Hardwick C.L.,Utah Geological Survey |
Allis R.,Utah Geological Survey |
Wannamaker P.E.,Energy and Geoscience Institute
Transactions - Geothermal Resources Council | Year: 2015
Magnetotelluric (MT) data are an integral part of geothermal resource exploration throughout the world. The Black Rock Desert (BRD), Utah, may be unique, with large datasets of MT soundings and gravity measurements in combination with oil exploration wells extending to 5 km depth possessing a variety of geophysical logs, and proven high heat flow in the central part of an underlying basin (temperatures exceeding 240°C at 3 m depth). Wireline geophysical data indicate basin fill signatures of 1 to 10 ohm-m and bedrock signatures of 10 to over 1000 ohm-m. Throughout the BRD, are large variations in lithology and, consequently, resistivity. Massive salt sections, when emplaced in clay-rich basin fill, show resistivities on the order of 100 ohm-m. The upper portions of the ID, 2D, and 3D resistivity models have reasonable agreement with the wireline data, whereas in the central part of the basin, the deeper portions of the wells and the models have disparities that are an order of magnitude different. Possibly the most striking difference is the bottom of the Pavant Butte well where temperatures reach 240°C and in-situ resistivities are 100 ohm-m, but the modeled resistivities are an order of magnitude lower (<10 ohm-m). Possible explanations for this difference are the existence of aligned conductive fracture networks deep within the bedrock with a small fraction of crustal fluids in the pore space or differences in the averaging scale of MT data versus downhole wireline data. While emergent signatures of a deeply rooted system are more than likely detected with MT soundings, the signature of our specific target (stratigraphic reservoir) remains elusive. © Copyright (2015) by Geothermal Resources Council All rights reserved.
Identifying the provenance of Leach's storm petrels in the North Atlantic using polychlorinated biphenyl signatures derived from comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry
Megson D.,University of Plymouth |
Brown T.A.,University of Plymouth |
Johnson G.W.,Energy and Geoscience Institute |
O'Sullivan G.,Mount Royal College, Calgary |
And 6 more authors.
Chemosphere | Year: 2014
PCB signatures can be used for source identification, exposure studies, age dating and bio-monitoring. This study uses comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-ToFMS) to produce a PCB signature comprised of over 80 PCBs for individual Leach's storm petrels (Oceanodroma leucorhoa). The Leach's storm petrel is a relatively small, elusive, understudied pelagic bird, which only returns to remote islands under darkness during the breeding season. Samples were obtained from 25 Leach's storm petrels found dead in Canada and the UK following storm events in 2006 and 2009. Tissue samples were extracted and analysed by GCxGC-ToFMS and results showed that 83 PCB congeners were present in >60% of samples. An assessment of the PCB signature in four different tissue types showed that it did not vary greatly in samples obtained from the gut, heart, liver and stomach. Multivariate statistical analysis identified a distinctive PCB signature in birds from Canada and Europe which was used to identify the regional provenance and transatlantic movement of individual birds. The findings showcase the ability of GCxGC-ToFMS to provide the high quality congener specific analysis that is necessary for PCB fingerprinting, as well as highlighting the potential of PCB signatures for use in ecological studies of movement, foraging and behaviour. © 2014 Elsevier Ltd.
Dilley L.M.,Hattenburg Dilley and Linnell LLC |
Moore J.,Energy and Geoscience Institute
Transactions - Geothermal Resources Council | Year: 2010
Fluid inclusion stratigraphy (FIS) uses gas analyses of fluid inclusions to determine fluid types in geothermal systems. Peaks in FIS data are assumed to be related to location of fractures. The working hypothesis is that open fracture systems can be identified by their FIS chemical signature; that there are differences based on the mineral assemblages and geology of the system; and that there are chemical precursors in the wall rock above open, large fractures. Correlating fracture locations in cores to peaks in the FIS data indicate that select chemical species are useful in distinguishing large fracture zones from small fractures. FIS data for Steamboat Springs, Karaha, Glass Moutain, and Coso geothermal systems indicate that species such as CO2, H 2S, and select organic species are useful in identifying fractures. Permeable zones are indicated by a large change in the relative concentrations of the ratio of CO2/N2. The large changes in the ratio of CO2/N2 when plotted with depth, correlate with lost circulation, alteration and vein locations on well logs and cores. Identifying dense fracture areas as well as large open fractures from small fracture systems would assist in evaluating the permeability of a well and in fracture stimulation selection for enhanced geothermal systems.
