Arrays of miniaturized temperature sensors were deployed in the lower completion of six subsea wells in Southeast Asia. The novel system allowed the operator to perform batch completion of the wells. A mechanical fluid loss control device included in the lower completion and a temporary plug set above the lower completion after gravel packing enabled the operator to return later with the upper completion. Upon deploying the upper completion, acquisition was activated and cleanup data were transmitted, allowing the operator to monitor flow from individual reservoir zones. Subsequently, production data have been transmitted in real time to the operator headquarters from an offshore production platform, allowing continuous reservoir modeling.
Key to the communication success was the use of mating inductive couplers, with the female coupler just below the gravel-pack packer and the mating male coupler at the bottom of the upper completion. This coupler has been proven reliable in the presence of standard field operations. In some cases, there were multiple activations of the coupler, and all were successful.
Success of the overall system required that each interconnecting component and interface work as designed. For example, each temperature sensor was designed to land on a blank section of the sand-screen joint above the coupling. A special coupling clamp secured each sensor. The intersensor spacing was designed to be slightly longer than the longest anticipated sand screen. At each joint, a rig device applied a small S-shaped bend to the cable between the sensors. As the bend was formed, this shortened the intersensor spacing for precise onsite depth adjustment.
Similar attention to detail was expended on cables and rig handling. The cable allowed inline splices using a welded seal technique adapted to this specific deployment, the first field deployment of this technique. Significant effort was expended in weld development and testing, but nonetheless there were opportunities to continuously improve on process components such as cable handling and splice preparation.
The proven robustness of the system has led to alternative completion configurations such as monitoring the sandface of wells using electric submersible pumps for enhanced recovery.