Drilling apparatus and methods for reducing circulation loss

Patent metadata

Field	Value
Publication number	US-2016201410-A1
Application number	US-201614993646-A
Country	US
Kind code	A1
Filing date	Jan 12, 2016
Priority date	Jan 13, 2015
Publication date	Jul 14, 2016
Grant date	—

Abstract

A loss mitigation bottom hole assembly for use in a wellbore to isolate a severe loss zone of a formation, including a drill bit for drilling a well bore, and a dual wall drill string connecting the drill bit to a fluid source, and having a first fluid passage for delivering fluid to a drill bit, and a separate second fluid passage for returning the fluid away from the drill bit. The assembly further includes a drilling liner circumscribing and attached to a bottom portion of the dual wall drill string, and surrounding the drill bit, the drilling liner having an end adjacent the drill bit to contain the fluid exiting the drill bit and prevent the fluid from entering the severe loss zone of the formation.

First claim

What is claimed is:

1 . A loss mitigation bottom hole assembly for use in a wellbore in a severe loss zone of a formation, comprising:
a drill bit for drilling a well bore; a dual wall drill string connecting the drill bit to a fluid source, and having a first fluid passage for delivering fluid to a drill bit, and a separate second fluid passage for returning the fluid away from the drill bit; and a drilling liner circumscribing and attached to a bottom portion of the dual wall drill string, and surrounding the drill bit, the drilling liner having an end adjacent the drill bit to contain the fluid exiting the drill bit and prevent the fluid from entering the severe loss zone of the formation.

2 . The loss mitigation bottom hole assembly of claim 1 , further comprising:
a liner running/setting tool for setting the drilling liner relative to a casing when the drilling liner reaches a desired location in the well bore bridging the severe loss zone of the formation.

3 . The loss mitigation bottom hole assembly of claim 2 , wherein the liner running/setting tool further comprises:
a collet retainer nut circumscribing the dual wall drill string and moveable between a first position and a second position axially relative to the dual wall drill string; a collet retainer nut activation mechanism controllable by an operator to move the collet retainer nut between the first position and the second position; a packer element circumscribing the drilling liner and in mechanical communication with the collet retainer nut, the packer element in an unenergized state when the collet retainer nut is in the first position, and in an energized state when the collet retainer nut is in the second position, so that when the collet retainer nut activation mechanism moves the collet retainer nut from the first position to the second position, the packer element is energized and seals the space between the drilling liner and the casing; and a toothed liner hanger slip circumscribing the drilling liner and in mechanical communication with the packer element, the toothed liner hanger slip disengaged from the casing when the packer element is not energized, and lockingly engaged with the casing when the packer element is energized, the toothed liner hanger slip preventing relative movement between the drilling liner and the casing when lockingly engaged with the casing.

4 . The liner running/setting tool of claim 3 , wherein the packer element has an angled surface positioned for forced insertion between the drilling liner and the toothed liner hanger slip when the packer element is energized, the angled surface pushing a portion of the toothed liner hanger slip into engagement with the casing when the packer element is energized.

5 . The loss mitigation bottom hole assembly of claim 1 , further comprising
a fluid return area adjacent the drill bit between the dual wall drill string and the drilling liner, the fluid return area receiving fluid exiting from the drill bit; and a cross-over port assembly providing fluid communication between the fluid return area and the second fluid passage.

6 . The loss mitigation bottom hole assembly of claim 5 , wherein the cross-over port assembly comprises:
a valve having a first end and a second end, and movable between an open position and a closed position; and a passage between the fluid return area and the second fluid passage bisected by the valve; the first end of the valve in pressure communication with the first fluid passage and the second end of the valve in pressure communication with the fluid return area, so that when pressure in the first fluid passage exceeds pressure in the fluid return area, the valve moves toward the open position.

7 . A liner running/setting tool for setting a drilling liner relative to a casing adjacent a severe loss zone of a well, comprising:
a collet retainer nut circumscribing a drill string in a well and moveable between a first position and a second position axially relative to the drill string; a collet retainer nut activation mechanism controllable by an operator to move the collet retainer nut between the first position and the second position; a packer element circumscribing the drilling liner and in mechanical communication with the collet retainer nut, the packer element in an unenergized state when the collet retainer nut is in the first position, and in an energized state when the collet retainer nut is in the second position, so that when the collet retainer nut activation mechanism moves the collet retainer nut from the first position to the second position, the packer element is energized and seals the space between the drilling liner and the casing; and a toothed liner hanger slip circumscribing the drilling liner and in mechanical communication with the packer element, the toothed liner hanger slip disengaged from the casing when the packer element is not energized, and lockingly engaged with the casing when the packer element is energized, the toothed liner hanger slip preventing relative movement between the drilling liner and the casing when lockingly engaged with the casing.

8 . The liner running/setting tool of claim 7 , wherein the packer element has an angled surface positioned for forced insertion between the drilling liner and the toothed liner hanger slip when the packer element is energized, the angled surface pushing a portion of the toothed liner hanger slip into engagement with the casing when the packer element is energized.

9 . The liner running/setting tool of claim 7 , wherein the collet retainer nut activation mechanism is a pump that applies hydraulic pressure to a surface of the collet retainer nut to push the collet retainer nut from the first position toward the second position.

10 . The liner running/setting tool of claim 7 , further comprising:
a collet fixedly attached to the drill string, the collet fixedly engaged with the drilling liner when the collet retainer nut is in the first position, and releasably engaged with the drilling liner when the collet retainer nut is in the second position.

11 . The liner running/setting tool of claim 7 , further comprising:
a pressure equalization passage fluidly connecting an area above the liner running/setting tool with an area below the running/setting tool to equalize pressure above and below the running/setting tool.

12 . The liner running/setting tool of claim 11 , further comprising:
a check valve in the pressure equalization passage to open and close the pressure equalization passage to fluid communication.

13 . A loss mitigation bottom hole assembly for use in a wellbore in a severe loss zone of a formation, comprising:
a drill bit for drilling a well bore; a dual wall drill string connecting the drill bit to a fluid source, and having a first fluid passage for delivering fluid to a drill bit, and a separate second fluid passage for returning the fluid away from the drill bit; a drilling liner circumscribing and attached to a bottom portion of the dual wall drill string, and surrounding the drill bit, the drilling liner having an end adjacent the drill bit to contain the fluid exiting the drill bit and prevent the fluid from entering the severe loss zone of the formation; a fluid return area adjacent the drill bit between the dual wall drill string and the drilling liner, the fluid return area receiving fluid exiting from the drill bit; and a cross-over port assembly providing fluid communication between the fluid return area and the second fluid passage, the cross-over port assembly comprising:
a valve having a first end and a second end, and movable between an open po

Assignees

• Saudi Arabian Oil Co

Inventors

• Zhou Shaohua

Classifications

• E21B21/103

  Down-hole by-pass valve arrangements, i.e. between the inside of the drill string and the annulus (valves specifically for maintaining circulation of drilling fluid while connecting or disconnecting tubular joints E21B21/019) · CPC title

• E21B7/20 Primary

  Driving or forcing casings or pipes into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes · CPC title

• E21B21/003 Primary

  Means for stopping loss of drilling fluid (plastering the borehole wall E21B33/138) · CPC title

• E21B17/18

  Pipes provided with plural fluid passages {(E21B17/203 takes precedence)} · CPC title

• E21B33/129

  with mechanical slips for hooking into the casing (E21B33/122, E21B33/124 take precedence) · CPC title