
386
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Shale Control Inhibitor
nely laminated or layered structure. Shale breaks easily into thin parallel
layers; a thinly laminated siltstone, mudstone, or claystone. Shale is soft but
sufciently hard packed (indurated), so as not to disintegrate upon becom-
ing wet. However, some shales absorb water and swell considerably, causing
problems in well drilling. Most shales are compacted and, consequently, do
not contain commercial quantities of oil and gas. (3) Rock formed from clay.
(4) Gas reserves found in unusually nonporous rock, requiring special drill-
ing and completion techniques.
Shale Control Inhibitor: Materials that slow or prev