Performance Report: Critical Cleanout Achieved During Drilling in Difficult Rocky Mountain Well

Rocky Mountains

Challenge: A Rocky Mountain operator had drilled approximately 328-427 ft (100-130 m) to reach a total depth of 9265 ft (2824 m). The drilling team experienced tight hole conditions and reamed to bottom, encountering some deviation control problems and creating a number of doglegs. These conditions resulted in a hole drag increase to 35,000 daN, which was approaching the rig limit on maximum hook load of 125,000 daN and the rig manager’s estimate of 110,000 daN.

Solution: The drilling team increased additions of Millenium Technologies Alcomer 120 L additive to 3 pails/ tour (to a maximum of 6 pails/day) and set the potassium level at 25,000 mg/L to improve hole cleaning. Coarse walnuts were added to the active system as pills and as a daily treatment. The bottomhole assembly was modified to have more Smith Services Hevi-Wate drill pipe and fewer drill collars to reduce string weight. The ALPINE DRILL BEADS product was added at a concentration of 3-5%, and a beads recovery unit was kept on standby.

Result: The drilling team’s addition of 100 sx of walnuts and increased additions of polymer to the active system failed to rectify the problem. The team decided to add the ALPINE DRILL BEADS product. The beads were spotted at the kickoff point (KOP) and at 656-ft (200-m) intervals from 8530 to 3609 ft (2600-1100 m). Hole drag improved by 5-6 daN on every pill. Drilling proceeded to the casing depth, after which the drilling team logged the well and ran the production string. Approximately 231 sx of the ALPINE DRILL BEADS product were used on this location.

The Details

The well was directionally drilled, with the KOP at 3228 ft (984 m), with a build rate of 2.5°/98 ft (2.5°/30 m) to a maximum of 32.65° in the direction of 30.05° azimuth by a depth of 4649 ft (1417 m). The hole angle was allowed to drop back to less than 5° from the middle Gething formation to form an S-curve and was maintained to TD. Hole conditions were good during connections and surveys. Tripping was performed with little time lost to reaming bridges and/or cleaning fill on bottom. Potassium concentrations were kept in the 20-22,000 mg/L range to maintain good wellbore stability. Maximum drag on trips was 14,000 daN.

At 8602 ft (2622 m), the drilling team tripped into the hole with a new BHA, changed the motor to 1.5° and reamed from 5069 to 5095 ft (1545 to 1553 m), and from 8333 to 8399 ft (2540 to 2560 m) for 3.5 hr, then washed to bottom.

The team then drilled ahead, increasing the potassium level to 25,000 mg/L, spotting an ALPINE DRILL BEADS pill at 3937 ft (1200 m) and dropping the string weight by 5000-6000 daN. The team drilled to 9108 ft (2776 m), spotted a second pill at the KOP and noted a 5 daN improvement. Drilling continued to 9239 ft (2816 m). The drilling team mixed and spotted a 7-m pill with 46 sx of ALPINE DRILL BEADS product at 8530, 7874, 6890, 4593 and 3609 ft (2600, 2400, 2100, 1400 and 1100 m) and worked into the formation while rotating at 75 rpm. The team drilled to TD, circulated the hole clean, then tripped out of the hole. The hole was tight.

The team spotted the ALPINE DRILL BEADS product from 8202 to 4265 ft (2500-1300 m) and pulled out of the hole to lay down directional tools. Ran back in slick, circulated, and conditioned the hole and mud, pulling out to log. The well was logged to bottom on the first attempt and a 4½-in. (114.3- mm) production string was run.

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