A two-step workflow was developed, with the models built by the Murphy
Oil team in Houston and supported locally by Schlumberger experts in
collaboration with the Schlumberger Exploration Hub in Aachen, Germany.
The first step was identifying the layers responsible for overpressure
and modifying their lithological composition to match calibration data from
offset wells. This regional pore pressure model also accounted for regional
faults, pressure relief points, sub-basin distribution, and salt deformation
In the second step, a higher-resolution geological model was built over
a focused area of interest by using high-resolution structural maps and facies
maps based on seismic character. The high-resolution model for the area of
interest could be run in under 12 hours, powered by recent improvements in
PetroMod software’s simulator speed. This speed enabled completing full
model runs overnight to provide pore pressure prediction results ahead of the
bit for morning meetings.
The model was calibrated daily using leakoff test results,
logging-whiledrilling formation pressure data, and information on drilling
Accurately predicting pore pressure ahead of the bit
The workflow in PetroMod software enabled integrating all available data
into the geological model for daily update and simulation. The results from the
simulations provided useful information on whether to follow the original
drilling plan or modify it to avoid drilling hazards. The pore pressure was
consistently accurately predicted for the well ahead of the bit and then the
model's performance refined by calibration to the measured data.
The drilling engineer used the predicted pore pressure and fracture
gradient to optimize well performance and thus reduce drilling costs and risk
in the expensive, hazardous subsalt drilling environment of the Gulf of Mexico.
The well was successfully drilled under budget and without safety