Predicting temperature distribution in the waxy oil-gas pipe flow

In the simulation of waxy oil–gas pipeline multiphase flow, the physical parameters and rheological properties of the multiphase fluid are the sensitivity functions of the temperature. The precise temperature distribution of multiphase fluid is the foundation of predicting the pressure distribution accurately, wax deposition rate, optimized design and operating analysis of waxy oil and gas pipeline, and so on. Based on the energy equation of oil–gas flow in pipeline, the explicit temperature drop formula (ETDF) for oil–gas steady state calculation is derived from the energy conservation analysis in micro-element. This new energy equation has considered many factors, such as heat transfer with the surroundings along the line, Joule–Thomson effect and impact of terrain undulation to potential energy. So it is an overall form of energy equation, which could reflect the actual fact of multiphase pipeline accurately. Elimination of temperature iteration loop and integration of the explicit temperature equation, instead of enthalpy energy equation, into the conjugated hydraulic and thermal computation have been found to improve the efficiency of algorithm. The calculation program of temperature drops of waxy oil–gas flow in pipelines is compiled on the basis of the ETDF employing modification of the specific heat of the waxy oil. This model is carried out with a practical waxy oil–gas two phase flow pipeline, and the temperature results are compared with OLGA. It is shown that this model has simulated the temperature distribution very well.

► The explicit temperature drop formula (ETDF) for oil–gas steady state calculation derived is be appropriate for the waxy oil.
► The ETDF could reflect the actual fact of multiphase pipeline accurately.
► The ETDF is an overall form of energy equation, which could reflect the actual fact of multiphase pipeline accurately.
► The ETDF applies to both the component model, also applies to the black oil model.
► The temperature iteration loop in the ETDF is canceled and it has improved the efficiency of algorithm.