Dome Structure Research Articles

Bolted joints for small and medium reticulated timber domes: experimental study, numerical simulation, and design strength estimation

This paper proposes a new type of bolted glulam joint for small-span and medium-span reticulated timber dome structures. The joint fastens the timber elements and the angled slotted-in steel plates together with steel bolts. Reasonably simplified experiments were designed and conducted to understand the mechanical properties of the proposed joint. Finite element models were also developed and calibrated with the tested results. A four-line model was provided to explain the mechanical properties of the joints, which were observed from the tests and simulations. To facilitate the future use of the proposed joint, theoretical derivations were provided to estimate its mechanical features. According to the estimation equations, bilinear moment–rotation curves could be easily obtained for the joints with different wood species, member sizes, joint designs, and/or bolt diameters. Finally, full-size structural models were created to investigate the static stability of K6 single-layered reticulated timber domes with the proposed joints. The influences on the ultimate structural stability capacity from the span, the rise-to-span ratio, the joint model (i.e., stiffness), the initial geometric imperfection introduced from the construction, and the load distribution were systematically investigated.

Energy-based seismic stability analysis of single-layer reticulated dome structures

Seismic stability of single-layer dome structures is closely related to both the external seismic ground motions and structural properties. The physical mechanism of seismic instability of single-layer reticulated dome structures is investigated from the perspective of energy, which can take into account both the external excitations and structural properties. First, the energy balance equation is established and the accuracy for calculating each energy component of structures is verified. Then, the energy-based criterion is introduced as a quantitative index for the identification of seismic stability/instability, where the first-passage of the intrinsic energy over the input energy demonstrates the seismic instability of single-layer reticulated dome structures. Besides, some qualitative indices are also employed to further confirm the judgement by the energy-based criterion. By using the proposed criterion, the critical peak ground acceleration for seismic stability of single-layer reticulated dome structures can be identified by using the incremental dynamic analysis. The energy-based criterion is also validated by comparisons with the B-R criterion. Parametric analyses are implemented to investigate the impacts of different structural parameters on seismic stability and characteristic responses of single-layer dome structures. • Seismic stability of single-layer reticulated dome structures relates to both structural parameters and external excitation. • An energy based criterion is introduced to identify the seismic instability. • The proposed criterion is validated by the comparison with the B-R criterion. • Parametric analyses are conducted to investigate the impacts of different parameters.

Provenance and salt structures of gypsum formations in Pb-Zn ore-bearing Lanping basin, Southwest China

Large-scale gypsum rocks associated with world-class Pb-Zn ore formations are widely distributed in the Lanping Basin, Sowthwest China. Geochemical studies alongside field investigations were conducted in this study to determine the source and evolutionary processes of the gypsum rocks in this area. The gypsum sequences in the Lanping Basin developed in two formations: the Triassic Sanhedong Formation and the Paleogene Yunlong Formation. The gypsum hosted in the former displays a primary thick-banded structure with δ34SV-CDT values in the range of 14.5‰–14.8‰. Combined with the 87Sr/86Sr values (0.707737–0.707783) of limestone, it can be suggested that the Sanhedong Formation is of marine origin. In contrast, the gypsum from the Paleogene Yunlong Formation is characterized by the dome, bead and diapiric salt structures, wider range of both 87Sr/86Sr (0.707695–0.708629) and δ34SV-CDT values (9.6‰–17‰), thus indicating a marine source but with the input of continental materials. The initial layered salt formations were formed by chemical deposition in a basin and were later intensely deformed by collisional orogeny during the Himalaya period. As a result, variable salt structures were formed. We hereby propose an evolutionary model to elucidate the genesis of the gypsum formations in the Lanping Basin.

