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PubMed | BP Exploration Alaska Inc., College of William and Mary, Cornell University, National Oceanic and Atmospheric Administration and 6 more.
Type: | Journal: Advances in experimental medicine and biology | Year: 2015

There are no standards for assessment of the cumulative effects of underwater sound. Quantitative assessments typically consider a single source, whereas qualitative assessments may include multiple sources but rarely identify response variables. As a step toward understanding the cumulative effects of underwater sound, we assessed the aggregated sounds of multiple sources received by migrating bowhead whales (Balaena mysticetus). The quantitative method models the sound field from multiple sources and simulates movement of a population through it. The qualitative method uses experts to assess the responses of individuals and populations to sound sources and identify the potential mechanisms. These methods increase the transparency of assessments.

Cater T.C.,Inc. Environmental Research and Services | Hopson C.,UMIAQ | Streever B.,BP Exploration Alaska Inc
Arctic | Year: 2015

Tundra sodding, a new technique available to rehabilitate disturbed wetlands in the Arctic, is based on Iñupiaq traditional knowledge. C. Hopson, an Iñupiaq elder from Barrow and author of this paper, guided the development and field application of this new technique by providing traditional knowledge he learned as a youth from his elders. Tundra sodding has several advantages over other land rehabilitation techniques, the most important being that it can establish a mature plant community of indigenous species in a single growing season. In all sampling years, the plant communities at sodded sites were dominated by two rhizomatous graminoids, Eriophorum angustifolium and Carex aquatilis. These sedges also were dominant in all years in reference tundra. Also common to the plant communities in both reference tundra and sodded sites were 18 other vascular species (grasses, evergreen and deciduous shrubs, and forbs). Results from two to five growing seasons indicate that tundra sod can reduce the overall subsidence due to thawing of shallow permafrost. We harvested sod on three occasions from an area slated for gravel mining. In the summers of 2007 and 2008, we transplanted 334 m2 of tundra sod to portions of three sites to test the feasibility of the method. In summer 2010, we used the experience gained from that work to rehabilitate an entire site (1114 m2). This tundra sodding technique is labor intensive and costly compared to other rehabilitation techniques, but it offers advantages that justify its use when rapid rehabilitation of a disturbed site is needed. © The Arctic Institute of North America.

Ferre E.C.,Southern Illinois University Carbondale | Michelsen K.J.,University of New Mexico | Ernst W.G.,Stanford University | Boyd J.D.,BP Exploration Alaska Inc. | Canon-Tapia E.,CICESE
American Mineralogist | Year: 2012

Petrological and geochemical variations within plutons reflect their magmatic and emplacement histories. Here we present new magnetic susceptibility (Km) data on the ∼163 Ma Barcroft granodiorite pluton in eastern California, which is exceptionally well exposed, especially in the vertical dimension. The Barcroft pluton offers exposures over a total of 2560 m of elevation and is an appropriate target to investigate variations of magnetic susceptibility. In ferromagnetic plutonic rocks, Km reflects mainly the abundance of magnetite, whereas in paramagnetic plutonic rocks it reflects primarily the abundance of mafic silicates. Magnetic susceptibility is also determined by magmatic processes such as crystal fractionation and by intensive parameters such as oxygen fugacity. Other magmatic processes, including magma replenishment, hybridization, and host-rock assimilation, may also influence Km variations. A first data set is based on 622 core samples that were measured in the laboratory. Our second data set comes from 1960 field measurements collected at 196 stations between ∼1600 and 4000 m elevation. Detailed surveys were performed at the outcrop scale to evaluate the impact of the ∼100 Ma McAfee Creek intrusion on the Barcroft background magnetic susceptibility. The combined data sets display a broad positive correlation between Km and elevation. Pluton mineralogy also appears to vary with elevation but is more difficult to quantify. At the outcrop scale, small dikes of the McAfee Creek granite transect the pluton and are responsible for a decrease in Km of the host granodioritic rocks toward the dikes due to late-stage magmatic or hydrothermal alteration. A contour map of K m shows a high degree of correlation with local topographic features such as deep canyons. Magnetic susceptibility of the Barcroft mafic rocks varies at the outcrop scale as a result of presence of petrological heterogeneities. However, these small-scale variations are embedded in a broader magnetic susceptibility trend due primarily to elevation, which reflects petrologic stratification of the pluton. The late-magmatic and hydrothermal alterations described in previous studies do not affect the spatial distribution of magnetic susceptibility. We propose that vertical increase of Km was primarily caused by crystal fractionation or another magmatic differentiation mechanism rather than by an externally driven increase in oxygen fugacity toward the roof of the intrusion.

