The first ever successful offshore installation of a permanent in-well optical seismic system has been made in BP Norway’s G-24 injector well in the Valhall field by Weatherford International Ltd.
This is the result of a two-year collaboration on advanced completion technology between BP Norway and Weatherford to design and manufacture a system suitable for deployment in an injection or production well. The equipment was installed in March 2006. It consists of five three-component optical accelerometer stations and an optical pressure/temperature gauge deployed with the production tubing near the reservoir.
Seismic system extension
“Installation of the in-well seismic sensors represents an important extension of the existing permanent seismic monitoring system over the Valhall field, says Olav Barkved, lead geophysicist for BP Norway’s Valhall field. “The new sensors allow for new applications and represent a means for calibrating the remote observations of production effects to the observations made in the well. The primary objective is improved management of water injection and production.”
“Weatherford’s optical in-well system is providing both continuous seismic and pressure/temperature monitoring data, and is also interfaced to the existing permanent ocean bottom cable system, says Tad Bostick, VP for Weatherford’s optical sensing systems. “This allows for the simultaneous collection of permanent seabed and downhole seismic data representing a significant milestone for the industry.”
Weatherford’s Clarion optical seismic system features advanced optical multiplexing based on Bragg grating technology. The system uses sensitive, miniature optical multicomponent accelerometers to continuously monitor active or passive seismic signals throughout the life of the well. Each tubing-conveyed seismic station uses a specially designed active clamping system that optimally couples the 3-C sensor to the casing and substantially decouples it from the production tubing. An optical pressure/temperature gauge is deployed along with the seismic sensors on a single fiber-optic cable.
Builds on previous work
Weatherford’s collaboration with BP Norway in this project builds on previous efforts to optimize optical sensor and deployment technology and processes for permanent in-well seismic sensing. “The installation of the optical seismic array completion in G-24 was excellent. This was made possible due to two factors - up front planning and field trials to help optimize the equipment handling procedures and the highly experienced dedicated team of engineers who saw the job from the design stage through to execution,” says Paul Angell, senior completion engineer for BP Norway.
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