Integrated Geohazards Evaluation and Risk Assessment for Subsea Facilities

Abstract

Offshore oil and gas developments in geologically active regions face a number of geohazards, including earthquake shaking, fault rupture, liquefaction, slope failure, and fluid escape. The magnitude and frequency of these hazards are often difficult to quantify; leading to large uncertainties in the risk analyses carried out for engineering development. Traditional deterministic hazard assessments often conclude that such regions are too problematic for development. This paper presents a recently developed probabilistic approach that integrates geohazard evaluation with engineering limit state analysis, which in turn allows a dynamic, streamlined approach to risk assessment. This Failure Modes and Effects Analysis (FMEA) ensures end user focus, with the drilling, subsea and pipeline, infield compression facility, and reservoir teams driving the process through quantification of the consequences of failure. It also enables reality checks and establishes a process for asking the right questions at the right time. This approach has the benefit of rapidly identifying the real geohazard and engineering issues. This, in turn, allows rapid decision making to be undertaken, not just for adjustments to offshore site survey programs, but also, in efficient allocation of engineering resources. It also provides a quantified risk based set of engineering decision tools suitable for life of field appraisal of both HSE and operational issues. The rapid assessment of CAPEX risk allows decisions to be made regarding reassessment of field design and/or identifying defensive measures requiring CAPEX reallocation.This integrated probabilistic approach to geohazard assessment and subsequent risk analysis significantly streamlines the decision processes required for field design. By employing an integrated team of engineering and geoscience experts, potential "project stopper" problems are swiftly identified and solved/avoided by rerouting/resiting facilities or enhancing engineering design. This approach has the potential to lead to significant cost savings and a reduction in time required for field development.

An integrated FMEA and MCDA based risk management approach to support life extension of subsea facilities in high-pressure–high-temperature (HPHT) conditions

“…Ward et al (2001) conducted a comprehensive analysis to identify the risks associated with deep-water operations in the GoM. Fenton et al (2002) presented an integrated probabilistic approach for geohazard evaluation and risk analysis of subsea facilities in harsh conditions. Henriksson et al (2004) elaborated on the risks associated with harsh environments and difficult seabed conditions and investigated how these risks may affect design and installation of different types of pipelines.…”

Comprehensive Risk-Evaluation Approaches for International E&P Operations

“…Fenton et al 7 found the process led to a more streamlined approach to field layout, the efficient utilization of resources to collect additional survey data, and the benefit of implementing mitigation measures upfront using a capital expenditure budget compared to doing so using an operations budget to address repairs and replacement. The method ultimately led to more robust design with approximately 80% of the facilities undergoing some readjustment.…”