Challenge: Conduct an extended well test in the deepest water (7,000 ft) and the highest pressure (25,000 psi) yet in the US Gulf of Mexico with real-time surface readout of bottomhole pressure and temperature
Solution: Semipermanently deployed WellWatcher™ permanent monitoring systems
Results: Reliable, uninterrupted real-time bottomhole data acquisition for 48.5 days from all three downhole gauges while monitoring sustained flow rate of 6,000 bbl/d of oil; minimized rig time spent to achieve well test objectives
Chevron planned an extended well test in the deepwater Jack No. 2 well in the Gulf of Mexico. Reliable, uninterrupted real-time data had to be obtained in 7,000 ft of water and a total depth of 27,500 ft, plus very high pressure of 25,000 psi. Reservoir uncertainties and extremely high daily rig spread rates required maximum efficiency.
With the drillstem test string, SLB ran a reliable WellWatcher permanent gauge system consisting of three quartz pressure and temperature gauges—rated for 25,000-psi and 425 degF—deployed using one dual and one single solid gauge mandrel and welded Intellitite™ downhole dual-seal dry-mate connectors. The proven reliability of the welded connector technology used in this system was considered a key advantage over wireline-deployed gauge options to acquire these data.
The electrical signal was routed through the SenTREE™ subsea test tree system on the seafloor. At the surface, the pressure and temperature information was monitored by Chevron and SLB personnel in real time during well test operations. This real-time surface readout was critical to the safety and efficiency of this well test.
The SLB gauge system transmitted critical downhole annulus and flow-stream bottomhole pressure and temperature information uninterrupted for 48.5 days. The well test averaged 6,000 bbl/d of oil.
The system facilitated onsite transient analysis of the downhole flowing and buildup data, allowed engineered execution of the well test, maximized well test flow rates while minimizing the risk of excessive drawdowns, minimized the rig time required to fulfill the objectives, and supplied invaluable assistance to drillstem test specialists.
