Patent ID: 9080393
Filing Date: 2015-07-14
Classification: E21B

Abstract:
1. A method for retrieving a drilling riser connected to a blow-out-preventer (BOP) located on a sea bed using a retrieval line having first and second ends, wherein the drilling riser is connected to a moored drilling vessel or a dynamically-positioned drilling vessel, either having a bottom opening, the method comprising the steps of: a) attaching the first end of the retrieval line to a second vessel; b) attaching the second end of the retrieval line to the drilling riser; c) disconnecting the riser from the BOP; d) initiating the assent of the disconnected drilling riser from the sea bed; e) the second vessel maintaining tension on the drilling riser as it ascends to the sea surface by creating a horizontal load that is opposite to a current load on a bottom end of the drilling riser; f) the second vessel releasing tension on the retrieval line as the drilling riser approaches the bottom of the drilling vessel; and g) disconnecting the retrieval line from the drilling riser, whereby the drilling riser is pulled through the bottom opening in the drilling vessel.