Schlumberger

Case Study: Pressure Measurement, Downhole Fluid Analysis, and Sampling in Extremely Tight Deepwater Reservoir

Challenge: Complete program of pressure measurement, downhole fluid analysis (DFA), and sample collection that a conventional single-probe formation tester was unable to perform in permeabilities at the limit of an unconventional reservoir facies (0.1–0.01 mD).

Solution: Deploy the Saturn 3D radial probe with its large surface flow area of multiple elliptical ports that makes it possible to induce and sustain flow in low-mobility formations for pressure testing and fluid acquisition.

Result: Achieved formation pressure measurements in mobilities as low as 0.01 mD/cP and flowed formation fluid to conduct DFA and capture samples in mobilities as low as 2 mD/cP.

Extremely tight reservoir conditions

An operator needed pressure measurements and fluid analysis and sampling for a deepwater West Africa well, but the very low mobilities of the reservoir sections were below the operating envelope for single-probe formation testers to flow fluid. In addition, using a straddle packer to isolate intervals would have been time consuming and could have delivered misleading data, owing to the large intrapacker sump volume.

Circumferential fluid flow

The Saturn 3D radial probe creates true 3D circumferential flow around the borehole even in very low-permeability formations. The four self-sealing elliptical ports have the industry’s largest surface flow area, totaling more than 79 in2, to quickly establish and maintain flow from the entire circumference of the wellbore instead of funneling fluid from the reservoir to a single access point. The Saturn design also minimizes storage volume effects. The result is quicker cleanup times and the efficient performance of pressure measurements, especially in low-mobility formations where conventional probes cannot function.

Reservoir pressure measurement at mobility below 0.1 mD/cP

In two successive intervals, the Saturn 3D radial probe measured formation pressure and flowed fluid for DFA using the InSitu Fluid Analyzer system and for sample collection. Stabilized pressure measurements were achieved down to mobilities of 0.01 mD/cP, and formation fluid was flowed for DFA and sampling at mobilities less than 2 mD/cP.

The operator plans to include the Saturn 3D radial probe in upcoming wireline logging programs.


Download: Pressure Measurement, Downhole Fluid Analysis, and Sampling in Extremely Tight Deepwater Reservoir (0.56 MB PDF)

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Fluid Flow and Pressure Data Where Not Previously Possible

Saturn 3D Radial Probe
The self-sealing Saturn 3D radial probe flows fluid circumferentially from the reservoir to extend formation testing to low permeabilities, heavy oil, unconsolidated reservoirs, near-critical fluids, and rugose boreholes.
Visit Saturn 3D Radial Probe page