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EnerJet is the name we use for our explosive/implosive type of cleaning method that involves the use of detonating cord and blasting caps attached to a wire carrier that is used to clean wells. Different strengths or grain sizes of detonating cord are used depending on the diameter, condition, and amount of encrustation on the casing. This cleaning method has been in common use in the water and oil industry for several decades.
Detonating Cord, EnerJet Coils and Wire
How do you know if a well needs to be cleaned?
A reduction in the pumping rate and increased drawdown are indications that a
well may need to be cleaned. Normally before a well is cleaned a
video
survey is run to inspect the well for damage, debris, depths and condition of
perforations. Damage to the well, breaks and holes for example, are usually repaired
before well cleaning is started (see
Swage Well Repair.) Large
pieces of debris are also removed from a well before cleaning using a bailer or fishing
tools. The debris can interfere with the cleaning and cause damage to the well to occur
during cleaning. If the perforations appear to be plugged with mineral deposits or
bacteria, cleaning may improve the well production and lower the entrance velocity of
water during pumping. High entrance velocities can enlarged perforations and increase sand
production and pump wear.
Before EnerJet
After EnerJet
What are the recommended loads for different casing sizes and ages?
The following is a table with our recommendations:
| Casing Diameter | Newer Casing | Older Casing |
| 8 Inch | Light Load | Light Load |
| 10 Inch | Light Load | Light Load |
| 12 Inch | Light Load | Light Load |
| 14 Inch | Medium Load | Medium Load |
| 16 Inch | Heavy Load | Medium Load |
| 18 Inch | Heavy Load | Heavy Load |
| 20 Inch | Heavy Load | Heavy Load |
| Light Load = | 25 grain | |
| Medium Load = | 50 grain | |
| Heavy Load = | 75 grain |
What is the procedure for EnerJet cleaning?
First a video survey is run to check for encrustation and perforation depths.
Next is to decide on how much of the perforated interval to clean and prepare the EnerJet.
Before cleaning a release has to be signed by the well owner or their agent.. Then the
perforated area of the well is cleaned using EnerJet followed by other methods if desired.
Cleaning the well can produce several feet of fill material at the bottom of the well so
bailing out the fill material before putting the well back into production is common
practice. In some cases a video survey is run after cleaning to view the results and check
for damage.
Basket and EnerJet
Attaching Blasting
Cap
How does EnerJet clean perforations?
Below is an illustration of the EnerJet Detonating Sequence. "A"
shows the EnerJet in place before shooting. There is a centralizer at the top and bottom
of the string, plus a basket at the bottom to catch a sample of the encrustation and
gravel that may enter the well during the cleaning process. "B" shows the gas
generated by the rapid burning rate of the detonating cord expanding out into the well.
The high energy gas breaks up encrustation as it moves through the perforations and into
the gravel pack and formation. In "C" the energy of the gas has been depleted
and the formation water pressure rapidly pushes the gas back into the well breaking up
more encrustation. EnerJet works better on hard mineral deposits than on bacteria or
algae; they seem to absorb the blast and are often treated with chemicals.
EnerJet Detonating Sequence
What other cleaning methods are available?
There are several other cleaning methods that can be used to clean a well
including brushing, chemicals, and high pressure jetting. All of these other methods can
also cause damage to casing. Running a wire brush to clean a well can clean the
perforations and the inside of the casing but does not go into the gravel pack and
formation. In corroded casing the brushes can tear holes in the casing. Chemicals clean
inside the well, gravel pack and formation but the chemicals have to either be neutralized
in the well or removed and disposed of, which can be expensive. High pressure jets can
shoot water into the gravel pack and formation but can also damage casing by cutting holes
during the jetting process. Cleaning a well poses some risks, but it is not unusual for
more than one method to be used on a well before it is returned to service. Increased
production with less drawdown and reduced entrance velocities are often the result.
