Analysis · Well Testing
Buildup & Drawdown
The two basic pressure transient tests. In a drawdown the well flows and bottomhole pressure falls; in a buildup the well is shut in and pressure rises.
What it does
Analysis of pressure against time and rate gives permeability and skin, reservoir pressure, and information on reservoir extent and geometry. A downhole shut in removes most of the wellbore volume, so radial flow appears much earlier than with a surface shut in.
Basics
| Drawdown | Well flowing, pressure falls |
| Buildup | Well shut in, pressure rises |
| Results | Permeability, skin, reservoir pressure, extent |
| Variant | Interference between wells |
| Alberta | AER Directive 040 |
Common failures
- Buildup ended before reaching radial flow
Troubleshooting
- Symptom
- Early buildup data dominated by the wellbore volume
- Likely cause
- Well shut in at surface
- What to check
- Shut in downhole and run the buildup long enough to reach radial flow