Browsing by Subject "Offshore"
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Item A techno-economic study of a CO₂-plume geothermal system in mature gas reservoirs of the Brazos Area protraction, Gulf of Mexico(2023-04-20) Klarin, Samuel Jacob; Livescu, Silviu; Chuchla, Richard J. (Richard Julian); Wisian, Kenneth; Webber, MichaelThe Brazos Area protraction of the Gulf of Mexico was the focus of exploration and development of Middle Miocene aged natural gas reservoirs along the Corsair fault trend for many decades of the late 20th century. With this development came the installation of supporting infrastructure. This included fixed offshore platforms and pipelines to bring the produced natural gas back to shore, roughly 65 kilometers in waters between 40 to 60 meters deep. As operations have shifted to deeper waters with larger reservoirs, much of this infrastructure has been left abandoned with removals being delayed due to the high decommissioning costs. Carbon capture and sequestration (CCS) and geothermal energy are two such technologies that received increased attention in the Gulf Coast region as efforts to reduce atmospheric CO₂ concentrations accelerate. Specifically, CO₂-plume geothermal (CPG) systems inject supercritical CO₂ (sCO₂) into a sandstone reservoir where the heat is extracted from the surrounding rock as the fluid migrates, then the fluid is produced into a direct-sCO₂ turbine power plant. Upon exiting the power cycle, the sCO₂ is then reinjected into the reservoir to start the sequence again. This study uses open-source well data from the National Geothermal Data System (NGDS), reservoir and infrastructure data from the Bureau of Ocean Energy Management (BOEM), and the Sequestration of CO₂ Tool (SCO₂T [superscript PRO]) software to conduct a resource assessment in terms of geothermal energy and CO₂-capacity of the gas reservoirs in the Brazos Area protraction and the potential power output and specific capital costs of greenfield and brownfield CPG systems. These characteristics are then used to adapt the CPG system to an offshore application exploiting the mature/depleted reservoir with the most potential, the BA133A_CM7D sand. This application is modeled by creating a workflow to conduct a techno-economic analysis involving three main schemes and the implications of current policy incentives under the Inflation Reduction Act of 2022, namely the 45Q carbon tax credit and the investment tax credit. The schemes analyzed are a Post-CCS CPG-only application (PCC), a combined CCS and CPG operation with newly built infrastructure (CCNB), and a combined CCS and CPG operation utilizing repurposed infrastructure (CCRI). The economic analysis yields a levelized cost of electricity (LCOE) range for the PCC scheme of 72-332 $/MWh. The reduction potential (25-78%) is driven by the amount of infrastructure reuse and ITC incentive at a 20 $/tCO₂ storage cost and 35 $/tCO₂ purchase price. The LCOE range under the CCNB and CCRI schemes are about 84-573 $/MWh (52-85% reduction potential) and 5-464 $/MWh (58-99% reduction potential), respectively. A sensitivity analysis was performed for 35, 60, and 85 $/tCO₂ purchase price and number of sCO₂ power plants (1-10) that can be installed on the platform. LCOE ranges for either CCNB or CCRI scenarios are shown to decrease from roughly 1,385 $/MWh to 441 $/MWh.Item Assessing an offshore carbon storage opportunity at Chandeleur Sound, Louisiana(2023-05-04) Li, Yushan, M.S. in Energy and Earth Resources; Hovorka, Susan D. (Susan Davis); Uroza, Carlos; Gil Egui, RamonCarbon Capture and Storage (CCS) is considered a crucial technology for climate change mitigation. Its primary objective is to reduce CO₂ emissions caused by human activities by capturing gas from large point sources or from direct air capture and injecting it into deep geologic formations. This study focuses on the geological characterization and CO₂ storage capacity estimation for an offshore state water site – Chandeleur Sound, Louisiana. Form literature review, the storage window is narrowed to Middle and Upper Miocene. 3-D seismic data was used for fault and horizon picking, stratal slicing and attribute mapping. Three attributes/methods were used in the stratal slices: Sum Negative Amplitude, RMS amplitude, and Spectral Decomposition. The slices give a qualitative overview of the depositional trends and faulting in Chandeleur Sound and concluded that the ideal storage intervals include the Upper Miocene in the southern area, the upper part of Middle Miocene, and a massive channel system near the top of Upper Miocene which is likely to be a deposit from the paleo Tennessee River. Well log correlation was used to identify seven reservoir zones. Detailed reservoir properties were defined for these zones. The thickest net sand interval within