Large Sedimentary Basins Research Articles

Structure of the Earth’s crust and tectonic evolution history of the Southern Indian Ocean (Antarctica)

The Southern Indian Ocean comprises large sedimentary basins of the Riiser-Larsen Sea (western sector); the Cosmonauts, Cooperation (Commonwealth), Davis seas (central sector); and the Mawson-d’Urville seas (eastern sector). The main tectonic provinces of the Southern Indian Ocean (Antarctica) have been outlined as a result of comprehensive interpretation of the geophysical data. Special attention is paid to determining the boundary between the rifted continental and oceanic crust. The basin of the Riiser-Larsen Sea was formed in the Early Jurassic under the action of the Karoo mantle plume. The intrusive complex, as a remote manifestation of the mantle plume, occurs along the inner boundary of the marginal rift. Opening of the ocean in the basin of Riiser-Larsen Sea started about 160 Ma ago and was characterized by rearrangement of plate motion and intense volcanic activity at the early stage. In the basin of the Cosmonauts, Cooperation, and Davis seas, the final stage of rifting was accompanied by the rise of the lithospheric mantle and by intrusive magmatism. The opening of the ocean started here 134 Ma ago. Emplacement of the Kerguelen plume resulted in jumping of ridges and detachment of continental crustal blocks from the Indian margin with the formation of the Kerguelen Plateau (microcontinent). The basin of the Mawson-d’Urville seas has evolved under conditions of long-term rifting since the Late Jurassic and is characterized by an extended zone of mantle unroofing. Breakup of the lithosphere between Australia and Antarctica developed asynchronously over a time interval of 95–65 Ma ago with propagation of MOR from the west eastward. The research was carried out using a great body of geophysical information (∼140000 km of CDP seismic profiling, more than 250 stations of seismic refraction sounding, and more than 250000 km of magnetic and gravity profiles) obtained by expeditions from many countries over more than 30 years.

Significance of carbon dioxide density estimates for basin-scale storage resource assessments

Abstract The geologic carbon dioxide (CO2) storage resource size is a function of the density of CO2 in the subsurface. The pressure and temperature of the storage reservoir at depth affect the CO2 density. Therefore, knowing these subsurface conditions allows for improved resource estimates of potential geologic CO2 storage capacity. In 2012, the U.S. Geological Survey (USGS) completed an assessment of geologic CO2 storage resources for large sedimentary basins in onshore and State waters areas of the U.S. Evaluating the subsurface conditions and CO2 density in these basins was integral to the assessment. To better understand these conditions, investigations of pressure and temperature gradients, typically derived from borehole data and analog studies, were assembled at the basin scale. Based on the USGS assessment results and findings here, changes in subsurface pressure and temperature may yield density changes up to 40 percent, which may translate into significant changes in storage resource estimates.

Main Controlled Elements for Accumulation of Ultro-Low Permeability Sandstone Oil Reservoir, Zhenjing Oilfield, Ordas Basin

Ordos Basin is the second largest sedimentary basin in China with very rich oil and gas resources. The exploration targets are typical reservoirs of low permeability. To determine the accumulation mechanism of tight sandstone reservoir, thin section, SEM, numerical calculation were used. The result showed that sandstone should be ultro-low permeability reservoirs with the high content feldspar and lithic arkose or feldspathic litharenite. The reservoir became tight while oil filling, buoyant force is too small to overcome the resistance of capillary force. Therefore, overpressure induced by source rock generation is the accumulation drive force.

Accumulation Mechanism of Ultro-Low Permeability Sandstone Reservoir, Huaqing Oilfield, Ordas Basin

Ordos Basin is the second largest sedimentary basin in China with very rich oil and gas resources. The exploration targets are typical reservoirs of low permeability, low pressure and low output. To determine the accumulation mechanism of tight sandstone reservoir, thin section, fluid inclusion, porosity and permeability measurement, numerical calculation were used. The result showed that sandstone became tight while oil filling, buoyant force is too small to overcome the resistance of capillary force. Therefore, overpressure induced by source rock generation is the accumulation drive force.

