Page 486 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 462

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Glossary

Array Sonic. Schlumberger wireline tool that digitizes compression-
al, shear, and Stoneley waveforms and is designed to minimize the
discrepancies between sonic and seismic data. Used for porosity
evaluation, shear seismic correlation, thin bed detection, fracture
prediction and detection, sand strength analysis, cement bond log-
ging and through-casing sonic logging. Can calculate rock mechani-
cal properties such as compressive strength and Poisson’s Ratio to
aid bit selection.

Attapulgite Clay. A colloidal, viscosity-building clay used principally
in salt-water muds. Attapulgite, a special fullers earth, is a hydrous
magnesium aluminum silicate.

Authority for Expenditure. A document signed by management that
authorizes funds to be spent against an approved budget.

Automatic Driller. Mechanism to automatically control the weight on
the bit.

Auxiliary Measurements Service. This Schlumberger module pro-
vides direct measurements of wellbore fluid resistivity and tempera-
ture, also cable tension below the toolstring head. Useful to run in
poor hole conditions; should allow differentiation of differential stick-
ing and keyseat sticking. Logs temperature gradients, allows detec-
tion of lost circulation zones and cement tops.

Back-Up. Refers to the act of holding one section of pipe or a bolt
while the other section of pipe or a nut is being turned.

Back-Up Tong. A tong suspended in the derrick, normally on the
driller’s right, used to hold box end of the tool joint while the pin end
is loosened and unscrewed. Also called a make-up tong, as it is
moved to pin end to tighten the joint to the recommended torque
after a joint is spun in.

Balance, Mud. A beam-type balance used in determining mud densi-
ty. It consists primarily of a base, graduated beam and constant-vol-
ume cup, lid, rider, knife edge and counterweight. Two types are

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