Modified Inverse-Injectivity Method for Stimulation Evaluation Proves Effective

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 200135, “A Comprehensive Method for Diverter-Performance Evaluation During Stimulation of Long-Interval Heterogeneous Reservoirs: A Case Study” by A.F. Safari and H. Panjalizadeh, Mehran Engineering and Well Services Company; M. Pournik, SPE, The University of Texas Rio Grande Valley; and H. Jafari and A. Zangeneh, Mehran Engineering and Well Services Company, prepared for the 2020 SPE Conference at Oman Petroleum and Energy Show, Muscat, Oman, 14-16 September. The paper has not been peer reviewed. Assessment of diversion performance is key to determining success of stimulation. Doubts remain, however, regarding the evaluation of diversion effectiveness. As diverter enters the formation, a hump in the surface pressure curve usually is expected. It then can be interpreted as supporting evidence for diversion. This, however, is a simplification of the fluid-diversion process. Such a hump may not be observed during a diversion stage even when the process is effective. In the complete paper, the inverse-injectivity method of evaluating matrix-stimulation performance is modified and validated with real data of two matrix-acidizing operations in a gas-condensate field. South Pars Gas Field In 1971, an enormous gas reservoir, the North Dome Field, was found in the Qatar Dome structure of the Persian Gulf. In the years since, surveys have highlighted the existence of abundant amounts of gas and condensate accumulations in a huge dome. This single gas-bearing structure is delineated by the geographical borders between Iran and Qatar in the Persian Gulf. According to one recent estimate, almost 19% of the world’s gas rests in this vast basin. The field includes two independent gas-bearing formations, Kangan (Triassic) and Upper Dalan (Permian). Each formation is divided into layers separated by impermeable barriers, namely K1, K2, K3, and K4. The K1 and K3 layers mostly are formed of dolomites and anhydrites. Layers K2 and K4 possess better reservoir specifications (i.e., highly permeable and porous, consisting of limestone and dolomite). An anhydrite-composed layer, the Nar Member, separates Layer K4 from the underlying K5 layer, which has nonsatisfactory reservoir qualities. Methodology In this study, the inverse injectivity and its integral and derivative plot are coupled with results of production logs to evaluate diverter-system performance in two real acidizing operations performed in the South Pars field. What makes this work different is the complexity of the treated reservoir in terms of the number of layers (four distinct formations), formation heterogeneity, and long perforation intervals (an approximately 1,000-ft net interval). The productivity index is a measure of the well’s production potential and is defined as a ratio of the total liquid surface rate to the pressure drop at the midpoint of the producing interval. Because the direction of flow in this case is in a direction opposite that of production, this parameter is considered as the reverse of the productivity index and is called inverse injectivity. In this study, a program is written to calculate modified inverse injectivity during two real matrix stimulations performed in the field. The equations used in this method are provided in the complete paper.

Interpretation of lineaments and faults near Summerville, South Carolina, USA, using LiDAR data: implications for the cause of the 1886 Charleston, South Carolina, earthquake

LiDAR (light detection and ranging) data acquired near Summerville, South Carolina, reveal numerous lineaments trending in various directions across the Middleton Place-Summerville seismic zone (MPSSZ) and surrounding area. These lineaments are defined by linear depressions and stream valleys that are developed within late Eocene to Holocene marine, marginal marine, and fluvial sediments of the Atlantic Coastal Plain. The 40-kmlong, ENE-WSW-oriented Deer Park lineament coincides with the Woodstock epicenter of the 1886 Charleston earthquake, suggesting that the main shock may have occurred along a fault associated with this lineament. The proximity of the 17-km-long, ENE-WSW-oriented Middleton Place lineament to the Middleton Place epicenter suggests that it too may have ruptured in 1886. Several E-W-oriented topographic scarps are also located near the area of modern seismicity, including the 3- to 5-km-long, south-facing McChune and Summerwood scarps. The McChune scarp is aligned with the E-W-trending portion of the Summerville scarp to the west, suggesting that both scarps may be from uplift to the north along the same fault. The McChune scarp and the Otranto and Middleton Place lineaments coincide with faults interpreted from previously acquired seismic-reflection profiles, suggesting that these features are surface expressions of Quaternary faults. Other lineaments east of the MPSSZ are associated with Neogene structural domes, indicating that the interpreted faults along these lineaments have been active during the late Cenozoic. The LiDAR data also revealed a ~350-m dextral offset of a middle Pleistocene beach ridge along the Woodstock fault and a ~20-km-long, NW-SE-oriented lineament to the east (Canterhilllineament) that appears to be the surface expression of the Charleston fault.