Case study: Successful application of 3D depth processing in Eromanga Basin, Queensland

The Eromanga Basin is a large Mesozoic sedimentary basin in Central and Northern Australia. It covers an area of 1,000,000 km2 and is the location of important onshore petroleum and natural gas deposits in Australia including the nation's largest onshore oilfield at Jackson. We performed a pre-stack time migration and later on a pre-stack depth migration sequence on a 300sqkm block in the basin with the objective to map out intricate formations for detection of areas with high potential for gas hydrocarbon. The basin contains an ancient meteorite crater (astrobleme) which distorts seismic images, and is made of sandstone, siltstone, mudstone, coal and shale. The oil and gas producing interval is located around 1,200m below the surface. Vibroseis seismic data was processed through an amplitude-preserved and surface-consistent sequence followed by offset-class regularisation and pre-stack migration. Refraction and residual statics were applied to correct for near surface time distortions. The time migrated data illustrates high signal-to-noise ratio with generally flat rock beddings with some noticeably complicated formations at known horizons, forming strong velocity boundaries. These formation oddities generally appear from Cadna-Owie ( C ) Formation and deeper; the Top C horizon is of significance for exploration as the top of the unit approximates a distinctive seismic reflector and is mappable over the entire basin. During depth-velocity modelling it was revealed that there are significant velocity variations (~500m/s) at Top C and other boundaries. Time imaging was not able to image these intervals properly. Depth migration improved seismic image quality especially in fault shadow zones, and areas with complex seismo-geological settings. The benefits of depth imaging on the Eromanga Basin data were demonstrated by significant uplift in structural conformity and increased confidence in interpretation results.

Influence of tectonics, sedimentation and aqueous flow cycles on the origin of global groundwater arsenic: Paradigms from three continents

Arsenic (As) is a trace element in the Earth’s crust. However, its presence in elevated concentrations in groundwaters of major aquifers around the world raises concern about its primary source(s). A close look at the global distribution of known As enriched areas reveals an intriguing systematic pattern, where most of the As enriched aquifers are parts of large sedimentary basins adjoining major orogenic belts, suggesting the existence of a large-scale geological process. Many of these sedimentary basins may be tectonically regarded as foreland basins that developed by lithospheric flexure at the time of mountain building processes (orogenesis) along convergent plate boundaries. Arsenic enrichment in the groundwater of these foreland basin aquifers may be ultimately sourced to crustal evolution processes related to plate tectonics, along with transportation of As-enriched magmatic rocks from the depth to surficial deposits, which subsequently release or mobilize the As to groundwater under conducive surficial biogeochemical processes. Circulating As-laden hydrothermal fluids may also be derived from magmas and form part of the discharge in the surficial hot springs in arc environments. These hydrothermal-genic deposits in orogenic belts may also act as the primary provenance for the As-laden sediments that are transported into foreland basins by wind, glacial erosion, and/or streams. Ultimately, the As-laden foreland sediments serve as modern-day aquifers, where the sediments release As into groundwater by water–rock interaction during various biogeochemical processes under conducive hydrogeochemical conditions. The significance of this hypothesis is that it proposes the existence of a common primary source for globally dispersed geogenic As-enriched aquifers, that have been so far mostly studied as individual occurrences. The proposed hypothesis can explain the widespread presence of As in areas as diverse as the Indus–Ganges–Brahmaputra basin (Himalayan orogen), the Chaco-Pampean basin (Andean orogen), Rocky mountain basin (Western Cordilleran orogen), New England and northeastern USA (the Applachian orogen).

