ULZhG hydrocarbon-based ultra light killing fluids for the wells with abnormally low formation pressure

Purpose of Use
Well-killing, even within the same area, requires an individual approach to the selection of killing fluid parameters. Well-killing fluids with low densities, which are able to prevent fluid loss, well productivity decreasing after maintenance and long period of resumption of stable output of the wells after maintenance, must be used for killing of the wells with abnormally low formation pressure.

Polyex has designed hydrocarbon-based Ultra Light Killing Fluids of ULZhG brand with densities from 0.53 g /cm3 for killing of the wells with abnormally low formation pressure for performing maintenance and repair works.

The product is a liquid based on refined petroleum fractions containing a Stabilizer, a Structure former and an Ultra-light filler.

The hydrocarbon base of the composition is the LIGHTRIX reagent. The base is refined petroleum fractions or pols (the pour point of the reagent, depending on the type of base, varies from minus 35°C to minus 50°C). LIGHTRIX Stabilizer is a homogeneous light fine powder that provides long-term stability and thermal stability of ULZhG. The EKS-EM®emulsifier developed by Polyex Company is used as an ultra-light filler, which is a polymer microspheres or microspheres of silicates of various nature, which allows significantly reducing and varying the density of the killing fluid. Depending on the nature of silicates, EXTELIGHT filler varies in terms of thermal resistance and resistance to mechanical damage.

Application Area
·       Killing of oil and gas wells with abnormally low reservoir pressure, including in reservoirs composed of rocks sensitive to water.


 Appearance Viscous suspension with the color varying from beige to dark brown  
Density, g/сm3 From 0.53 g/сm3 to 0.9 g/сm3
Bookfield viscosity at 50 s-1, at 20°С, not higher than
400 mPa·s
Freezing point, not higher than   Minus 20°С
Thermal stability* confirmed by laboratory tests
Up to 120°С
Aggregative stability of ultra light well-killing fluid checked in laboratory conditions 
At least 3 days 

Customer Benefits

  • Possibility to achieve well killing fluid density starting from 0.53 g/cm3 provides the possibility of gas-lift wells completion with no coil tubing (the minimum achievable density of hydrocarbon emulsions is 0.9 g/cm3).

  • Workability of low density killing fluid at low temperatures (confirmed by testing application temperature up to minus 20°C).

  • Workability of low density killing fluid at high temperatures (confirmed by testing application temperature up to 120°C). 

  • Low corrosiveness.

  • Possibility of re-use of oil-based killing (provided that the used kill fluid is purified with a hydro cyclone).

  • Applicability for reservoirs composed of minerals sensitive to water.

  • Average well resumption period after killing with ULZhG makes 3 days. (Well resumption period after killing with standard hydrocarbon emulsions is up to 10 days)

Process Technique

Hydrocarbon-based Ultra light killing fluid ULZhG is supplied component-wise and is mixed right before the application at site at a brine preparation unit. Hydrocarbon phase is selected depending on the required application temperature.

To obtain information that is more detailed and select the optimal consumption rates of chemicals for making of ultra-light killing fluids, it is recommended to contact the sales and service specialists of the Polyex company. 

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