Abstract

A cased hole well with inflow control devices (ICDs) was logged for production profiling as part of a field trial campaign testing a new fiber-optic wireline system. Pulled by a conventional tractor, both the fiber-optic wireline and a set of conventional production logging tools (PLTs) were placed at the bottom of a horizontal wellbore, locating the fiber across the reservoir for sensing purposes. The well produced at two different choke settings, enabling both technologies to capture low flow rate as well as high flow rate. The main objective with the testing was to compare the two technologies for production flow allocation and learn more about fiber-optic analytics.

The two different measurements were performed as close in time as possible. While the fiber-optic cable was sensing, the PLT was stationary and not logging, and while PLT was logging, the fiber optic was deactivated. From fiber optics, high-quality noise logging plots were generated with distributed acoustics (DAS), identifying the inflow points despite the relatively challenging acoustic environment. Propagating sound allowed for a profile of fluid sound speed to be established. Distributed temperature (DTS) was less useful on this job due to some accidental inflow of borehole fluid causing hydrogen darkening. This affected the multi-mode fiber more than the single-mode fiber; hence, DTS data could not be used. The wireline-based MAPS tool consisted of capacitance-, resistivity- and spinner-array. With the sensors located on bow springs, the tool detected various flow patterns 360 degrees around the borehole. The fiber-optic cable is located low side in a horizontal wellbore and might be affected by this in a laminated flow situation. Still, the fiber-optic sensing system managed to provide useful flow information, comparable to the PLT tool.

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