Page 149 - Handbook Of Multiphase Flow Assurance

Asphaltenes 145

6500 ft

7000 ft

7500 ft

8000 ft

8500 ft

9000 ft
FIG. 5.28 Variation of asphaltene deposit location and thickness in a well tubing of 4.5 in. nominal size with depth
and time (redrawn, from Haskett and Tartera, 1965): Red outline 29 Jan, Orange outline 18 Feb, Yellow outline 9 Mar,
Green outline 12 Apr, Blue outline 8 May.

Monitoring and remote sensing of asphaltenes

• Currently used techniques
Asphaltene detection in production systems is mainly limited to observation of solids accu-
mulated in separator inlet strainer or in scraper receiver. Loss of operability of control equip-
ment such as SCSSV which have to be periodically tested per regulatory requirements may
also indicate asphaltene deposition, but it could also be caused by scale deposition. Hydrate
is unlikely because SCSSVs are set in a well at a depth warmer than the hydrate stability tem-
perature for the water hydrostatic pressure.
• Emerging techniques
Additional early warning of asphaltene deposition may be if a sensor transmitter such as
pressure or a temperature gauge reading appears to drift to a lower value. Asphaltene may
be depositing over the probe and altering its actual condition; the gauge reading is true of the
changed conditions, but biased by the deposited layer of solids.
• Integrated systems
Integrated production monitoring systems rely on correlating readings from all available
pressure, temperature gauges and flow meters to show the most likely flow rate in the pro-
duction system. Integrated systems may have additional monitoring software modules to de-
tect and interpret deviations from steady values as a flow restriction. Systems may be trained