Riser and Subsea Asset Field Life Extension

Event:
SNAME
Date:
February 2015
Author:
D. Nashikkar, W. Mo, V. Achanta - 2H, S. Lyon - Lonestar

Many offshore floating hosts and subsea assets commissioned in the Gulf of Mexico are approaching the end of their design life. Existing fields continue to produce due to enhanced recovery while adjacent fields are considered to be tied back into aging facilities. Hence, there is motivation to extend the service life of these subsea assets beyond the original design life.

Condition assessment and life extension analysis for the assets is required to ensure safe operations during extended field life. This paper discusses the general roadmap and activities performed to provide assurance that extended operational life of riser and subsea assets will not create integrity risks.

Life extension of a typical riser system on a production platform is discussed as a case study. The case study is mainly focused on riser but can be generalized to subsea assets. The paper reviews the original designs of the assets in conjunction with the extended service requirements. Inspection and operational information from ongoing integrity management of these assets is utilized to understand the health of the existing asset. Use of actual history of loading to understand the fatigue history of the structures is discussed. The paper also includes evaluation of the impact that updated metocean and the latest code requirements have on robust extension of the asset field lives.

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