Schlumberger

Performance Report: Stuck Pipe Spotting Fluid for Invert Emulsion Fluids PIPE-LAX OB Field Trial

Challenge: A drilling program in Eastern Venezuela called for the use of an all-oil diesel oil-based mud (OBM) in a formation comprised of mostly shale (90%) and some sandstone. Historically, these wells have been troublesome due to wellbore instability caused by mechanically unstable shale as well as mud density management across a wide range of pressure required for hole stability.

Solution: M-I SWACO engineers recommended PIPE-LAX OB, a spotting fluid designed to free stuck drillstrings when using invert-emulsion fluids. PIPE-LAX OB fluid is a single-package, liquid blend made for fast mixing and frees the drillstring by penetrating through and cracking the filter cake to free differentially stuck pipe.

Result: PIPE-LAX OB degraded the filter cake faster and more effectively than previously used traditional pills. The use of the PIPE-LAX OB pill circumvented the need for a sidetrack and the loss of the bottom-hole assembly (BHA), valued at approximately $250,000.

Lab tests indicated that the spotting fluid remained active after 30 hr of exposure and showed no compatibility issues with OBM products.

A 13.7 lb/gal PIPE-LAX OB pill was mixed using 10.4 bbl of PIPE-LAX OB and 307 lb/bbl of barite. The 12.6 bbl pill at was spotted in the annulus, pressured up to 200 psi for 5 min, allowed to soak for a couple of hours. The washpipe was pulled out of the hole and run in hole with fishing string, bumper sub + jar + accelerator + 5 in. drill pipe. It was latched to the fish at 7,756 ft; after overpulling the pipe at 230,000 lb the fish was dragged to surface and retrieved.

The lab testing protocol was as follows.

  • Run API fluid loss on OBM (base fluid), quantify cumulative volumes in cc for each 15 min interval up to 60 min
  • Clean up filter press while keeping wall cake intact.
  • Add treatment fluid to API filter press cell with wall cake intact.
  • Run API fluid loss.
  • Check spurt loss and quantify volumes in cc for each 15 min interval up to 60 min.
  • Repeat procedure for all samples of treatment fluid and compare results.

Download: Stuck Pipe Spotting Fluid for Invert Emulsion Fluids PIPE-LAX OB Field Trial (0.61 MB PDF)

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