Seismic-Frequency- vs. Seismic-Interval-Velocity-Based Pore-Pressure Prediction

Fig. 1—Base map of the PTA.

The process of risk and uncertainty reduction in unconventional-drilling operations starts with improving techniques for pore-pressure modeling. A study conducted in a near‑salt field in deepwater Gulf of Mexico (GOM) that compared the accuracy of seismic-frequency- and seismic-interval-velocity-based methodologies showed significantly higher accuracy for the seismic-frequency-based approach in wells that were in near- or subsalt environments and higher overall accuracy for all wells.

Introduction

The current standard practice for modern pore-pressure prediction relies on interval velocities obtained through seismic surveys. The methodology has seen many changes, but transforms used for interval-velocity-based pore-pressure prediction are for the most part still heavily reliant on the assumption that the porosity trend is directly related to pore pressure. Also, rock velocities are highly dependent on factors such as lithology and porosity, which may have nothing to do with effective stress, the key factor that all pore-pressure models are designed to predict. A seismic application for formation-pressure prediction has been explored that avoids any and all assumed relationships between porosity and effective stress: seismic-frequency-based pore-pressure prediction.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 167915, “Seismic-Frequency- vs. Seismic-Interval-Velocity-Based Pore-Pressure-Prediction Methodologies for a Near-Salt Field in Mississippi Canyon, Gulf of Mexico: Accuracy Analysis and Implications,” by T. Mannon, Stone Energy and University of Louisiana at Lafayette; S. Salehi, University of Louisiana at Lafayette; and R. Young, eSeis, prepared for the 2014 SPE Drilling Conference and Exhibition, Fort Worth, Texas, USA, 4–6 March. The paper has not been peer reviewed.
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Seismic-Frequency- vs. Seismic-Interval-Velocity-Based Pore-Pressure Prediction

01 March 2015

Volume: 67 | Issue: 3

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