DNV GL Oil and Gas

Groningen, Netherlands

DNV GL Oil and Gas

Groningen, Netherlands
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Jansen S.,Deltares | Van Burgel M.,DNV GL Oil and Gas | Gerritse J.,Deltares | Buchler M.,Swiss Society for Corrosion Protection
NACE - International Corrosion Conference Series | Year: 2017

Uncertainties are present about the mechanisms of cathodic protection (CP) and its effectiveness to limit or completely stop Microbiologically Influenced Corrosion (MIC). The goal of this research was to improve the understanding of the mechanisms of CP by determining the interactions between corrosion and local chemical parameters, such as pH, under varying CP conditions, both in the absence and presence of MIC. Electrical resistance (ER) probes, covered with a biofilm of sulphate-reducing microorganisms, were subjected to a series of CP potentials. In some cases MIC could not be stopped by CP, even at very negative potentials. The application of CP potentials resulted in an increase of the pH near the steel surface. In the absence of a biofilm CP could raise the pH above 13, whereas the pH remained below 8 in the presence of an active MIC biofilm. These findings show that MIC biofilms can reduce the effectiveness of CP by maintaining a mild pH, supporting their activity. Once biofilms have established, it may be very hard or even impossible to stop MIC with CP, irrespective of the potential applied. This suggests that CP strategies should be aimed at preventing MIC biofilms to develop from the start. © 2017 by NACE International.

Helgaker J.F.,DNV GL Oil and Gas | IJzermans S.,Woodside Energy | Landheim T.J.,DNV GL Oil and Gas | Eeg T.B.,DNV GL Oil and Gas | And 2 more authors.
SPE Journal | Year: 2017

Unbonded flexible pipelines are commonly used in offshore field developments to transport oil and gas to production facilities. Sand is an inevitable byproduct from oil-and-gas production. Sand erosion has become an important concern for both design of new field developments and prolongation of existing oil-and-gas fields, especially for fields with low mixture density and high velocities. Erosion in smooth pipes can be determined with industry-standard erosion-prediction methodologies. However, these models are usually valid for smooth pipes only, with limited information available on erosion in flexible pipes. This paper presents experimental results from a large-scale erosion test of an unbonded flexible pipe. A 9.75-in. inner-diameter (ID) flexible pipe with a bending radius of 2.5m was exposed to sand and proppant particles at velocities ranging from 30 to 47 m/s. Erosion was determined by performing weight-loss measurements at selected cut-out windows, at 0, 20, 40, 60, and 80° along the outer periphery of the carcass. In addition, microscopy analysis was performed on selected eroded carcass pieces to determine the localized erosion contour of the flexible carcass geometry. Results show that the highest erosion is found at the leading edge of the carcass strip. Experimental results are compared with computational-fluid-dynamics (CFD) simulations and industry-standard erosion-prediction methodologies. Copyright © 2017 Society of Petroleum Engineers.

Gersen S.,DNV GL Oil and Gas | van Essen M.,DNV GL Oil and Gas | van Dijk G.,DNV GL Oil and Gas | Levinsky H.,University of Groningen
Combustion and Flame | Year: 2014

The physicochemical origins of how changes in fuel composition affect autoignition of the end gas, leading to engine knock, are analyzed for a natural gas engine. Experiments in a lean-burn, high-speed medium-BMEP gas engine are performed using a reference natural gas with systematically varied fractions of admixed ethane, propane and hydrogen. Thermodynamic analysis of the measured non-knocking pressure histories shows that, in addition to the expected changes arising from changes in the heat capacity of the mixture, changes in the combustion duration relative to the compression cycle (the combustion "phasing") caused by variations in burning velocity dominate the effects of fuel composition on the temperature (and pressure) of the end gas. Thus, despite the increase in the heat capacity of the fuel-air mixture with addition of ethane and propane, the change in combustion phasing is actually seen to increase the maximum end-gas temperature slightly for these fuel components. By the same token, the substantial change in combustion duration upon hydrogen addition strongly increases the end-gas temperature, beyond that caused by the decrease in mixture heat capacity. The impact of these variations in in-cylinder conditions on the knock tendency of the fuel have been assessed using autoignition delay times computed using SENKIN and a detailed chemical mechanism for the end gas under the conditions extant in the engine. The results show that the ignition-promoting effect of hydrogen is mainly the result of the increase in end-gas temperature and pressure, while addition of ethane and propane promotes ignition primarily by changing the chemical autoignition behavior of the fuel itself. Comparison of the computed end-gas autoignition delay time, based on the complete measured pressure history of each gas, with the measured Knock-Limited Spark Timing shows that the computed delay time accurately reflects the measured knock tendency of the fuels. © 2014 The Combustion Institute.

