High Temperature Influence in Pore Pressure Prediction – Case Study in Offshore Malaysia

Pore pressure studies are key components for well design engineering and economics consideration to safely reach deep petroleum resources. However, in deeper reservoirs, additional geological processes are favorable for secondary overpressure mechanisms which may lead to uncertainty in pore pressure prediction. Analyses conducted are interpreted together with petrophysical, stress and pressure plots such as depth-based velocity-density, porosity-effective vertical stress, field data (formation and temperature) and observations (stress and pressure measurements). The results show the highest uncertainties in predictions versus actual measurements are often observed at 80 to 140 degree Celsius. This temperature range is often related to less predictable fluid properties and pressure due to probable complex geological processes such as hydrocarbon generation, diagenesis, metagenesis, chemical compaction and alteration. For each temperature range, the estimation errors are plotted and assessed based on field observations. The paper highlights the differences between estimation of pore pressure and actual measurements at a range of temperatures and the evaluation of uncertainties associated with temperature in pore pressure prediction. The origins of overpressure and associated geological processes are important in providing thorough and improved understanding on the effects of temperature and the pore pressure prediction reliability. The paper presents an improved methodology and workflow in pore pressure prediction coupled with petrophysical analysis for range of temperatures which provides additional insights for timely decision making. It also aims to encourage the community and industry to consider the replication and potentially improving the workflow for determining uncertainty and increasing understanding in pore pressure prediction at elevated temperatures.