HOUSTON --In a paper prepared for Offshore Technology Conference presentation, the process by which permanent optical sensors were developed and deployed for subsea use. An optical wet mate tree connector and optical instrumentation were developed and qualified for subsea use, leading to deployment of a fiber optic system for pressure/temperature and array temperature sensing.
In place 135 mi (217 km) offshore Angola since early last year, Weatherford International used current best practices, API and MIL specs, IWIS recommended practices along with the project-specific demands because there were no universally accepted standards for such a technology application. The development consists of 25 wells tied to four manifolds with 64 km (40 mi) of production flow lines going to an FPSO. The run from the wells to the FPSO is an added 40 km (25 mi).
In order to reach this goal, Weatherford had to:
- Establish subsea instrument and component standards to build a test regime to qualify the new optical sensing technology
- Develop, qualify, and interface a subsea connector system for wellhead and tubing hanger penetration
- Develop, qualify, and interface a new subsea optical instrument deployed in an atmospheric housing
- Design an in-well monitoring system that could deliver accurate reservoir pressure/temperature data from the well sand face to the surface.
Using a document published by a group of offshore West Africa operators as a start, a subsea components qualification study began focused on the optical system and its parts from below the tubing hanger through to the ROV optical connections. This extension of the study also considered the standards in API 17D. As a result, each component and the complete system all were tested. Another study investigated the downhole, in-well optical cable. The result of these studies was a general specification for subsea systems/subsea mateable electric/optic connectors.
With these guidelines, the developed system went through a final Site Integration Test in Angola.
As of late 2008, the system successfully was deployed and tested using the rig workover control system. Based on this project, Weatherford says subsea optical monitoring systems are ready for installation and that standard project practice can successfully reach hardware integration and interfacing.