The 5-in-diameter radial probe with the industry's largest flow area
In consideration of the limited capability of conventional single probes
to effectively perform formation testing operations in low-permeability
carbonate rock and the long station times and operational risk associated with
using a dual packer, Schlumberger recommended using the 5-in Saturn 3D radial
probe for more effective fluid extraction. The four self-sealing elliptical
ports of the Saturn probe have the industry's largest inlet flow area of 59.49
in2 for this hole size, which brings pressure measurement and
sampling to previously inaccessible reservoirs. The combination of zero sump
and the fully circumferential inlet enables quickly establishing flow and
removing mud filtrate, leading to representative DFA and sample capture.
The InSitu Fluid Analyzer system was integrated in the MDT modular
formation dynamics tester string to conduct real-time DFA on the samples to
confirm fluid purity and measure fluid properties at reservoir conditions for
establishing early understanding.
Successful sampling at 0.05-mD/cP mobility, where conventional probes
Two downhole oil samples were successfully collected from the zone of
interest, with the differential pressure ranging from 5,500 psi to a maximum of
6,500 psi, which is well outside of the operating range for a dual-packer
configuration for formation testing. Following sampling, the formation pressure
was measured by allowing an extended buildup. The mobility was calculated to be
0.05 mD/cP, which is outside the operating range of a conventional single
probe. This wealth of critical information was acquired within only 4.5 h on
station, mitigating the risk of sticking and minimizing rig time.
Deployment of the 5-in Saturn 3D radial probe made it possible to
collect the first formation oil sample in this field from the subsalt
reservoir. On the basis of the pressure and fluid characterization data
obtained, the operator had sufficient information to continue exploration and
appraisal work in the area.