Apparatus and method to reduce fluid pressure in a wellbore
AssigneeWeatherford/Lamb, Inc.
InventorsDavid Hosie, R. K. Bansal, Peter B. Moyes
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Abstract
The present invention generally provides apparatus and methods for reducing the pressure of a circulating fluid in a wellbore. In one aspect of the invention an ECD (equivalent circulation density) reduction tool provides a means for drilling extended reach deep (ERD) wells with heavyweight drilling fluids by minimizing the effect of friction head on bottomhole pressure so that circulating density of the fluid is close to its actual density. With an ECD reduction tool located in the upper section of the well, the friction head is substantially reduced, which substantially reduces chances of fracturing a formation.
Claims13
A method of drilling a wellbore, comprising:
- injecting drilling fluid through a drill string disposed in the wellbore, the drill string comprising a motor, a pump, a packer, and a drill bit disposed at an end of the drill string, the drilling fluid:
- operating the motor,
- exiting the drill bit, and
- carrying cuttings from the drill bit into an annulus defined between the wellbore and the drill string;
- and
- diverting the drilling fluid and cuttings (returns) from the annulus and through the pump using the packer engaged with a casing, the pump:
- rotationally coupled to the motor, thereby being operated by the motor, and
- adding energy to the returns, thereby reducing an equivalent circulation density (ECD) of the returns.
Dependencies are inferred from the claim text.