Texas’ geothermal resource base: A raster-integration method for estimating in-place geothermal-energy resources using ArcGIS

The large sedimentary basins of Texas have been and are currently the subject of intensive petroleum exploration and production. The Gulf Coast, East Texas, the Anadarko Basin, and West Texas have all produced significant volumes of both oil and gas. Many of the fields and reservoirs within these basins are now mature or reaching the end of their productive lives and present an opportunity for these deep formations to be transitioned from petroleum production to geothermal-energy production using the existing infrastructure and the legacy of geologic information created by the oil and gas industry.The Gulf Coast and the Anadarko Basin have previously been analyzed for thermal energy in place, although formations in East and West Texas have not. A problem lies in the fact that previous studies may have overestimated thermal energy by employing a more simplistic method, in which a basin is split into one or more uniform-temperature blocks for which thermal energy in place is calculated. This is overcome in the present study by using ArcGIS to create a maximum extractable depth raster for both maximum well depth and maximum extractable depth in regions of Texas. The thermal energy in place is then derived through integration of the geothermal gradient raster over the block volume defined by the maximum depth raster to estimate thermal energy in place. A reference temperature of 93°C (200°F) is used.The results of this methodology indicate that 1.66E+23Joules (2.71E+13bbl oil equivalent) reside in place in Texas that is accessible using existing wells. Regionally the Gulf Coast contains 3.20E+22Joules (5.24E+12bbl oil equivalent), East Texas contains 4.04E+22Joules (6.60E+12bbl oil equivalent), West Texas contains 1.42E+22Joules (2.32E+12bbl oil equivalent), and North Texas contains 4.20E+21Joules (6.87E+11bbl oil equivalent).

Monitoring CO2 injection for carbon capture and storage using time-lapse 3D VSPs

Carbon capture and storage (CCS) is the process through which a nearly pure carbon dioxide (CO2) stream is captured, separated from flue gas or other industrial processes, compressed, transported to an appropriate storage site, and injected deep underground into a geological formation where it can be safely stored for long-term geologic storage (Benson, 2005). Large sedimentary basins, such as the Illinois, Michigan, and Western Canadian sedimentary basins are good targets for CCS, as they are in close proximity to large CO2 emitters and are composed of the appropriate saline formations and overlying nonpermeable formations. In 2003, the U.S. Department of Energy's National Energy Technology Laboratory (DOE-NETL) created a nationwide network of federal, state, and private sector partnerships to determine the most suitable technologies, regulations, and infrastructure for future CCS in different areas of the North America (Office of Fossil Energy, 2013).

Basin‐scale CO2 storage capacity assessment of deep saline aquifers in the Songliao Basin, northeast China

AbstractGeological storage of CO2 in deep saline aquifers has become one of the most important methods of reducing the emission of anthropogenic greenhouse gas into the atmosphere. The assessment of potential CO2 storage capacity is an important part of geological storage design. In this study, the potential CO2 storage capacity in the deep saline aquifers of the Songliao Basin – a large sedimentary basin in northeastern China – was assessed on a basin scale. The study results showed that: (1) deep saline aquifers suitable for geological CO2 storage occur mainly in the Cretaceous layers. Six deep saline aquifers were identified as potential storage formations, all with good reservoir‐caprock properties. (2) The residual gas trapping storage capacity and solubility trapping storage capacity of CO2 were considered for theoretical storage capacity estimation and the total CO2 storage capacity is 160030.00 × 106 t in the deep saline aquifers. The effective storage capacity was 19983.89 × 106 t, 78368.16 × 106 t and 215512.40 × 106 t with the storage efficiency factors of 0.0051, 0.02 and 0.055, respectively, and the average value is 104621.50 × 106 t. Storage intensity is defined as the effectiveness of unit area storage capability and the value of each tectonic unit ranges from 0.21 to 1.10 × 106 t/km2, with an average storage intensity for the whole Songliao Basin of 0.63 × 106 t/km2. The saline formations could be used to store CO2 for at least 55 years with a great CO2 emission annual growth rate of 10%, and for about 980 years with the CO2 emission annual growth rate of 1%. (3) Comparative analysis of the deep saline storage capacities in the basin showed that the Northern Plunge area and Central Downwarp area have the highest potential for CO2 storage in saline aquifer. These results could be used as important guidelines for the selection and design of CO2 storage fields in the Songliao Basin, China.

