The short 5" sensor generates short electromagnetic pulses to survey tubing and casing of small diameters up to 5". The length of the sensor defines the minimum detectable size of defects, which is 0.9" for the short one.
The medium 13" sensor is optimised to scan metal barriers of up to 10" in diameter. As this sensor module generates electromagnetic pulses of higher amplitude and longer duration than the short one, it can detect defects in the more distant second and third barriers of 2–10" diameter. The minimum detectable size of defects is 1.8".
The long 19" sensor generates the longest electromagnetic pulses of highest amplitude and detects responses from metal barriers appearing in magnetisation decays at late times. This sensor is designed to scan metal barriers upto 18 5/8” in diameter with a total thickness of up to 2"
Collars, X-nipples and other completion components can be identified directlyin raw time responses. However, metal loss (such as due to corrosion or perforations) cannot be displayed directly, and the data must first be processed using TGT’s proprietary software to simulate the response. A comparison of logging data and the simulated response then reveals metal loss, even behind multiple barriers.
The informative DELTA panel shows differences between simulated and real responses. This panel provides sharp image contrast and shows metal losses in fine detail.
EmPulse is a memory tool and, therefore, can be conveyed on slickline.This feature greatly reduces operating costs allowing the EmPulse to be used as a diagnostic tool to assess well integrity and prevent failures before they occur. The tool is also equipped with a pressure sensor to detect pressure drops due to tubing leaks and with a temperature sensor to detect deviations from the geothermal profile outside the tubing. In addition, the tool can be run in combination with the Spectral Noise Logging (SNL HD) memory tool to detect fluid movements, even behind multiple barriers, providing a unique through-tubing well integrity suite implemented with a slim memory toolstring.