Heavy oils and native asphalt commercial field development is concerned with research on different issues, refer to production, transportation and processing. Investigation on the possibility of heavy oils and native asphalt conversion under field conditions, including downhole treatment, in order to decrease crude oil viscosity is one of the promising research trends in this field. The stated conversion is feasible under thermolysis and aquathermolysis processes, among others. Overwhelmingly important and relevant objective is determination of common factors and development of scientific basis of the mentioned processes.