Anderson W.V.,Energy and Geoscience Institute |
Anderson W.V.,University of Utah |
Bruhn R.L.,University of Utah |
Moore J.N.,Energy and Geoscience Institute
Transactions - Geothermal Resources Council | Year: 2012
This report presents data and conclusions concerning the role of low-angle faulting in the formation of Thermo Hot Springs and the effects it may have on fluid flow and production. The conclusions are that Thermo Hot Springs is formed by a low-angle normal or detachment fault that places Mesozoic and upper Paleozoic sedimentary rock in the upper plate over underlying metamorphic rock and granite. The Mesozoic section is overlain by a sequence of Tertiary to Quaternary volcanic and sedimentary deposits. High-angle normal faults offset the sedimentary and volcanic section, and in some, if not all, cases penetrate and offset the low-angle detachment fault. The high-angle normal faulting has two primary strikes: one is the northern strike of classical Basin and Range faulting, and the other is a roughly east-west striking set of normal faults. These faults may hydraulically compartmentalize the reservoir but also provide pathways for fluids to ascend upwards from beneath the detachment fault. The low-angle detachment fault model for Thermo Hot Springs structure has regional implications for geothermal prospecting in the Basin and Range terrain of southwestern Utah. This region is underlain by several known detachment faults of Middle to Late Tertiary age, which may act to laterally channel hot fluids at depth over large areas with little surface expression except where the low-angle faults are breached by younger faulting. That is, blind geothermal reservoirs may well occur at depth with few if any surface manifestations such as springs or tufa mounds. We suspect that thrust faults of Mesozoic age may also play a similar role to the Tertiary detachment faults in channeling fluids laterally in the Basin and Range region of southwestern Utah, but this is apparently not the case at Thermo Hot Springs.
Jones C.,Energy and Geoscience Institute |
Moore J.,Energy and Geoscience Institute |
Pollard B.,Fort Bidwell Indian Community Council
Transactions - Geothermal Resources Council | Year: 2010
A fourth exploration well within Fort Bidwell Indian Community (FBIC) lands has been successfully drilled to a total depth of 4,670 feet. Mud return temperatures and cuttings analysis are consistent with the hydrothermal model on which the well location was based. Wireline surveys have encountered an obstruction just below the casing shoe, and further evaluation of this well and resource awaits clean-out and testing activities.
Zhou J.,University of Utah |
Huang H.,Idaho National Laboratory |
Deo M.,University of Utah |
Jiang S.,Energy and Geoscience Institute
Society of Petroleum Engineers - Unconventional Resources Technology Conference, URTeC 2015 | Year: 2015
Because of the low permeability in shale plays, closely spaced hydraulic fractures and multilateral horizontal wells are generally required to improve production. Therefore, understanding the potential fracture interaction and stress evolution is critical in optimizing fracture/well design and completion strategy in multi-stage horizontal wells. In this paper, a novel fully coupled reservoir flow and geomechanics model based on the dual-lattice system is developed to simulate multiple non-planar fractures propagation. The numerical model from Discrete Element Method (DEM) is used to simulate the mechanics of fracture propagations and interactions, while a conjugate irregular lattice network is generated to represent fluid flow in both fractures and formation. The fluid flow in the formation is controlled by Darcy's law, but within fractures it is simulated by using cubic law for laminar flow through parallel plates. Initiation, growth and coalescence of the microcracks will lead to the generation of macroscopic fractures, which is explicitly mimicked by failure and removal of bonds between particles from the discrete element network. We investigate the fracture propagation path in both homogeneous and heterogeneous reservoirs using the simulator developed. Stress shadow caused by the transverse fracture will change the orientation of principal stress in the fracture neighborhood, which may inhibit or alter the growth direction of nearby fracture clusters. However, the initial in-situ stress anisotropy often helps overcome this phenomenon. Under large in-situ stress anisotropy, the hydraulic fractures are more likely to propagate in a direction that is perpendicular to the minimum horizontal stress. Under small in-situ stress anisotropy, there is a greater chance for fractures from nearby clusters to merge with each other. Then, we examine the differences in fracture geometry caused by fracturing in cemented or uncemented wellbore. Moreover, the impact of intrinsic reservoir heterogeneity caused by the rock fabric and mineralogy on fracture nucleation and propagation paths is examined through a three-layered reservoir. Finally, we apply the method to a realistic heterogeneous dataset. Copyright 2015, Unconventional Resources Technology Conference.
