Performance Report: Fast Torque Reduction on Highly Deviated Hole with Horizontal Drain Achieved in Yemen

Challenge: Previous wells drilled horizontal sections through basement formation with viscosified water. Consistently high torque values were observed with “greasing” and blinding of the shaker screens whenever trace oil was seen during the retort test (less 0.1% by volume). The second problem was the limitation of Max Torque=19,523.8 N.m for 3½-IF Connection drill pipe that resulted in a limitation of maximum torque available at the rotary table set up to 15,000 N.m. The original lubricants were replaced by LUBE-1722 lubricant on a trial basis.

Solution: The latest product development, tested in the M-I SWACO laboratory in accordance with EC Directives, recommended LUBE-1722 lubricant to be more efficient, with no thermal destabilization in the 6-in. drilling phase. The objective was to drill and build up to 90 deg with a 9-deg/30-m (98-ft) high deviated hole as a 750-m (2,461-ft) horizontal drain.

Result: At 3,195 m (10,482 ft) with a 88.52º hole inclination, high torque values were observed in the range of 11,500 N.m. 0.2% by volume (v/v) LUBE -1722 lubricant was added to the circulating volume that resulted in a reduction in torque to 4,880 N.m and drilling performance improved. Torque reduction was greater than 50% of the original torque. Addition of 0.1% v/v LUBE -1722 lubricant was continuously added as the torque value increased to near +/-10,000 N.m; decreasing torque values were observed immediately.
0.1% v/v by volume LUBE -1722 lubricant was added prior to tripping out of the hole. No over-pull or drag was reported during the trip. Periodic treatments with LUBE -1722 lubricant were made drilling the drain section to maintain the lubricant concentration.
The well was drilled deviated to TD=3,905 m (12,812 ft) with 830 m (2,723 ft) of horizontal drain; the final concentration of LUBE -1722 in the circulating system was 0.25% v/v. Retort test showed traces of oil, but no foaming or greasing occurred at the shakers during drilling.
It was also pointed out by the directional driller, LUBE -1722 lubricant in the circulating system improved sliding performance, reduced vibration and improved MWD signal quality.
M-I SWACO engineers recommend the product use for future wells to improve drilling performance of the horizontal drain section; treatment recommendation is 0.3% v/v LUBE -1722 directly to the circulating system. The LUBE -1722 lubricant can effectively reduce the downhole torque and has good compatibility with most water base fluids.

Well Information
Location Onshore 957 m (3,140 ft)/MSL elevation, Yemen
Total Measured Depth (MD) 3,908 m (12,822 ft)
Total Vertical Depth (TVD) 2,834 m (9,298 ft)
Casing Size 7-in. (178-mm) Liner
Casing Shoe Depth 2,915 m (9,564 ft)
Open hole Size 6 in. (152 -mm)
Open hole Inclination 90.4 degrees
Reservoir Lithology Fractured basement
Bottom hole Temperature 99.8°C (212°F)

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