Well Side-Track Optimization Using Electromagnetic and Ultrasonic Measurements Across Dual Strings for Well Integrity Assurance

Abstract

This paper describes the application of a combined answer from Electromagnetic and Ultrasonic imaging measurements to assess the well integrity prior to well side track and Whip-Stock setting. This solution was applied in a very old well in Raudhatain field in Kuwait that was completed since 1959. To optimize the cut depth for the side track across the single string, it was essential to identify an accurate depth of the external casing shoe, in addition to evaluation of both internal and external casings integrity and the cement bond quality for zonal isolation assurance. Data was acquired in September 2015 where the Electromagnetic log along with Ultrasonic images have been utilized with the advantage to provide answer in sections completed with dual strings for well integrity assessment. The log results could detect the external casing shoe at the depth 7170-ft, presented good pipe integrity for the internal casing, and indicated good pipe condition with minor metal loss in the external casing across the double strings interval. The measured outer casing shoe was found 21-ft deeper than the theoretical from the old well sketch data, hence the depth of the well side track and Whip-Stock setting were optimized accordingly. Failing to confirm the actual depth of the external casing shoe could have unintentionally led into drilling the side track across the double casing section resulting in undesirable workover operations and rig cost. Drilling a side track in dual pipe completed interval would also result-in damaging the outer casing and high remedial cost that cannot be predicted. The operator "Kuwait Oil Company" has achieved their objective to side-track the well across single casing string without taking any risk and avoiding any implications through wireline technology and solutions.