Beyond Gas Bubbles in Norwegian Oil Fields: An Integrated Technique to Understand Reservoir Fluid Distribution

The understanding of fluid phases in reservoirs poses significant challenges, particularly when dealing with depletion, moving contacts, gas injection, or any physical phenomenon. Such conditions can complicate conventional petrophysical evaluations, and neutron-density separation and borehole resistivity responses can lead to ambiguous interpretation. To address these complexities and make informed reservoir development decisions, results from various techniques and sources, such as advanced mud gas analysis, fluid sampling, and petrophysical data, are integrated to gain additional insights while drilling. In the example of a depleted oil field, zones of interest were identified based on the analysis of mud gas and conventional logs. However, the presence of both oil and gas phases in the transition zone made it difficult to get an accurate fluid interpretation. Consequently, a sampling tool is deployed to confirm the flowing phase, and new cutoffs for the mud gas measurement (as per Cely et al., 2023 and Bravo et al., 2024b) in this reservoir were established, allowing calibration of subsequent wells in the same field. Post-well pressure-volume-temperature (PVT) analysis showed consistent fluid properties with the real-time measurements taken by the sampling tool. Moreover, this paper presents additional cross-comparison plots to reinforce confidence in technology adoption and its added value.