Real-time annulus pressure and temperature data justifies string design and verifies WELLCAT™ model.
18th September 2017
Metrol has been providing pressure and temperature data from the trapped annuli of subsea wells since July 2005 and this has often revealed unexpected results. Understanding how thermally induced annular fluid expansion can affect the pressure design limits of the casing can help plan efficient well architecture.
On one occasion gauges were positioned in the B and C annulus, it was thought by the client that the B annulus would vent to the formation but cement had unexpectedly passed the 14” shoe and closed the annulus preventing thermally induced pressure bleeding off.
Data has also been collected during DST’s as well as long term production wells. On another occasion the SENTINEL-AM™ pressure data from the B annulus allowed the client to increase the flow rate by a factor of three above the WELLCAT™ predicted pressure and still remain well within casing collapse safety margins. On later analysis of the SENTINEL-AM™ data, this was caused by bottom hole higher temperature fluid being trapped in the annulus, cooling and increasing the margin for expansion during the test. Understanding this real time allowed the client to draw the well down and collect more meaningful well test data.