Hydraulic Fracturing: Best Remedy for Condensate Banking Effects in Tight Gas-Condensate Reservoirs

Abstract

Available headroom (difference between dewpoint and reservoir pressure) in liquid rich gas reservoirs and drawdown scenario affect the condensate dropout near the wellbore. Although effects of the liquid dropout are well understood in radial system, addition of hydraulic fracture in the low perm reservoirs complicates the saturation profile in reservoirs. Massive hydraulic fracturing in vertical tight sand wells adds effective surface area to flow and can mathematically be considered as placing long horizontal wells to reduce overall well draw downs. This work shows that this additional contact with matrix rock, therefore, can play a major impact in mitigating or postponing the impact of skin caused by condensate banking. This paper presents a real case of Pressure Transient Analysis (PTA) for hydraulically fractured wells in unconventional gas-condensate reservoirs. Detailed analysis of PTA will be discussed and addressed using analytical and high-resolution numerical models in which compositional multi-phase flow is considered. The numerical model is history matched and fine-tuned on pre-frac and post-frac well test results. The impact of hydraulic fracture half-length, fracture conductivity and matrix relative permeability on condensate banking effects will be addressed via a numerical simulation study for various scenarios. The paper will demonstrate the value of hydraulic fracturing in reducing condensate baking effect on well productivity and, by inference, the impact on the long-term economic value of gas-condensate wells.