WellSKATE Conveyance Accessories Decrease Probe Seal Failures by 90%, West Africa | SLB

WellSKATE Conveyance Accessories Decrease Probe Seal Failures by 90%, West Africa

Published: 12/12/2013

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Difficult sampling environment

An operator in West Africa was experiencing multiple difficulties in measuring pressure and collecting fluid samples in deviated 12 1/4-in boreholes. Toolstrings incorporating the MDT modular dynamic formation tester were having difficulty reaching total depth at up to 33° deviation while generating tension at about 10,000 lbf, resulting in one MDT toolstring being lost in hole. Probe seals were failing at a high 30% rate. A means of reducing friction to improve conveyance success and orienting the tester to assure good sealing was needed.

Significantly reduced friction

WellSKATE conveyance accessories help toolstrings achieve deeper well access and reduce the risk of differential sticking in challenging environments. By enabling rolling, instead of sliding, the accessories significantly decrease the frictional forces present both in running in and pulling out of the well.

Conveyance efficiency is further increased by lessening the toolstring's sensitivity to washouts, rugose hole profiles, and other irregularities. Fishing probability is minimized because the WellSKATE accessories position the toolstring away from the borehole wall, including during station logging.

Eighty stations to total depth

Installing three WellSKATE dual-wheel roller accessories close to the probe on the MDT tester toolstring served a dual purpose in improving operational success. The rollers reduced friction to lower the usual 10,000-lbf tension to about 8,500 lbf, enabling the tool to easily reach total depth. The rollers also maintained relative bearing at approximately 180° across all 80 stations in the well, which kept the probe in the ideal facing-down orientation. With the probe properly aligned, the usual high seal failure rate of 30% was slashed by more than 90% to only one lost seal.

Graph: WellSKATE Conveyance Accessories Decrease Probe Seal Failures by 90%, West Africa
By maintaining the MDT tester toolstring at approximately 180° in the 33°-deviated 12¼-in borehole, the dual-wheel WellSKATE conveyance accessories kept the probe facing down to successfully seal for measuring pressure at 80 stations along with collecting fluid samples

Challenge: Reduce sticking and improve probe sealing for MDT modular dynamic formation tester pressure measurements and fluid sampling in 12 1/4-in deviated boreholes in West Africa

Solution: Decrease friction and maintain tool orientation and standoff by installing three WellSKATE low-friction well conveyance accessories close to the probe of the MDT tester toolstring

Results: Slashed the rate of seal loss from the typical 30% to only 1 failure for 80 stations in the 33° deviated well by maintaining the relative bearing of the probe at the ideal deployment orientation

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