the Chandeleur Sound area is found in the center. Static and dynamic storage capacity calculations estimate a total storage capacity of 306 to 2,000 million metric tons. of CO₂, depending on boundary condition. The value of 306 Mt is the most realistic and is used for source-sink matching. Chandeleur Sound is close to Louisiana Chemical Corridor (LCC) and has plenty of point sources for CO₂ supply. The costs associated with carbon capture, transport and storage and were considered. Pipeline is the only transport scenario considered for large volumes that must be transported on land and then into shallow marine settings. CO₂ pipeline regulations include both federal and state level jurisdiction. Pipeline costs estimation using FECM/NETL CO₂ Transport Cost Model and Terrain-based approach concluded that a 20 inches pipeline from the carbon gathering hub to the injection site would have a construction cost from $140 million to $1.16 billion in 2023’s dollars.Item Assessment of Geological Storage Capacity of the Southeastern U.S. for CO2 in Brines and Economic Use for EOR(SECARB Industry Briefing, 2006-01-18) Hovorka, Susan D.; Holtz, Mark H.; Smyth, Rebecca C.; Nunez Lopez, Vanessa; Kim, Eugene; Breton, Catherine L.; Scanlon, Bridget R.; Reedy, Reedy C.; Paine, Jeffrey; Tinker, Scott; Duncan, IanItem Design of large diameter monopiles for offshore wind turbines in clay(2016-08) Senanayake, Asitha Indun Madusanka Joshua; Gilbert, Robert B. (Robert Bruce), 1965-; Wang, Shin-Tower; Cox, Brady; Manuel, Lance; Murff, James DOffshore wind power has great potential as a clean and renewable energy source that is capable of reducing our reliance on fossil fuels. The main drawback of offshore wind power is its comparatively high capital cost. One area in which this cost can be reduced is by optimizing the design of these structures. More efficient foundation designs is key in this regard. The p-y method is extensively used for the design and analysis of laterally loaded piles due to its simplicity and versatility. Matlock (1970) or the API RP 2GEO (2011) “soft” clay p-y model is the guideline of choice for normally consolidated to moderately overconsolidated clays. However, this p-y model is not yet verified for piles with very large diameters and low aspect ratios. Design of wind turbine monopiles is governed by serviceability limits such as the natural frequency of the structure and the accumulated tilt under long-term low-amplitude cyclic loads, but these guidelines have not been verified for serviceability limit state designs. The main objectives of this study were to: (a) assess the ability of the Matlock (1970) p-y model to accurately model the behavior of laterally loaded piles at both small and large displacements, (b) investigate the effect of gapping on the backside of laterally loaded piles and develop a theoretical framework to quantify its effect and predict its occurrence, (c) re-examine the derivation of lateral bearing capacity factors (N p ) used in published p-y models, (d) evaluate the effect of large numbers of small-amplitude cyclic load on the stiffness and the post-cyclic ultimate capacity of laterally loaded piles, (e) assess the ability of the Matlock (1970) p-y model to adequately account for pile diameter effects, (f) assess the ability of the Matlock (1970) p-y model to accurately predict the behavior of a pile in a variety of undrained shear strength versus depth profiles, (g) assess the ability of published p-y models to accurately predict the natural frequency of wind turbine structures. The methodology consisted of analyzing field tests, laboratory model tests (1-g and centrifuge), and numerical modeling. An extensive database of field tests and laboratory centrifuge tests was compiled. This data was then supplemented by a series of 1-g model tests in a variety of clay test beds (normally consolidated to heavily overconsolidated, kaolinite and Gulf of Mexico clay) carried out at The University of Texas at Austin and 3-d finite-elements models using Abaqus carried out by Ensoft Inc. The following conclusions were drawn from this study: (a) Matlock (1970) p-y model underestimates the lateral soil resistance on piles in normally consolidated and overconsolidated clays, regardless of pile diameter or aspect ratio, (b) the effect of gapping plays an important role in determining the pile response as it can lead to a loss of capacity and a reduction in stiffness, (c) lateral bearing capacity factors used in the Matlock (1970) model are too low, (d) the degradation in the stiffness of the pile response, when subjected to cyclic loading, was limited to approximately 30% and occurred within the first 100 cycles, (e) the method of normalizing used in the Matlock (1970) model successfully accounts for pile diameter effects, (f) estimates of the