The production of hydrocarbons often involves a concurrent gas and liquid (oil/water) flow in the wellbore. As a multiphase/multicomponent gas-oil mixture flows from the reservoir to the surface, pressure, temperature, composition, and liquid holdup distributions are interrelated. However, most two-phase wellbore simulations are currently performed using "black oil" models. In this project, a compositional wellbore model is coupled with a reservoir simulator to compute pressure and temperature distribution. Compositions of liquid and gaseous phases in the wellbore are determined from two-phase flash calculations and taking into consideration the slip between phases. The temperature profile is calculated in the wellbore to give a more accurate liquid holdup and pressure drop.
The wellbore model is coupled to a reservoir simulator to calculate fluid-flow between reservoir and wellbore. The pressure and temperature distributions of the compositional model are compared to the black oil model. Although the input requirements and computing expenses are higher for compositional model compared to the black oil, the results show that in some cases, such as those involving highly-volatile oil and retrograde condensate gas, ignoring compositional effects may lead to errors in wellbore pressure profile. The model is then extended to allow for fluid flow in horizontal wellbores. The simulator is capable of modeling concurrent flow of gas, oil, and water in horizontal and vertical wellbores. Progress is underway to model asphaltene precipitation and deposition in wellbores.