Measure pore pressure for managed pressure drilling
StethoScope FPWD tool was chosen to directly measure pore pressure. The
@balance Services MPD system used this pore pressure information to set the
lower safe boundary for MPD dynamic fingerprinting. Geoservices, a Schlumberger
company, also used the data in its 24/7 pore pressure updating.
The well was drilled with a statically underbalanced mud weight using
MPD backpressure to keep the pressure in the wellbore slightly overbalanced.
When the permeable zones were reached, the StethoScope tool was deployed to
measure formation pressure. The safe mud-weight window was approximately 0.7
lbm/galUS. Pressures recorded formation equivalent mud weights as high as 18.2
lbm/galUS, which were repeated for verification within 1.5 psi.
The StethoScope tool ran for more than 430 hours below the rotary table,
its longest run in Asia. NPT was zero despite more than 300 hours of pumping
and static formation temperature of 158 degC.