Abstract: An apparatus to facilitate the replacement of a grinding wheel secured to a mounting plate. The apparatus includes a frame having two spaced-apart uprights. An elongated support bar extends between and is pivotally mounted to the uprights while a mounting plate of a grinding wheel is detachably secured to the support bar. A lift table is mounted to the frame between the uprights and movable between a raised position in which the lift table is positioned adjacent the support bar and a lowered position in which the lift table is spaced downwardly from the support bar. The lift table is dimensioned to support a grinding wheel. An actuator is mounted to the frame and selectively moves the lift table between its raised and lowered positions.

Abstract: A method for removing or dissolving calcareous materials in a subterranean formation or in a wellbore consists of two basic steps. In the first step, an aqueous acid solution is injected into the formation or wellbore. The aqueous acid solution contains between from about 15 to about 99 weight percent of an organic acid selected from formic acid, acetic acid or a mixture of formic acid and acetic acid. Water or brine is then injected into the formation or wellbore. The amount of water or brine injected into the formation or wellbore is an amount sufficient to reduce the concentration of organic acid in the formation or wellbore to no greater than 10 weight percent.