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. 02, 1978
Filed:
Sep. 15, 1976
Johnce E Hall, Broken Arrow, OK (US);
William D Greenfield, Tulsa, OK (US);
Standard Oil Company (Indiana), Chicago, IL (US);
Abstract
The riser pipe, e.g., 21 inches in diameter, extends from the ship to an anchored wellhead assembly on the ocean floor. A drill bit and drill string are guided down through the inside of the riser pipe and the anchored wellhead assembly to perform drilling operations in the ocean floor. Various strings of casing for lining the borehole wall, which is thus drilled, are run down through the interior of the riser pipe. The first string of casing run is of relatively large diameter, e.g., 20 inches in diameter followed by 133/8 or 103/4 strings. Intermediate strings are typically 95/8 or 75/8, depending on the previous string diameters. As heavier drilling muds are used, the riser tension needed to prevent buckling is increased. To reduce the tension required, we place a sleeve of low density in the annulus between the drill string and the riser pipe interior wall, leaving a much smaller annulus between the drill pipe and the insert, thus displacing the heavier mud with a lighter weight insert.