This paper introduces and evaluates a next-generation acoustic conformance-monitoring system that helps identify the depth and accurate radial location of undesirable leaks in a well. Determining the leak's flow pattern in and around the wellbore is also used to understand activity within the surrounding wellbore region.

The acoustic conformance tool was run employing a memory slickline operation in a well located offshore Sarawak, Malaysia. The tool successfully acquired both low- and high-fidelity data, which were subsequently used for leak characterization analysis. Using an array of acoustic sensors, the tool is capable of detecting undesirable flow throughout the well structure. The vertical accuracy is within inches and estimates the radial location around the wellbore. Before the operation, careful and thorough prejob design is necessary for data acquisition to help reduce uncertainty in post-interpretation. These include detailed operational sequences in terms of leak stimulation of various annuli in the well to obtain optimum results. Subsequently, the signals are analyzed using a beam-forming method to identify leak distances and a flow map to further understand flow characteristics.

The study well is a gas producer completed with a 7-in. single string. Post-data processing and interpretation revealed a continuous high-frequency noise spectrum from the bottom of the logging interval to the surface, indicating gas movement, which was further confirmed by two-dimensional (2D) flow map analysis. Results indicated gas movement in Annuli C and B. Based on results, production logging sensors, and well completion statuses, inferences were made regarding this gas movement and its possible sources—a cement window in Annulus C and cement channel in Annulus B.

This technology accurately identifies and pinpoints leak sources, assisting the asset owner with planning and designing remedial work to help reduce undesirable fluid, which benefits total production.

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