The Use of Modern Wireline Logs in the Characterization of a Complex Reservoir - A Case Study from EIS

A case study is presented in this paper to indicate that the modern logs significantly improved formation evaluations for complex reservoirs when combined with the conventional logs. Traditionally, petrophysical formation evaluation using conventional logs (Wireline and LWD) is a qualitative and subjective exercise that relies upon the simultaneous interpretation of multiple conventional wireline logs. In this study, an integrated petrophysical evaluation based on modern logs (e.g. XPT, NMR, FMI and DSI) has been undertaken to characterize complex reservoirs under the conditions of variable water salinities, high irreducible saturation and fractures. Our study results show that the conventional logs provided the typical qualitative reservoir parameters for formation evaluation. However, the usage of modern logs not only improved the traditional CPI interpretation but also minimized the effects of external factors and improved the reservoir characterization. The study based on a gas field from the East Irish Sea shows that the approach resulted in better identification of fluid types, the determination of gas-water contacts and permeability, as well as building saturation-height functions, fractures identification and AVO response analysis.