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Thermal removal of wax

In thermal technique melting of wax is usually done by the injection owater/chemicals.

This technique is simple, low cost and the results are immediate.

Well deposits can vary from a mushy consistency at the upper end ofto hard, crystalline waxes at the bottom.

The type of wax is a function of the carbon atoms in the molecule.

Soft wax: C12 to C25

hard wax: C25 to C50+

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The following is a listing of a few of the wax types that may be encotypical well deposits:

As we can see,The melting temperature increases with the carbon nu

We have to plan our injection timeand temperatureaccording to the w

Wax

Component

Carbon

Number

Melting Point

C F

Pentadecane C15 10 50

Hexadecane C16 20 68

Octadecane C18 28 82

Eicosane C20 38 10

Tetracosane C24 51 12

Triacontane C35 75 16

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Now, when hot oil/hot water is injected into a well, the heat of the ftransfers to the cooler well bore equipment and waxes in the uppethe well.

As pumping of the hot treating fluid continues the heated zone progthe well bore removing additional deposits.

However, the treatment will not completely clean the well unless fluid is hot enough and injected long enough to reach the melting hard waxes at the lower end of the deposit.

Specially designed HOT OIL UNITS are used to heat the lease oil

temperature of 200 to 500

F and either bullhead it into the well othrough a work string.

Fig. Hot Oiler

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If the paraffin depositing is solid it will often have to be washed outstring.

The CT is an excellent tool used in conjunction with hot oil for theparaffin.

Process:

- The CTU is rigged up in standard manner.

- A high temperature pack-off rubber should be used in

the pack-off.

- The hot oil trucksdischarge line is connected to the

rotating hub of the CTU reel.

- Hot oil/hot water should be circulated through the CT

until the CT is hot prior to going in the hole.

Fig. CTU

Fig. Paraffin rem

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Cautions:

- Circulation of the hot fluid should be maintained from surface to approfeet below the fresh water zones.

- Circulation should be maintained for at least two hours after reachin

depth. This will ensure melting away all the paraffin rather than simphole through it.

- Returns should be monitored to be sure the oil is hot enough to mebefore circulation is stopped.

Extreme cautions:

- If the hot oil/chemical should come in contact with someone, it adherea much more severe burn than would hot water.

- Extreme care should be used when moving the coiled tubing while cfluid.

Advantages:

- CTU provides continuous circulation from surface to bottom.

- CTU has a very effective blowout preventer and pack-off assembly.

- Its operation is fast effective and economical.