Page 292 - Applied Petroleum Geomechanics

CHAPTER 8

Pore pressure prediction and

monitoring

Contents

8.1 Introduction 282
8.2 Pore pressure prediction from hydraulics 284
8.2.1 Pore pressure in a hydraulically connected formation 284
8.2.2 Shallow gas flow and pore pressure elevation by gas columns 287
8.2.3 Centroid effect 288
8.2.4 Vertical and lateral transfer and drainage 291
8.3 Principle of pore pressure prediction for shales 292
8.4 Pore pressure prediction from porosity 293
8.4.1 Depth-dependent porosity method 293
8.4.2 Case application of the porosity method 294
8.5 Pore pressure prediction from resistivity 297
8.5.1 Eaton’s resistivity method 297
8.5.2 Modified Eaton’s resistivity method 298
8.5.3 From Archie’s resistivity equation 300
8.5.4 Resistivity corrections from temperature and salinity 301
8.6 Pore pressure prediction from velocity and transit time 301
8.6.1 Eaton’s method and its improvement 302
8.6.1.1 Eaton’s method 302
8.6.1.2 Modified Eaton’s method 302
8.6.2 Bowers’ method 304
8.6.3 Miller’s method 306
8.6.4 Tau model 306
8.6.5 Depth-dependent sonic method 307
8.6.6 Distinguishing gas effect on compressional transit time 309
8.6.7 Smectite and illite impacts on pore pressure prediction 309
8.7 Predrill pore pressure prediction and calibration 311
8.7.1 Calibration from formation pressure tests 312
8.7.2 Calibration from well influx, kick, and connection gas 313
8.7.3 Calibration from wellbore instability events 313
8.7.4 Predrill pore pressure prediction in the prospect well 315
8.7.4.1 From seismic interval velocity 315
8.7.4.2 From analog wells 315
8.8 Real-time pore pressure detection 317
8.8.1 Procedures of real-time pore pressure detections 317
8.8.2 Real-time pore pressure detectiondresistivity and sonic methods 319
8.8.3 Real-time pore pressure detectiondcorrected d-exponent method 319
Applied Petroleum Geomechanics
ISBN 978-0-12-814814-3 Copyright © 2019 Elsevier Inc.
https://doi.org/10.1016/B978-0-12-814814-3.00008-3 All rights reserved. 281