Pressure and Fluid Contacts · Module P2
Formation tests and data quality
A pressure plot is only as good as the tests on it. This module explains what a wireline pretest measures, how mobility and the hydrostatic readings taken before and after a test reveal its quality, why tight sands read high, and how to import a service company report, convert its depths and units, handle retests and keep a reason for every test that is left out.
- Level
- Intermediate
- Position
- Module 2 of 8
- Video
- About 19 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
- Drawdown, build-up and the stabilized pressure
- Mobility and what a low value warns of
- Hydrostatic readings before and after, and gauge drift
- Supercharging in low-mobility sands
- Importing a report: columns, units and depth basis
- Retests at the same depth
Learning outcomes
After the module you should be able to:
- Build a test list you can defend row by row.
- Classify a test as valid, tight, lost seal, supercharged or unstable
- Explain why a minimum mobility cut-off protects a gradient fit
A short preview
In a low-permeability sand, filtrate that invaded while the hole was drilled has not bled away when the probe sets, so the tool reads formation pressure plus part of that excess. The error grows as mobility falls. Picture five tests down a water leg: four with mobility above 50 mD/cP sit on a clean 0.45 psi/ft line, while the fifth, at 0.4 mD/cP, reads 25 psi above it. Kept in, that one point tilts the fit and can shift a contact by tens of feet; screened out with its reason written down, it costs nothing.
Who it is for
Petrophysicists, reservoir engineers and geoscientists who screen formation pressure tests, pick fluid contacts and carry them into volumes for exploration, appraisal and development decisions.
Prerequisites: None required; working familiarity with well logs and volumetrics helps. The hands-on steps use the Pressure Analysis panel in Formation Evaluation.
Take the module in the Learning Hub
Pressure and Fluid Contacts: Specialty course, sold separately: eight modules that turn a formation tester report into fluid contacts you can defend, from screened tests and gradients to capillary entry height and a contact range in the volume. The lesson opens in the Learning Hub once the track is purchased; graded quizzes and the certificate come with the certified option.