Asphaltene is one of the heavier components of crude oil. When the pressure or temperature conditions in a well change, this substance can separate from the oil and start to deposit, like sugar crystallizing in cold tea. These deposits can block the production path, especially in critical points like the choke.
What happens when blockage occurs at the choke?
- UCT: Usually stable or sligthly decreases
- WHP: Increases
- Flow Rate: Less fluid reaches the surface
What happens when blockage occurs inside the tubing?
When asphaltene deposits accumulate inside the tubing and restrict flow:
- UCT: drops, because less hot fluid is reaching the surface
- WHP: drops
- Flow Rate: Less fluid reaches the surface
- The WHP curve may show fluctuations
So, a simultaneous drop in both temperature and pressure while the well is still flowing usually indicates a partial tubing blockage, often due to asphaltene. After removing the blockage (e.g., via solvent injection (Xylene) or cleaning job), flow is reestablished and pressure and temperature return to normal values.
