Alteration of asphaltic crude rheology with electromagnetic and ultrasonic irradiation

Electromagnetic heating and ultrasonic irradiation have the unique advantage of minimizing heat loss in the pipe or even in the unnecessary sections of the wellbore. In Canada, these processes have received significant attention in the context of heavy oil recovery. In Alaska, where heat loss to the surrounding makes the steam flooding process ineffective, electromagnetic heating is being reviewed as an option to recover heavy oil and gas from hydrates. Electromagnetic heating or ultrasonic irradiation can be effective in carbonate reservoirs as well. However, recently, concerns have been raised regarding irreversible alterations of crude oil properties due to these otherwise non-intrusive processes. This paper investigates the extent of thermal alterations of crude oil properties due to electromagnetic or ultrasonic irradiation. Experiments also involved the determination of thermal conductivity of carbonate rock, United Arab Emirates (UAE) crude and water for various mixtures. This followed the study of the effect of electromagnetic power for a given frequency on the thermal alteration of UAE crude in the presence of carbonate rock. The role of residual water saturation was also studied. Experiments showed that the efficiency of electromagnetic heating is very high and can be used to heat near the wellbore with minimal energy input. However, the presence of asphaltenes led to some irreversible alteration in crude oil rheology. The physics behind this alteration is investigated in this paper. Such alteration was not evident in the presence of ultrasonic treatment, even though the viscosity reduction during ultrasonic treatment was significant.