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Price A.,Dominion | Alvarez L.A.,University of Essex | Whitby C.,University of Essex | Larsen J.,Maersk Olie og Gas AS
NACE - International Corrosion Conference Series | Year: 2010

Molecular biological methods have been used for some years to identify and quantify active microorganisms present in a commercial oil reservoir where biogenic sulfide production is routinely controlled by nitrate injection. In order to gain a more complete understanding of the effects of nitrate injection on the activity of sulfate reducing prokaryotes (SRP, (which encompasses sulfate reducing Bacteria (SRB)) and sulfate reducing Archaea (SRA)), the mRNA for dsrA present in produced water samples was quantified by reverse transcription quantitative PCR (RT-qPCR); mRNA for dsrA should only be produced by SRP actively reducing sulfate. The aims of this study were: to help further our understanding on the mode of action of nitrate on SRP activity e.g. competitive inhibition by nitrate utilising Bacteria (NUB), nitrite toxicity, change in reduction-oxidation potential or a metabolism switch from sulfate to nitrate reduction, and; to provide a rapid monitoring tool for SRP activity. Since messenger RNA is known to be unstable and is rapidly processed within cells, the first task was to design a laboratory experiment to demonstrate that mRNA for dsrA could be detected and quantified in produced water samples. Produced water samples were spiked with a SRP culture grown from the produced water sample and the mRNA for dsrA was successfully detected and quantified. For the field study, fresh produced water samples were obtained from two wells where direct seawater and nitrate breakthrough has occurred. DAPI, FISH & RT-qPCR analyses were performed directly on the water samples. This paper describes the use of RT-qPCR and detection of mRNA for dsrA as a tool for monitoring SRP activity in biogenic sulfide-producing reservoirs. In order to gain an understanding of the SRB sulfidogenesis activity, a combination of quantifying SRB numbers by FISH, and quantification of the levels of dsrA mRNA, in order to calculate the number of dsrA transcripts per cell is required. The technique has the potential to ascertain the effects of nitrate injection on SRP populations, for instance, in the case of Desulfovibrio; do species of this bacterium preferentially reduce nitrate rather than sulfate? The technique may also be used to determine the recovery of SRP activity following nitrate or biocide dosing. ©2010 by NACE International.


Price A.,Oil Plus Ltd. | Alvarez L.A.,University of Essex | Whitby C.,University of Essex | Larsen J.,Maersk Olie Og Gas AS
NACE - International Corrosion Conference Series | Year: 2010

Molecular biological methods have been used for some years to identify and quantify active microorganisms present in a commercial oil reservoir where biogenic sulfide production is routinely controlled by nitrate injection. In order to gain a more complete understanding of the effects of nitrate injection on the activity of sulfate reducing prokaryotes (SRP, (which encompasses sulfate reducing Bacteria (SRB)) and sulfate reducing Archaea (SRA)), the mRNA for dsrA present in produced water samples was quantified by reverse transcription quantitative PCR (RT-qPCR); mRNA for dsrA should only be produced by SRP actively reducing sulfate. The aims of this study were: to help further ourunderstanding on the mode of action of nitrate on SRP activity e.g. competitive inhibition by nitrate utilising Bacteria (NUB), nitrite toxicity, change in reduction-oxidation potential or a metabolism switch from sulfate to nitrate reduction, and; to provide a rapid monitoring tool for SRP activity. Since messenger RNA is known to be unstable and is rapidly processed within cells, the first task was to design a laboratory experiment to demonstrate that mRNA for dsrA could be detected and quantified in produced water samples. Produced water samples were spiked with a SRP culture grown from the produced water sample and the mRNA for dsrA was successfully detected and quantified. For the field study, fresh produced water samples were obtained from two wells where direct seawater and nitrate breakthrough has occurred. DAPI, FISH & RT-qPCR analyses were performed directly on the water samples. This paper describes the use of RT-qPCR and detection of mRNA for dsrA as a tool for monitoring SRP activity in biogenic sulfide-producing reservoirs. In order to gain an understanding of the SRB sulfidogenesis activity, a combination of quantifying SRB numbers by FISH, and quantification of the levels of dsrA mRNA, in order to calculate the number of dsrA transcripts per cell is required. The technique has the potential to ascertain the effects of nitrate injection on SRP populations, for instance, in the case of Desulfovibrio; do species of this bacterium preferentially reduce nitrate rather than sulfate? The technique may also be used to determine the recovery of SRP activity following nitrate or biocide dosing. © 2010 by NACE International.