Svedeman S.J.,Southwest Research Institute | Brady J.L.,BP Exploration Alaska Inc.
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2013

Laboratory tests were conducted to evaluate the effectiveness of oil/water separation in a deviated well casing that is located below the perforation intervals. Downhole water separation and reinjection is needed to reduce well operating costs associated with producing large amounts of water to the surface. In the casing separator, produced water flows downward from the well perforations with entrained oil buoyantly separated to the topside of the casing. A dip tube, running to the bottom of the casing, feeds a downhole pump that pumps the water into another level in the reservoir. A test facility was constructed to test the casing separator performance at a variety of well inclination angles, production flow rates, water cuts, and reinjection water flow rates. At each operating condition, the amount of oil entrained in the reinjection water was measured to determine the maximum amount of water that could be separated and still provide "clean" water to the downhole pump. Tests were conducted over well inclination angles from 18° to 75°. The maximum water velocity in the casing separator, for clean water, varied from 0.2 ft/sec to 0.4 ft/sec. The test results provided the information needed to determine how much water could be separated in the casing separator. With the separator performance data, the economics of reinjecting water with a downhole pump could be evaluated. Copyright 2013, Society of Petroleum Engineers.

Hunter R.B.,C and A Energy Services | Collett T.S.,U.S. Geological Survey | Boswell R.,U.S. National Energy Technology Laboratory | Anderson B.J.,U.S. National Energy Technology Laboratory | And 5 more authors.
Marine and Petroleum Geology | Year: 2011

The Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled within the Alaska North Slope (ANS) Milne Point Unit (MPU) from February 3 to 19, 2007. The well was conducted as part of a Cooperative Research Agreement (CRA) project co-sponsored since 2001 by BP Exploration (Alaska), Inc. (BPXA) and the U.S. Department of Energy (DOE) in collaboration with the U.S. Geological Survey (USGS) to help determine whether ANS gas hydrate can become a technically and commercially viable gas resource. Early in the effort, regional reservoir characterization and reservoir simulation modeling studies indicated that up to 0.34 trillion cubic meters (tcm; 12 trillion cubic feet, tcf) gas may be technically recoverable from 0.92 tcm (33 tcf) gas-in-place within the Eileen gas hydrate accumulation near industry infrastructure within ANS MPU, Prudhoe Bay Unit (PBU), and Kuparuk River Unit (KRU) areas. To further constrain these estimates and to enable the selection of a test site for further data acquisition, the USGS reprocessed and interpreted MPU 3D seismic data provided by BPXA to delineate 14 prospects containing significant highly-saturated gas hydrate-bearing sand reservoirs. The "Mount Elbert" site was selected to drill a stratigraphic test well to acquire a full suite of wireline log, core, and formation pressure test data. Drilling results and data interpretation confirmed pre-drill predictions and thus increased confidence in both the prospect interpretation methods and in the wider ANS gas hydrate resource estimates. The interpreted data from the Mount Elbert well provide insight into and reduce uncertainty of key gas hydrate-bearing reservoir properties, enable further refinement and validation of the numerical simulation of the production potential of both MPU and broader ANS gas hydrate resources, and help determine viability of potential field sites for future extended term production testing. Drilling and data acquisition operations demonstrated that gas hydrate scientific research programs can be safely, effectively, and efficiently conducted within ANS infrastructure. The program success resulted in a technical team recommendation to project management to drill and complete a long-term production test within the area of existing ANS infrastructure. If approved by stakeholders, this long-term test would build on prior arctic research efforts to better constrain the potential gas rates and volumes that could be produced from gas hydrate-bearing sand reservoirs. © 2010 Elsevier Ltd.

Sacks A.,Pennsylvania State University | Sacks A.,BP Exploration Alaska Inc. | Saffer D.M.,Pennsylvania State University | Saffer D.M.,BP Exploration Alaska Inc. | Fisher D.,Pennsylvania State University
Geochemistry, Geophysics, Geosystems | Year: 2013

We use a high-resolution 3-D seismic survey to map a population of recent normal faults within the Kumano Basin of the Nankai subduction zone, in order to quantify patterns of strain and stress state over the last 0.44 Myr. We identify distinct fault populations that define three phases of extension. Phases 1 and 2 comprise NW-SE striking faults located along the western basin edge and in the northwestern portion of the study area, respectively. The NE-SW striking faults of phase 3 comprise the largest population, and extend ~20 km landward from the basin's seaward edge. Phase 2 faults typically terminate within a few reflectors of the seafloor, whereas most phase 3 faults form seafloor scarps. Inversion of the fault populations documents NE-SW extension during phases 1 and 2 and NW-SE extension during phase 3, consistent with both core-scale structures and horizontal stress orientations observed at Integrated Ocean Drilling Program (IODP) boreholes. Slip on phase 3 faults accommodates strain of up to ~1-2%, concentrated near the basin's seaward edge. Inversion for a best-fit stress tensor yields a subvertical σ1 and subhorizontal σ2 and σ3 for all faulting phases. We find that during phase 3 in most portions of the basin, σ2 = σ3 (SHmax = Shmin), reflecting widely varying fault strikes. This contrasts with distinct S Hmax and Shmin magnitudes inferred from IODP borehole data; these observations may be reconciled if the orientation of maximum horizontal stress fluctuates due to variation of subduction parallel compression through the seismic cycle. ©2013. American Geophysical Union. All Rights Reserved.

