Wet Christmas Tree Interface for Depressurizing Underwater Flowlines

Abstract

Oil and gas flowlines plugging due to hydrate formation is one of the main reasons for production losses in deep water production systems. Therefore, several hydrate prevention and mitigation techniques have been constantly developed and applied by industry. Regarding hydrate dissociation techniques, efforts focus on avoiding the use of naval resources, such as workover rigs or special vessels, because of the high cost involved and, very often, the poor readiness. This work presents an ROV connection device, installed in the Production Adapter Base / Tubing Head Spool (PAB / THS) of a Wet Christmas Tree (WCT), which allows coupling a local system of fluids depressurizing and handling, eliminating the need of a classified vessel to handle hydrocarbons. Besides allowing faster hydrate removal in subsea flowlines, the proposed method do not require any technological development since it consists of the integrated use of subsea devices and tools commonly used in the offshore industry.