Brauser E.M.,University of Utah |
Rose P.E.,University of Utah |
Rose P.E.,Energy and Geoscience Institute |
McLennan J.D.,University of Utah |
And 2 more authors.
Applied Spectroscopy | Year: 2015
A combination of optical absorption and scattering is used to detect tracer species in a strongly scattering medium. An optical setup was developed, consisting of a dual-beam scattering detection scheme in which sample scattering beam overlaps with the characteristic absorption feature of quantum dot tracer species, while the reference scattering beam is outside any absorption features of the tracer. This scheme was successfully tested in engineered breakthrough tests typical of wastewater and subsurface fluid analysis, as well as in batch analysis of oil and gas reservoir fluids and biological samples. Tracers were detected even under highly scattering conditions, conditions in which conventional absorption or fluorescence methods failed. © 2015 Society for Applied Spectroscopy.
Pathak M.,University of Utah |
Deo M.,University of Utah |
Craig J.,Eni Exploration and Production Division |
Levey R.,Energy and Geoscience Institute
Society of Petroleum Engineers - SPE/AAPG/SEG Unconventional Resources Technology Conference | Year: 2016
Recent developments in shale technology have revolutionized oil and gas production in the United States. However, there is still a strong requirement for assessing the prospectivity of emerging shale plays, both in the United States and internationally. This paper is an attempt to generalize the results from three major US shale plays: Bakken, Eagle Ford and Niobrara, and to use these to assess the prospectivity of emerging shale plays elsewhere. Porosity, permeability, total organic carbon (TOC) content, thickness, brittleness, composition and maturity of shales are all important in the generation and retention of hydrocarbons. Factors such as depositional environment, uplift and burial, proximity to porous media, presence of natural factures, and reservoir pressure distribution over geologic time all also affect the ability of shales to retain hydrocarbons and be economically productive reservoirs. As an example, in the Eagle Ford Shale, regional overpressure has been generated through disequilibrium compaction as a result of rapid burial from the Late Cretaceous to the Palaeogene. Post-burial uplift is least in the Central Eagle Ford and the generated over pressure is, therefore, best preserved there. Overpressured shale reservoirs usually have high free gas contents. This is critical for high fluid flow rates from shales. Across the Karnes Trough in the northeast of the play, there is a good seal to the Eagle Ford Formation and, hence, good production, despite the fact that the production from the overlying Austin Chalk reservoir is poor in this area. Thus, the potential of a particular shale reservoir to produce hydrocarbons could be generalized into a "retention" factor. The geologic features that control the retention and production of hydrocarbons in these three shale plays are compared and analyzed. An attempt is made to correlate these factors and their contributions over geologic time scales in order to estimate hydrocarbon in-place in each. The results obtained from the study of these three major shale plays are generalized to provide insights into the relationships between geologic features, retention and production trends for shale plays. 'Retention' factor charts are prepared to provide a quick assessment of the prospectivity of emerging shale resources plays. Copyright 2014, Unconventional Resources Technology Conference (URTeC).