Superconducting dome revealed by surface structure dependence in single unit cell FeSe on SrTiO3(001)

We report the superconducting properties of single unit cell FeSe prepared on ${\mathrm{SrTiO}}_{3}\phantom{\rule{0.28em}{0ex}}(\mathrm{STO})\phantom{\rule{0.28em}{0ex}}(001)\text{\ensuremath{-}}c(6\ifmmode\times\else\texttimes\fi{}2)$ using scanning tunneling microscopy/spectroscopy (STM/STS). A surface superstructure of $c(6\ifmmode\times\else\texttimes\fi{}2)$ was obtained by annealing the substrate under an oxygen atmosphere. A $3\ifmmode\times\else\texttimes\fi{}1$ periodicity, which corresponds to the topmost Ti atoms of the substrate, was observed in high-resolution STM images, and the superconducting gap size was $11.5\ifmmode\pm\else\textpm\fi{}2.5\phantom{\rule{0.28em}{0ex}}\mathrm{meV}$. A nonsuperconducting region with additional $\sqrt{2}\ifmmode\times\else\texttimes\fi{}\sqrt{2}$ periodicity was also found, and this originates from the difference in the arrangement of the Sr and Ti atoms at the surface. We conclude that there is a universal superconducting dome structure in the (electron-doping level)---(superconducting gap size) phase diagram by comparing with previous results that controlled the surface of the substrate/film and the gap size can be maximized/minimized by selecting the appropriate STO surface superstructure.

Quantum electronics and optics at the interface of solid neon and superfluid helium

We predict a new quantum electronic structure at the interface between two condensed phases of noble-gas elements: solid neon and superfluid helium. An excess electron injected onto this interface self-confines its wavefunction into a nanometric dome structure. Its size varies with pressure and optical transitions cover a broad mid-infrared spectrum. A collection of such electrons can form a classical Wigner crystal resembling a quantum-dot array on a triangular lattice. Under ultrafast laser illumination, this Wigner crystal can exhibit the quantum optical phenomenon of superradiance in the picosecond time scale. The ultralong spin-coherence time and micron-scale deterministic configurability allow the electrons in this system to serve as quantum information carriers. Their spin states can be controlled and readout by on-chip single-electron devices.

Structural evolution and exhumation of the Yulong dome: Constraints on middle crustal flow in southeastern Tibetan Plateau in response to the India-Eurasia collision

It is generally accepted that lateral rigid block extrusion of the Sundaland block in southeastern Tibetan plateau accommodated the India-Eurasia collision. Recent studies, however, revealed that channel flow of low-viscosity middle to lower crust can explain outward growth of the Tibetan plateau. Controversies continue as to which of these processes is most significant and how the crustal mass flew if happened in response to the India-Eurasia collision. In this contribution, we focus on characterizing the Cenozoic ductile deformation of the Yulong complex beyond the eastern Himalayan Syntaxis. Detailed structural, microstructural, fabrics and thermo-chronological studies demonstrate that the Yulong complex constitutes an anticlinal dome structure. Three stages of structural deformation, i.e., D1-a pure shear-dominated deformation, D2-a simple shear-dominated progressive deformation and D3-a superposition deformation, contributed to the formation and exhumation of the dome structure. The main stage of exhumation of the Yulong dome occurred in Oligocene-Miocene (34-8 Ma). The core part experienced fast cooling from ~425 °C at ca. 11–12 Ma to ~110 °C at ca. 8–9 Ma with cooling rate of 105–109 °C/Ma. However, the limb experienced relatively slow cooling, with cooling rate of 10.8 °C/Ma from 33.5 Ma to 16 Ma. Such a cooling pattern (earlier, slower in the limbs and later, faster in the core) is interpreted as the result of exhumation by anticlinal folding. Structural analysis reveals that the doming was coeval with bedding-parallel shearing of the Yulong complex. We show, from the present study, that Oligo-Miocene crustal flow occurred along subhorizontal shear zones throughout the middle to lower crust in eastern and southeastern Tibetan Plateau. Top-to-the south or southeast subhorizontal shearing during doming possibly resulted from combined effects of southward gravitational sliding of rigid upper crust and northward flow of viscous lower crust relative to the middle-upper crust.