Day R.H.,Abr Incenvironmental Research And Services | Rose J.R.,Abr Incenvironmental Research And Services | Prichard A.K.,Abr Incenvironmental Research And Services | Streever B.,BP Exploration Alaska Inc
Arctic | Year: 2015

We studied movement rates and the general flight behavior of bird flocks seen on radar and recorded visually at Northstar Island, Arctic Alaska, from 13 to 27 September 2002. Most of this period (13 - 19 and 21 - 27 September) had no gas-flaring events, but a major gas-flaring event occurred on the night of 20 September. Movement rates of targets on radar and of bird flocks recorded visually in the first ~50%-60% of the night were much lower during the non-flaring period than during the night of flaring, whereas rates in the last ~40%-50% of the night were similar in all periods. The general flight behavior of birds also differed significantly, with higher percentages of both radar targets and bird flocks exhibiting straight-line (directional) flight behaviors during the non-flaring periods and higher percentages of radar targets and bird flocks exhibiting non-straight-line (erratic and circling) flight behaviors during the gas-flaring period. During the night of gas flaring, the bright illumination appeared to have an effect only after sunset, when flocks of birds circled the island after being drawn in from what appeared to be a substantial distance from the island. On both radar and visual sampling, the number of bird flocks approaching the island declined over the evening, and the attractiveness of the light from flaring appeared to decline. The visibility of the moon appeared to have little effect on the behavior of birds. Because illumination from extensive gas-flaring is such a strong attractant to migrating birds and because most bird flocks fly at low altitudes over the water, flaring booms on coastal and offshore oil-production platforms in Arctic Alaska should be positioned higher than the mean flight altitudes of migrating birds to reduce the chances of incineration. © The Arctic Institute of North America.

La Plante W.C.,BP Exploration Alaska Inc.
Welding Journal | Year: 2012

Experts state that knowledge of welding technology, engineering, and inspection are crucial to the Prudhoe Bay oilfield operations at the North Slope and the Trans-Alaska Pipeline System (TAPS) infrastructure. Accurate work-force manning estimates are required for pipeline applications, such as pipe replacement and repair, pipeline construction replacement and repair, and pipeline construction. Special training is provided for personnel traveling to Prudhoe Bay for the first time that covers safety and health criteria, environmental regulations, policies, and procedures; and workplace hazard awareness. Specific consideration is given to the acquisition of critical personnel in addition to project material and equipment requirements. Mechanical testing and fracture toughness of weld metal and base materials also represents a critical characteristic in Performance Qualification Record (PQR) and welder performance qualification.

Wilkes J.C.,Southwest Research Institute | Wade J.,Southwest Research Institute | Rimpel A.,Southwest Research Institute | Moore J.,Southwest Research Institute | And 3 more authors.
Proceedings of the ASME Turbo Expo | Year: 2016

High speed foil bearings are currently used in increasingly demanding, high performance applications. The application under consideration is a 120 krpm natural gas turboexpandercompressor, which requires 38 mm (1.5 in.) foil journal bearings with high stiffness and load capacity to help enhance rotordynamic stability. This paper describes the development of the foil bearing for this application and includes measured stiffness and damping coefficients recorded on a high-speed dynamic bearing test rig. The dynamic test data were taken for several different foil bearing configurations with varying spring-element foil thicknesses, number of spring-element foils, and bearing shim thickness. All three parameters have a direct impact on bearing clearance. The influence of these different parameters on measured stiffness and damping coefficients and thermal performance of the bearings are presented and discussed. Copyright © 2016 by ASME.

PubMed | BP Exploration Alaska Inc. and LAMA Ecological
Type: | Journal: Advances in experimental medicine and biology | Year: 2015

Before operating air guns in Alaska, industry is usually required to model underwater sound isopleths, some of which have implications for the mitigation and monitoring of potential marine mammal impacts. Field measurements are often required to confirm or revise model predictions. We compared modeled and measured air gun sound isopleths from 2006 to 2012 and found poor agreement. Natural variability in the marine environment, application of precautionary correction factors, and data interpretation in the generation of circular isopleths all contributed to the observed poor agreement. A broader understanding of the realities of modeled and measured underwater sound isopleths will contribute to improved mitigation practices.

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