AN OFFSHORE GABON INTEGRATED RESERVOIR EVALUATION APPROACH USING WIRELINE NMR AND PUMPOUT FORMATION TESTER

摘要

Oil, gas, and condensate are produced in offshore Gabon where conventional formation evaluation techniques are often inadequate. Clay volume, water saturation, and reservoir quality are highly variable and unpredictable based on only conventional logs. Nuclear magnetic resonance (NMR) T2 analysis is used to quantify clay volume and reservoir quality, and 2D NMR is used to establish fluid type. Fluid type analysis is a key formation evaluation facet because reservoir compartmentalization is prevalent, resulting in unanticipated fluid column profiles, including free water on top of oil and oil on top of gas. Although NMR fluid type analysis enhances fluid column profiling, the method is affected by mud filtrate invasion because of limited NMR depth of investigation, which compromises the validity of the technique in some cases.