A New Approach for Water Entry Point Identification in Small Tubulars

Identification of early water breakthrough is essential for proper reservoir management. To face this issue a full suite of production logging methods has been developed to locate water entry points in the well and evaluate their magnitude. These tools are normally recorded in perforated casing intervals below tubing shoe and therefore most of them are designed to provide the best response in a tubing free cased environment. On the other hand, the compelling need to investigate production by means of Sliding Side Doors (SSD) valves, forced to use production logging tools in unconventional situations such as small tubing, giving responses not always reliable due to high downhole fluid velocity and high friction effects. This challenging experience highlights water entry point determination in wells completed with dual tubing string, where multilayer gas levels produce through several SSDs. In this environment the conventional gas/water holdups production logging methods (gradiomanometer and capacitance) fail. A tool able to provide gas/water holdup using optical refraction method, with sensors normally mounted on caliper arms to log over standard tubular sizes, was modified placing the sensors at the bottom of the tool body. This technique provided reliable gas/water holdup data used to compute gas and water contribution from each SSD, as shown by some examples described in the paper.