Method and apparatus for controlling bottom hole pressure in a subterranean formation during rig pump operation
First Claim
1. An apparatus for maintaining pressure in a wellbore during drilling operations, wherein the wellbore has casing set and cemented into place, the apparatus comprising:
- a reservoir containing fluid from the wellbore;
a drill string in fluid communication with the reservoir, wherein an annulus is defined between the wellbore and the drill string;
a pressure transducer in the drill string to measure pressure in the annulus;
a rotating control device isolating pressure in the annulus and communicating fluid from the reservoir to the drill string and diverting fluid and solids from the annulus;
a first flow meter for measuring a flow rate of fluid and solids diverted from the annulus;
an adjustable choke in fluid communication with the rotating control device controllablly bleeding off pressurized fluid from the annulus, wherein the adjustable choke has a valve element with a position controlled by a first control pressure signal and an opposing second control pressure signal;
solids control equipment receiving fluid and solids from the adjustable choke and removing the solids from the fluid;
a fluid conduit for directing fluid from the solids control equipment to the reservoir;
a processor receiving the measured pressure from the pressure transducer and calculating a set point backpressure; and
a backpressure pump in fluid communication with the reservoir and applying a backpressure between the first flow meter and the adjustable choke based on the calculated set point.
2 Assignments
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Accused Products
Abstract
A method for maintaining pressure in a wellbore during drilling operations 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 off pressurized fluid from the annulus, separating solids from the fluid, and directing the fluid back to the reservoir. An apparatus for maintaining pressure in a wellbore during drilling operations includes an adjustable choke for controllably bleeding off pressurized fluid from the wellbore annulus, a backpressure pump for applying a calculated set point backpressure, and a processor for controlling the adjustable choke and backpressure pump.
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Citations
6 Claims
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1. An apparatus for maintaining pressure in a wellbore during drilling operations, wherein the wellbore has casing set and cemented into place, the apparatus comprising:
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a reservoir containing fluid from the wellbore; a drill string in fluid communication with the reservoir, wherein an annulus is defined between the wellbore and the drill string; a pressure transducer in the drill string to measure pressure in the annulus; a rotating control device isolating pressure in the annulus and communicating fluid from the reservoir to the drill string and diverting fluid and solids from the annulus; a first flow meter for measuring a flow rate of fluid and solids diverted from the annulus; an adjustable choke in fluid communication with the rotating control device controllablly bleeding off pressurized fluid from the annulus, wherein the adjustable choke has a valve element with a position controlled by a first control pressure signal and an opposing second control pressure signal; solids control equipment receiving fluid and solids from the adjustable choke and removing the solids from the fluid; a fluid conduit for directing fluid from the solids control equipment to the reservoir; a processor receiving the measured pressure from the pressure transducer and calculating a set point backpressure; and a backpressure pump in fluid communication with the reservoir and applying a backpressure between the first flow meter and the adjustable choke based on the calculated set point. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification