Multi-sensor workflow for evaluation of gas flow in multiple casing strings

Patent metadata

Field	Value
Publication number	US-9547105-B2
Application number	US-201515111622-A
Country	US
Kind code	B2
Filing date	Sep 4, 2015
Priority date	Sep 10, 2014
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

A distance of a gas flow path and a velocity of the gas flow therein are calculated using pulsed neutron data and noise data. The gas saturation and distance to flow path obtained from the pulsed neutron data and gas velocity and distance to flow path obtained from the noise data are compared with each other to obtain a first calculated distance and a first calculated velocity. The distance and the velocity of the gas flow are calculated using Doppler data. The distance and velocity values are compared with the first calculated distance and first calculated velocity to obtain a second calculated distance and velocity values. The distance and the velocity of the gas flow are calculated using temperature data. The distance and velocity values are compared with the second calculated distance and velocity to determine a distance of a cement interface and a velocity of a gas flow therein.

First claim

What is claimed is:

1. A method, comprising:
introducing a tool string into a wellbore, the wellbore at least partially lined with a first casing and a second casing concentrically overlapping a portion of the first casing, wherein a first annulus is defined between the first and second casings and filled with a first cement, and a second annulus is defined between the second casing and the wellbore and filled with a second cement;
obtaining data from a pulsed neutron sensor, a noise sensor, a Doppler sensor, and a temperature sensor, all included in the tool string;
determining a gas presence in a flow path located at a cement interface in the wellbore and a first distance of the flow path from the tool string using a pulsed neutron log borehole model and the data obtained from the pulsed neutron sensor;
calculating a second distance of the flow path from the tool string and a first velocity of a gas flow in the flow path using a noise log borehole model and the data obtained from the noise sensor;
correlating the first distance and the gas presence with the second distance and the first velocity to obtain a first calculated distance of the flow path and a first calculated velocity of the gas flow in the flow path;
calculating a third distance of the flow path from the tool string and a second velocity of the gas flow in the flow path using a Doppler borehole model and the data obtained from the Doppler sensor;
comparing the third distance and the second velocity with the first calculated distance and first calculated velocity, respectively, to obtain a second calculated distance of the flow path and a second calculated velocity of the gas flow in the flow path;
calculating a fourth distance of the flow path from the tool string and a third velocity of the gas flow in the flow path using a temperature borehole model and the data obtained from the temperature sensor; and
comparing the fourth distance and the third velocity with the second calculated distance and the second calculated velocity, respectively, to determine a width of the cement interface, a distance of the cement interface from the tool string, and a velocity of a gas flow in the cement interface.

2. The method of claim 1 , wherein obtaining data from the pulsed neutron sensor comprises obtaining an amount of gas saturation in the flow path.

3. The method of claim 1 , wherein obtaining data from the noise sensor comprises one or more of obtaining amplitudes of noise signals detected by the noise sensor from the wellbore, obtaining a frequency spectrum of the noise signals, obtaining a relative phase shift between the noise signals, obtaining frequency ratios of near and far noise signals, and obtaining power spectral density of the noise signals.

4. The method of claim 1 , wherein obtaining data from the Doppler sensor comprises one or more of obtaining an amplitude and frequency information of an acoustic wave as modified by the wellbore, and obtaining a frequency shift between an acoustic wave emitted by the Doppler sensor into the wellbore and the modified acoustic wave.

5. The method of claim 1 , obtaining data from the temperature sensor comprises one or more of obtaining a temperature of the wellbore, obtaining a temperature gradient of the wellbore, and obtaining a derivative of a temperature profile of the wellbore.

6. The method of claim 1 , further comprising updating at least one of the pulsed neutron log borehole model and the noise log borehole model when the gas presence in the flow path, the first distance of the flow path, the second distance of the flow path, and the first velocity of the gas flow do not conform with each other.

7. The method of claim 6 , further comprising recalculating one or more of the gas presence in the flow path, the first distance of the flow path, the second distance of the flow path, and the first velocity of the gas flow using a corresponding updated model.

8. The method of claim 1 , further comprising updating one or more of the pulsed neutron log borehole model, the noise log borehole model, and the Doppler borehole model when a difference between the first calculated distance and the third distance and a difference between the first calculated velocity and the second velocity is greater than a predetermined value.

9. The method of claim 8 , further comprising recalculating one or more of the gas presence in the flow path, the first distance of the flow path, the second distance of the flow path, the first velocity of the gas flow, the third distance of the flow path, and the second velocity of the gas flow using a corresponding updated model.

10. The method of claim 1 , further comprising updating one or more of the pulsed neutron log borehole model, the noise log borehole model, the Doppler borehole model, and the temperature borehole model when a difference between the second calculated distance and the fourth distance and a difference between the second calculated velocity and the third velocity is greater than a predetermined value.

11. The method of claim 10 , further comprising recalculating one or more of the gas presence in the flow path, the first distance of the flow path, the second distance of the flow path, the first velocity of the gas flow, the third distance of the flow path, the second velocity of the gas flow, the fourth distance of the flow path, and the third velocity of the gas flow using a corresponding updated model.

12. The method of claim 1 , further comprising obtaining the temperature borehole model from a static borehole model.

13. A well system, comprising:
a tool string conveyable into a wellbore drilled through one or more subterranean formations, wherein the wellbore is at least partially lined with a first casing and a second casing concentrically overlapping a portion of the first casing, and wherein a first annulus is defined between the first and second casings and filled with a first cement, a second annulus is defined between the second casing and the wellbore and filled with a second cement, and the tool string includes at least a pulsed neutron sensor, a noise sensor, a Doppler sensor, and a temperature sensor; and
a computer system including a processor and a non-transitory computer readable medium, the computer system communicatively coupled to the tool string, and the computer readable medium stores a computer readable program code, when executed by the processor, configures the processor to:
operate the pulsed neutron sensor to obtain pulsed neutron log (PNL) data from the wellbore;
determine a gas presence in a flow path located at a cement interface in the wellbore and a first distance of the flow path from the tool string using a pulsed neutron log borehole model and the PNL data;
operate the noise sensor to obtain noise log (NL) data from the wellbore;
calculate a second distance of the flow path from the tool string and a first velocity of the gas flow in the flow path using a noise log borehole model and the NL data;
correlate the first distance and the gas presence with the second distance and the first velocity to obtain a first calculated distance of the flow path and a first calculated velocity of the gas flow in the flow path;
operate the Doppler sensor to obtain Doppler log (DL) data from the wellbore;
calculate a third distance of the flow path from the tool string and a second velocity of the gas flow in the flow path using a Doppler borehole model and the DL data;
compare the third distance with the first calculated distance to obtain a second calculated distance of the flow path and compare the second velocity and the first calculated velocity to obtain a second calculated velocity

Assignees

• Halliburton Energy Services Inc
• Halliburton Energy Sevices Inc

Inventors

• Quintero Luis F

Classifications

• E21B47/07

  Temperature · CPC title

• E21B47/005

  Monitoring or checking of cementation quality or level · CPC title

• G01V11/002 Primary

  Details, e.g. power supply systems for logging instruments, transmitting or recording data, specially adapted for well logging, also if the prospecting method is irrelevant (means for transmitting well survey signals E21B47/12; signal transmission systems in general G08C; transmission in general H04B) · CPC title

• G01V5/102

  the neutron source being of the pulsed type · CPC title

• E21B47/065

  Fixed Constructions · mapped topic