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US 7,372,263 B2Granted
Apparatus and method for measuring cased hole fluid flow with NMR
AssigneeBaker Hughes Incorporated
InventorCarl Edwards
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Abstract
A method and apparatus useful to determine characteristics of fluid flow, such as fluid holdup and flow velocity. The apparatus comprises a flow tube, a permanent magnet, a first set of coils, and a second set of coils. The first set of coils creates a radio frequency magnetic field within the flow tube with a series of refocusing pulses. The second set of coils encodes velocity information onto the fluid molecules using rotating frame zeugmatography that is later decoded and used to estimate the fluid flow velocity.
Claims14
A method of measuring fluid flow comprising:
- applying a static magnetic field to the flow;
- applying at least one electro-magnetic pulse sequence to the flow, said electromagnetic pulse comprising a rotating frame portion and a refocusing portion, wherein the refocusing portion encodes fluid flow molecule position and later in time decodes the fluid flow molecule position and wherein the electro-magnetic pulse sequence produces signals;
- measuring the residual nutation angle between the encoded fluid flow molecules and the decoded fluid flow molecules;
- estimating fluid velocity using the residual nutation angle between the encoded molecule position and the decoded molecule position;
- obtaining a fluid velocity value and making the fluid velocity value available to the user for assessing a characteristic of a wellbore.
2 more elements
Dependencies are inferred from the claim text.