Alternate Ways to Determine Pore Pressure Information: A Multi-Pronged Approach Enhances Conventional Real-Time Techniques

Summary A conventional pore pressure prediction workflow bases the prejob model on surface seismic data, assumes under-compaction is the primary pressure mechanism and that changes in pore pressure can be monitored while drilling using available log measurements. This workflow can perform well in the conditions where it applies but it is limited in that it ignores many other sources of information that can tell the analyst something about the current pore pressure regime to help constrain the uncertainties in the model and that can work in situations that are not caused by under-compaction alone. A more comprehensive approach considers the response of any available source of information while drilling that could be affected by changes in pore pressure. These include event gas peaks and their component ratios, annular pressure profiles, cavings analysis and the multitude of drilling parameters available at the wellsite. These can help the analyst determine if the well is under-balance or ballooning and can provide indications of pore pressure concerns before they may affect conventional log responses. The inclusion of these indicators in the analyst’s workflow can aid in managing risk and improve drilling safety.