LOW FREQUENCY DISTRIBUTED ACOUSTIC SENSING

• US 20170260842A1
• Filed: 03/08/2017
• Published: 09/14/2017
• Est. Priority Date: 03/09/2016
• Status: Active Grant

• Current Assignee: Conocophillips Company (ConocoPhillips)
• Original Assignee: Conocophillips Company (ConocoPhillips)
• Inventors: JIN, Ge, MOSHER, Charles C., FILICE, Frank P., KRUEGER, Kyle R., ROY, Baishali, TURA, Ali, JURICK, Dana M.
• Granted Patent: US 10,458,228 B2
• Time in Patent Office: Days
• CPC Class Codes: E21B 43/26 by forming crevices or fractures
• CPC Class Codes: E21B 47/0224 using seismic or acoustic means
• CPC Class Codes: E21B 47/0228 using electromagnetic energy or detectors therefor
• CPC Class Codes: E21B 47/07 Temperature
• CPC Class Codes: E21B 47/101 using acoustic energy
• CPC Class Codes: E21B 47/102 using electrical indications: using light radiations
• CPC Class Codes: E21B 47/107 using acoustic means
• CPC Class Codes: E21B 47/113 using electrical indications; using light radiations
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves
• CPC Class Codes: G01B 11/161 by interferometric means
• CPC Class Codes: G01H 9/004 using fibre optic sensors light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125
• CPC Class Codes: G01K 11/32 using changes in transmittance, scattering or luminescence in optical fibres
• CPC Class Codes: G01V 1/226 Optoseismic systems
• CPC Class Codes: G01V 1/40 specially adapted for well-logging

Abstract

The invention relates to DAS observation has been proven to be useful for monitoring hydraulic fracturing operations. While published literature has shown focus on the high-frequency components (>1 Hz) of the data, this invention discloses that much of the usable information may reside in the very low frequency band (0-50 milliHz). Due to the large volume of a DAS dataset, an efficient workflow has been developed to process the data by utilizing the parallel computing and the data storage. The processing approach enhances the signal while decreases the data size by 10000 times, thereby enabling easier consumption by other multi-disciplinary groups for further analysis and interpretation. The polarity changes as seen from the high signal to noise ratio (SNR) low frequency DAS images are currently being utilized for interpretation of completions efficiency monitoring in hydraulically stimulated wells.

Claims

1. A process for monitoring hydrocarbon production where the process comprises:

a) installing one or more fiber optic cables along a wellbore in a hydrocarbon formation;

b) installing one or more interrogators on at least one fiber optic cable;

c) interrogating at least one fiber optic cable with an interrogation signal;

d) obtaining one or more datasets from the interrogator;

e) converting one or more datasets from the interrogator into a continuous record;

f) transforming the continuous record with a low-pass filter to 1-50 milliHz while down sampling the data into a transformed well signal;

g) interpreting the transformed well signal; and

h) improving hydrocarbon production from said hydrocarbon formation.

2. The method of one of claim 1, wherein said transformed well signal is an in-well signal from the wellbore of interest consisting of a production well or an injection well.

3. The method of one of claim 1, wherein said transformed well signal is a cross-well signal from a wellbore that is adjacent to the well of interest consisting of a production well, and injection well, a monitoring well, a vertical well, or the like.

4. The method of one of claim 1, wherein the hydrocarbon formation is undergoing hydraulic fracturing, start-up, shut-in, enhanced oil recovery, waterflood, steamflood, water alternating gas treatment, or other well treatment.

5. The method of one of claim 1, wherein the continuous record is transformed with an ultra-low frequency filter from 0 to 1 mHz, 5 mHz, 10 mHz, 15 mHz, 20 mHz, 30 mHz, 45 mHz, or 50 mHz.

6. The method of one of claim 1, wherein the continuous record is downsampled to 1, 3, 5, 10, 15, 20, 25, 50, 75, or 100 second intervals.

7. A method of monitoring hydrocarbon production comprising, installing one or more fiber optic cables along a wellbore in a hydrocarbon formation;

interrogating at least one fiber optic cable with an interrogator;

obtaining one or more datasets from the interrogator;

converting one or more datasets from the interrogator into a continuous record;

transforming the continuous record with a low-pass filter to 1-50 milliHz while down sampling the data into a transformed well signal;

interpreting the transformed well signal; and

monitoring hydrocarbon production from said hydrocarbon formation.

8. The method of one of claim 7, wherein said transformed well signal is a in-well signal from the wellbore of interest consisting of a production well or an injection well.

9. The method of one of claim 7, wherein said transformed well signal is a cross-well signal from a wellbore that is adjacent to the well of interest consisting of a production well, and injection well, a monitoring well, a vertical well, or the like.

10. The method of one of claim 7, wherein the hydrocarbon formation is undergoing hydraulic fracturing, start-up, shut-in, enhanced oil recovery, waterflood, steamflood, water alternating gas treatment, or other well treatment.

11. The method of one of claim 7, wherein the continuous record is transformed with an ultra-low frequency filter from 0 to 1 mHz, 5 mHz, 10 mHz, 15 mHz, 20 mHz, 30 mHz, 45 mHz, or 50 mHz.

12. The method of one of claim 7, wherein the continuous record is downsampled to 1, 3, 5, 10, 15, 20, 25, 50, 75, or 100 second intervals.

13. A method to determine the effectiveness of a hydrocarbon well treatment comprising:

a) installing one or more fiber optic cables along a wellbore in a hydrocarbon formation;

b) installing one or more interrogators on at least one fiber optic cable;

c) interrogating at least one fiber optic cable with an interrogation signal before, during, and after a well treatment;

d) obtaining one or more datasets from the interrogator;

e) converting one or more datasets from the interrogator into a continuous record;

f) transforming the continuous record with a low-pass filter to 1-50 milliHz while down sampling the data into a transformed well signal;

g) interpreting the transformed well signal; and

h) improving hydrocarbon production from said hydrocarbon formation.

14. The method of one of claim 13, wherein said transformed well signal is a in-well signal from the wellbore of interest consisting of a production well or an injection well.

15. The method of one of claim 13, wherein said transformed well signal is a cross-well signal from a wellbore that is adjacent to the well of interest consisting of a production well, and injection well, a monitoring well, a vertical well, or the like.

16. The method of one of claim 13, wherein the hydrocarbon formation is undergoing hydraulic fracturing, start-up, shut-in, enhanced oil recovery, waterflood, steamflood, water alternating gas treatment, or other well treatment.

17. The method of one of claim 13, wherein the continuous record is transformed with an ultra-low frequency filter from 0 to 1 mHz, 5 mHz, 10 mHz, 15 mHz, 20 mHz, 30 mHz, 45 mHz, or 50 mHz.

18. The method of one of claim 13, wherein the continuous record is downsampled to 1, 3, 5, 10, 15, 20, 25, 50, 75, or 100 second intervals.