Page 190 - Origin and Prediction of Abnormal Formation Pressures

DRILLING PARAMETERS 165

OTHER PRESSURE INDICATOR METHODS

Several unconventional methods for detecting overpressured formations and, possi-
bly, even predicting transition zones ahead of the drill bit have been investigated in detail
by Fertl and Timko (1973a,b). These methods include: (1) shale cuttings resistivity, (2)
filtration rate of shale slurry; (3) filtrate (shale water) color; (4) shale cuttings moisture
index; (5) litho-function plots; (6) bicarbonate content of shale slurry filtrate; (7) redox
and pH potential measurements; (8) distribution of specific ions in shale slurry filtrates.

DRILLING CONCEPTS IN OVERPRESSURED ENVIRONMENTS
Maximum well control and minimum cost are key factors in present-day drilling
operations. To achieve this, a basic understanding of two key formation pressures, i.e.,
formation pore pressure and fracture pressure, is a prerequisite. This aspect has been
discussed in detail by Chilingarian and Vorabutr (1981).

BIBLIOGRAPHY
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