Propagation behaviour of a hemispherical blast wave on a dome roof

Dome structures are often employed for industrial buildings and may be potential targets of terrorist attacks or accidental explosion. Military design manuals that are commonly used for structural design practice are based on the assumption that the blast wave reflects on an infinite or finite flat surface. These semi-empirical formulae ignore the blast wave propagation behaviour on a finite and variable-curvature reflector. The purpose of this research work is to estimate the blast load on dome structures during an external explosion. To achieve this objective, two laboratory-scale spherical dome structures were tested experimentally with 11 different blast cases. Following the experimental analysis, numerical parametric analysis based on ANSYS/AUTODYN was carried out to study the propagation and reflection on dome roofs. In addition, the performance of the Mach effect, reflection effect, diffraction effect, clearing effect and decay coefficient of the blast wave on the dome roof were investigated for different structural and explosion parameters. Based on this, a series of empirical equations are proposed to describe the temporal and spatial blast load distribution on a dome roof mounted on a supporting structure. This new load model described in the paper has been validated as it is able to predict the results of the experimental measurement on dome structures within experimental error.

Genesis of the Markam gneiss dome within the Songpan-Ganzi orogenic belt, eastern Tibetan Plateau

The Markam gneiss dome within the Songpan-Ganzi orogenic belt, eastern Tibetan Plateau, is cored by the Keryin-Taiyanghe granitoids and mantled by Upper Triassic, turbiditic, metasedimentary rocks, which have been intruded by numerous pegmatites and veins. The large-scale Markam detachment fault separates the granitoid core from the overlying Upper Triassic metasedimentary rocks. Microstructures and quartz fabrics from the Markam detachment fault show a top-to-the-south shearing sense and point to formation under high temperatures (>650 °C). New zircon UPb geochronological data from the Markam gneiss dome reveal two stages for the granitoid core at ca. 226–212 Ma and ca. 224–218 Ma. In addition, zircon UPb dating of syn-tectonically deformed pegmatites in the Markam detachment fault shows that the detachment fault was initiated at ca. 212–207 Ma. Later-stage, undeformed pegmatites (including spodumene-bearing varieties) that form sill- and dyke-networks have ages of ca. 200–190 Ma. Our data indicate that formation of the Markam gneiss dome was triggered by development of the Markam detachment fault after the emplacement of the granitoid core. And the following diapiric uplift of the granitoids continued the growth of the Markam gneiss dome, resulting in formation of a thermal domal structure, which further uplifted the magma to a more favorable metallogenic environment and controlled the occurrence of the ore veins. Thus, it indicates that the spodumene-bearing pegmatites emplaced under extensional and decompressional conditions during the Songpan-Ganzi exhumation orogeny.