Quirk D.G.,Maersk Olie og Gas AS | Schodt N.,Maersk Olie og Gas AS | Lassen B.,Maersk Olie og Gas AS | Ings S.J.,Dalhousie University | And 3 more authors.
Geological Society Special Publication | Year: 2012

Salt flows downslope, irrespective of overburden. In salt basins on passive margins, the salt will tilt and flow towards the ocean immediately after continental rifting has ended due to thermal subsidence. Using real examples, as well as physical and numerical models, tilting is shown to be relatively rapid, enhanced by isostatic rebound updip and loading downdip where salt pools and inflates behind an outer high. In the Santos, Campos and Kwanza basins, this outer high is represented by an embryonic mid-Atlantic ridge, amplified in height by the differential weight of the inflating salt. Widespread extension and translation of overburden, utilizing both seaward- and landward-dipping normal faults, characterizes the early evolution of the inboard region. Inflation and contraction occur outboard, the effects of which tend to expand in a landward direction over time. Rapid accumulation of salt implies wholesale dewatering of pre-salt sediments, the water possibly permeating the salt once it has reached a burial depth of c. 3 km. The process of thermal subsidence, salt drainage and isostatic amplification is an efficient mechanism for moving sediment on passive margins tens of kilometres seaward during a relatively short period and helps explain why great thicknesses of salt can accumulate there in the first place. © The Geological Society of London 2012.


Grant
Agency: Cordis | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2012-ITN | Award Amount: 3.90M | Year: 2013

The CO2-REACT ITN has been created to address twin objectives: (1) to provide urgently needed training in CO2 storage preparing candidates for critical roles in the coming years and (2) to significantly advance our understanding of the fate and consequences of CO2 injection into the subsurface during carbon storage efforts. The CO2-REACT ITN addresses these objectives through a balanced combination of 6 academic and 6 industrial teams. The academic partners have been selected for their unique and diverse expertise in the reactivity of carbonate phases at scales ranging from the atomic to the field scale. The six industry partners were selected to represent a spectrum of the largest stakeholders in CO2 storage. By formally joining these teams, we are creating a training/research platform that is unique in the world in its ability to understand the fate and consequences of CO2 injected into subsurface reservoirs using an impressive array of experimental and modeling techniques. CO2-REACT aims to train 13 ESRs and 1 ER, through an integrated and coherent set of research and training activities that will significantly improve our understanding of the consequences of injecting CO2 into the subsurface. We chose this technical focus because: (1) new knowledge is essential for solving a critical societal problem, (2) the problem is interdisciplinary, requiring input from chemistry, geology, physics, chemistry, hydrology and engineering, (3) producing solutions that industry can implement will promote tight academia-industry collaboration, a true plus for the trainees and and 4) by focusing on a single theme, close interaction and collaboration among the CO2-REACT teams is fostered. An additional societal objective of CO2-REACT is help to raise public awareness to the needs, challenges and safety issues in subsurface CO2 storage through public outreach efforts.


Grant
Agency: Cordis | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2011-ITN | Award Amount: 3.80M | Year: 2012

The MINSC Initial Training Network (ITN) is comprised of partners from first-rate universities and high-level industrial partners located in the United Kingdom, France, Denmark, Iceland, Germany, Norway, and Italy. The prime aims of this network is to provide research and training opportunities to a new generation of young fellows in fundamental and collaborative research projects related to the nucleation and growth of a series of relevant scale mineral systems in the absence or presence of inhibitors agents. The training will combine molecular level research with studies linked to clear industrial processes at the field-level. The ultimate goal is to better understand one of the highly relevant problems in oil, geothermal and food industrial processes: pipe clogging and surface corrosion by mineral scale precipitates during production. To achieve this, the network will combine training of early stage and experienced researchers in state-of-the-art techniques of mineral formation and characterization both in laboratory and industrial settings with research objectives that aim at quantifying the nucleation and growth of several mineral systems: carbonates, sulphates/sulphides, oxalates and silicates. Scaling can often be retarded via inhibitors but their role in affecting rates of formation of these minerals in solution, on surfaces as well as in real-world industrial settings (i.e., pipes, cores etc.) are unknown. We will determine these rates in laboratory experiments and implement and test these novel findings directly in industrial power plant systems. The prime industrially-driven science goal is twofold (a) to better understand what leads to the precipitation of a series of mineral scales causing a massive decrease in efficiency and increased cost for industrial processes (i.e., oil and gas production, geothermal energy, beer) and (b) to develop processes/inhibitors that can help mitigate and / or prevent scale formation in such environments.