Overview on the Strong-Motion Data Recorded during the May-June 2012 Emilia Seismic Sequence

Online Material: Supplemental table, figures. On 20 May 2012, at 02:03:52 GMT, an earthquake with M w 6.1 (Regional Centroid Moment Tensor [RCMT]; http://www.bo.ingv.it/RCMT) occurred in northern Italy striking a densely populated area. The mainshock was followed a few hours later by two severe aftershocks having the same local magnitude ( M L 5.1, Fig. 1a), and by hundreds of smaller aftershocks. Nine days later, on 29 May, at 07:00:03 GMT, a second event with moment magnitude M w 6.0 (RCMT; http://www.bo.ingv.it/RCMT) occurred to the west, on an adjacent fault segment. This event was also followed by hundreds of aftershocks, three of them having local magnitudes 5.3, 5.2, and 5.1 (Fig. 1a; locations from Istituto Nazionale di Geofisica e Vulcanologia, hereinafter INGV; http://iside.rm.ingv.it/; Malagnini et al. , 2012; Scognamiglio et al. , 2012). Despite the moderate number of casualties if compared to other major events in Italian history, the economic loss was extremely high, resulting in about EUR 5 billion (AON Benfield, 2012; http://www.aon.com/), as the majority of Italian industrial activities and infrastructure concentrate in this area, the eastern Po plain, which is the largest sedimentary basin in Italy. Figure 1. (a) Simplified geological sketch of the Po plain and surrounding northern Apennines and Southern Alps fold‐and‐thrust belts. Key to symbols: stars, earthquakes of M >5 of the 2012 Emilia–Romagna seismic sequence, dimension proportional to the magnitude; dark gray areas, Composite Seismogenic Sources (CSS) of the DISS database (http://diss.rm.ingv.it), the upper tip of the fault plane is highlighted in black. Focal mechanisms of the 20 and 29 May 2012 earthquakes are from the TDMT database (http://cnt.rm.ingv.it/tdmt.html). (b) Simplified geological sections crossing the Po plain and showing thickness variation of the Plio‐Quaternary sedimentary sequence correlated with syncline–anticline pairs of the northern Apennines and Southern Alps thrust belts. Modified from Cassano et al. (1986), sections 1, 2, …

Petrostratigraphic evolution of the Thrace Basin (Bulgaria, Greece, Turkey) within the context of Eocene-Oligocene post-collisional evolution of the Vardar-İzmir-Ankara suture zone

Eocene-Oligocene paleogeographic/paleotectonic reconstructions of the Rhodopian – northern Aegean – western Black Sea region largely ignore the Thrace Basin, a large sedimentary basin up to 9 km thick that has been long interpreted as a forearc basin developed in a context of northward subduction. Recent structural, stratigraphic, petrologic, and sedimentologic data challenge this notion and may instead be interpreted within a context of upper-plate extension during the complex transition between the collisional tectonic regime related to the closure of Vardar-İzmir-Ankara oceanic realm and the extensional regime characterizing the Oligocene-Neogene evolution of the Aegean and peri-Aegean regions. The detritus filling the Thrace Basin was derived from two main sediment source areas: (i) the mostly metamorphic terrains of the Rhodopes to the west and (ii) the Vardar-İzmir-Ankara and Biga (intra-Pontide?) subduction-accretion prisms to the southwest. During most of the Eocene-Oligocene, the entire basin was characterized by a complex physiography, as shown by commercial seismic lines in the subsurface and abrupt lateral facies change at the surface. Such physiography was controlled by a series of basement highs trending from WNW-ESE (in the eastern and northern portions of the basin) to WSW-ENE (in the western and southern portions of the basin) which influenced sediment dispersal and the areal distribution of paleoenvironments.

