A new approach for analysis of production data from constant production rate wells in gas condensate reservoirs

Abstract

Production data analysis provides key parameters to a series of reservoir engineering calculations such as reserve estimation, inflow performance calculations, and well production forecast. Although techniques of production data analysis for oil and dry gas reservoirs have advanced significantly over the past few decades, application of these techniques for analyzing production data of gas condensate reservoirs has not been fully studied despite its great practical importance. In this work, a simple yet accurate methodology is presented for reliable estimation of initial gas in place and average reservoir pressure in gas condensate reservoirs. We define new pseudopressure and material balance time functions suitable for gas condensate systems. According to our observations, a Cartesian plot of modified normalized pseudopressure versus modified material balance pseudotime of gas condensate production data yields three distinct regions. In this study we will show that the middle region is unusable and should be distinguished and removed from the analysis. The required input data are bottom hole flowing pressures, gas and condensate production rates, and constant volume depletion (CVD) test data. This study provides example analyses and establishes guidelines for the analysis and interpretation of long term production data in gas condensate reservoirs using developed Cartesian plot.