Skovhus T.L.,Danish Technological Institute DTI | Holmkvist L.,Danish Technological Institute DTI | Andersen K.,Maersk Olie og Gas AS | Pedersen H.,Maersk Olie og Gas AS | Larsen J.,Maersk Olie og Gas AS
Society of Petroleum Engineers - SPE International Conference and Exhibition on Oilfield Corrosion 2012 | Year: 2012

Monitoring of Microbiologically Influenced Corrosion (MIC) in the oil industry has in the past been conducted mainly on sulfate-reducing bacteria (SRB) using cultivation based techniques. However, with the introduction of novel DNA-based methods for enumeration of microbes, more accurate and fast methods are now available which offer better determination of MIC on a routine basis. The content of produced water in the Halfdan oil system during production is relatively low (BS&W < 1-2%) and MIC has for this reason not been considered to be a threat to the system integrity. Initial results from wall thickness inspection of oil export spools have indicated on-going corrosion. As a consequence, spools have been replaced, enabling sampling of cut-out sections of the spools. These cut-out sections have been sent onshore to DTI Oil & Gas for further investigation of general corrosion, MIC and scale composition. The investigation demonstrated that the analysed Halfdan oil export spool sections were highly corroded. This conclusion was based on visual inspection of the metal surfaces of the cut-out sections that revealed presence of under-deposit and pitting corrosion underneath thick layers of solid scale material. In support of the visual indications of corrosion, it was demonstrated that MIC related microorganisms were present in the solids in close contact with the metal surface together with corrosion products. In particular, high numbers of the hydrogen consuming methanogens (10 8-10 9 cells g -1) were situated in the scale directly in contact with the carbon steel pipe wall. These important findings could only be achieved when results obtained from X-Ray analysis (WDXRF) and visual inspections of the oil export spools were combined with DNA-based enumeration methods (qPCR). Based on the obtained results, this paper discusses how microbial numbers obtained from DNA-based enumeration methods are evaluated and interpreted in the best way with respect to general risk assessment and system integrity measures of aging offshore assets in the Danish Sector of the North Sea. Copyright 2012, Society of Petroleum Engineers.


Skovhus T.L.,Danish Technological Institute DTI | Sorensen K.B.,Danish Technological Institute DTI | Larsen J.,Maersk Olie Og Gas AS | Rasmussen K.,Maersk Olie Og Gas AS | Jensen M.,Maersk Olie Og Gas AS
Society of Petroleum Engineers - 5th SPE International Conference on Oilfield Corrosion 2010 | Year: 2010

The use of culture-based microbiological methods is slow and can only measure the few sulfate-reducing Bacteria (SRB) that can be cultivated. Faster and more accurate techniques for the diagnostics of microbiologically influenced corrosion (MIC) are therefore required. This paper demonstrates the benefits of applying state-of-the-art molecular microbiology methods (MMM) to the identification and quantification of the microorganisms contributing to corrosion in oil production facilities. For quantification of troublesome microorganisms MMM can be applied directly to solid samples from the oil field without the need for culture media. The corrosion mechanism was investigated in two different cases: (i) a piece of piping with high corrosion rates from the water outlet of a separator from the Halfdan oil field, and (ii) a similar piece of piping from the Dan oil field with much lower rates of corrosion. The chemical distribution of elements was analysed using X-ray diffraction and the levels of MIC causing microorganisms were determined with qPCR (a DNA-based quantification method). The results showed that corrosion in the piping from Halfdan was caused by MIC. The results also showed that not only SRB were involved in the observed MIC. High numbers of sulfate-reducing prokaryotes (SRP) and methanogens were measured in material from the Halfdan separator with high corrosion rates. The methanogens were particular abundant close to the metal/scale interface. The data indicates that the high level of microorganisms in the Halfdan separator speeds up the corrosion process by efficiently consuming hydrogen released during dissolution of iron. Finally, the paper discusses the strength of applying qPCR as a standardized, high-throughput routine monitoring tool for MIC diagnostics when developing more reliable integrity management programs in the future. This study has shown that the improved molecular microbiological approach to MIC is important when designing and testing remedial actions towards MIC in oil field systems. Copyright 2010, Society of Petroleum Engineers.


