Dual gradient managed pressure drilling
US9328575B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 2013 |
| Grant date | May 3, 2016 |
| Priority date | — |
| Expiry date | Jun 28, 2034 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B21/001
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A method of drilling a subsea wellbore includes drilling the wellbore by injecting drilling fluid through a tubular string extending into the wellbore from an offshore drilling unit (ODU) and rotating a drill bit disposed on a bottom of the tubular string. The method further includes, while drilling the wellbore: mixing lifting fluid with drilling returns at a flow rate proportionate to a flow rate of the drilling fluid, thereby forming a return mixture. The lifting fluid has a density substantially less than a density of the drilling fluid. The return mixture has a density substantially less than the drilling fluid density. The method further includes, while drilling the wellbore: measuring a flow rate of the returns or the return mixture; and comparing the measured flow rate to the drilling fluid flow rate to ensure control of a formation being drilled.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.