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A new system to remove acid soluble cement

IP.com Disclosure Number: IPCOM000247018D
Publication Date: 2016-Jul-26
Document File: 2 page(s) / 87K

Publishing Venue

The IP.com Prior Art Database

Abstract

Acid soluble cement, made by adding easily dissolved calcium carbonate particles to ordinary Portland cement, is often used downhole in the oil industry as a temporary plug and to control loss of circulation. Once this special cement has done its job, acids such as hydrochloric acid are used to dissolve this cement plug. An "acid-free" method of dissolving acid soluble cement is revealed. Super-chelators such as GLDA (glutamic acid diacetic acid) are currently being used to replace acid in removing calcium carbonate scale. This same chelating ability can be used to dissolve the calcium carbonate added to acid soluble cement

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Title:    A New System to Remove Acid Soluble Cement

Abstract:         Acid soluble cement, made by adding easily dissolved calcium carbonate particles to ordinary Portland cement, is often used downhole in the oil industry as a temporary plug and to control loss of circulation. Once this special cement has done its job, acids such as hydrochloric acid are used to dissolve this cement plug. An "acid-free" method of dissolving acid soluble cement is revealed. Super-chelators such as GLDA (glutamic acid diacetic acid) are currently being used to replace acid in removing calcium carbonate scale. This same chelating ability can be used to dissolve the calcium carbonate added to acid soluble cement.

Description:     Chelating agents and chelating agent precursors such as glutamic acid diacetic acid, methylglycine diacetic acid, and other carboxylic acid derivatives of certain amides, anhydrides, phospholipids, aromatics, or esters, including their salts, are known to strongly bind with cations such as calcium. Their chelating strength can be enough to pull calcium out of calcium carbonate, leading, in an aqueous system, to the dissolution and removal of calcium carbonate. Currently these chelators are used in the cleaning industry to prevent the formation of soap scum and in other industries, including the petroleum industry, to remove calcium carbonate scales. In this new system the chelators will dissolve/remove calcium carbonate that had been added to ordinary Portland cement so that after a period of time the chelators bring about the removal of the acid soluble cement plug without the need of an acid. The chelators will solubilize the calcium rather than acid. There are several possible ways the chelators could be placed in contact with the acid soluble cement. The following list should not be considered comprehensive and the limit of possible methods. 1) After the cement has set, an aqueous solution of the chelators can be pumped down to the section of cement to be dissolved. This can be accomplished through the tubulars already in place, through coiled tubing, or via some other conduit. 2) Dry forms of the chelators can be added to the cement slurry. 3) Encapsulated forms of the chelators can be added to the cement slurry, delaying their activity until something releases the chelato...