natural frequency of wind turbine structure based on the API RP 2GEO (2011) p-y model are lower than those based on the Matlock (1970) and Jeanjean (2009) p-y models.Item Dynamic response and reliability analysis of an offshore wind turbine supported by a semi-submersible platform(2015-12) Thomas, Edwin, M.S. in Engineering; Manuel, LanceWind Energy is the fastest growing renewable energy source in the world. The trend is expected to continue with falling costs of technology, energy security concerns and the need to address environmental issues. Offshore wind turbines have a few important advantages over land-based turbines; offshore sites experience stronger and less turbulent winds, there are fewer negative aesthetic impacts in an offshore location, there is greater ease in the transport of wind turbine components over sea than on land, etc. Large offshore wind turbines mounted atop floating platforms offer a viable solution for deepwater sites. Of the various floating platform concepts that are being considered, a moored semi-submersible platform is considered in this study. The dynamic response and reliability analysis of a 13.2~MW offshore wind turbine supported by a moored semi-submersible platform is the subject of this study. A model for this integrated system has been developed and its various physical, geometric, and dynamic properties have been studied in this and another associated study. Loads data for the extreme and fatigue analysis of such systems are generally attained by running time-domain simulations for a range of sea states that are representative of the expected site-specific metocean conditions. The selected site of interest in the North Sea has a water depth of 200 m. The Environmental Contour (EC) method is used to identify sea states of interest that are associated with a target return period (50 years). These sea states are considered in short-term (1-hour) simulations of the integrated turbine-platform-mooring system. The dynamic behavior of the integrated wind turbine system is studied. Critical sea states for the various response loads are identified and the sensitivity of the system to the metocean conditions is discussed. Estimation of 50-year response levels (for turbine loads, platform motions, and the mooring line tension at the fairlead) associated with the target probability is subsequently carried out using 2D and 3D Inverse First-Order Reliability Method (FORM) approaches.Item Experimental in-plane behavior of a generic scale model drag embedment anchor in Kaolinite test beds(2011-05) McCarthy, Katelyn Barbara; Gilbert, Robert B. (Robert Bruce), 1965-; Rathje, Ellen M.The trajectory and capacity are key components of the design of drag embedment anchor and drag-in vertically loaded anchors. This experimental testing program quantifies two factors that describe the anchor trajectory and capacity: the equilibrium bearing factor (Ne) and the tangential bearing factor (Ne). These factors can aid in the development of a numerical model of anchor behavior. A magnetometer device is used to track the orientation and location of the anchor during drag embedment. The results of the experimental testing program were compared with the results from a predictive model. The experimental program consisted of drag embedment tests with various testing conditions including different anchor line diameters and different initial pitch orientations. The results with the different anchor lines indicated that thinner anchor lines cause the anchor to dive deeper in the soil. The different initial pitch results indicate that regardless of the initial pitch of the anchor, the anchor rotates to a unique pitch trajectory within 2 fluke lengths.Item On the development of a semi-submersible offshore floating platform and mooring system for a 13.2 mw wind turbine(2015-12) Liu, Jinsong, Ph. D.; Manuel, LanceOver the past decades, wind energy has emerged as an alternative to conventional power generation that is economical, environmentally friendly, and importantly renewable. Specifically, offshore wind energy is being con- sidered by a number of countries to harness the stronger and more consistent wind resource compared to that over land. To meet the projected “20% energy from wind by 2030” scenario that was announced in 2006, 54 GW of added wind energy capacity needs to come from offshore according to a National Renewable Energy Laboratory (NREL) study. In this study, we discuss the development of a semi-submersible floating offshore platform with a catenary mooring system to support a very large vi 13.2 MW wind turbine with 100 m blades. An iterative design process is applied to baseline models with Froude scaling in order to achieve preliminary static stability. Structural dynamic analyses are performed to investigate the performance of the new