Patent ID: 9732565
Date: 2017-08-15
CPC Classifications: B63B,E21B

Claim:
1. A method for riser string handling on an offshore drilling vessel, the offshore drilling vessel comprising: a hull having a moonpool extending through the hull; a multiple firing line hoist system mounted on the hull at said moonpool, the multiple firing line hoist system comprising: a riser tensioner system arranged in the second firing line, adapted to be connected to a top end of the riser string, in order to suspend the riser string from in the second firing line; a suspended riser transfer device, comprising: wherein a first parking position for the frame of the suspended riser transfer device of the offshore drilling vessel is provided in the vicinity of the first firing line, in a direction opposed to the second firing line, and wherein the rails of the suspended riser transfer device extend beyond the first firing line to the first parking position, wherein a second parking position for the frame of the suspended riser transfer device of the offshore drilling vessel is provided in the vicinity of the second firing line, in a direction opposed to the first firing line, and wherein the rails of the suspended riser transfer device extend beyond the second firing line to the second parking position, and wherein the suspended riser transfer device of the offshore drilling vessel further comprises: the method comprising the following steps: a) building and lowering the riser string in the first firing line, and simultaneously assembling and preparing the riser tensioner system in the second firing line; b) suspending the riser string from the first load attachment device; c) positioning the riser hang-off assembly in the open configuration in the first firing line; d) positioning the upper end of the riser string in the riser hang-off assembly and actuating the riser hang-off assembly to the closed configuration; e) transferring the weight of the riser string from the first load attachment device to the riser hang-off assembly; f) disconnecting the first load attachment device from the riser string; g) displacing the riser hang-off assembly in the suspended riser transfer path while the riser hang-off assembly supports the riser string in the gimbal device from the first firing line to the second firing line; h) connecting the top end of the riser string to the riser tensioner system; i) transferring the weight of the riser string from the riser hang-off assembly to the riser tensioner system; j) actuating the riser hang-off assembly to the open configuration and thus disconnecting the riser hang-off assembly from the riser string; and k) displacing the riser hang-off assembly in the suspended riser transfer path from the second firing line to the first firing line.