Tectonic evolution of Kutch sedimentary basin, western India

Lithological variations, circular spectral anomalies, geological structures such as folds, faults, lineaments and shear zones of Kutch sedimentary basin were interpreted using IRS-LISS III satellite data. Aeromagnetic data was also interpreted qualitatively and quantitatively and a number of anomalous magnetic zones, faults, lineaments and domal structures were mapped. Magnetic basement depths and thickness of sediments were also computed. A number of alternate basement ridges/highs/uplifted blocks and depressions/lows/downthrown blocks were delineated. The information obtained from satellite remote sensing and aeromagnetic data were then integrated and the results were compared with published literature on gravity, magnetic (ground), magnetotelluric and seismic data, and also with field geology and well data. Structural controls in spatial domain (latitude, longitude and depth) were derived by establishing spatial relationship among different geological structures with reference to the geological time scale. Numerous horst and graben structures (ridges and sub-basins) as well as a number of master faults were delineated which serve as vital information with regard to hydrocarbon prospects and earthquake vulnerability, respectively. Based on the information obtained from this integrated study, a conceptual tectonometamorphic model along with sedimentation and igneous activity (ophiolitic and basaltic) has been constructed which has a significant bearing on the sequence of events that occurred during the deformational history of Kutch sedimentary basin resulting into the present day tectonic configuration.

Deep crustal source of gneiss dome revealed by eclogite in migmatite (Montagne Noire, French Massif Central)

AbstractIn orogens worldwide and throughout geologic time, large volumes of deep continental crust have been exhumed in domal structures. Extension‐driven ascent of bodies of deep, hot crust is a very efficient mechanism for rapid heat and mass transfer from deep to shallow crustal levels and is therefore an important mechanism in the evolution of continents. The dominant rock type in exhumed domes is quartzofeldspathic gneiss (typically migmatitic) that does not record its former high‐pressure (HP) conditions in its equilibrium mineral assemblage; rather, it records the conditions of emplacement and cooling in the mid/shallow crust. Mafic rocks included in gneiss may, however, contain a fragmentary record of a HP history, and are evidence that their host rocks were also deeply sourced. An excellent example of exhumed deep crust that retains a partial HP record is in the Montagne Noire dome, French Massif Central, which contains well‐preserved eclogite (garnet+omphacite+rutile+quartz) in migmatite in two locations: one in the dome core and the other at the dome margin. Both eclogites record P ~ 1.5 ± 0.2 GPa at T ~ 700 ± 20°C, but differ from each other in whole‐rock and mineral composition, deformation features (shape and crystallographic preferred orientation, CPO), extent of record of prograde metamorphism in garnet and zircon, and degree of preservation of inherited zircon. Rim ages of zircon in both eclogites overlap with the oldest crystallization ages of host gneiss at c. 310 Ma, interpreted based on zircon rare earth element abundance in eclogite zircon as the age of HP metamorphism. Dome‐margin eclogite zircon retains a widespread record of protolith age (c. 470–450 Ma, the same as host gneiss protolith age), whereas dome‐core eclogite zircon has more scarce preservation of inherited zircon. Possible explanations for differences in the two eclogites relate to differences in the protolith mafic magma composition and history and/or the duration of metamorphic heating and extent of interaction with aqueous fluid, affecting zircon crystallization. Differences in HP deformation fabrics may relate to the position of the eclogite facies rocks relative to zones of transpression and transtension at an early stage of dome development. Regardless of differences, both eclogites experienced HP metamorphism and deformation in the deep crust at c. 310 Ma and were exhumed by lithospheric extension—with their host migmatite—near the end of the Variscan orogeny. The deep crust in this region was rapidly exhumed from ~50 to <10 km, where it equilibrated under low‐P/high‐T conditions, leaving a sparse but compelling record of the deep origin of most of the crust now exposed in the dome.

Velocity-amplified monostable dual-charged electret dome energy harvester using low-speed finger tapping

Power generation from linear finger-tapping-based electrostatic energy harvesting (FTEEH) devices is hindered by the slow capacitance variation under low-speed finger-tapping (FT) motion. Herein, a velocity amplification mechanism is proposed, which exploits the snap-through behavior of a dual-charged electret monostable dome structure and thus greatly enhances the power generation of FTEEH devices from slow FT motion. The kinetic energy and velocity amplification during the buckling event were effectively predicted for various specimens using the modified Föppl–von Kármán equations and Hamilton's principle. A high degree of dynamic velocity amplification was demonstrated both theoretically and experimentally and quantified with respect to the velocity gain and power gain. Specifically, the velocity of the capacitance variation of the designed FTEEH device, driven by a slow FT motion at 2.7 cm/s, was substantially increased to 18.5 cm/s, affording a high velocity gain of 6.9 and a correspondingly large power gain of 6.8. The proposed velocity-amplified nonlinear FTEEH device was compared with recently developed linear FTEEH devices that do not utilize this velocity amplification mechanism and found to yield a large pulse width of 90.0 ms (full width) and a high volumetric power density of 1015.7 μW/cm3.

