Polyketone Tubing Liners

Economically Extending Mean Time Between Failures

Lightning Rod and Pipe provides various lined tubing materials that significantly increase the meantime between failures in PCP and rod pumping applications. LightningFlo™ LF115 lined tubing uses a unique polymer that has been shown to significantly lower frictional wear from rod movement, resist corrosion-causing chemicals, and maintain integrity in high temperature operations.

Thermoplastic liners have been used in downhole oil and gas applications for over twenty years. However, early liners used in the oil and gas industry were plagued with a high cost-benefit ratio that made them only economically feasible for high-producing, highly profitable wells.

Now, a high-performance resin is available that address the challenges seen with early resins. Not only does this high-performance resin provide high working temperatures, it also performs better against corrosion, has lower coefficients of friction, and stands up better to abrasive wear all at a lower cost than its predecessors.

LightningFlo™ LF115 lined tubing is made from a raised temperature polyolefin ketone (POK) or polyketone. This resin is now being extruded into thermoplastic tubing liners at a much lower price than other high performance resins. POK was originally commercialized by Shell Chemical as a replacement for HDPE in offshore applications where higher performance was needed, making it well suited for challenging applications.

Thermoplastic liners tend to collapse when pressure is reduced abruptly inside the liner in the presence of an annular pressure. This can occur in oil wells when the tubing is pressured up and bled off rapidly. The tendency to collapse is much greater if the permeability of the liner is high. Laboratory testing shows that a 5-inch pipe lined with POK has twice the collapse strength at room temperature than a pipe lined with HDPE liner.

POK polymers have very few known solvents. The polymer is particularly resistant to salt solutions, hydrocarbons, and most other chemicals present in oilfield applications.

Testing Results

Successful laboratory tests have validated the specifications of the liners. Multicomponent crude exposure testing was done over an eight-month time period over a temperature range from 20°C to 80°C. The modulus, yield stress, and elongation properties were relatively unchanged after this test. A separate eight-month test exposed POK to a fluid from a North Sea sour gas environment at 105°C. Tensile properties stabilized after two days of exposure and remained relatively unchanged for the remainder of the testing period.


Technology

POK has a highly crystalline with a compact crystal structure that provides strength and minimal porosity. This unique engineering plastic with a carbon-only backbone resists chemical reaction with solvents which are destructive to other plastic liners. The carbon-only backbone provides strong gas barrier properties and excellent abrasion/chemical/fuel resistance. Its linear molecular chains are perfectly alternating carbon monoxide and alpha olefin structures that ultimately creates a unique balance of strength, chemical resistance and barrier properties that make it well suited for downhole well conditions.

Lightning Rod and Pipe is the exclusive provider of POK tubing liners. The POK liners have been proven to extend the mean time between failures in well installations in multiple locations and various operating conditions.

The LightningFlo™ LF115 lined tubing is recommended for tubing that is susceptible to frictional wear or corrosive reactions such as:

  • Reciprocating Rod Lift
  • Progressing Cavity Pump
  • Salt Water Injection Wells (SWD)
  • Rod Guides
  • Flow Lines

It has excellent permeation performance in wet H2S and CO2 and resists to attack or swelling from hydrocarbons, ketones, esters and ethers, inorganic salts, as wells acid and base pH levels.

Its excellent ductility in a broad temperature range makes it mechanically resilient and resistant to elongation and impact deformations. Creep performance has been minimal in field use. It can also be subjected to larger cyclic deformations than other ETPs before irreversible deformation (fatigue), and it resists hydrolysis.

Mechanical Properties

Tensile Property (ASTM D638) PK PA11 BESNO P40TL PVDF Kynar 710 PVDF Solef 1010 HDPE PE3408
Modulus, Kpsi 223 35.8 322 333 158
Yield Stress, psi 8740 - 8000 7970 3900
Yield Strain, % 24.5 - 7.92 8.42 12.4
Break Stress, psi 11900 5920 6180 5750 3350