Method and apparatus for controlling bottom hole pressure in a subterranean formation during rig pump operation
First Claim
1. A method for maintaining pressure in a wellbore during drilling operations comprising:
- feeding a drill fluid through a reservoir conduit from a reservoir;
diverting the drill fluid from the reservoir conduit to a first drill fluid line and through a drill string;
circulating the drill, fluid through, the drill string to an annulus between the drill string and the wellbore wherein the drill fluid exits the annulus as a return fluid;
directing the drill fluid from the reservoir conduit to a second drill fluid line and through a backpressure pump;
mixing the return fluid with the drill fluid fed through the backpressure pump from the reservoir conduit to form a mixed fluid; and
feeding the mixed fluid to a controllable choke for applying backpressure to the annulus.
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Accused Products
Abstract
A method for maintaining pressure in a wellbore during drilling operations is disclosed. The method includes the steps of providing fluid from a reservoir through a drill string, circulating the fluid from the drill string to an annulus between the drill string and the wellbore, isolating pressure in the annulus, measuring pressure in the annulus, calculating a set point backpressure, applying back pressure to the annulus based on the set point back pressure, diverting fluid from the annulus to a controllable choke, controllably bleeding pressurized fluid from the annulus, separating solids from the fluid, and directing the fluid to the reservoir. An apparatus for maintaining pressure in a wellbore during drilling operations that includes an adjustable choke for controllably bleeding off pressurized fluid from the wellbore annulus. A backpressure pump for applying a set point backpressure, and a processor for controlling the adjustable choke and backpressure pump are also disclosed.
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Citations
14 Claims
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1. A method for maintaining pressure in a wellbore during drilling operations comprising:
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feeding a drill fluid through a reservoir conduit from a reservoir; diverting the drill fluid from the reservoir conduit to a first drill fluid line and through a drill string; circulating the drill, fluid through, the drill string to an annulus between the drill string and the wellbore wherein the drill fluid exits the annulus as a return fluid; directing the drill fluid from the reservoir conduit to a second drill fluid line and through a backpressure pump; mixing the return fluid with the drill fluid fed through the backpressure pump from the reservoir conduit to form a mixed fluid; and feeding the mixed fluid to a controllable choke for applying backpressure to the annulus. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for maintaining pressure in a wellbore during drilling operations comprising;
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a reservoir conduit extending from, a reservoir and having a controllable variable valve provided therein, wherein drill fluid flows from the reservoir through the reservoir conduit and the controllable variable valve to a drill string disposed in the wellbore and further flows from the drill string into an annulus defined between the wellbore and the drill string, wherein the drill fluid returns from the annulus as return fluid; a return conduit through which the return fluid flows from the annulus toward a backpressure control device; backpressure pump in fluid communication with the reservoir conduit via the controllable variable valve, the backpressure pump pumping the drill fluid from the reservoir to the return conduit at a location along the return conduit upstream of the backpressure control device; and a controller configured to determine a backpressure set point based on one or more measurements taken from the system. - View Dependent Claims (9, 10, 11, 12)
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13. A system for maintaining pressure in a wellbore during drilling operations comprising:
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a reservoir conduit extending from a reservoir and having a three-way fluid junction provided therein; a first drill fluid line extending from the three-way fluid junction to a drill string disposed in the wellbore; wherein drill fluid flows from the reservoir through the reservoir conduit, the three-way fluid junction, and the first drill fluid line to the drill string and further flows from the drill string into an annulus defined between the wellbore and the drill string, wherein the drill fluid returns from the annulus as return fluid; a return conduit through which the return fluid flows from the annulus toward a backpressure control device; a second drill fluid line extending from the three-way fluid junction to a backpressure pump, the backpressure pump pumping the drill fluid from the reservoir conduit to the return conduit at a location along the return conduit upstream of the backpressure control device; and a controller configured to determine a backpressure set point based on one or more measurements taken from the system. - View Dependent Claims (14)
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Specification