Ahmad M.,DNV GL Oil and Gas | Gersen S.,DNV GL Oil and Gas
Energy Procedia | Year: 2014

The capture of CO2 from power plants and other large industrial sources is offering a main solution to reduce CO2 emissions. The captured mixture will contain impurities like nitrogen, argon, oxygen, water and some toxic elements like sulfur and nitrogen oxides, the types and quantities of which depend on the type of fuel and the capture process. The presence of free water formation in the transportation pipeline causes severe corrosion problems, flow assurance failure and might damage valves and instrumentations. In the presence of free water, CO2 dissolves in the aqueous phase and will partly ionize to form a weak acid. Thus, free water formation should be avoided. This work aims to investigate the solubility of water in CO2 mixtures under pipeline operation conditions in the temperature range of (5 - 35 °C) and the pressure range of (90 - 150 bar). A test set up was constructed, which consists of a high pressure reactor in which a CO2 mixture containing water at initial soluble conditions was prepared. The purpose of this study is to identify the maximum water content level which could be allowed in CO2 transportation pipelines. The experimental data generated were then compared to the calculations of two mixture models: The GERG-2008 model and the EOS-CG model. © 2014 The Authors Published by Elsevier Ltd.

Brown J.,DNV GL | Holt H.,DNV GL Oil and Gas | Helle K.,DNV GL
Energy Procedia | Year: 2014

The second phase of the CO2PIPETRANS Joint Industry Project (JIP) aims to fill knowledge gaps associated with the safe and reliable pipeline transport of CO2. The JIP has three main focus areas and technical work packages designed to address these. The work packages collect experimental data and experience on dense phase CO2 release model validation data, pipeline fracture arrest, and corrosion. This paper presents an overview of results and conclusions from the work package focusing on collection of data for validation of release models. The JIP consists of 15 partner organisations, who are: Arcelor Mittal, BP, DNV GL, Endesa, ENI, E.on Ruhrgas, Gassco, Gassnova, Health and Safety Executive (HSE) UK, Maersk Oil, Petrobras, Petroleum Safety Authority (PSA) Norway, Shell, V&M Tubes, and Vattenfall. The objective of the CO2 release model validation data work package was to collect and make available data for validating release and dispersion models for dense phase CO2. This involved releasing dense phase CO2 from large inventories through orifices ranging in size 6mm to 150mm onto a suitably sized array of instruments to measure the CO2 concentration and temperature profiles. The condition of the CO2 being released was up to 150 barg and 150°C with release durations up to 10 minutes. Most of the releases were in a horizontal orientation 1m above the ground but during some of the tests the orientation was changed to be upwards, downwards to impact the ground, or into an enclosure. In addition to the CO2 releases described above, the work package also undertook rapid depressurisation of a long horizontal pipe containing 100 barg CO2 in order to collect data, amongst other aspects, on shock wave propagation. These experiments used a 200m long, 50mm diameter pipe mounted on load cells with an orifice plate and explosive initiated bursting disk at one end. In addition to measuring data within the pipe during the rapid depressurisation tests, dispersion and temperature data was also recorded downstream of the release for release model validation purposes. The paper presents an overview of the frontier experimental work mentioned above along with discussion on the output of the data review that was subsequently completed during which recorded data was compared with model predictions. Validation of dispersion models and safety studies reduces the uncertainty and hence conservatism required in these studies thereby making design and implementation of CO2 pipelines safer and more cost effective. © 2014 The Authors Published by Elsevier Ltd.

