Drilling system and method for controlling equivalent circulating density during drilling of wellbores
US7270185B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 2002 |
| Grant date | Sep 18, 2007 |
| Priority date | — |
| Expiry date | Jul 9, 2022 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B43/12
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A drilling system for drilling subsea wellbores includes a tubing-conveyed drill bit that passes through a subsea wellhead. Surface supplied drilling fluid flows through the tubing, discharges at the drill bit, returns to the wellhead through a wellbore annulus, and flows to the surface via a riser extending from the wellhead. A flow restriction device positioned in the riser restricts the flow of the returning fluid while an active fluid device controllably discharges fluid from a location below to just above the flow restriction device in the riser, thereby controlling bottomhole pressure and equivalent circulating density (“ECD”). Alternatively, the fluid is discharged into a separate return line thereby providing dual gradient drilling while controlling bottomhole pressure and ECD. A controller controls the energy and thus the speed of the pump in response to downhole measurement(s) to maintain the ECD at a predetermined value or within a predetermined range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.