Groundwater Visualisation System (GVS): A software framework for integrated display and interrogation of conceptual hydrogeological models, data and time-series animation

Summary Management of groundwater systems requires realistic conceptual hydrogeological models as a framework for numerical simulation modelling, but also for system understanding and communicating this to stakeholders and the broader community. To help overcome these challenges we developed GVS (Groundwater Visualisation System), a stand-alone desktop software package that uses interactive 3D visualisation and animation techniques. The goal was a user-friendly groundwater management tool that could support a range of existing real-world and pre-processed data, both surface and subsurface, including geology and various types of temporal hydrological information. GVS allows these data to be integrated into a single conceptual hydrogeological model. In addition, 3D geological models produced externally using other software packages, can readily be imported into GVS models, as can outputs of simulations (e.g. piezometric surfaces) produced by software such as MODFLOW or FEFLOW. Boreholes can be integrated, showing any down-hole data and properties, including screen information, intersected geology, water level data and water chemistry. Animation is used to display spatial and temporal changes, with time-series data such as rainfall, standing water levels and electrical conductivity, displaying dynamic processes. Time and space variations can be presented using a range of contouring and colour mapping techniques, in addition to interactive plots of time-series parameters. Other types of data, for example, demographics and cultural information, can also be readily incorporated. The GVS software can execute on a standard Windows or Linux-based PC with a minimum of 2 GB RAM, and the model output is easy and inexpensive to distribute, by download or via USB/DVD/CD. Example models are described here for three groundwater systems in Queensland, northeastern Australia: two unconfined alluvial groundwater systems with intensive irrigation, the Lockyer Valley and the upper Condamine Valley, and the Surat Basin, a large sedimentary basin of confined artesian aquifers. This latter example required more detail in the hydrostratigraphy, correlation of formations with drillholes and visualisation of simulation piezometric surfaces. Both alluvial system GVS models were developed during drought conditions to support government strategies to implement groundwater management. The Surat Basin model was industry sponsored research, for coal seam gas groundwater management and community information and consultation. The “virtual” groundwater systems in these 3D GVS models can be interactively interrogated by standard functions, plus production of 2D cross-sections, data selection from the 3D scene, rear end database and plot displays. A unique feature is that GVS allows investigation of time-series data across different display modes, both 2D and 3D. GVS has been used successfully as a tool to enhance community/stakeholder understanding and knowledge of groundwater systems and is of value for training and educational purposes. Projects completed confirm that GVS provides a powerful support to management and decision making, and as a tool for interpretation of groundwater system hydrological processes. A highly effective visualisation output is the production of short videos (e.g. 2–5 min) based on sequences of camera ‘fly-throughs’ and screen images. Further work involves developing support for multi-screen displays and touch-screen technologies, distributed rendering, gestural interaction systems. To highlight the visualisation and animation capability of the GVS software, links to related multimedia hosted online sites are included in the references.

CO2 Storage Potential in the Nordic Region

European research projects mapping and assessing geological storage capacity have indicated a large potential in the Nordic region accounting for 59% of the total mapped European storage capacity of 358 Gt. These studies, however did only include storage capacities from Denmark and Norway and thus failed to review the capacities from Finland, Iceland and Sweden. A new Nordic expertise centre for CCS named NORDICCS will in the coming years attempt to improve the mapping of CO2 storage sites and storage capacity estimations within the Nordic region. Preliminary results indicate that large sedimentary basins in the Baltic Sea, the Skagerrak area, the North Sea and the area offshore mid-Norway will be able to store large amounts of CO2 in deep saline aquifers and depleted oil and gas fields. In addition early research results from Iceland indicate a large potential for in-situ mineralisation of CO2 in porous basalts, and a minor potential for mineral trapping in ultramafic rocks in Finland. Data from all five Nordic countries underlines results of the previous European projects; the total updated assessed geological storage potential in selected areas is 76 Gt for in saline aquifers, 29 Gt for hydrocarbon fields and between 62-333 Gt for areas with potential for mineral trapping.

Impact of Rock Weathering on the Chemical Composition of Groundwater Determined by Inverse Modeling in Large Sedimentary Basins

This study focuses on the geochemistry of groundwater in a large sedimentary Eocene aquifer system. The main goals of the investigation are determining the influence of rock weathering and quantifying the inputs from each of the end-members (i.e., silicate, carbonate, evaporite) by using an inverse method approach of mass budget equations. We report here the results obtained on 42 groundwater samples collected in a large aquifer (The) in the Adour- Garonne district (SW France). Mass budget equations solved using an inverse method allowed us to estimate the contribution of the different sources among which, carbonate inputs dominate, evaporites often play a secondary role, and silicate inputs may be important.

Potential of Sub-seafloor CO2 Geological Storage in Northern South China Sea and its Importance for CCS Development in South China

The South China, especially Guangdong Province, as the most developed area of China emitted large CO2 from energy consumption and industrial production, actively advocates low-carbon development strategies. As an effective option to reduce CO2 emissions, CCS is potentially an effective option to reduce CO2 emissions to low-carbon economy development of South China, especially to Guangdong province. The CO2 storage potential in sedimentary basins onshore South China is limited as previous indicated. So the potential of sub-seafloor CO2 storage in offshore basins would be important. According to the assessment in this paper, large sedimentary basins offshore in the northern SCS have huge CO2 storage potential. Miocene deltaic, coastal plain, and neritic clastic rocks in these basins contain high-porosity and high-permeability aquifers and excellent seals. The estimated effective storage capacity, which is 2.6% of the theoretical capacity, is ∼300 GtCO2 in PRMB, ∼57 GtCO2 in BBGB, ∼41Gt CO2 in QDNB and∼160Gt CO2 in YGHB. On the whole, the Tertiary sedimentary basins in northern SCS margin have large storage capacities of abut 567Gt CO2, which provide a promising storage option for CCS implementation in South China. As the high costs is a major obstacles for sub-seafloor CO2 storage, the reuse of infrastructures for oil and gas development, such as platforms, wells and pipelines, would be the first choice. Although the theoretical storage capacities of the offshore oil and gas fields in the northern SCS are small, they distributed as groups and clusters and associated with sufficient quantified CO2 storage capacity in the saline aquifers. Further assessments are needed to define the residual life (= equipment life minus the field life) of the infrastructures, their practical and matched storage capacities, as well as a proper character and site screening particularly in regard to containment and risk of leakage. All these have been done well ahead of the real abandons of the oil/gas fields, so that the fields are in “CO2 Storage Readlines (CSR)”.

Potential methane reservoirs beneath Antarctica

Once thought to be devoid of life, the ice-covered parts of Antarctica are now known to be a reservoir of metabolically active microbial cells and organic carbon. The potential for methanogenic archaea to support the degradation of organic carbon to methane beneath the ice, however, has not yet been evaluated. Large sedimentary basins containing marine sequences up to 14 kilometres thick and an estimated 21,000 petagrams (1 Pg equals 10(15) g) of organic carbon are buried beneath the Antarctic Ice Sheet. No data exist for rates of methanogenesis in sub-Antarctic marine sediments. Here we present experimental data from other subglacial environments that demonstrate the potential for overridden organic matter beneath glacial systems to produce methane. We also numerically simulate the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model and show that pressure/temperature conditions favour methane hydrate formation down to sediment depths of about 300 metres in West Antarctica and 700 metres in East Antarctica. Our results demonstrate the potential for methane hydrate accumulation in Antarctic sedimentary basins, where the total inventory depends on rates of organic carbon degradation and conditions at the ice-sheet bed. We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage.

