Evaluation of wireline formation tester in gas condensate reservoir

Abstract

Currently, the pressure behavior study from well tests in gas condensate reservoir has been the subject of much research. However, it has not been reported that the pressure derivative from wireline formation test is used to detect condensate drop-out around wellbore. This study aims to investigate the effect of condensate drop-out on pressure transient data obtained from wireline formation test in gas condensate reservoir. A reservoir simulator was used to determine pressure responses from wireline formation tests for single layer homogeneous gas condensate reservoir. Then, the pressure transient analysis software was used to estimate reservoir parameters. A single layer homogeneous reservoir with lean gas condensate fluid was used as a base case to investigate the pressure and phase behavior during drawdown and build-up period when the flowing pressure is above and below the dew point pressure. After that, a single layer is investigated for the effects of drawdown rate, initial fluid composition, test duration, probe size, probe position, initial reservoir pressure, permeability anisotropy and horizontal permeability on the pressure behavior. All the investigations were performed to determine whether the results from WFT conducted in gas condensate reservoir can provide satisfactory information under different reservoir scenarios and tool limitation. The results show that with certain conditions, the condensate bank effect can be recognized as a spherical composite behavior on the pressure derivative obtained from WFT.