Te oil producer wells, in the southern are of Saudi Arabia, are mostly completed as horizontal open hole (OH). Some of these wells are dead or on itermittent production due to high water cut, which is caused mainly by water influx through carbonate fissures or fractures. Multiple water shut off (WSO) jobs using inflatable packers, were performed between 2005 and 2010 but failed during execution because of the packers setting failure in OH.
The WSO candidate selection process starts with reservoir and production data evaluation, then requires a coiled tubing logging run to identify the water source and adjust the required isolating fluids formulation and volume. For the execution, there is a need to control the placement, inflation, injection and disconnect of the inflatable packers in order to ensure successful WSO treatment.
This paper describes how the fiber optic enabled coiled tubing (FOECT) system, enabling realtime downhole data measurement, can optimize the WSO treatments design, execution and evaluation, and increase their success rate.
For the job design, production logging tools were run with FOECT string to detect the water source, measure the BHT required for the formulation of WSO fluids, obtain a GR log, and get an X-Y OH caliper critical to decide the best setting depth for the inflatable packer and to confirm the required WSO fluids volume.
For the job execution, the depth correlation for the packer setting was performed with the fiber optic bottom hole assembly FOBHA-GR. The inflation of the packer and the injection through it were monitored and adjusted realtime with the FOBHA-PTC measurement inside and outside the FOCT string. The confirmation of the packer setting and the release from it were confirmed with the world's first applications of FOBHA-Tension/Compression sub.
Recent production results showed previously dead well flowed at significant oil rate with 10% water cut after performing a WSO with FOECT innovative solution.
The integrated FOECT solution, eliminating engineering assumptions during the full cycle of design-execution-evaluation, is a proven WSO technique in OH, which can bring many wells back to economical production.