Welcome to the peer-reviewed papers section of Oil and Gas Facilities, which includes five papers this month. I am very pleased that we can offer an additional paper, and I want to thank the numerous technical editors and three associate editors for the extra efforts required to make this happen. I know that many of you especially value this portion of the magazine, and with this expansion, we hope that it becomes even more relevant to our readers.
Our first paper deals with pipeline embedment, a fundamental input to the assessment of pipe/soil interaction (PSI), which is the largest uncertainty faced in the design of offshore pipelines subject to lateral-buckling and walking phenomena. However, pipeline embedment is notoriously difficult to predict because of the inherent uncertainty of the installation process. By the use of high-quality observations of pipeline embedment, an updated methodology to predict this parameter was developed and subsequently verified successfully. The paper presents this revised methodology, which clearly has the potential to improve assessments of embedment and thus, provide more-accurate PSI responses.
The second paper deals with another offshore topic—hybrid-power systems that increase energy efficiency and reduce emissions. As emission controls are becoming more widespread around the world, emissions reduction in oil and gas exploration and production operations is increasingly relevant. Hybrid-power systems can address some of these issues with batteries to offset peak loads, thereby reducing size requirements for the total system. This paper provides an overview of the battery systems that can be applied for offshore applications with the objective of serving as a selection guide.
The third paper covers steel risers on a turret-moored floating production, storage, and offloading (FPSO) facility. The Espirito Santo, located offshore Brazil, was the first such FPSO, having begun operation in 2009. This paper summarizes the basis for selecting steel risers for this particular development, how the risers and umbilicals interface with the turret, and the impact of the riser choice on the turret design. The paper also describes the manner in which the in-service inspection of the riser system is performed and provides a summary of the inspection results.
The next paper deals with reliability analysis of Arctic oil and gas facilities. More specifically, it describes the way in which one can manage the lack of adequate reliability data for such facilities. Historical data gathered in normal-climate regions may not be appropriate for Arctic regions because they do not include the effects of harsh Arctic operating conditions. In this study, the expert-judgement process is used as a tool to modify the data to account for these adverse impacts, and then the fuzzy set theory is applied to deal with various sources of bias and uncertainties that are involved in expert judgements. The paper concludes with a case study to illustrate this approach.
The final paper deals with horizontal heater treaters used to separate oil/water emulsions. Conventional burners used in these heaters can cause hot spots that result in coking of the viscous emulsion on the outer surface of the firetube, leading to an early failure of the firetube. To address this issue, a conventional burner can be replaced with an all-radiant distributed-flux burner that spreads the heat over a much larger area, with a very uniform flame shape. This design not only reduces the peak heat flux surrounding the combustion zone significantly, but heat is also distributed farther down the length of the firetube, improving its overall performance and efficiency. This paper presents data from both pilot tests and field tests of a recent burner retrofit of a horizontal heater treater at an oil-sands field in northern Canada to illustrate these aspects.
I hope that you will review these interesting papers and feel encouraged to submit a discussion, if you feel that the content of a particular paper warrants further debate or comments, or a paper for peer review. We welcome either one, and you will find instructions for submitting your contribution below.
Gerald Verbeek, Peer-Review Editor,
Verbeek Management Services
Williams Chirinos, Inexertus
Galen Dino, Audubon Engineering Solutions
Sudhakar Mahajanam, ConocoPhillips