Small-size ROV launched from underwater TV system for observation in scientific drillings

During re-entry operations in offshore drilling, the drill pipe needs to be monitored in order for the drillship to maintain or change its position. In oil and gas drillings, conventional remotely operated vehicles (ROVs) are used for such operations. However, in scientific drillings, conventional ROVs cannot be used because target water depths can be as large as 7,000 m. The scientific drilling vessel Chikyu facilitates underwater TV system equipped cameras but without any thrusters. Due to limited mobility, monitoring re-entry operations can be difficult. Thus, a small-size ROV was developed to be installed in the existing underwater TV system as payload. During the design phase, experiments were conducted to evaluate thruster performance and to confirm operability in a water tank, and computational fluid dynamics simulation was done to obtain information on the hydrodynamic forces at work.