An Overview of Challenges and Errors in Sampling and Recombination of Gas Condensate Fluids

A proper understanding of reservoir fluid phase behavior is the first crucial step in the development and production of an oil/gas field. This paper addresses the challenges and errors associated with the fluid sampling that may arise before, during and after the sampling operation. For this aim, DST and PVT data of exploration and production wells of a supergiant offshore gas condensate reservoir were analyzed. It was found that well conditioning and flow stability are essential before sampling. The main sources of error during the sampling include separator instability, lack of vapor-liquid equilibrium, volume ratio of separator outlets, and the presence of contaminants. Analysis of separator outlet streams further indicated deviation from equilibrium for some wells, which can have direct impact on dew-point pressure and condensate gas ratio (CGR) prediction of well stream. Improper fluid handling, oil and gas leakage, and the presence of corrosive compounds can severely affect the quality of the recombined fluid.