Spectral Leak Detection
Leaks in casing, tubing and completions and communications between them have a dramatic impact on well integrity, productivity and economics. Well integrity issues can directly impact HSE and corporate reputation. The Spectral Leak Detection (SPEC-LD*) is a component of TGT’s Well Integrity Platform. The SPEC-LD* is designed to measure fluid flow behind multiple casings by passive High-Definition Spectral Noise Logging (SNL-HD*) combined with High-Precision Temperature (HPT) logging to pinpoint leak sources and quantify them.
Our Client had a well with two production zones. The bottom zone produced naturally through the tubing and the upper zone produced through the tubing-casing annulus. After some years of production, the bottom reservoir started to produce water and the Client plugged it to reduce water cut. The upper zone continued to produce oil with zero water cut. A few months later, production from the annulus suddenly dropped and water cut increased to 60%. The client requested TGT to perform diagnostics for the tubing-casing annulus and find the water source.
TGT reviewed the well history and suggested assessing well integrity because we suspected that water might come from aquifer zones below through a casing leak as well as from the bottom reservoir through a tubing leak or behind the casing.
A SPEC-LD* survey identified communication between the tubing and the tubing-casing annulus. Communication was found to occur through the tubing leak at the collar joint, and the water was found to come from the aquifer.
Due to a busy work schedule, the Client requested TGT to analyse the data and propose a temporary solution to shut off the water zone and restore well production. TGT suggested plugging the tubing below the leakage area, which resulted in the recovery of 2500 BOPD with zero water cut.