model using a finite element method approach for the tower and a boundary integral equation (panel) method for the platform. The steady-state response of the system under uniform wind and regular waves is first studied to evaluate the performance of the integrated system. Response amplitude operators (RAOs) are computed in the time domain using white- noise wave excitation; this serves to highlight nonlinear as well as dynamic characteristics of the system. Finally, the stochastic dynamic response of the system is studied to assess the global performance for sea states defined by wind fields with turbulence and long-crested irregular waves.Item Regional character of the lower Tuscaloosa formation depositional systems and trends in reservoir quality(2012-12) Woolf, Kurtus Steven; Wood, Lesli J.For decades the Upper Cretaceous Lower Tuscaloosa Formation of the U.S. Gulf Coast has been considered an onshore hydrocarbon play with no equivalent offshore deposits. A better understanding of the Lower Tuscaloosa sequence stratigraphic and paleogeographic framework, source-to-sink depositional environments, magnitude of fluvial systems, regional trends in reservoir quality, and structural influences on its deposition along with newly acquired data from offshore wells has changed this decades-long paradigm of the Lower Tuscaloosa as simply an onshore play. The mid-Cenomanian unconformity, underlying the Lower Tuscaloosa, formed an extensive regional network of incised valleys. This incision and accompanying low accommodation allowed for sediment bypass and deposition of over 330 m thick gravity-driven sand-rich deposits over 400 km from their equivalent shelf edge. Subsequently a transgressive systems tract comprised of four fluvial sequences in the Lower Tuscaloosa Massive sand and an overlying estuarine sequence (Stringer sand) filled the incised valleys. Both wave- and tide-dominated deltaic facies of the Lower Tuscaloosa are located at the mouths of incised valleys proximal to the shelf edge. Deltaic and estuarine depositional environments were interpreted from impoverished trace fossil suites of the Cruziana Ichnofacies and detailed sedimentological observations. The location and trend of valleys are controlled by basement structures. Lower Tuscaloosa rivers were 3.8m – 7.8m deep and 145m – 721m wide comparable to the Siwalik Group outcrop and the modern Missouri River. These systems were capable of transporting large amounts of sediment indicating the Lower Tuscaloosa was capable of transporting large amounts of sediments to the shelf edge for resedimentation into the deep offshore. Anomalously high porosity (>25%) and permeability (>1200md) in the Lower Tuscaloosa at stratigraphic depths below 20,000 ft. are influenced by chlorite coating the detrital grains. Chlorite coatings block quartz nucleation sites inhibiting quartz cementation. Chlorite coats in the Lower Tuscaloosa are controlled by the presence and abundance of volcanic rock fragments supplying the ions needed for the formation of chlorite. Chlorite decrease to the east in sediments derived from the Appalachian Mountains. An increase in chlorite in westward samples correlates with an increase of volcanic rock fragments derived from the Ouachita Mountains.Item Texas offshore wind power and water desalination potential(2015-05) Beceiro, Jose Daniel; Spence, David B.; Webber, Michael E., 1971-Texas leads the nation in oil and gas production as well as renewable energy production. Texas also leads the nation in installed wind power and is the 6th largest wind market in the world. Over the past decade, Texas has gone from nearly zero megawatts of installed wind to now over 14,000 megawatts. Texas has an immense onshore wind resource that has been exploited. However, another of Texas' large untapped energy resources has yet to be explored -- offshore wind. Texas is also experiencing one of the most severe and longest sustained drought cycles in the state's history. Texas is blessed with a vast supply of ocean water and brackish groundwater trapped in aquifers, but energy-intensive water desalination plants are required to purify the water to potable standards. Offshore wind has the ability to turn large-scale water desalination into an economical solution. This thesis focuses on offshore wind and water desalination technology development, cost competitiveness with competing renewable energy and thermo electric generation resources on the ERCOT nodal grid, and the opportunity to couple water desalination facilities with offshore wind farms to enhance overall project economics, reduce the cost of electricity, and increase the supply of fresh water. An economic model evaluating offshore wind-powered water desalination is utilized to demonstrate the viability of implementing these technologies across the state.