PIPE-LAX W EH Stuck-Pipe Spotting Fluid | Schlumberger


Stuck-pipe spotting fluid

PIPE-LAX W EH stuck-pipe spotting fluid is a liquid one-drum product for preparing weighted oil-based spotting fluids. It contains gellants, emulsifiers, wetting agents and filtercake-breaking materials. PIPE-LAX W EH spotting fluid can be mixed in diesel oil or mineral oil without special rig or mixing equipment.

Typical Physical Properties
Physical appearance Dark-brown, oily liquid
Specific gravity 1.0–1.1
Pour point <32 degF [0 degC]
Flash point 84 degF [29 degC] (Pensky–Martens closed cup)


  • All wells that require a weighted soak solution to free differentially stuck pipe
  • For either diesel oil or mineral oil using any makeup water
  • Densities of PIPE-LAX W EH fluid spots are in the range of 8–18 ppg

Success in freeing differentially stuck pipe is greatest when the soaking solution is spotted in the minimum amount of time after the pipe becomes stuck. A soak solution that can be quickly mixed and spotted often frees the drillstring before fishing operations are required. Because PIPE-LAX W EH spotting fluid is a single-package liquid blend, it is easy to mix and prepare quickly.

PIPE-LAX W EH spotting fluid yields excellent oil-wetting characteristics and is formulated to ensure rapid penetration through the filtercake to the formation. The quantity of the PIPE-LAX W EH spotting fluid (50–200 bbl [8–32 m3]) should be placed in the annulus around the suspected stuck pipe area, and one or two barrels of fresh spotting fluid should be pumped every hour. PIPE-LAX W EH spotting fluid remains effective when contaminated by water-based mud.


  • Simple, single-drum product that requires no other additives
  • Can be used in diesel oil, crude oil or low-toxicity oil
  • Does not require high shear or long mixing time, enabling quick and effective application


The chart below lists the required quantities for formulating one barrel of PIPE-LAX W EH solution in diesel oil with M-I BAR barite. This formulation is designed to produce the minimum viscosity required to support weight material. The concentration of PIPE-LAX W EH stuck- pipe additive should be increased from 3.36 galUS/bbl [80 L/m3] to 4.0–4.5 galUS/bbl [95–107 L/m3] when higher viscosities are required or if mineral oil is being used. If it is necessary to reduce the viscosity of PIPE-LAX W EH fluid, dilution with oil or the addition of 0.25–0.5 lbm/bbl [0.71–1.43 kg/m3] of VERSAWET oil-based mud surfactant is recommended.

For 1 bbl of Spotting Fluid

Mud Weight, ppg Diesel Oil, bbl PIPE-LAX W Fluid, galUS Freshwater, bbl M-I BAR Barite, lbm
8 0.620 3.36 0.280 25.6
10 0.580 3.36 0.260 138.6
12 0.540 3.36 0.220 248.5
14 0.490 3.36 0.210 349.3
16 0.510 3.36 0.110 458.5
18 0.440 3.36 0.100 567

For 1 m3 of Spotting Fluid

Mud Weight, sg Diesel Oil, L PIPE-LAX W Fluid, L
Freshwater, L M-I BAR Barite, kg
0.96 620 80 280 73
1.20 580 80 260 396
1.44 540 80 220 710
1.68 490 80 210 995
1.92 510 80 110 1,310
2.16 440 80 100 1,620

More spotting fluid may be required in low-toxicity mineral oils to obtain the desired rheological properties and gel strengths.


Preparing PIPE-LAX W EH fluid is quick and simple.

  1. Clean the spotting tank (slug pit or available rig tank) of any drilling mud. Flush mixing lines with water and drain.
  2. Add the necessary amounts of oil and PIPE-LAX W EH fluid followed by water. Shear with centrifugal pump for 30 minutes minimum until a stable emulsion forms.
  3. Add weight material until desired density is achieved. Adjust the viscosity by adding PIPE-LAX W EH fluid, adding organoclay or adding oil or VERSAWET surfactant to reduce viscosity.

Spotting procedure

Most frequently, it is the drill collars that become differentially stuck. The placement of a PIPE-LAX W EH fluid is relatively simple.

  1. Determine the number of barrels of PIPE-LAX W EH spot required to fill the annular space around the drillstring from the bit to the differentially stuck zone. To this calculated volume, add at least 25%. The extra volume remains inside the drillstring to allow for the periodic displacement of additional spotting fluid.
  2. Determine the proper pumping time to spot the fluid across the affected area. Displace, then shut off the pumps.
  3. Work the pipe regularly and use jars if possible. Displace 0.5–1 bbl [80–159 L] of PIPE-LAX W EH fluid every half hour to keep the pipe covered.
  4. When the pipe is freed, or if the spot needs to be circulated out of the hole, the PIPE-LAX W EH fluid can be incorporated into the drilling mud system. In offshore wells being drilled in environmentally sensitive areas, it might be necessary to catch the fluid in a tank to segregate it from the drilling fluid.

Toxicity and handling

Bioassay information is available upon request. Handle as an industrial chemical, wearing protective equipment and observing the precautions described in the safety data sheet.

Packaging and storage

PIPE-LAX W EH spotting fluid is packaged in 55-galUS [208-L] drums. Keep away from heat, sparks, and open flame. Keep in cool, dry, ventilated storage area and in closed containers. Keep in original container.

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