Trace back of depleted-saturated lean gas condensate reservoir original fluid: Condensate stabilization technique

摘要

Gas condensate reservoirs denote an important source of hydrocarbon reserves and have long been identified as a reservoir type, possessing the most complicated flow and complex thermodynamic behaviors. On the other hand, collection of a sample that dependably represents the reservoir fluid is vital in simulation and flow behavior considerations particularly for gas condensate reservoir fluids. Because of multiphase flow in near well bore region, even during early depletion stages, recombined separator or directly obtained bottom-hole samples may not represent original reservoir fluid. The problem becomes more complex when he average pressure declines below saturation one and consequently condensate saturation distributes in whole drainage area. As a consequent, reservoir fluid should be sampled as early as possible during the production life of a reservoir. This paper presents a novel and relatively simple method for determination of representative initial fluid of a depleted-saturated lean gas condensate reservoir, using at least available data of original fluid including dew point pressure and producing GOR properties. The procedure was supported by thermodynamic PVT programs and reservoir simulations. An equation of state based PVT program was expertly tuned with properties of an assumed initial fluid sample and was used in the phase behavior deliberation and reservoir simulation. Suitable conditions for sampling are also investigated. Comparative studies show that recombination with simultaneous matching of GOR and dew point pressure can trace back initial reservoir fluid acceptably.