Title:
DUAL-GRADIENT DRILLING USING NITROGEN INJECTION
Document Type and Number:
WIPO Patent Application WO2004033845
Kind Code:
A3
Abstract:
Methods and apparatus for drilling subsea wells in deep water using dual-gradient drilling techniques. One preferred embodiment includes a high pressure riser (170)running from a drilling platform at the surface to the seafloor. The base of the riser is connected to a wellhead that is anchored to the seafloor. Pressure control equipment is disposed on the upper end of the riser at the drilling platform. A coiled tubing drill string (130) is run through the riser and into the subsea formation. The drill string preferably includes a pressure sensing device (136) that can be used in transmitting real-time downhole pressure data to the surface. A riser injection system (160) is provided to inject a lower density fluid into the riser annulus in order to reduce the density of the fluids in the riser annulus and therefore reduce the hydrostatic pressure within the wellbore.
Inventors:
FARABEE LELDON MARK
NAQUIN CAREY JOHN
LAURSEN PATRICK EMMETT
NAQUIN CAREY JOHN
LAURSEN PATRICK EMMETT
Application Number:
PCT/US2003/030490
Publication Date:
May 27, 2004
Filing Date:
September 29, 2003
Export Citation:
Assignee:
HALLIBURTON ENERGY SERV INC (US)
International Classes:
E21B21/08; E21B21/14; (IPC1-7): E21B7/12
Foreign References:
| US6668943B1 | 2003-12-30 | |||
| US6484816B1 | 2002-11-26 |
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