Inflow Performance Relationships for Gas Condensates

Abstract

Abstract In this work, we describe a fast scheme to obtain time-dependent IPR curves for a depleting gas-condensate well without resorting to the use of simulation. The model reflects the flowing characteristics inside the reservoir. In addition, it is self-checking and consistent with the overall analysis of gas-condensate reservoir behavior. We also investigate the adequacy of reservoir material balance for gas-condensates to generate the IPR curves for a depleting gas-condensate well. Transient effects are not considered in this work. Inflow Performance Relationships (IPR’s) are a critical element in the design of new wells and in the monitoring and optimization of existing producing wells. In addition to Vogel-type relationships, various IPR models for different well geometry and different flow regimes have been presented. Generally, these models take advantage of analytical solutions for single-phase oil and for single-phase gas, to generate a flow rate profile with flowing pressure as a parameter. For gas-condensate wells, standard dry-gas deliverability equations based on isochronal testing have always been used as IPR models. Unfortunately, due to severe deliverability reduction caused by condensate blockage, this approach is inadequate and usually leads to erroneous results. In reality, the pressure drop that occurs in gas-condensate reservoirs operating below dew-point, is affected by up to three zones, i.e. 1) inner zone where both phases, gas and free condensate, are flowing, 2) middle zone where two phases coexist but only gas is mobile and 3) outer zone where only the single phase gas is flowing. We verified the method with synthetic examples and good agreement was achieved in all cases.