Long-Term Performance of Hydraulically Fractured Layered Rich Gas Condensate Reservoir

Abstract

Abstract Compositional simulator has been used to investigate the effect of hydraulic fracture on the performance of a layered rich gas condensate reservoir. The reservoir consists of five layers having permeabilities ranging from 0.08 to 115 md with about 68 % of the gas reserve located in the lowest permeability layer. The fracture is assumed to penetrate all layers. The results of this investigation show that hydraulic fracturing is effective in improving the productivity (PI) of the gas condensate wells both above and below the dew point pressure by about three folds as compared to the non-fractured wells. Hydraulic fractures are also found to delay the dew point pressure and consequently extend the production plateau above the dew point pressure. The results also show that as the dimensionless fracture conductivity increases, the long-term performance of the gas condensate reservoir is improved, and the improvement is more pronounced for longer fractures. It is also observed that once the dew point pressure is reached, the flowing bottom hole pressure drops sharply to the specified minimum flowing bottom hole pressure in the fractured and non - fractured cases. However, the drop is less severe in the fractured case. This sharp drop in the flowing bottom hole pressure results in dropping the productivity of the gas condensate wells. At early times after reaching the dew point pressure the highest condensate saturations along the fracture faces are found to be in the highest permeability layer. However, at late times (after reaching pseudo steady state) it decreases and stabilizes at certain level above the critical condensate saturation. Finally, formation cross-flow is found to improve the productivity of the fractured and the non-fractured wells. However, the improvement is more pronounced in the fractured cases. Introduction Hydraulic fracturing has been proven to be one of the most effective techniques for improving the productivity of dry gas reservoirs. Acid fracturing and hydraulic fracturing have also found to be effective in improving the productivity of gas condensate reservoirs1–6. Ref. 1 presents field results showing successful acid stimulation jobs in the Arun Field. It presents results showing improvement in well deliverablity by 41 to 113 percent. But no long- term data are presented.