Case Study: Rapid, Accurate Flow Rate Measurements Optimize Lift
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Vx technology extends well testing to “untestable” wells offshore West Africa
Challenge: A new deepwater well offshore West Africa, completed with a gravel pack and brine completion fluid, lost fluid during postgravel-pack upper-hole operations. In addition, the crude formed a stable emulsion with the completion brine, causing water to carry over into the oil leg of the separator and making oil-meter measurements artificially high.
Solution: Vx technology, developed by Schlumberger and Framo Engineering A/S, made multiphase testing quicker and more efficient. This advanced flowmeter technology, used in both PhaseTester mobile units and PhaseWatcher permanent installations, requires no phase separation and is insensitive to slugs, foam, and emulsions.
Result: Comparing the volume of lost completion fluids with the PhaseTester measurements made it possible to monitor cleanup, optimize lift, and predict the well's ability to flow naturally.
Low-temperature effluent, high cleanup rates
A new deepwater well offshore West Africa, completed with a gravel pack and brine completion fluid, lost fluid during postgravel-pack upper-hole operations. Low-temperature effluent, combined with high cleanup rates, caused severe foaming of the crude in the test separator. The resulting liquid carryover prevented accurate measurement of gas rates through the orifice plate meter. In addition, the crude formed a stable emulsion with the completion brine, causing water to carry over into the oil leg of the separator and making oil-meter measurements artificially high. The emulsion could not be broken, and therefore water content in the oil could not be determined. Because of these problems the client selected Vx technology for subsequent wells.
Complete measurement 45 times per second
Accurate measurements of gas, oil and water flow rates are essential for diagnosis and optimization of well and field performance. In the past these measurements required use of bulky mobile test units or large, maintenance intensive test facilities.
Vx technology makes multiphase testing quicker and more efficient. This advanced flowmeter technology, used in both PhaseTester mobile units and PhaseWatcher permanent installations, requires no phase separation and is insensitive to slugs, foam, and emulsions. Suitable for even “untestable” wells, it is used for
- production well testing
- production allocation
- production trends
- artificial lift optimization
- well cleanup optimization
- subsea well testing
- exploration and appraisal testing.
Vx technology couples venturi mass flow rate and dual-energy gamma ray phase holdup measurements. The high-speed detector processes 1 million points per second for a complete calculation of water, oil, and gas fractions every 22 ms.
The PhaseTester service, which uses a lightweight mobile unit designed for easy deployment, covers all steps of the testing process, from design to reservoir interpretation. This service can be tailored to meet specific needs, including sitespecific safety analysis, wellsite operations, well test reporting, well data analysis, and production diagnosis.
Real-time monitoring reduced lifting costs
A PhaseTester unit monitored cleanup and measured backflow of nonreservoir fluids during the period when a conventional test system was bypassed and no data were obtained. Real-time monitoring of brine, oil, and gas rates identified the crossover from brine to oil and gas production, permitting the nitrogen lift to be stopped as soon as it was no longer needed. Comparing the volume of lost completion fluids with the PhaseTester measurements made it possible to monitor cleanup, optimize lift, and predict the well’s ability to flow naturally.
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