Schlumberger Technology Corporation

Justin Cremer

Zaurayze Tarique

Blaine Dow

Scott Coffey

A method for maintaining a constant bottom hole pressure during wellbore drilling operations, the method comprising supplying drilling fluid to the drill string via a top drive at a first pressure while flow of drilling fluid out of a wellbore annulus is restricted by a choke to hold pressure in a wellbore annulus and supplying drilling fluid to the drill string via the top drive at a second pressure lower than the first pressure and to a circulation coupler at a third pressure while flow of drilling fluid out of a wellbore annulus is restricted by a choke to hold pressure in the annulus, wherein the sum of the second and third pressures is approximately the same as the first pressure. The method also comprises supplying drilling fluid to the drill string via the circulation coupler at the third pressure while pumping drilling fluid into the wellbore annulus by a back pressure pump, wherein the bottom hole pressure at the bottom of the wellbore is maintained substantially constant during all steps of supplying drilling fluid to the drill string.

Non-stop circulation system for maintaining bottom hole pressure

An iron roughneck for constant circulation of drilling mud during operation of a drill string, the iron roughneck comprising: a frame; a wrench unit supported by the frame, wherein the wrench unit is capable of gripping a drill string; a spinner unit supported by the frame, wherein the spinner unit is capable of engaging and spinning a drill pipe; and a circulation coupler supported by the frame, wherein the circulation coupler forms a chamber around the drill string.

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Houston, TX, United States of America

Justin Cremer