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Game Day: January 29 – February 1
Home base: #707
Presenting: 4 ROSEN Papers
Platinum Elite Sponsor: The ROSEN Group
Each new opponent at bat presents a new combination of different skillsets that require agile adjustments of your game. Similarly, each asset presents a unique set of challenges, conditions and threats, requiring a solution that is both flexible and precise. This is why at PPIM 2018, we will be highlighting our Combined Diagnostic Solutions, which can be tailored to carry various combinations from ROSEN’s extensive technology portfolio to identify the various threats to a pipeline’s integrity. After all, a team that knows how to make the right defensive plays is a winning team.
We will also introduce our new asset integrity management software, NIMA. Just as a player must see the whole field and predict the actions of the opponent to make a good decision, an operator must have a comprehensive understanding of the asset’s current condition and predictable behavior to ensure proper asset care. NIMA was recently developed to assist operators in efficient management of high quantities of complex data, simplifying the integrity assessment process and ultimately enabling effective decision-making.
With our comprehensive solutions, we provide a precise statement about the overall integrity of the asset. Visit with our experts and perfect your integrity management game plan.
Multi-diameter ILI tools, bridging diameter changes between two and more than ten inches, are the main - and often only - solution to allow for inline inspection of complex pipeline systems.
In the oil and gas market, there are two different areas where the aforementioned diameter changes tend to occur. Each has its own individual characteristics that differ largely from each other:
1. Onshore Systems are mainly used for product distribution. These commonly feature various lines of different lengths and various pipe diameters that have grown together over time. The main similarities of these systems comprise short radius bends and/or miter bends, more often than not low pressures, and/or significant variations in flow volume and direction.
2. Offshore Systems are usually longer distance pipeline systems that use the diameter difference to overcome pressure variations, or export lines that feed into main trunk lines with larger diameters. Important challenges in these cases are, among others, high pressures, e.g. due to deep water location, gas velocities, challenging installations, and high wall thickness.
Both areas require an individual approach to tackle the contradictory challenges these pipelines pose. For example, in situations where high pressure may be aiding a continuous flow, we require a tool technology and design that can withstand pressures up to 7500 PSI or more. Conversely, low pressure will not affect the tool itself, but will have a deteriorating effect on the run behavior and therefore will require a completely different approach to reducing friction between ILI tool and inner pipe wall.
In its over 30 years of serving the Oil & Gas industry, ROSEN has developed a multitude of solutions resulting in the largest tool fleet on the market, virtually covering the entire range of multi-diameter pipelines. This paper will present case studies to highlight some of the significant achievements that have been made in this area over the years.
The usual practice when assessing the integrity of a cracked structure is to idealize the crack as an ellipse if buried or a semi-ellipse if surface breaking. The length of this idealized crack is established as the overall length reported by the inspection and the through-wall height as the maximum height reported anywhere along the length of the crack. This approach is simple and expected to be conservative. It is the approach of codified assessment methods such as BS 7910 and API 579.
Inline inspection technology for steel transmission pipelines has developed to the point where vendors can now report the actual profile of an axial crack. While simple screening assessments will continue to use the maximum height and length, modelling of the actual crack profile is now possible for critical cases. This may remove excessive conservatism from the assessment, thus avoiding unnecessary shutdowns or repairs.
This paper presents results from a study in which finite element analysis (FEA) has been used to model a series of actual crack profiles found by inline inspection, and derive stress intensity factors. The stress intensity factors calculated for these profiles have been compared to the stress intensity factors calculated using “handbook” stress intensity factor solutions based on both the total length and maximum height of the cracks, and an effective-area-type approach to assess sub-profiles within the full crack profile.
The study showed that, for some of the actual crack profles, the maximum stress intensity factor values found anywhere along the crack were approximately half as high as those derived from “handbook” stress intensity factor solutions, indicating a potentially large conservatism in the codified methods, where failure is dominated by fracture.
However, it was noted that, for some of the crack profiles, locally high values of stress intensity factor were obtained at re-entrant regions in the crack profile, which are not captured by the common approach of calculating stress intensity factor based on an idealized semi-ellipse shape and the total length and maximum depth of the crack profile. It was therefore not possible to draw a general conclusion about the benefit of calculating stress intensity factor based on the actual crack profile.
Dents reported by inline inspection (ILI) with associated metal loss pose a challenge for operators. Current regulations addressing dents with metal loss target gouging resulting from mechanical damage. Dents associated with gouging are particularly challenging to assess without excavations due to uncertainties in the shape of the gouge and the potential for cracking. However, many pipelines contain dents interacting with mild corrosion, which can be assessed to determine their acceptability without the need to conduct expensive excavations. This paper presents a case study demonstrating how a remaining life analysis can be used to assess a bottom side dent interacting with corrosion. The process begins with an expert review of the ILI signals to confirm the nature of the metal loss features, followed by multiple finite element analyses that address the burst pressure and remaining life of a dent interacting with metal loss. The assessment examines the impact of restraint on the remaining life of the dent, and reviews the different methodologies that can be used to assess dents interacting with corrosion, including approaches based on typical S-N curves and fracture mechanics. The paper concludes by providing guidance to operators for assessing bottom side dents interacting with corrosion.Close
It is now widely accepted that operational pigging is a key operational and maintenance activity for maintaining production efficiency in pipelines. Although the removal of unwanted liquids from a pipeline is necessary, this in turn creates its own operational problems. The management of this unwanted liquid is a critical stalling point at many receiving and processing facilities, and understanding the chain of events leading up to the receipt of the cleaning tool is crucial.
It was expected that during cleaning of a 36” trunk line, large liquid volumes would be generated. If this liquid was allowed to flow without restriction, it would arrive onshore at a rate that would overload the slug catcher. A flow assurance study was required to estimate the amount of liquid expected at the slug catcher in order to ensure a continuous gas supply to downstream users. The analysis was carried out on selected sensitivity studies based on flowrate, venting control at tool receiver, tool properties e.g. bypass, etc. to recommend the desired procedure and ensure a successful cleaning run.
In the current work, a comparison between the modelled behavior and predictions generated by the OLGA® multiphase flow model was compared against actual field data upon receipt of the cleaning tool.