DETECTION OF TRACERS USED IN HYDROCARBON WELLS

• US 20110240287A1
• Filed: 04/02/2010
• Published: 10/06/2011
• Est. Priority Date: 04/02/2010
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Jones, Timothy, Meredith, Andrew, Lawrence, Nathan, Hartshorne, Robert Seth, Tustin, Gary John
• Granted Patent: US 8,596,354 B2
• Time in Patent Office: Days
• US Class Current: 166/250.12
• CPC Class Codes: E21B 47/11 using tracers; using radioactivity

Abstract

In an arrangement for monitoring of flow within a hydrocarbon well or reservoir by means of one or more tracers which are placed at subterranean locations such that they may be present in flow produced from the well, the analysis of the flow produced from the well is carried out using an electrochemical method, preferably voltammetry, to detect tracer chosen to undergo a detectable electrochemical reaction. The tracer may be provided as nanoparticles in the well fluid.

Claims

1. A method of monitoring flow within a hydrocarbon well or within a hydrocarbon reservoir penetrated by the well, comprising:

placing one or more tracer materials at one or more subterranean locations from which they may potentially enter flow produced from the well,

causing or allowing release of tracer from one or more said locations, and

monitoring flow from the well by subjecting it to an electrochemical reaction in order to determine the presence of one or more tracers in the flow.

2. A method according to claim 1 wherein the electrochemical reaction is a redox reaction.

3. A method according to claim 1 wherein the step of monitoring flow comprises providing electrodes connected to a source of electrical potential, bringing a sample or portion of the flow into contact with the electrodes and applying potential to the electrodes to bring about electrochemical reaction, while measuring the current flow.

4. A method according to claim 3 carried out as voltammetry in which potential applied to the electrodes is varied over a range, while measuring the current flow as potential is varied.

5. A method according to claim 4 in which the potential applied to the electrodes is varied in steps superimposed on a progressive variation over a range.

6. A method according to claim 4 in which the voltammetry is stripping voltammetry comprising a first stage of accumulation on an electrode followed by a shorter second stage in which potential applied to the electrodes is varied over a range, while measuring the current flow as potential is varied.

7. A method according to claim 1 wherein at least one said tracer comprises an ionic species capable of undergoing a redox reaction.

8. A method according to claim 1 wherein at least one said tracer comprises nanoparticles.

9. A method according to claim 3 wherein a plurality of electrodes are carried on a single substrate.

10. A method according to claim 1 which is a method of monitoring flow within a reservoir from at least one injection well to at least one production well, wherein at least one said tracer is mixed with fluid pumped into a reservoir via the injection well and the step of monitoring flow is applied to flow from the production well.

11. A method according to claim 1 which is a method of monitoring hydraulic fracturing, wherein at least one said tracer is mixed with fracturing fluid pumped into a well and the step of monitoring flow is applied to flow back from the well.

12. A method according to claim 1 which is a method of monitoring flow from a plurality of separate locations for entry of hydrocarbon into a well, wherein different tracers are associated with respective different entry locations.

13. A method according to claim 12 wherein the well comprises valve means for regulating flow from different entry locations.

14. A method according to claim 12 wherein the well comprises at least one lateral subdivided into separate sections, with different tracers associated with respective different sections of the lateral.

15. A method according to claim 1 wherein one or more tracer materials at one or more locations is enclosed within a medium to release tracer when in contact with aqueous fluid.