The wells in the southern area of Saudi Arabia are mostly horizontal wells in highly fractured carbonate reservoirs. Due to high water cut caused by water influxes through the fractures, some of these wells were dead or on intermittent production between 2005 and 2010. To increase oil production, we performed several water shutoff jobs using inflatable packers with mixed results.

The water shutoff candidate selection process starts with a reservoir and production data evaluation, followed by a coiled tubing (CT) logging run to identify the water source and adjust the required isolating fluids formulation and volume. Successful execution of the water shutoff treatment requires controlling the placement, inflation, injection, and disconnect of the inflatable packers.

Fiber-optic enabled coiled tubing (FOECT) systems, which enable real-time downhole data measurement, can optimize water shutoff treatment design, execution, and evaluation—increasing the success ratio.

For the job design, we ran production logging tools on the FOECT string to detect the water source, measure the bottomhole temperature required for the formulation of water shutoff fluids, obtain a gamma ray and/or casing collar locator (CCL) log, and get an X-Y open hole (OH) caliper critical. This helped us determine the best setting depth for the inflatable packer in the openhole section, and confirm the required water shutoff fluids volume.

The depth correlation for the packer setting was performed with a fiber-optic bottomhole assembly (BHA) gamma ray conveyed on CT. This enabled us to monitor and adjust the inflation of the packer, and the injection through it, in real time Then, the packer setting and release was confirmed with the world's first application of a fiber-optic, CT-conveyed tension and compression tool.

Recent production results showed significantly higher production with no more than 10% water cut. The integrated CT solution proved to be an effective water shutoff technique in these horizontal wells, and has potential to bring many wells around the world back to economic production.