A triple-porosity radial composite model for two-phase well test analysis of volatile oil in fractured-vuggy reservoirs

In this study, by employing a novel analytical model for well test analysis, characterization is performed for a fractured-vuggy reservoir containing volatile oil with flowing wellbore pressure below the bubble-point pressure. Well test analysis in such medium is challenging due to complications in reservoir geology and fluid behavior. Rock complications arise because of existence of three media which interact with one another due to different flow behavior. Fluid related challenges are caused by gas liberation and two phase flow near the well bore. To perform the analysis, a synthetic model was investigated and pressure data were generated. Pressure data in such reservoir exhibited a radial composite behavior. Subsequently, a triple porosity radial composite model was developed for analysis and parameter estimations in such reservoirs. It is shown that reservoir parameters could be predicted with acceptable accuracy using the proposed model. The estimated effective permeabilities in all cases were close to the actual value, with absolute relative error less than 0.1. However the obtained interporosity flow parameters were slightly different from single phase parameters due to the presence of gas bank near the wellbore.