Full Offline Well Cementing Implementation Resulting in Significant Time Savings and Improvement in Operational Efficiency

Abstract

The current global low oil price environment has driven many operators to consider having a quicker and more efficient operations and reduction of the well construction cost. Recently in Field A which was located in offshore Sarawak, Malaysia, four monobore completion wells were successfully batch drilled and cemented offline through ingenious planning. This involves skidding of rig floor away from the well to allow access for the cementing operations to be performed underneath the rig floor simultaneously while drilling operations are allowed to resume above it. This paper will discuss about the offline activities performed, well barriers classification and the offline cementing techniques including the cementing design slurries employed from the top hole section until the final tubing section cementing. Offline activities were able to be performed before and after the rig skidding package is moved from one slot to another, thus reducing the overall project time. These activities included but were not limited to offline cementing, wellhead installation and tubular rack back on the derrick. Once the conductor was cleaned to the shoe, casing was run and the rig will skid to the next conductor slot and offline cementing adapters were installed on the wellhead. As the rig continues with the drilling operations, cementing operations will be performed offline below the rig floor. For the conductor section, 3 conduits were run and cemented simultaneously within a conductor offline. For the next section, the intermediate hole was drilled to its section TD, casing was run to bottom and cement head was installed offline after the rig skidded to next well. The next operation which included mud circulation and casing cementing was also performed offline. These same operational steps were repeated for all wells including the offline tubing cementing operations. The cement slurries were designed as per well requirement which was a conventional Class-G cement slurry design for the conductor and the intermediate section. LCM material and sealing spacer were prepared onboard to mitigate any potential losses which could happen during drilling or cementing operations. For the tubing cementing section, self-healing cement system was introduced to ensure well integrity and zonal isolation is guaranteed for the life of the well. All four wells were drilled and completed within 34 days, resulting in a time saving of 30 hours just for cementing operations; which was 23 % of cumulative time savings. This drilling and cementing approach will be a footprint to the operator for all future development wells.