Free stuck drillstrings when using invert-emulsion drilling fluids.
|Casing shoe||13 ⅜ in. at 3,000 ft (914 m)|
|Interval drilled||7,910 ft (2,411 m) of 12¼-in. hole|
|Hole angle at TD||27.79 degrees|
|Borehole static temperature||170° F (76.6° C)|
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.
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.
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.
“We obtained higher spurt loss and higher cumulative volumes in Eastern Venezuela where wellbore instability has been caused by mechanically unstable shale. All sorts of pipe-freeing products have been used in this region.”
Armando Rivera, Fluid Engineer, M-I SWACO
If you’d like to know more about the PIPE-LAX OB product and how it’s performing for our other customers, please call the M-I SWACO office nearest you.
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.
Solution: M-I SWACO engineers recommended PIPE-LAX OB, a spotting fluid designed to free stuck drillstrings when using invert-emulsion fluids.