Method and apparatus for setting an underwater drilling system
US4759413A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 13, 1987 |
| Grant date | Jul 26, 1988 |
| Priority date | — |
| Expiry date | Apr 13, 2007 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/02
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A method and apparatus for setting an underwater conductor pipe in which the conductor pipe is lowered into the wellhole on a drill string as the borehole is being formed by a drill bit and underreamer positioned at the end of the drill string below the end of the conductor pipe. The drill string and conductor pipe are detachably interconnected by a housing latch which includes means for detachably securing the drill string and drilling assembly to the conductor pipe. The drill string is provided with an upper latch sub, which retains and supports the drill string in its fully extended position within the conductor pipe, and a lower latch sub which retains and supports the drill string in the retracted position. As the apparatus is lowered a drill motor actuates the drilling assembly such that the well hole is formed in the ocean floor. Drilling continues until the permanent guide base of the conductor pipe engages the ocean floor. Thereafter, the upper latch sub is released and the drill string is retracted until the lower latch engages the latchhousing. The outer annulus of the conductor pipe is then cemented into place while pressure within the conductor pipe is maintained to pr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.