April Webinar Presentation

DATE:  THURSDAY, April 21, 2022 @ 12:00 pm

TOPIC: Log-Based Pore Pressure Prediction Method for Unconventional Resources

Kim McLean, Elive Menyoli, Cintya Galicia, David Garcia, Philippe Ecoublet, Dennis Ellison, Adrien Caudron

PRESENTER: Kim McLean, Emerson

Abstract

Pore pressure is a key parameter for economic development of unconventional reservoirs, partly due to the correlation between over-pressured areas and productivity, and safety. In unconventional reservoirs, standard Eaton methods for pore pressure prediction generally fail because the rocks are more lithified and there are more lithologically and mineralogically varied formations compared to the thick turbidite sequences in conventional reservoirs. Variations in sonic velocities are not caused solely by pore pressure, but also by changes in rock lithology (composition and mineralogy), kerogen content and TOC. The pore pressure prediction method proposed in this paper is an extension of Eaton-based velocity-effective stress approach that accounts for the significant inorganic mineralogy and lithology variations that occur in unconventional resource stratigraphies. Based on a rock physics model, the approach corrects for mineralogy and porosity variations to obtain in-situ sonic velocity where over-pressure is the main controlling factor on the corrected sonic velocities. The influence of organic minerals (kerogen, TOC) on sonic velocities and density in mud rock are also accounted for in this approach. Using basic well log data, the primary mineral compositions per depth are estimated from multi-mineral inversion, while mineral facies were predicted through a machine learning module. Kerogen is incorporated as part of the rock constituent minerals. After correcting for these factors, the proposed method gives pore pressure prediction results that conform with measured DFIT pressure data. Figure 1 shows a comparison of log-estimated pore pressure using traditional Eaton method (green) and the pressure estimated using the method presented in this paper (orange), applied on a study in South Texas. The green curve shows the start of overpressure at lower Austin Chalk and stays high over the entire Eagleford formation. On the other hand, the orange curve shows the overall section being normal pressure until Lower Eagleford formation.

Bio

Kim received her Bachelor’s of Science degree from the University of New Orleans before carrying on to Central Washington University where she studied the structural geology of the Tien Shan in Kyrgyzstan for her Master’s thesis. After receiving her MSc, Kim entered the energy industry with her initial focus on geology, though most of her career has focused on log analysis and petrophysics. In her professional career, she worked at Halliburton, and Paradigm before spending two years as the petrophysicist for the Pike Asset team with BP in Calgary.

Kim rejoined Paradigm, now Emerson, in 2016, and in 2020, Kim became the head of the Formation Evaluation and Drilling technical team for North America.