Applied Ultrasonic Technology in Well Bore Leak Detection

Abstract:

For nearly a century engineers have utilized electronic measurement devices to evaluate and diagnose well bore conditions.  These devices are as varied in nature as the principles of physics on which they were based.  Although useful, some of this equipment can more often than not provide data that is more subjective rather than conclusive.  When utilizing various devices to determine causes of sustained casing pressure, tubular leaks or failures in other down hole hardware, it is very useful to have data which will enable an operator to move effectively and economically select a remediation method.  In an effort to provide this needed accuracy, a tool has been developed based upon the principles of ultrasound.  The tool utilizes passive ultrasonic sensors in conjunction with a unique method of digital signal processing (DSP). As the tool is passed through the vicinity of a leak, the ultrasonic sensor detects the frequencies generated by the turbulent flow at the leak point. The signal is then amplified and sent through the DSP module in the tool. The DSP unit is equipped with a large amount of flash RAM running a series of modular signal processing programs.  This process filters out any unwanted background energies caused by mechanical noise or other interference.  The result is a fully digitized signal of the leak signature which is then transmitted up-hole via a wireline telemetry system to the surface read out system.  The tool will measure leaks as small as .1 liters/minute with an accuracy of one meter in production tubing casing and a variety of other pressure containing hardware.  Case histories are provided which illustrate the tools ability to accurately detect leaks in a variety of scenarios leading to a direct economic benefit.