Ann Elisabeth Albright Blomberg

• Waarum, Ivar-Kristian; Blomberg, Ann Elisabeth Albright; Eek, Espen; Brown, Jock; Ulfsnes, Amund; Carpenter, Mike; Grimsrud, Torleiv S.; Park, Joonsang; Cornelissen, Gerard & Sparrevik, Per (2017). CCS Leakage Detection Technology - Industry Needs, Government Regulations, and Sensor Performance. Energy Procedia.  ISSN 1876-6102.  114, s 3613- 3627 . doi: 10.1016/j.egypro.2017.03.1493 Fulltekst i vitenarkiv. Vis sammendrag

  Reliable CCS monitoring is vital in order to confirm that injected CO2 stays in the reservoir as intended, and that any occurring leakage is promptly detected allowing corrective actions to be initiated. Motivations for implementing monitoring strategies beyond the legal minimum required by government regulations, can be divided into economic, environmental and reputational factors, where the latter is significant; adequate monitoring is important for attaining public acceptance. CCS monitoring methods can be divided into deep focused (reservoir, overburden) and shallow focused (seabed, water column) methods. Shallow monitoring methods include acoustic and chemical sensors placed in the water column. For the CCS application, these sensor technologies are complementary; acoustic sensors are sensitive to CO2 in gas phase and chemical sensors can detect water-dissolved CO2 or formation fluids. We discuss the motivations for CCS monitoring, and offer a structured overview of acoustic and chemical technologies for CCS monitoring at the seabed and in the water column. Each technology is evaluated in terms of its applicability to CCS monitoring, highlighting its strengths and limitations for detection, quantification and characterization of CCS related leakage. We conclude that while state of the art sensor technology is sufficient to meet government requirements, there is potential for improved integrated monitoring through optimal use and combination of technologies. The concept of integrated monitoring where different sensor types measure different parameters is emerging as a promising monitoring strategy.

• Blomberg, Ann Elisabeth Albright; Sæbø, Torstein Olsmo; Hansen, Roy Edgar; Pedersen, Rolf B. & Austeng, Andreas (2016). Automatic detection of marine gas seeps using an interferometric sidescan sonar. IEEE Journal of Oceanic Engineering.  ISSN 0364-9059.  PP(99) . doi: 10.1109/JOE.2016.2592559
• Blomberg, Ann Elisabeth Albright; Austeng, Andreas; Hansen, Roy Edgar & Synnes, Stig Asle Vaksvik (2013). Improving Sonar Performance in Shallow Water Using Adaptive Beamforming. IEEE Journal of Oceanic Engineering.  ISSN 0364-9059.  38(2), s 297- 307 . doi: 10.1109/JOE.2012.2226643
• Blomberg, Ann Elisabeth Albright; Nilsen, Carl-Inge Colombo; Austeng, Andreas & Hansen, Roy Edgar (2013). Adaptive sonar imaging using aperture coherence. IEEE Journal of Oceanic Engineering.  ISSN 0364-9059.  38(1), s 98- 108 . doi: 10.1109/JOE.2012.2210295
• Blomberg, Ann Elisabeth Albright; Austeng, Andreas & Hansen, Roy Edgar (2012). Adaptive beamforming applied to a cylindrical sonar array using an interpolated array transformation. IEEE Journal of Oceanic Engineering.  ISSN 0364-9059.  37(1), s 25- 34 . doi: 10.1109/JOE.2011.2169611
• Blomberg, Ann Elisabeth Albright; Nilsen, Carl-Inge Colombo; Sæbø, Torstein Olsmo; Hansen, Roy Edgar & Austeng, Andreas (2012). Detecting and Localizing Gas Seeps at the Seafloor Using an Interferometric Sidescan Sonar, In  11th European Conference on Underwater Acoustics 2012 (ECUA 2012).  Curran Associates, Inc..  ISBN 978-1-62276-192-0.  Vol 1.  s 597 - 604

