Almost half of Western Canada's natural-gas production comes from the Triassic-aged Montney formation, which is rich in condensate. It is significant to efficiently develop liquid-rich Montney formation. The objective of this study is to investigate phase behaviors and condensate blockage in liquid-rich Montney formation. Further, the development potential of the liquid-rich Montney formation and the timing of production gas reinjection were fully discussed.
In this study, the compositional field scale numerical model is construct to simulate condensate distribution and phase behaviors during long-term production and produced gas injection periods in a fractured tight gas condensate reservoir. Two different types of gas condensate fluids obtained from the liquid-rich Montney formation. The first fluid named Fluid A is rich in condensate and its dew point pressure is closer to formation pressure, and the other named Fluid B is poor of condensate and its dew point pressure is much smaller than formation pressure. Two fluid are compared in terms of the location and time of condensate accumulation based on compositional and field scale modelling.
This study concluded that the gas-oil ratio with production time of a gas well is characterized by two stable stages, and the process of rising gas-oil ratio is the time when condensate appears and accumulates in the formation. Condensate blockage mainly occurs in the matrix near the fracture, and the location and time of condensate accumulation are affected by the condensate oil content and dew point pressure. For Fluid A, condensate blockage occurs quickly and maintains a large range (within tens of meters near the fracture), which causes production capacity of gas well decreasing. Early reinjection of produced gas can significantly relieve the damage of condensate blockage and improve the recovery of condensate and gas. In contrast, considering the economic cost, it may not be necessary to reinject the produced gas for Fluid B.
This work can provide a better understanding of retrograde condensation and condensate blockage in a tight condensate gas reservoir. It also provides a reference for the evaluation of timing of production gas reinjection.