Abstract
This paper compares the near-wellbore behaviors and productivities of a vertical non-fractured well and a vertical hydraulically fractured well in a low permeability, lean/intermediate gas condensate reservoir, when the flowing well bottomhole pressure falls below the dew point pressure. Under this condition, two phases, reservoir gas and liquid condensate, coexist near the wellbore and a condensate bank is formed, reducing the productivity of well.
Productivity impairment is investigated with single well, fine grid, compositional simulations and analyzes of simulated pressure transient tests.
Reservoir simulation and simulated pressure transient tests show that, in this low permeability reservoir, there is no evidence of capillary number effects, due to low sustainable production rates and high interfacial tension. Effect of production rate and time on well productivity is investigated.
Fracturing the well before the formation of the condensate bank significantly improves productivity. Stimulation reduces the pressure drawdown, leading to less liquid condensate drop-out near the wellbore, thus delaying the formation of the condensate bank. The length of the fracture controls the productivity: a long fracture yields a higher productivity improvement, despite a lower dimensionless fracture conductivity, because the reduction in pressure drawdown far exceeds the pressure loss inside the finite conductivity fracture. Stimulation of the well after the formation of the condensate bank, with a fracture length extending beyond the bank, is also investigated.
Challenges associated with the simulation of hydraulic fractures in gas condensate field studies are briefly discussed.
