubular; b) using the CU and the piping to increase the pressure in a portion of the throughbore around the tubular and against the closing means to a predetermined shut-in pressure; c) selecting a predetermined regression model having a plurality of constant but undetermined coefficients, and expressing the pressure in said portion of the throughbore as a function of time; d) using a signal that is representative of the pressure in said defined portion of the throughbore over successive time points and solving for the value of said coefficients of said regression model; e) using said coefficients from step (d) and said regression model of step (c) to forecast the time when the rate of pressure change in said portion of the throughbore approximates a predetermined rate of pressure change; f) using said coefficients from step (d), said regression model of step (c), and said time of step (e) to forecast the pressure in said portion of the throughbore; g) repeating steps (d) through (f) until successive forecasts of said pressure in said portion of the throughbore stabilize relative to a predetermined convergence test; and h) producing a visual indication when said successive forecasts stabilize.