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• Blomberg, Ann Elisabeth Albright; Austeng, Andreas; Hansen, Roy Edgar & Pedersen, Rolf B. (2014). Alternative SAS processing for gas seep detection.
• Pedersen, Rolf B.; Blomberg, Ann Elisabeth Albright; Landschulze, Karin; Baumberger, Tamara; Økland, Ingeborg Elisabet; Reigstad, Laila Johanne; Gracias, Nuno; Mørkved, Pål Tore; Thorseth, Ingunn Hindenes; Cevatoglu, Melis; James, Rachael & Häckel, Matthias (2014). The Hugin Fracture.
• Austeng, Andreas; Blomberg, Ann Elisabeth Albright & Hansen, Roy Edgar (2013). Aperture Coherence in Active Sonar Image Enhancement: A Review.
• Pedersen, Rolf B.; Blomberg, Ann Elisabeth Albright; Landschulze, Karin; Baumberger, Tamara; Økland, Ingeborg Elisabet; Reigstad, Laila Johanne; Gracias, Nuno; Mørkved, Pål Tore & Thorseth, Ingunn Hindenes (2013). Discovery of a 3 km long seafloor fracture system in the Central North Sea. Vis sammendrag

  We have discovered a 3 km long seafloor fracture system in the Central North Sea (block 16/4). The discovery was made using a synthetic aperture sonar (HISAS) mounted on a Kongsberg Hugin AUV. The surface expression of the structure – named the Hugin Fracture - changes along the strike and it is characterized by: 1) linear; 2) en echelon; and 3) branching segments. Ring-structures, that typically are 5-10 meters across, are common along the feature. Micro-bathymetry acquired using the HISAS system demonstrates that sub-meter scale elevation changes occur across the fracture. Microbial mats occur along different parts of the structure showing that active seepage is taking place. AUV based photo-imaging of parts of the structure shows that the microbial mats predominantly are associated with ring structures and some of the linear fracture segments. Sediment pore waters extracted from push cores show Na, Cl and Mg contents that are 10-15% lower compared to background pore fluid concentrations. This points towards a fresh water input. The fracture pore fluid compositions are also characterized by elevated methane, ammonium and hydrogen sulphide contents compared to the background seawater. The presence of these volatiles is likely caused by subsurface microbial activity, and carbon isotope analyses confirm a biological source of the detected methane. However, the presence of ethane (CH4/C2H6 of 126) indicates a small input of a thermogenic carbon to these fluids. Subsurface imaging using a hull mounted parametric sub bottom profiler reveal Holocene stratified sediments overlying quaternary moraine in the area. The sub bottom profiler data show sub-meter scale vertical movements along the fracture. Associated with the structures are small bright spots that may reflect gas accumulations. No deep-seated fault system is apparent below the fracture in 3D seismic data from the area. However, the 3D seismic data show that the structure is located above the boundary of a channel-like feature present around 150m subseafloor. This subsurface feature probably represents a shallow fluvial channel that formed during glaciation/deglaciation. A structural connection between the seafloor seepage structure and a fluvial channel is supported by the pore water chemistry at the investigated seepage sites. High undrained shear strengths (up to 180 kN/m2) have been measured in the shallow clay-rich sediments that are present in this area (Sejrup et al. 1987). We therefore propose that the Hugin Fracture formed by brittle failure of such stiff sediments as a result of differential compaction located to the margin of the shallow fluvial channel. The discovery of the Hugin Fracture demonstrates that the clay-rich and impermeable sediments that represent the uppermost seal of the Utsira Formation may be broken as a result of brittle failure, and that km-scale fracture systems may form as a result. The fracturing of this impermeable top layer may connect permeable fluvial channels to the seafloor. The presence in the fluids of hydrocarbons (ethane) that typically form by deep thermogenic processes suggests that this shallow fluid flow system is connected, or has been connected, to sedimentary sequences that are present below the Utsira Formation.

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