Two-phase separator indicates low flow rate
Sirte Oil Company, operating under the National Oil Corporation of
Libya, tested 22 production wells in the Lahib field at its central flow rate
measuring facility. The total oil and condensate production was slightly more
than 3,180 m³/d [20,000 bbl/d]. Production rates for these wells ranged
from 7 m³/d to 375 m³/d [45 bbl/d to 2,356 bbl/d], with flow
temperatures to 106 degC [222 degF].
Using a two-phase separator, a service company measured the total liquid
flow rate and estimated the oil flow rate using the water cut, but it was
unable to measure gas flow rates for some of the wells. The company’s
tests of the 22 wells indicated a total flow rate of 2,627 m³/d [16,520
bbl/d], which was more than 17% less than the measurements provided by
Sirte’s measuring facility.
Three-phase technology provides new measurements
Sirte called on Schlumberger to verify the cumulative flow using
CleanPhase flow rate measurement technology. The three-phase well test
separator was used in a stand-alone configuration equipped with Coriolis meters
and an electromagnetic meter. The Coriolis meters measure oil and gas mass flow
rate rather than volumetric flow, so they are not affected by variances in
fluid density, viscosity, pressure, or temperature. The electromagnetic meter
monitors the water flow rate; its fullbore design prevents clogging by allowing
greater solids volumes to pass through the CleanPhase separator during well
cleanup.
With this setup, the system separated the fluids efficiently and
measured each phase accurately. Furthermore, environmental risks were reduced
because there was no need to dispose of unseparated fluids during cleanup
periods. The system was fitted with SmartWeir technology, which accommodates
fluctuating water flow rates and high water cuts, allows the oil/ water
interface level and total liquid level to be adjusted, and enables the
separator to be online even during the cleanup phase.