Abstract: Improved methods of placing a gravel pack in a wellbore and in one or more perforations extending from the wellbore into a producing zone are provided. The methods basically comprise the steps of placing a screen in the wellbore adjacent the perforations, and then injecting a low viscosity carrier liquid having a particulate solid pack material suspended therein into the space between the screen and the walls of the wellbore containing the perforations. The pack material has a specific gravity substantially the same as the specific gravity of the carrier liquid whereby a low viscosity carrier liquid can be utilized and the carrier liquid-pack material suspension contains a high loading of pack material.

Abstract: A controllable breaker for use in viscosified fluids utilized in the treatment of subterranean formations comprising a low molecular weight condensation product of hydroxyacetic acid with up to 15 wt % cocondensing compounds containing other hydroxy-, carboxylic-acid, or hydroxycarboxylic-acid moieties. The condensation product has an average molecular weight in the range of from about 200 to about 4000, a generally crystalline structure, a melting point above about 100.degree. C. and is substantially insoluble in the viscosified fluid at ambient temperatures. The breaker is admixed with the viscosified fluid in an amount sufficient to effect controlled breaking of the fluid upon being heated to a temperature above 70.degree. F. within a subterranean formation.

Abstract: Methods of acidizing a subterranean well formation, acidizing compositions and sequestering additives for preventing the precipitation of metal compounds in the formation.