TDDirect CD Service Saves Apache Energy 7 Rig Days in Australia's North West Shelf | Schlumberger
Case Study
Location
Australia, Oceania, Offshore
Details

Challenge: Drill a 12 1/4-in horizontal well section of at least 1,000 m in an unstable formation offshore Australia

Solution: Use a TDDirect CD casing-while-drilling service with a rotary steerable system (RSS) assembly and an underreamer

Results: Cased while drilling a 1,054-m horizontal well section in one run, saving 7 rig days

Products Used

TDDirect CD Service Saves Apache Energy 7 Rig Days in Australia's North West Shelf

Casing while drilling finishes 12 1/4-in, 1,054-m horizontal well section in one run

Demanding application causes excessive NPT

While working in Australia's North West Shelf, Apache Energy encountered wellbore instability while drilling development wells, which caused hole problems and the loss of a wellbore. During the operation, greater-than-normal NPT resulted from controlling circulation losses, making wiper trips, tripping in and out, and running casing. Apache wanted to reduce NPT-related costs and improve performance by reducing off-bottom risks when drilling the 12 1/4-in sections.

Greater wellbore integrity eliminates borehole collapse issues

To help Apache reduce NPT and minimize operational risk, the TDDirect CD casing-while-drilling service with a retrievable BHA was used. The 12 1/4-in section was directionally drilled from the 13 3/8-in shoe to TD in a single run, using 9 5/8-in casing instead of a conventional drillstring. Casing the wellbore while drilling eliminated the danger of borehole collapse before casing could be run.

The TDDirect CD service retrievable BHA included an RSS to drill a pilot hole and an underreamer to enlarge the borehole to 12 1/4 in. The BHA was actively steered to avoid unstable regions and wellbore collision risks using real-time MWD measurements. The resulting wellbore inclination increased from 27° to 90°, holding angle to section TD at 2,197-m MD and 723-m TVD. Once TD was reached, the underreamer's cutters were retracted, the BHA was unlocked from the 9 5/8-in casing and retrieved on drillpipe, and the casing was cemented.

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This comparison of time versus depth for a recently drilled TDDirect CD service well and an offset well after the formation integrity test to cement in place shows a reduction in NPT as well as a 7-day time savings.

Casing while drilling saves 7 rig days, sets world records

Compared with nearly 13 days to drill the offset well by conventional means, the TDDirect CD service ran casing to TD while drilling in 5.88 days, saving approximately 7 rig days. In addition to reducing Apache's NPT-related costs and drilling time, the run eliminated the need for a long liner run on the next section. The operation also resulted in three TDDirect CD service world records for

  • the longest 95⁄8-in interval drilled in one run with a single retrievable casing-while-drilling BHA
  • the longest 95⁄8-in horizontal section drilled—1,054 m with a TVD of 723 m
  • The longest 95⁄8-in horizontal well section drilled with a casing-while- drilling RSS BHA—3.04 throw ratio of MD to TVD
Graph: TDDirect CD Service Saves Apache Energy 7 Rig Days in Australia’s North West Shelf - Casing while drilling finishes 12¼-in, 1,054-m horizontal well section in one run
The chart shows the difference in the time needed to construct the 12¼-in section in the offset well using conventional drilling and the time to construct the current well section using casing while drilling.
Products Used

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