Prefabricated Dome Structures with Walls Made of Soil Composites and Urea-Formaldehyde Foam Insulation (UFFI) as a Way to Solve Transport Infrastructure Problems in Permafrost Regions

The territory of Russia extends from West to East for more than 10 thousand kilometres. Recently, this land has become of strategic importance on the international arena. The future development of Russia and its international situation will largely depend on the timely development of these territories. The development of infrastructure in permafrost regions requires the use of not only special construction technologies and materials, but also special design solutions that can reduce further operating costs, while maintaining the most comfortable conditions for human life and activities

Exhumation and landscape evolution in eastern South China since the Cretaceous: New insights from fission-track thermochronology

Widespread extensional half-/grabens with red bed sedimentation, dome structures, and magma intrusions/eruptions with polymetallic mineralization within South China during the Cretaceous-Cenozoic provide a natural laboratory to understand intracontinental deformation and plate tectonics. In order to decipher the tectonic and landscape evolution of eastern South China, this study presents new low-temperature thermochronology from a broad region covering major tectonic units including the Xuefeng, Jiuling, Nanling, and Wuyi mountains. Zircon and apatite fission track dates, length distribution, and thermal history modeling reveal a prominent and rapid cooling phase during ~125–80 Ma across the paleo-highland in eastern South China. A synthesis of existing thermochronologic data and geological observations suggests that NE/NNE-striking syn-sedimentary faults system with half-/graben basins, rapid exhumation of Cretaceous magma and pre-Cretaceous basement, and final extension of dome structures were all initiated in a back-arc setting during this period (~80-125 Ma). Eastern South China during the Paleogene was characterized by a tectonic quiescence during which insignificant exhumation, peneplanation, and local sedimentation occurred, forming regional low-amplitude, long-wavelength topography. Accelerated regional cooling commenced in the late Oligocene or early Miocene in response to the far-field effect of the India-Asia continental convergence. Additionally, the termination of red-colored gypsum-salt-bearing sediment in the Neogene suggests a paleo-environmental change within South China, from an arid to a monsoonal climate; such change was likely the result of the topographic uplift of the Tibetan Plateau and its margins.

Consideration of Al-Wajid graben tectono-stratigraphy by analysis of geophysical data, Saudi Arabia

Al-Wajid graben is one of the largest Precambrian fault-bound basins in Saudi Arabia. Seismic reflection data show a deep-seated dome structure in the middle of the graben, which can be interpreted as a salt dome, an inversion structure, or even an igneous pluton. This ambiguity makes it difficult to understand the tectono-stratigraphy of Al-Wajid graben. In this paper we sought to understand the tectono-stratigraphy of Al-Wajid graben by analysis of various remote sensing geophysical data including vertical seismic profile (VSP), gravity, magnetic and seismic reflection data.Determination of depth to basement from the magnetic data suggests that the dome structure is non-magnetic since the depth solutions were obtained at the bottom of the structure. Processing of the VSP data was useful in estimating some physical parameters for the structure in question such as acoustic impedance, velocity, and density. The estimated density is 2700 kg/m3, which suggests that the structure is unlikely to be salt and most likely to be a dense mafic or metamorphic of non-magnetic rocks. This interpretation is consistent with extension and subsidence of the graben.The integrated interpretation of seismic, VSP, gravity, and magnetic data proposes that Al-Wajid graben is a deep trough intruded by dense magmatic rocks before opening the graben. The cooling of these igneous rocks has caused local densification and continuous subsidence that implied downward bending of the crust, creating the basin as a cratonic graben. Since Precambrian, the graben has been affected by several tectonic phases of extension and compression, ending with positive inversion.

