Paraffin build up prevented by invention from Univ. of Texas

Eliminating paraffin and wax in tubing strings could lower production costs significantly

Wax and paraffin build up in mature oil wells could become a thing of the past, thanks to an invention from University of Texas Austin researchers.

Paraffin and wax build up can require one or two clean outs per year, adding costs and taking well off production.

Petroleum and Geosystems Engineering Prof. Mukul Sharma, along with Drs. Raymond Zowarka, Jr. and Siddharth Pratap in UT’s Center for Electromechanics, have developed a design that generates heat at a localized spot in the production tubing string, melting any wax and paraffin build up.

No external power supply is required, as the heat is generated from the relative motion between a set of magnets and a magnetically conductive surface.The relative motion produces eddy currents that heat the conductor, and the energy input to the unit can be provided by the vertical travel of the sucker rod pump.

Since the invention integrates the heater with existing infrastructure, it requires no changes to the pump jack method of oil delivery.

The accumulation over time of non-volatile compounds in “cold spots” in the tubing creates high pressures and flow constrictions that at the very least contribute to accelerated pump wear, and at worst constrict the flow altogether.

Standard treatment methods include the circulation of hot drilling fluid through the tubing string to melt any buildup of paraffin and wax, and to circulate out the melted material or downhole heater elements that require separate power supplies and create added cost in resources and time to deploy.

These methods can result in a great deal of heat loss from the surface to the formation, are highly inefficient, and therefore costly.

They are often used several times per year, taking production off-line in order to clean out the wax build up in the production string.

The installation of non-electrically powered heating elements directly in the flow path in the well string and located at the appropriate depths where “cold spots” are known to form eliminates wax buildup in the first place.

The UT Austin invention integrates the heater with the existing infrastructure requiring no changes to the pump jack method of oil delivery. The only change is the potential requirement of slightly increased pumping power to drive the heater.