Geomechanics · Module G8
Deviated Wells, Uncertainty and the Capstone
The capstone takes a calibrated model into a deviated well and from a single answer to a range. It covers rotating the stresses into the borehole frame, why the stable window narrows or widens with trajectory, a screening check for sand production, sampling uncertain parameters to obtain low and high windows with their main drivers, and the documentation a reviewer needs to follow the model.
- Level
- Intermediate
- Position
- Module 8 of 8
- Video
- About 17 minutes, narrated
- Format
- Narrated video lesson with captions and slide reading view; with the certified option, a quiz whose pass unlocks the next module.
What the module covers
- Rotating the stresses into borehole coordinates
- Inclination, azimuth and the stable window
- Screening for sand production
- Parameter sampling and P10–P90 windows
- Rank correlation to find the drivers
- What a one-dimensional model cannot capture
Learning outcomes
After the module you should be able to:
- Deliver a deviated-well model with its P10–P90 window, named drivers and stated limits.
- Compare the mud weight window of a vertical and a deviated well
- Name the parameters that control how wide the window is
A short preview
A single mud weight window hides how much of it rests on assumptions. Sampling the uncertain inputs, such as the strength correlation, friction angle, Biot coefficient, tectonic strains and pore pressure exponent, a few hundred times gives a spread of collapse and fracture limits at every depth. If the floor of the window has a P90 of 14.9 ppg and the ceiling a P10 of 15.6 ppg, the range that holds in most cases is only 0.7 ppg wide, half of what the base case shows. Ranking the inputs against that width shows which measurement would narrow it most.
Who it is for
Drilling, completion and reservoir engineers, petrophysicists and geoscientists who build or review pore pressure and wellbore stability predictions for well planning.
Prerequisites: None required; working familiarity with well logs helps. The hands-on steps use the Geomechanics workspace, available from the Professional plan.
Take the module in the Learning Hub
Geomechanics: Specialty course, sold separately: eight modules that build a calibrated 1D mechanical earth model from logs, from elastic properties and pore pressure to the mud weight window and its range. The lesson opens in the Learning Hub once the track is purchased; graded quizzes and the certificate come with the certified option.