In July and again in September 2019, six-fiber downhole fiber optic wet-mate connections were successfully landed on fiber enabled lower completions, "lighting up" the completion from the wellhead to the reservoir. The tools that enable this technology must simultaneously align six fibers the diameter of a human hair end-to-end in a downhole environment.
These deployments are the first successful installations of fiber optic downhole wet connects in the North Sea and it represents a step change in the information that can be obtained from permanently installed sensors at the reservoir in a multi-trip completion. To date, opportunities for fiber optic sensing have been quite limited in multi-trip completion systems. This has restricted the use of many fiber optic technologies to the upper completion rather than where it can provide the most impactful data - at the reservoir.
This paper will present a brief history of the development and validation of this fiber optic connector system design including specific qualification testing for these North Sea wells. The fiber optic downhole wet-mate connector is a result of more than a decade of engineering design, testing and qualification. Further refinements were made with this specific group of wells in mind, and the system was optimized, assessed and tested with support from the operator. A close working relationship between the operator and the service company enabled optimization of the tools as well as the entire completion to reduce the risk of NPT and infant mortality of the equipment.
The operations resulted in a successful connection of all six fibers and a fiber optic instrumented lower completion with full well surveillance capability. Six individual fibers were connected simultaneously, enabling sensing of distributed temperature, distributed acoustics, and two pressure/temperature gauges on the exterior of the lower completion with direct contact to the reservoir. Optical losses across the connector were less than 0.5 dB for all fibers.
This fiber enabled completion allows the completions and reservoir engineers to gather and interpret the distributed data that obtained by the interrogators from the interaction of the optical fiber and its surrounding environment.