System and method to estimate a property of a fluid flow

Abstract

An apparatus and method estimate a property of a fluid flow. The apparatus includes a nuclear magnetic resonance (NMR) tool performing an NMR measurement on the fluid in a sensitive volume. The apparatus also includes a processor receiving the NMR measurement from the NMR tool, determining a frequency or phase change of the spin echo signals from the NMR measurement, and estimating the property using the frequency or phase change.

1 . An apparatus for estimating a property of a fluid flow, the apparatus comprising:
 a nuclear magnetic resonance (NMR) tool configured to perform an NMR measurement on the fluid in a sensitive volume by establishing a magnetic field in the sensitive volume that exhibits a change in magnitude in a direction of the fluid flow, the NMR measurement comprising spin echo signals; and   a processor configured to receive an NMR measurement from the NMR tool, determine a frequency or phase change of the spin echo signals from the NMR measurement, and estimate the property using the frequency or phase change.   
     
     
         2 . The apparatus according to  claim 1 , wherein the change in magnitude of the magnetic field is an increase or a decrease. 
     
     
         3 . The apparatus according to  claim 1 , wherein the frequency change comprises an increase in a center of gravity of a frequency spectrum of the spin echo signals. 
     
     
         4 . The apparatus according to  claim 1 , wherein the frequency change comprises a decrease in a center of gravity of a frequency spectrum of the spin echo signals. 
     
     
         5 . The apparatus according to  claim 1 , wherein the frequency change is determined by one of a changing phase error or a Fourier transform of the spin echo signals. 
     
     
         6 . The apparatus according  claim 1 , wherein the property is a flow rate of the fluid flowing through the sensitive volume. 
     
     
         7 . The apparatus according to  claim 1 , wherein the property is the direction of the fluid flow through the sensitive volume. 
     
     
         8 . The apparatus according to  claim 1 , further comprising a carrier configured to be conveyed through a borehole, wherein the NMR tool is disposed at the carrier, the NMR measurement is performed in a formation penetrated by the borehole, and the property is a downhole fluid flow property. 
     
     
         9 . The apparatus according to  claim 8 , wherein the carrier comprises a wireline, a slickline, a drill string, or coiled tubing. 
     
     
         10 . The apparatus according to  claim 8 , further comprising one or more stabilizers configured to reduce lateral movement of the NMR tool in the borehole. 
     
     
         11 . The apparatus according to  claim 8 , wherein the magnitude of the magnetic field decreases with increasing radial distance from the NMR tool. 
     
     
         12 . A method of estimating a property of a fluid flow, the method comprising:
 performing a nuclear magnetic resonance (NMR) measurement on the fluid in a sensitive volume using an NMR tool configured to establish a magnetic field in the sensitive volume that exhibits a change in magnitude in a direction of the fluid flow, the NMR measurement comprising spin echo signals;   determining a frequency or phase change of the spin echo signals from the NMR measurement; and   estimating the property using the frequency or phase change.   
     
     
         13 . The method according to  claim 12 , wherein the change in magnitude of the magnetic field is an increase or a decrease. 
     
     
         14 . The method according to  claim 12 , wherein the frequency change comprises an increase in a center of gravity of a frequency spectrum of the spin echo signals. 
     
     
         15 . The method according to  claim 12 , wherein the frequency change comprises a decrease in a center of gravity of a frequency spectrum of the spin echo signals. 
     
     
         16 . The method according to  claim 12 , wherein the frequency change is determined by one of a changing phase error or a Fourier transform of the spin echo signals. 
     
     
         17 . The method according to  claim 12 , further comprising calibrating the NMR tool with a known flow rate or a fluid. 
     
     
         18 . The method according to  claim 12 , further comprising calibrating the NMR tool by performing an NMR simulation using a computer processor. 
     
     
         19 . The method according to  claim 12 , further comprising conveying a carrier through a borehole, wherein the performing the NMR measurement includes performing the NMR measurement in a formation penetrated by a borehole and the property is a downhole fluid flow property, the NMR measurement being performed by the NMR tool disposed at the carrier. 
     
     
         20 . The method according to  claim 19 , wherein the estimating the property includes estimating a flow rate of fluid flowing through the sensitive volume. 
     
     
         21 . The method according to  claim 19 , wherein a hydrostatic pressure of drilling fluid in the borehole is less than or greater than a formation fluid pressure at a depth in the borehole of the NMR tool. 
     
     
         22 . The method according to  claim 19 , wherein the magnitude of the magnetic field decreases with increasing radial distance from the NMR tool. 
     
     
         23 . A non-transitory computer readable medium comprising computer executable instructions which, when executed by a processor, cause the processor to perform a method of estimating a property of a fluid flow, the method comprising:
 receiving a nuclear magnetic resonance (NMR) measurement on the fluid in a sensitive volume using an NMR tool configured to establish a magnetic field in the sensitive volume that changes in magnitude in a direction of the fluid flow, the NMR measurement comprising spin echo signals;   determining a magnitude of frequency change of the spin echo signals from the NMR measurement; and   estimating the property using the frequency change.