Over the past years the usage of coiled tubing as a prefer method to deploy long and heavy guns in highly deviated wells has been widely spread in the oil industry to provide a single run without killing the well, perforate in underbalance conditions, reduce risks and improve job efficiency. The three wells are located in the Caspian Sea. In two wells, the objective was to isolate lower intervals and perforate a new zone through tubing and casing between two packers. On the other well, the objective was to perforate a new interval through casing after running a new completion and isolate lower production zones.
Due to the challenges involving gross length of the new intervals, guns size, well deviation and live deployment needs several techniques were evaluated. The best approach was to use an Advance Live-Well Deployment (ALWD) system to deploy and retrieve the guns with a tube wire-enabled Coiled Tubing Telemetry (CTT) system focus on both safety and cost saving compare with conventional wireline perforating. Extensive job planning involved coiled tubing (CT) simulations to reach target depths, shock loading modeling to ensure forces are within CT string limitations, system integration test to verify deployment/reverse technique procedure and system communication to electrically activate guns.
CTT integrated sensor assembly was used during deployment/reverse operation with a tension, compression and torque (TCT) sub-assembly to monitor accurate upward/downward forces. In addition, CTT logging adapter assembly was used for depth correlation and electrical guns activation. The ALWD system; composed by connectors and deployment blow out preventor (BOP), prove to be an efficient way to run, perforate and retrieve gross intervals of 212 m, 246 m and 104 m with guns successfully. During all these jobs several lessons learnt were created in order to improve the deployment/reverse procedure for future jobs including not only operational steps but also deployment/reverse bottom-hole assembly (BHA) configurations.
Based on the success of these case histories, the ALWD combined with CTT system has been proven to be the preferred method when dealing with long perforation intervals in life well conditions, thru-tubing environment.