Allen J.L.,Energy and Geoscience Institute |
Allen J.L.,University of Utah |
Johnson C.L.,University of Utah
Sedimentology | Year: 2011
Marginal marine deposits of the John Henry Member, Upper Cretaceous Straight Cliffs Formation, were deposited within a moderately high accommodation and high sediment supply setting that facilitated preservation of both transgressive and regressive marginal marine deposits. Complete transgressive-regressive cycles, comprising barrier island lagoonal transgressive deposits interfingered with regressive shoreface facies, are distinguished based on their internal facies architecture and bounding surfaces. Two main types of boundaries occur between the transgressive and regressive portions of each cycle: (i) surfaces that record the maximum regression and onset of transgression (bounding surface A); and (ii) surfaces that place deeper facies on top of shallower facies (bounding surface B). The base of a transgressive facies (bounding surface A) is defined by a process change from wave-dominated to tide-dominated facies, or a coaly/shelly interval indicating a shift from a regressive to a transgressive regime. The surface recording such a process change can be erosional or non-erosive and conformable. A shift to deeper facies occurs at the base of regressive shoreface deposits along both flooding surfaces and wave ravinement surfaces (bounding surface B). These two main bounding surfaces and their subtypes generate three distinct transgressive-regressive cycle architectures: (i) tabular, shoaling-upward marine parasequences that are bounded by flooding surfaces; (ii) transgressive and regressive unit wedges that thin basinward and landward, respectively; and (iii) tabular, transgressive lagoonal shales with intervening regressive coaly intervals. The preservation of transgressive facies under moderately high accommodation and sediment supply conditions greatly affects stratigraphic architecture of transgressive-regressive cycles. Acknowledging variation in transgressive-regressive cycles, and recognizing transgressive successions that correlate to flooding surfaces basinward, are both critical to achieving an accurate sequence stratigraphic interpretation of high-frequency cycles. © 2011 The Authors.
Stuart C.J.,Energy and Geoscience Institute |
Nemcok M.,Slovak Academy of Sciences |
Vangelov D.,Sofia University |
Higgins E.R.,Vintage Petroleum |
And 3 more authors.
AAPG Bulletin | Year: 2011
Analysis of structural and sedimentologic data from onshore outcrops, offshore wells, and offshore seismic profiles indicates that the thrust belt geometry in eastern Bulgaria from the Paleocene to the Holocene is characterized by a southeastward plunge toward the western Black Sea Basin. This plunge was caused by (1) a combination of eastward-thinning continental crust in the west and oceanic crust in the east; (2) a postrift thermal subsidence of the continental crust; (3) buttressing and no buttressing of the Moesian platform against the thrust belt in its western and eastern parts, respectively; and (4) northeastward thrust belt advance. These factors controlled the overall eastward-diminishing uplift of the thrust belt and associated eastward sediment funneling into the Black Sea. Evidence for the eastward-fading uplift and buttressing includes the (1) eastward decreasing amount of shortening along constructed cross sections, yielding 30,10.5,11, and 4 km (18.6, 6.5, 6.8, and 2.5 mi, respectively) from west to east, respectively; (2) eastward trend of more complete stratigraphie sections and shallower erosional levels; and (3) eastward increase in decollement depths, being 3.7, 3.8, 9.5 to 13.5, and 12.3 to 14.1 km (2.3, 2.4, 5.9-8.4, and 7.6-8.8 mi). The age of the last thrusting is progressively younger toward the east from the middle Eocene through the late Eocene to the Oligocene from west to east, respectively. Onshore parts of the thrust belt, which were significantly affected by buttressing against the Moesian platform, exhibit thrusting followed by late Eocene gravitational collapse, Oligocene quiescence, and Neogene extension. The thrust belt part farther east exhibits thrusting followed by Oligocene-Neogene extension. A Paleocene-middle Eocene piggyback basin formed in the onshore part of the thrust belt, centered in the East Balkan zone, with a southeastward- plunging axis, which migrated northeastward with basin shortening and filling. The development of the East Balkan thrust belt and its later extensional modification had a dominant control over sediment transport, lithofacies, and depositional patterns. Developing thrust belt fold structures, together with the orogenic hinterland and highs in the foreland, formed a northeastward and eastward expanding system of sediment input. Southeastward-plunging axes of the foreland basin and the Paleocene-middle Eocene piggyback basin were the principal sediment transport pathways, together with subordinate internal synclinal axes. These depressions funneled sediments toward and into the western Black Sea Basin. As orogenesis advanced to the northeast, former depositional areas were uplifted and eroded, providing local sources of sediment. Copyright ©2011. The American Association of Petroleum Geologists.