Continuous size optimization of large-scale dome structureswith dynamic constraints

In this study size optimization of large-scale dome structures with dynamic constraints is presented. In the optimal design of these structure, the Jaya algorithm is used to find minimal size of design variables. The design variables are the cross-sectional areas of the steel truss bar elements. To take into account the constraints which are the first five natural frequencies of the structures, the finite element analysis is coded in Matlab programs using eigen values of the stiffness matrix of the dome structures. The Jaya algorithm and the finite elements codes are combined by the help of the Matlab - GUI (Graphical User Interface) programming to carry out the optimization process for the dome structures. To show the efficiency and the advances of the Jaya algorithm, 1180 bar dome structure and the 1410 bar dome structure were tested by taking into the frequency constraints. The optimal results obtained by the proposed algorithm are compared with those given in the literature to demonstrate the performance of the Jaya algorithm. At the end of the study, it is concluded that the proposed algorithm can be effectively used in the optimal design of large-scale dome structures.

The influence of coupling on the whole process of construction simulation of chord dome structure

：Chord dome structure is a new type of hybrid prestressed spatial steel structure system, which is often used in large-span structures. During the construction of the structure, it is necessary to apply prestress to the ring cable. Taking the chord dome roof of Hebei North University gymnasium as an example, the whole process of prestressed cable construction is simulated and analyzed by using the finite element software ANSYS. The hoop cable of the dome roof can slide freely in the hoop direction, and the attribute of free sliding in the ANSYS interface is "coupling". In this paper, two kinds of simulation models, coupling and uncoupling, are established to compare, and then to explore the influence of coupling on the construction process of string dome structure.

Chiswick and Kew fields, Blocks 49/4a, 49/4b, 49/4c, 49/5a and 49/5b, UK North Sea

Abstract The Chiswick Field is a Carboniferous gas field located in UK Blocks 49/4a and 49/4b in the Southern North Sea, approximately 18 km NW of the Markham Field, close to the UK–Netherlands median line. The Kew Field is situated approximately 3 km NE of the Chiswick Field. The Kew structure is a NW–SE-trending horst separated from the Chiswick Field, a large anticlinal domal structure, by a major NW–SE fault and a structural low. The productive reservoir units are Carboniferous (Westphalian A and B) fluvial sandstones. Both fields are situated on the eastern edge of the Silverpit Basin (part of the Southern Permian Basin). The initial exploration drilling had Leman Sandstone Formation as the primary objective, but the first wells encountered a tight Permian reservoir with gas-bearing Carboniferous reservoirs, subsequently appraised and developed. The current estimate for the gas initially in place of Chiswick and Kew is respectively 687 bcf and 85 bcf in the Carboniferous reservoir. The fields to date (Q4 2018) have produced respectively 220 bcf and 33 bcf sales gas. Gas recovery is through natural depletion from hydraulically fractured, horizontal development wells.

The Elswick Field, Bowland Basin, UK Onshore

Abstract The Elswick Field is located within Exploration Licence EXL 269a (Cuadrilla Resources Ltd is the operator) on the Fylde peninsula, West Lancashire, UK. It is the first producing onshore gas field to be developed by hydraulic fracture stimulation in the region. Production from the single well field started in 1996 and has produced over 0.5 bcf for onsite electricity generation. Geologically, the field lies within a Tertiary domal structure within the Elswick Graben, Bowland Basin. The reservoir is the Permian Collyhurst Sandstone Formation: tight, low-porosity fluvial desert sandstones, alluvial fan conglomerates and argillaceous sandstones. The reservoir quality is primarily controlled by depositional processes further reduced by diagenesis. Depth to the reservoir is 3331 ft TVDSS with the gas–water contact at 3400 ft TVDSS and with a net pay thickness of 38 ft.