Ellingsen H.P.,DNV GL Oil and Gas | Shin H.C.,DNV GL Oil and Gas
RINA, Royal Institution of Naval Architects - ICSOT Korea: Safety of Offshore and Subsea Structures in Extreme and Accidental Conditions 2015, Papers | Year: 2015

This paper discusses DNV GL's key observations with regards to critical success factors and pitfalls in offshore oil & gas projects built in Korea. DNV GL has in close dialogue with the industry and people involved in ongoing projects looked into causes for delays and prepared initiatives and suggestions to improve efficiency and reduce project risk in offshore Oil & Gas projects. As a result, a JIP was initiated to establish a new international industry standard for offshore oil and gas projects. The importance of standardization and the initial results of the ongoing Offshore Standardization JIP will be presented and discussed. © 2015: The Royal Institution of Naval Architects.

Ramirez J.E.,DNV GL Oil and Gas | Taylor C.D.,DNV GL Oil and Gas
Advanced Materials and Processes | Year: 2014

Corrosion is commonly defined as the deterioration of a material or its properties because of a reaction with its environment. It is a natural process due to a high energy state induced in metals and alloys during refining, processing, and manufacturing. Corrosion can cause dangerous and expensive damage and failures of everything from pipelines, bridges, and public buildings to vehicles, ships, and airplanes, and from water and wastewater systems to medical implants, communication systems, and electronic devices. However, there are well established methods to prevent and control corrosion that can reduce or eliminate its impact on public safety the economy, and the environment. The same is true of gas fields that are highly corrosive. Reliable materials for deep well construction must have high strength and corrosion resistance at high temperatures to avoid potential failures.

Yang K.W.,DNV GL Oil and Gas
RINA, Royal Institution of Naval Architects - ICSOT Korea: Safety of Offshore and Subsea Structures in Extreme and Accidental Conditions 2015, Papers | Year: 2015

According to the Petroleum Safety Authority Norway (PSA) regulations, risk and working environment analyses shall be carried out to manage major accidents, environmental and other risk, to ensure a sound working environment and to provide support for decision making related to design, construction and operation phases of offshore facilities operated on the Norwegian Continental Shelf (NCS). Due to strict requirements for the risk and working environment analyses in NORSOK standards referred to in the PSA regulations and lack of experience of users, there have been challenges on implementing the analyses and utilizing the results of the analyses. This paper will provide an introduction to implementation and application of the risk and working environment analyses for offshore facilities on the NCS based on the PSA regulations and NORSOK standards. © 2015: The Royal Institution of Naval Architects.

Hashemi H.,Technical University of Denmark | Christensen J.M.,Technical University of Denmark | Gersen S.,DNV GL Oil and Gas | Glarborg P.,Technical University of Denmark
Proceedings of the Combustion Institute | Year: 2015

Hydrogen oxidation at 50 bar and temperatures of 700-900 K was investigated in a high pressure laminar flow reactor under highly diluted conditions. The experiments provided information about H2 oxidation at pressures above the third explosion limit. The fuel-air equivalence ratio of the reactants was varied from very oxidizing to strongly reducing conditions. The results supplement high-pressure data from RCM (900-1100 K) and shock tubes (900-2200 K). At the reducing conditions (Φ = 12), oxidation started at 748-775 K while it was shifted to 798-823 K for stoichiometric and oxidizing conditions (Φ = 1.03 and 0.05). At very oxidizing conditions (O2 atmosphere, Φ = 0.0009), the temperature for onset of reaction was reduced to 775-798 K. The data were interpreted in terms of a detailed chemical kinetic model, drawn mostly from work of Burke and coworkers. In the present study, the rate constants for the reactions HO2 + OH, OH + OH, and HO2 + HO2 were updated based on recent determinations. The modeling predictions were in good agreement with the measurements in the flow reactor. The predicted H2 oxidation rate was sensitive to the rate of the HO2 + OH reaction, particularly at lean conditions, and the present data support recent values for the rate constant. In addition to the current experiments, the mechanism was evaluated against ignition delay time measurements from rapid compression machines and shock tubes. The model was used to analyze the complex dependence of the ignition delay for H2 on temperature and pressure. © 2014 The Combustion Institute.

Laughton A.,DNV GL Oil and Gas
Proceedings of the American Gas Association, Operating Section | Year: 2015

This paper describes how to use the GERG-2008 equation of state (ISO 20765 parts 2 & 3) to calculate the hydrocarbon dew point of natural gas mixtures.

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