Patent ID: 7699103

Claim:
A method for inserting a fiber optical sensing cable into an underwater well, comprising connecting a housing comprising a coiled fiber optical sensing cable to the wellhead of the well such that an opening in the wall of the housing is connected to a guide tube extending into the underwater well; inserting a lower end of the fiber optical sensing cable via the opening into the guide tube, thereby uncoiling at least part of the fiber optical sensing cable; and connecting an upper end of the fiber optical sensing cable to an optical signal transmission or receiving unit; wherein the lower end of the fiber optical sensing cable is U-shaped and comprises a U-shaped nose section which interconnects a pair of substantially parallel cable sections having upper and lower ends, wherein the nose section is inserted into the guide tube such that the nose section pulls at least the lower ends of the substantially parallel cable sections into the guide tube, and wherein the upper ends of the cable sections are connected to the optical signal transmission or receiving unit; and wherein the guide tube is U-shaped and the opening is connected to the upper end of a first leg of the guide tube, and wherein the upper end of a second leg of the guide tube is connected to a second opening in the wall of the housing, and wherein the U-shaped nose section and at least the lower parts of the substantially parallel sections of the fiber optical sensing cable that are interconnected by the U-shaped nose section are pumped down through the first leg of the guide tube towards a U-turn of the guide tube and through the U-turn at least partially up into the second leg of the guide tube.