Method and system for measurement of fluid flow in a drilling rig return line
First Claim
1. A system for obtaining an indication of volumetric flow of a drilling mud exiting a well bore through an annulus between a drill pipe and the well bore and up to a bell nipple and out to a drilling rig return line connected to said bell nipple at an angle such that said drilling mud partially fills said return line and is in supercritical flow in said return line, said return line having a known physical configuration, said system comprising:
- a) a non-intrusive mud level sensor means located in or in proximity to said return line for sensing the height of the mud flowing in the return line without affecting mud flow and for providing signals indicative thereof; and
b) means responsive to said level sensor signals, and in conjunction with return line configuration, for providing an indication of the flow-out volume of the mud from said well bore.
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Accused Products
Abstract
Improved methods and systems are provided for determining a volumetric flow rate of mud in a return line without the aid of a velocity probe. A mud level sensor is located in a return line chimney preferably in close proximity to the bell nipple. The sensor senses the height of the mud flowing in the return line. Where an ultraonsic transceiver is used as the sensor, temperature sensors in the chimney and return line determine a temperature gradient in the return line which provides a speed of sound correction as does a target at a known distance from the transceiver. A computer receives the uncorrected mud height and the speed of sound information, and determines the flow-out volume of the mud. Flow-out volume is related to the mud height, the geometry of the return line, and mud parameters. In a more complete system, the computer calibrates the determined flow-out volume with the flow-in volume, and provides a correction factor which is used to provide a corrected flow-out determination. The computer also monitors delta flow (flow-out minus flow-in), and based on the rate of change of delta flow determines when an undesirable condition such as a kick or fluid loss occurs. Where the system is to be used on rig which is subject to movement (e.g. a floating rig), an angle sensor is employed to help determine instantaneous flow-out, and the flow-out determinations are averaged over the movement cycle of the rig as determined by heave position sensors available on the rig.
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Citations
33 Claims
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1. A system for obtaining an indication of volumetric flow of a drilling mud exiting a well bore through an annulus between a drill pipe and the well bore and up to a bell nipple and out to a drilling rig return line connected to said bell nipple at an angle such that said drilling mud partially fills said return line and is in supercritical flow in said return line, said return line having a known physical configuration, said system comprising:
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a) a non-intrusive mud level sensor means located in or in proximity to said return line for sensing the height of the mud flowing in the return line without affecting mud flow and for providing signals indicative thereof; and b) means responsive to said level sensor signals, and in conjunction with return line configuration, for providing an indication of the flow-out volume of the mud from said well bore. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for determining, without obtaining a direct indication of mud velocity from a velocity measurement probe, an indication of the volumetric flow rate of a drilling mud exiting a well bore through an annulus between a drill pipe and the well bore and up to a bell nipple and out to a drilling rig return line said return line having a known physical configuration and being connected to said bell nipple, said drilling mud partially filling said return line, said method comprising:
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a) sensing the height of the mud flowing in the return line at a location in said return line where said mud is in supercritical flow, and providing signals indicative thereof; b) determining flow-out volume of the mud as a function of at least said mud height signals, and the physical configuration of said return line. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification