Schlumberger

Case Study: SAFE-LUBE Lubricant Reduces Torque and Drag in Brines on the North Slope

Challenge: The well was drilled and completed to 20,927 ft (6378 m) measured depth (MD) and 6643 ft (2025 m) true vertical depth. Swell packers were used in the 4½‐in. liner for zonal isolation with the deepest set at 18,750 ft (5715 m) MD. The well was drilled with FLOPRO NT fluid and then displaced to 9.8‐lb/gal (1.18 SG) NaCl brine.
The drilling rig moved off the location and it was necessary to displace the completion fluid to diesel to ensure the proper swelling of the packers before the well was put on water injection. The Schlumberger coiled tubing modeling software (CoilCade) predicted that the 1.75‐in. tapered string would just be able to reach the desired depth without the use of a pipe straightener. The procedure was to jet out the completion fluid with seawater to the maximum attainable depth and displace the well to diesel. The coiled tubing reached a depth of 18,454 ft (5625 m) on the initial run. As the fluid was displaced and the pipe reciprocated, the maximum depth decreased to 18,250 ft (5563 m).

Solution: In an effort to enable the coiled tubing to reach the desired depth in this well, M‐I SWACO added SAFE-LUBE lubricant at approximately 0.65% by volume, to 175‐200 bbl (28‐32 m3) of seawater. The treated seawater was then circulated down the coiled tubing and up the annulus.

Result: The friction reduction allowed the coil to reach a maximum depth of 19,679 ft (5998 m). The up‐weight at 18,000 ft (5486 m) was decreased from 36‐40K to 32K after the SAFE-LUBE product addition. The coil was able to reach 1429 ft (435 m) deeper with the lubricant to displace the well and allow the deepest packer to be set in diesel.

Well Information
Location North Slope, Alaska, USA
Production well intervention March 2006

 

The Situation

The well was drilled and completed to 20,927 ft (6378 m) measured depth (MD) and 6643 ft (2025 m) true vertical depth. Swell packers were used in the 4½‐in. liner for zonal isolation with the deepest set at 18,750 ft (5715 m) MD. The well was drilled with FLOPRO NT fluid and then displaced to 9.8‐lb/gal (1.18 SG) NaCl brine.

The drilling rig moved off the location and it was necessary to displace the completion fluid to diesel to ensure the proper swelling of the packers before the well was put on water injection. The Schlumberger coiled tubing modeling software (CoilCade) predicted that the 1.75‐in. tapered string would just be able to reach the desired depth without the use of a pipe straightener. The procedure was to jet out the completion fluid with seawater to the maximum attainable depth and displace the well to diesel. The coiled tubing reached a depth of 18,454 ft (5625 m) on the initial run. As the fluid was displaced and the pipe reciprocated, the maximum depth decreased to 18,250 ft (5563 m).

The Solution

In an effort to enable the coiled tubing to reach the desired depth in this well, M‐I SWACO added SAFE-LUBE lubricant at approximately 0.65% by volume, to 175‐200 bbl (28‐32 m3) of seawater. The treated seawater was then circulated down the coiled tubing and up the annulus.

The Results

The friction reduction allowed the coil to reach a maximum depth of 19,679 ft (5998 m). The up‐weight at 18,000 ft (5486 m) was decreased from 36‐40K to 32K after the SAFE-LUBE product addition. The coil was able to reach 1429 ft (435 m) deeper with the lubricant to displace the well and allow the deepest packer to be set in diesel.

The Details

Approximately 175‐200 bbl of seawater was loaded onto a vacuum truck, and a drum of SAFE-LUBE fluid was transported from the M‐I SWACO mud plant in Prudhoe Bay to the well location. One drum was added directly to the vacuum truck, giving a concentration of 0.65‐0.74%. The recommended concentration is 0.6%.


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“The up‐weight was reduced from 36‐40Kto 32K, making it possible to run the coil another 1429 ft (435 m) into the well to achieve desired results.”
Judy Means
Sr. Drilling Fluids Specialist
M‐I SWACO