for week of May 22, 2006:
Bar hole (noun) A round hole, usually about 3 inches in diameter, that is found near the top of casing joints in some older wells. Bar holes (two holes at 180 degrees of each other) were cut in the casing during installation, to allow a steel bar to be passed horizontally through the holes. The bar was then used to support the casing as it was lowered into the well. Bar holes are seldom used anymore during casing installation and have been replaced by the casing clamp.