Root causes of hydrocarbon leaks on offshore petroleum installations

Abstract

Hydrocarbon leaks on offshore installations may result in severe consequences to personnel, to the environment and to assets. In order to prevent such leaks, it is crucial to understand their root causes. The objective of this paper is to study the circumstances of hydrocarbon leaks on the Norwegian continental shelf (NCS). In the study, all reported hydrocarbon leaks from process inventories on all offshore installations on the NCS, with an initial leak rate higher than 0.1 kg/s in the period 2008-2014, have been considered. This includes 78 hydrocarbon leaks, of which about 60 % have occurred during manual intervention on normally pressurized systems. The dominating activity when leaks occur is preventive maintenance. A significant fraction of the leaks occur during the preparation for maintenance; such a preparation is typically carried out during the night shift. About half of the leaks are associated with wellhead area and manifolds, separation and compression systems. A substantial fraction of the leaks can be associated with verification faults, dominated by the failure to comply with procedural requirements that are needed to carry out independent verification.

Major accident prevention illustrated by hydrocarbon leak case studies: A comparison between Brazilian and Norwegian offshore functional petroleum safety regulatory approaches

“…This 'context-dependent performance' is the most important bond between human behavior and safety culture, as the safety management in a dynamic context must consider the mechanisms that influence behavior rather than only points human errors and violations. Several studies support the human factor relevance in offshore risk and have shown the critical role played by safety culture, especially regarding the occurrence of HCLs (Vinnem et al, 2016(Vinnem et al, , 2010Vinnem and Røed, 2015). Thus, the prevailing organizational safety culture is recognized as a major influence on workforce behavior regarding safety, which is reflected in organization performance (Givehchi et al, 2017).…”

Potential increase in oil and gas well leakage due to earthquakes

“…It is difficult to attribute wellbore leakage to earthquakes because there typically are other contributing factors and because of the detection problem. There are many factors that influence leakage with or without earthquakes that can be broadly categorized into technical degradation of the system, human intervention, process disturbance, inherent design errors, and external events, as identified to assess leakage risk on offshore petroleum installations [39]. Although advanced wireline downhole methods for determining well casing and cementing issues exist, they are not frequently done due to high cost and instrusiveness.…”

A study of maintenance-related major accident cases in the 21st century

“…A report from Australia indicates that 33% of hydrocarbon topside gas releases between 1985 and 1988 in Australia were linked to maintenance (NOPSA, 2008). A similar study of gas releases in the Norwegian offshore industry shows that over 65% of major hydrocarbon leaks on the Norwegian sector of the North Sea were linked to maintenance (Vinnem et al, 2007). Furthermore, a study of 242 accidents in relation to storage tanks in both industries between 1960 and 2003 reveals that about 30% of such accidents were caused by human errors including poor operation and maintenance (Chang and Lin, 2006).…”