E-I-Tubing – Heat traced insulated tubing with threaded connection
Majus E-I-Tubing is a vacuum insulated tubing (I-Tubing) with an electrical heat tracing system incorporated. It can be used as a production tubing to avoid wax deposition when passive insulation is not sufficient. Thanks to the high thermal performance design, low electrical power and low voltage are enough to compensate the thermal loss through the line.
In some application where the oil shall be kept above a specific temperature to avoid wax or paraffin deposition, a passive insulation solution (ex. I-tubing) could not be sufficient. This could be the case when the wax appearance temperature is very closed to the reservoir temperature or the length of the tubing line is important or the GOR is high and the gas decompression cools the oil.
In such cases, the oil temperature will drop below the appearance temperature. One answer to this harsh flowing conditions is to send heat along the tubing line through electrical wire. But the amount of heat requested by the tubing line could be tremendous if using a non-insulated tubing: most of the heat provided by the electrical cable is dissipated to the external environmental. The electrical power requested is very important and the electrical cable big enough to resist high voltage and high amperage. Therefore, CAPEX and OPEX are high. Moreover, without thermal insulation, the temperature around the tubing will not be homogenous and some cold spot could appear locally and lead to wax/paraffin deposition.
Considering the limitation of common heat tracing system, MAJUS developed the E-I-Tubing product. It is based on the top thermal performance of the I-tubing and with major innovations to include a robust heat tracing cable. This new design combining a passive insulation and a heat tracing system allows more than 90% of the heat dissipated by the electrical cable to go into the tubing. When a typical application would request 300kW for one well, the E-I-Tubing would need only 20kW with no cold spot.
Some electrical wires are applied on the external diameter of the tubing between the tubing and the insulation. The quantity of wire applied depends of the amount of heat requested by the tubing line: typically between 1 and 10 wires. The selected electrical cable are small size cable. When specifically design, the E-I-Tubing could have negative heat loss: the heat traced system will bring enough heat to compensate the thermal heat loss through the system and to bring additional heat to the fluid.
When Majus vacuum insulated tubings gets its limit, the E-I-Tubing can be used by operators in some critical operations like:
- Mitigate paraffinic/wax deposition in well with wax appearance temperature very closed to reservoir temperature
- Restart of well production after a shutdown during which paraffin/wax deposition occur
The benefits of the E-I-Tubing are the following:
- Very low electrical power requested
- With the heat tracing system, the E-I-Tubing is equivalent to a tubing with no heat loss or even with negative heat loss
- Low CAPEX, low OPEX
- Compact design
- No need of mechanical scrapping or chemical flushing to remove wax/paraffin
- HSE: less well operation to remove wax or paraffin
- Increase of production because no production shutdown are requested to remove wax/paraffin