Quirk D.G.,Maersk Olie og Gas AS | Pilcher R.S.,Hess Corporation
Geological Society Special Publication | Year: 2012

This paper describes a common type of salt wall found in extensional regimes which possess the characteristics: cover strata truncated against both flanks; an asymmetric appearance in cross-section caused by normal fault-related growth patterns; and at least one unconformity and onlap surface separating strata which are tilted in opposite directions. This type of structure evolves by a process known as flip-flop salt tectonics starting with a roller where a normal fault detaches down one flank of the embryonic salt body. The structure grows as salt flows towards the low-stress zone below the crest of the footwall causing it to swell and tilt backwards until it becomes gravitationally unstable, until the cover strata on one or both sides welds out or until the salt emerges at surface. Further growth is then accommodated by switching to a new counter-dipping fault that detaches on the opposite flank of the salt body leading to a flip in hanging-wall/footwall polarity marked by an unconformity and onlap surface. The salt body continues to grow beneath the new footwall, causing partial inversion of the old hanging wall. Additional switches may occur, leading to tall flip-flop structures until the source of salt is depleted. © The Geological Society of London 2012.


Maystrenko Y.P.,Helmholtz Center Potsdam | Maystrenko Y.P.,Geological Survey of Norway | Scheck-Wenderoth M.,Helmholtz Center Potsdam | Hartwig A.,Helmholtz Center Potsdam | And 4 more authors.
Tectonophysics | Year: 2013

To understand the structure of the Southwest African continental margin, a lithosphere-scale 3D structural model has been developed, covering the marginal Cretaceous-Cenozoic Orange, Luderitz, Walvis and Namibe basins, the easternmost Walvis Ridge offshore. Onshore, the model includes two late-Proterozoic Owambo (Etosha) and Nama basins. This 3D model integrates published thickness maps (sediment isopach maps), shallow seismic and well data as well as published deep seismic information and has been additionally constrained by 3D gravity and thermal modelling. Using 3D gravity modelling, the first order configuration of the crystalline crust has been resolved with respect to the location of the continent-ocean boundary. The distribution of a high-density lower crustal layer indicates a continuous body extending below the Cretaceous-Cenozoic depocentres and aligned parallel to the coast line. In addition, high-density zones within the continental crystalline crust had to be included in the model to fit observed and calculated gravity. The obtained Moho topography correlates with the major tectonic units of this continental margin. The results of the 3D thermal modelling indicate that there is a clear relationship between the location of thickened sediments and areas with increased temperatures within the upper 10. km of the 3D model. This indicates that the low thermal conductivity of the sediments increases heat storage within the areas covered by thick sediments. Within the deeper crust, the main feature of the temperature distribution is the transition across the continental margin from the relatively cold oceanic part to the warm continental one. This regional pattern is controlled by the thickness of the crystalline continental crust, which is characterized by an increased radiogenic heat production. At a depth of 80-90. km, the temperature becomes higher beneath the oceanic domain than beneath the continent, reflecting the configuration of the lower thermal boundary which is represented by an isothermal lithosphere-asthenosphere boundary. © 2013 Elsevier B.V.


Anka Z.,Helmholtz Center Potsdam | Ondrak R.,Helmholtz Center Potsdam | Kowitz A.,Helmholtz Center Potsdam | Schodt N.,Maersk Olie og Gas AS
Tectonophysics | Year: 2013

We present a combined approach of interpretation of 2D seismic-reflection data and numerical modelling of hydrocarbon generation and migration across the southern slope of the Lower Congo Basin, in order to investigate the factors controlling timing and distribution of hydrocarbon leakage in this area. We identified three main families of past and present-day leakage features: (1) Mid-Upper Miocene seismic chimneys concentrated basinwards and ending up on buried pockmarks, (2) Plio-Pleistocene chimneys, rather clustered to the east of the study area and ending up in seafloor pockmarks, and (3) fewer scattered chimneys identified within the Miocene sequences ending up in shallow enhanced reflectors ("Flat spots"). Stratigraphic and structural elements seem to control the distribution of these features. At least two major events of leakage occurred during the Middle-Late Miocene and intermittently during the Pliocene-Present. External factors as sediment supply are associated to the Miocene leakage event, whilst internal structural elements probably triggered the Pliocene to present-day leakage. A major seabed morphological feature, represented by a margin-paralleled belt of more than 1-km-wide mounds, was identified above growth faults to the east of the study area. Data-constrained 2D HC generation and migration modelling suggests a genetic link between these structures and vertical migration/leakage of thermogenic methane sourced from either currently mature Oligo-Miocene source rocks or secondary cracking and further expulsion from over-mature Upper-Cretaceous source rocks. Hence, the mounds are likely to represent a lineation of methane-derived carbonate build-ups. Despite the natural limitations of a 2D migration model, when combined and calibrated with observations from seismic data, it can be used as a valid tool to assess petroleum migration routes in sedimentary basins. To the best of our knowledge, this is the first integrated approach combining both seismic observations and numerical modelling carried out in the Angola basin. © 2012 Elsevier B.V.

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