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:
Apr. 14, 2020
Filed:
Dec. 22, 2014
Kureha Corporation, Tokyo, JP;
Masayuki Okura, Tokyo, JP;
Takeo Takahashi, Tokyo, JP;
KUREHA CORPORATION, Tokyo, JP;
Abstract
A plug for well drilling includes a mandrel and at least one diametrically expandable annular rubber member and at least one slip disposed on an outer circumferential surface orthogonal to an axial direction of the mandrel; (i) the mandrel being formed from a degradable material; and (ii) the at least one diametrically expandable annular rubber member being formed from a degradable rubber material having a rate of decrease of not less than 5% in 50% strain compressive stress after immersion in water at a temperature of 150° C. for 24 hours relative to the compressive stress before immersion; and/or having a rate of loss of mass of from 5 to 100% after immersion in water at a temperature of 150° C. for 72 hours relative to the mass before immersion. A well drilling method includes a step of isolating a borehole using the plug for well drilling, part or all of the plug being degraded thereafter.