Page 9 - Origin and Prediction of Abnormal Formation Pressures

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The patterns of fluid flow powered by compaction disequilibrium or tectonic stress
conditions, presence of salt beds and higher than normal geothermal temperatures create
changes in the salinity of the pore water and its content of dissolved gases that flow out
of and through the sediment/rock pore space. These processes determine the subsurface
pressure regime, its integrity and stratigraphic distribution, and diagenetic/catagenetic
alteration. The nature of abnormal pressure zones fluctuates over geologic time, and
diagenetic/catagenetic history is manifested in the aqueous geochemistry and corre-
sponding changes in the associated mineralogy especially clay mineralogy. Discussion
on the lack of smectite to illite transformation in the Caspian Basin is enlightening.
The book is offered in the hope that our knowledge will provide a new foundation
for bringing about improved field performance, initiating innovative field and laboratory
research, and nurturing analytical dialogue among the geoscientists and engineers.
In addition to the customary topics discussed, there are two chapters that address
other associated issues. One important ancillary topic is production-induced surface
subsidence. Subsidence is the result of abnormally-low formation pressures owing to the
production of fluids. The influx of shale water into the depleting hydrocarbon-producing
zones results in shale compaction. The other chapter explores the use of analytical
model studies, which complete the abnormal pressure picture by adding insight into
likely pressure prediction strategies.
In conclusion, this book is a welcome addition to the petroleum literature.

H.H. Rieke
Lafayette, LA, USA