The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 07, 1996
Filed:
Dec. 14, 1993
James W Dobson, Houston, TX (US);
Texas United Chemical Corporation, Houston, TX (US);
Abstract
The invention provides (1) a method of increasing the thermal stability of an aqueous polysaccharide-containing fluid by adding thereto magnesia and a thiosulfate salt; (2) a drilling, completion, or workover fluid comprising an aqueous liquid, a water soluble polysaccharide, magnesia, and a thiosulfate salt; and (3) an additive for increasing the thermal stability of an aqueous polysaccharide-containing fluid which comprises magnesia and a thiosulfate salt in a weight ratio of magnesia to thiosulfate salt from about 0.15/1 to about 6.67/1. The preferred magnesia has an activity index less than 100, most preferably less than 50. The preferred thiosulfate salt is sodium thiosulfate. The preferred polysaccharide is selected from the group consisting of xanthan gum, epichlorohydrin crosslinked starch, carboxymethyl cellulose, and mixtures thereof. The preferred aqueous liquid is a saturated sodium chloride solution.