Flexodrilling used for deep-water seabed reconnaissance
A low-cost plumbline method permits easy tripping and complete remote control of drilling and coring. The surface support is a small displacement vessel (850 metric tons for the Terebel) equipped with dynamic anchoring for nearly instantaneouos positioning at a given spot no matter what the water depth may be. Instruments,motors, and downhole tools for drilling and coring are simply hung on the end of a continuous flexible power-conducting line that is wound and unwound quickly and efficiently between surface and bottom and is protected from heave effect by special onboard equipment. The downhole equipment consists of the following: (1) an electrodrill driving a drilling and coring bit on the bottom a core barrel; (2) an electric pump for seawater circulation during drilling and coring; and (3) sensors and relays for remotely controlling these instruments, including sensors for detecting traction, torque, inclination and pressure as well as a relay for switching up the central part of the drilling bit and coring at the desired depth. Surface equipment mainly consists of a drum and traction caterpillar gripper for storing and continuously winding or unwinding the flexible cable and a hydraulic slide to cancel out effects of the ship's heave on the flexible line. The equipment was operated for the first time in the Mediterranean off Toulon.
- Research Organization:
- Inst Francais du Petrole
- OSTI ID:
- 5269726
- Journal Information:
- Ocean Ind.; (United States), Vol. 5:7
- Country of Publication:
- United States
- Language:
- English
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