Wellbore leak detection systems and methods of using the same

Abstract

A leak detection system for a wellbore. The leak detection system includes: (1) at least one sensor configured to be positioned outside of a casing of the wellbore; (2) an interrogation system for sending signals to, and receiving signals from, the at least one sensor; and (3) an optical lead cable disposed between the interrogation system and the at least one sensor. A method of detecting a fluid leak in a wellbore is also disclosed.

Description

RELATED APPLICATION[0001]This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61 / 525,269, filed on Aug. 19, 2011, the content of which is incorporated in this application by reference.TECHNICAL FIELD[0002]This invention relates generally to the field of optical fiber sensing systems and, more particularly, to improved systems and methods for accurately sensing fluid migration in and around a wellbore.BACKGROUND OF THE INVENTION[0003]The migration of fluid (e.g., gases, unwanted liquids, etc.) to the surface from deep gas formations is a problem that can lead to disastrous consequences. Underground gas storage facilities have demonstrated a long history of environmental problems caused by unwanted gas migration. Gas migration is also a concern from abandoned (i.e., plugged) wells that are no longer in use. However, it is the widespread production of natural gas from tight shale beds via the combination of horizontal drilling and hydraulic fr...

AI Technical Summary

Benefits of technology

The present invention provides a leak detection system for a wellbore that includes a sensor, an interrogation system, and an optical lead cable. This system can detect fluid leaks in the wellbore by transmitting light from the interrogator to the sensor, receiving the return signals, and processing them to determine if there is an indication of a fluid leak from the wellbore casing. This invention is useful for ensuring the safe and reliable operation of wellbrows.

Problems solved by technology

The migration of fluid (e.g., gases, unwanted liquids, etc.) to the surface from deep gas formations is a problem that can lead to disastrous consequences.

Underground gas storage facilities have demonstrated a long history of environmental problems caused by unwanted gas migration.

One particular concern is the possibility of natural gas migrating from a deep shale gas producing zone to near surface aquifers, thus contaminating the water and / or collecting in low lying surface areas with dangerous implications.

For example, this migration may occur along the outside of the wellbore casing due to degraded or improperly installed cement.

Fluid under such high pressure may result in the development of channels along the outside of the wellbore casing through the cement itself, between the cement and the casing, between the cement and the surrounding earth, or some combination thereof.

Such a technique is not practical for monitoring a producing well, for example, because it requires suspension of gas or oil production, costly removal of production hardware (e.g., tubing, etc.), installation of a sensor or sensor string, detection and interpretation of data, and removal of the sensor or sensor string.

Further, detecting leakage outside of the wellbore casing (i.e., through the various layers of casing / production tubing) using such a technique involves significant challenges.

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