Method of detecting fluid in-flows downhole

• US 8,245,780 B2
• Filed: 02/09/2010
• Issued: 08/21/2012
• Est. Priority Date: 02/09/2009
• Status: Active Grant

• Current Assignee: Shell USA Incorporated (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Fidan, Erkan, Molenaar, Menno Mathieu, Oz, Bora, Minchau, Michael Charles
• Primary Examiner(s): Stephenson, Daniel P
• Application Number:
  US13/148,424
• Publication Number:
  US 20120018149A1
• Time in Patent Office: 924 Days
• Field of Search: 166/64, 166/250.01, 166/250.03, 166/254.2, 166/72, 250/227.14, 250/227.16, 250/227.18
• US Class Current: 166/250.03
• CPC Class Codes: E21B 47/114 using light radiation
• CPC Class Codes: G01V 8/16 using optical fibres

Abstract

A method of measuring fluid in-flow in a region of interest in a wellbore comprises deploying a fiber optic cable concurrently with placement of a downhole tubular, transmitting a light signal along the cable and receiving a reflected signal from the region of interest, and interpreting the received signal to obtain information about fluid flowing in the region of interest. The wellbore may include a horizontal portion. The received signal may also be interpreted by assessing amplitude and frequency spectra across array of channels, conditioning the received signal by removing at least a portion of the signal that is not related to flow, assessing flow regimes across depths and times, calculating axial flow/s within the wellbore using relationships for axial flow, and calculating flow into or out of the wellbore at one or more points using relationships for flow through an orifice.

Claims

1. A method of measuring fluid in-flow in a region of interest in a wellbore, comprising:

a) deploying a fiber optic cable concurrently with placement of a downhole tubular;

b) transmitting a light signal along the cable and receiving a reflected signal from the region of interest; and

c) interpreting the received signal to obtain information about fluid flowing into or out of the wellbore in the region of interest;

wherein step c) comprises;

i) assessing amplitude and frequency spectra across an array of channels;

ii) conditioning the received signal by removing at least a portion of the signal that is not related to flow;

iii) assessing flow regimes across depths and times;

iv) calculating axial flow/s within the wellbore using relationships for axial flow; and

v) calculating flow into or out of the wellbore at one or more points using relationships for flow through an orifice.

2. The method according to claim 1 wherein the wellbore contains a velocity string and step c) is carried out without removing the velocity string.

3. The method according to claim 1 wherein the wellbore includes a horizontal portion.

4. The method according to claim 1 wherein the fiber optic cable is free of Bragg gratings.

5. The method according to claim 1 wherein step c) further includes:

c1) detecting a change over time in said received signal; and

c2) interpreting said change so as to obtain information about a change in fluid inflow.

6. The method according to claim 1 wherein step c) further includes the step of:

vi) comparing the results of steps iv) and v), and minimizing errors using additional constraining information.

7. The method according to claim 6 wherein the addition constraining information is selected from the group consisting of wellhead flowrates, and temperature measurements.

8. The method according to claim 1, further including the steps of:

d) repeating steps a) and b) over time so as to obtain information about a change in fluid inflow.