Geophysical Images of the North Anatolian Fault Zone in the Erzincan Basin, Eastern Turkey, and their Tectonic Implications

The collision between the Arabian and Eurasian plates in eastern Turkey causes the Anatolian block to move westward. The North Anatolian Fault (NAF) is a major strike-slip fault that forms the northern boundary of the Anatolian block, and the Erzincan Basin is the largest sedimentary basin on the NAF. In the last century, two large earthquakes have ruptured the NAF within the Erzincan Basin and caused major damage (M s = 8.0 in 1939 and M s = 6.8 in 1992). The seismic hazard in Erzincan from future earthquakes on the NAF is significant because the unconsolidated sedimentary basin can amplify the ground motion during an earthquake. The amount of amplification depends on the thickness and geometry of the basin. Geophysical constraints can be used to image basin depth and predict the amount of seismic amplification. In this study, the basin geometry and fault zone structure were investigated using broadband magnetotelluric (MT) data collected on two profiles crossing the Erzincan Basin. A total of 24 broadband MT stations were acquired with 1–2 km spacing in 2005. Inversion of the MT data with 1D, 2D and 3D algorithms showed that the maximum thickness of the unconsolidated sediments is ~3 km in the Erzincan Basin. The MT resistivity models show that the northern flanks of the basin have a steeper dip than the southern flanks, and the basin deepens towards the east where it has a depth of 3.5 km. The MT models also show that the structure of the NAF may vary from east to west along the Erzincan Basin.

Offshore Sediment Character and Sand Resource Assessment of the Northern Gulf of Mexico, Florida to Texas

Abstract The Gulf of Mexico (GOM) continental shelf, extending approximately 1600 km from the Florida west coast to the U.S.–Mexico border, is a large sedimentary basin that has been the focus of much geologic study and surveys during the past 70 years, related mostly to oil and gas exploration. Relatively little attention has been focused on mapping and assessing offshore sediment character and resources, such as sand. It is increasingly recognized, however, that baseline scientific information on seafloor sediment character and composition is needed for managing and protecting natural resources and for providing information on sand availability and quality for potential use in a variety of coastal restoration and protection projects in all five of the states from Florida to Texas. The geomorphologic character and shallow sedimentary stratigraphy of the GOM shelf has been determined over geologic time by sediment inputs from rivers; sea-level fluctuations up to 120 m, resulting in transgressions and regr...

Deep structure of the crust beneath the Sea of Okhotsk inferred from 3D seismic density modeling

Potential field anomalies of the Sea of Okhotsk region are analyzed for compiling a map of the basement’s tectonic structures. A 3D density model of the Earth’s crust is constructed using seismogeological and experimental-petrophysical data, which made it possible to obtain a visual image of main structures of the region reflecting the observable geophysical anomalies. The obtained data allow a domain located in the central part of the Sea of Okhotsk beyond the limits of the exclusive economic zone of the Russian Federation to be considered as a natural continuation of the continental shelf since the latter is structurally similar to western Kamchatka. The deep structural boundaries rise beneath the large sedimentary Deryugin and Tinro basins, which is characteristic of petroliferous basins.

The Comprehensive Test for Geothermal Tail-Water Disposal

Geothermal reservoirs and groundwater resources in layered porous media in large sedimentary basins have enormous exploitation potential because of their extensive distribution, great quantity, and feasible temperatures and drilling depths. The discharge of geothermal wastewater (i.e. tail-water) on the surface is a serious environmental issue because of its high salinity content, so the Bureau of Geology Exploration and Mineral Resources Exploitation in Shandong Province, China called for the study of the disposal technique of the geothermal tail-water. The disposal test process is as follows: take the waste of geothermal water to make physics-chemistry preparative disposal; filtration with manganese-sand set and/or double-medium equipment; filtration with ion exchange resins; nanofiltration membrane separation; and reverse osmosis separation. After separation, the cheap, clean water can be used as a material for chemical plants. However, in the case of deeply embedded geothermal groundwater resources, connate water(buried water), or bad recharge conditions, must be dried up for a long time exploitation, causing ground depression. Therefore, it is concluded that systems utilizing reinjection, i.e. closed-circuit cycle mode injection, in sandstone reservoirs are ideal for the realization of sustainable exploitation of the geothermal groundwater resources with favorable environmental conditions on the surface.