Search

Time-frequency analysis (TFA) is a widely used reservoir prediction technology. During the identification of sand bodies using TFA, abnormally high values in the high-frequency portion of the spectrum usually indicate the presence of thin sand bodies. However, owing to the complexity of the depositional environment, the spatial distribution of thin sand bodies is often variable, and multiple phases of sand bodies—superimposed on each other—can occur with uneven thicknesses. A frequency information extraction technique based on time-frequency ridges (TFRs) is proposed in this study to identify stable TFRs in the time-frequency spectrum of a rearranged smooth pseudo-Wigner–Ville distribution with high energy aggregation, as well as to extract the main- and high-frequency energy contents relative to them. To enhance the ability of these energy components to detect thin sand bodies, a frequency-energy weighting factor is computed. By performing the aforementioned steps, information about each frequency band can be obtained and a comprehensive depiction of sand bodies with different thicknesses achieved. It is concluded that by using the proposed method thin sand bodies such as small riverbeds can be effectively characterized using seismic data.

Integrated analyses of in situ zircon U-Pb ages and geochemistry were conducted on both granitic and metasedimentary borehole samples from immediately below the Cenozoic sedimentary cover of the northern South China Sea basin. Our work suggests that basement rocks of the South China Sea basin are not Proterozoic or Paleozoic rocks, as previously speculated based on gravity-magnetic inversion work. The analyzed metavolcaniclastic and metasedimentary rocks were likely deposited at or soon after ca. 145 Ma but prior to ca. 85 Ma. A nearby source in coastal South China is proposed based on the generally immature nature of the metasedimentary rocks and the lack of detritus from older basement rocks farther inland. The vast majority of the metavolcaniclastic samples have sparse ca. 250–190 Ma (particularly 200–190 Ma) zircons. This magmatic quiescence is consistent with the existence of a coastal magmatic gap to the east of Hainan Island during this time, previously interpreted as reflecting a period of flat-slab subduction. Metaclastic samples mostly exhibit a dominant ca. 180–120 Ma zircon population, indicating extensive magmatism along the coastal areas. This finding, together with previously reported ca. 190–180 Ma I-type coastal granites and our newly dated ca. 115–98 Ma volcanic and granitic rocks under the western part of the South China Sea basin can best be interpreted by the former presence of an Andean-type continental arc during the Middle Jurassic – Early Cretaceous. Magmatism along this arc ceased soon after 90 Ma or before ca. 85 Ma, with its last pulse represented by a small group of ca. 100–85 Ma granitic intrusions in the eastern part of the northern South China Sea basin. The arc appears to have jumped toward the Western Pacific Ocean at or soon after 90 Ma, starting the development of the Western Pacific-type plate margin.

During the Miocene, when the Zhujiang Formation was deposited, the eastern part of the Pearl River Mouth Basin, northern South China Sea, underwent intense mixed siliciclastic and carbonate sedimentation, particularly on the platform of the marginal ramp of the Dongsha Rise, northeastern margin of the South China Sea. Cores and well logs from industrial boreholes were collected and systematically investigated to reveal the sedimentary-petrographic characteristics of the mixed deposits and their formative processes. Four lithotypes were differentiated in the deposits, that is, (1) sandstone, (2) dolomitic sandstone and calcitic sandstone, (3) sandy dolomite and sandy limestone, and (4) dolomite, bioclastic limestone, and micrite limestone, which were formed by three major types of mixing processes: punctuated, facies, and in situ mixing processes. The porosity and permeability of the mixed deposits indicated that the siliciclastic component of the mixed deposits that experienced punctuated mixing formed the most high-quality hydrocarbon reservoirs. Exploration revealed that the lithologic reserves in the study area were mainly developed in mixed sedimentation areas. Our results suggest that the mixed sedimentation area, particularly with pure sandstone sedimentation or bioclastic sandstone, that underwent compaction or structural fracture activities, may be the next preference for lithologic exploration.

The anisotropy of rockfill materials has a significant influence on the performance of engineering structures. However, relevant research data are very limited, because of the difficulty with preparing specimens with different inclination angles using traditional methods. Furthermore, the anisotropy test of rockfill materials is complex and complicated, especially for triaxial tests, in which the major principal stress plane intersects with the compaction plane at different angles. In this study, the geometric characteristics of a typical particle fraction consisting of a specific rockfill material were statistically investigated, and the distribution characteristics of particle orientation in specimens prepared via different compaction methods were examined. For high-density rockfill materials, a set of specimen preparation devices for inclined compaction planes was developed, and a series of conventional triaxial compression tests with different principal stress direction angles were conducted. The results reveal that the principal stress direction angle has a significant effect on the modulus, shear strength, and dilatancy of the compacted rockfill materials. Analysis of the relationship between the principal stress direction angles, change in the stress state, and change in the corresponding dominant shear plane shows that the angle between the compacted surface and dominant shear plane is closely related to interlocking resistance associated with the particle orientation. In addition, different principal stress direction angles can change the extent of the particle interlocking effect, causing the specimen to exhibit different degrees of anisotropy.

The prolonged convergence along the Southeast Asian margin from the Mesozoic to Cenozoic shaped the region into a complex tectonic collage of microblocks of diverse origin and evolutionary history. Among these microblocks, the formation and paleogeographic evolution of the Palawan continental terrane remain issues of uncertainty and controversy, especially regarding the petrogenesis of the oldest rocks and the conjugate relationship with the South China margin. This study examined these issues from the perspective of detrital fingerprints (including geochemistry, heavy mineral, and zircon U-Pb geochronology) of Mesozoic to Cenozoic strata from Palawan Island and basins of the northern South China Sea. The across-margin comparison of provenance signatures, favored by a comprehensive data compilation and a revision of the stratigraphic framework using the youngest zircon ages, provides insights into regional paleogeographic reconstructions from the Jurassic to the Miocene. The results reveal provenance shifts that correspond to the paleogeography of the Palawan continental terrane evolving from an accretionary complex in the Jurassic to a rifted margin in the early Cenozoic and finally to a microcontinent in the middle Cenozoic. Based on comparable provenance signatures, the terrane is interpreted to have been conjugated to the northeastern South China Sea margin from the Mesozoic until the Oligocene spreading of the South China Sea. The terrane likely existed as a northern passive margin of the proto–South China Sea from the latest Cretaceous to early Cenozoic before the oceanic crust of the latter was emplaced over the former during the Oligocene–Miocene.

The Huizhou Movement refers to the Middle Eocene tectonic transition from the early to the late Wenchang Rifting stage (about 43 Ma ago) in the Pearl River Mouth Basin. Based on seismic reflection, drilling, logging and geological data, fault characteristic analysis, denudation thickness recovery, magmatism statistics, regional tectonic dynamics comparison and other methods are used to reveal the characteristics, properties and dynamic mechanism of the Huizhou Movement. The Huizhou Movement mainly shows the North-South transition of rifting and the migration along the faults, basement uplift, magmatic diapir and stratigraphic denudation. It is believed that the Huizhou Movement is a comprehensive reflection of plate interaction and lithospheric thinning process in the Pearl River Mouth Basin, which is closely related to the transition of lithosphere from initial rifting to rapid thinning, the India-Eurasia hard collision and the change of subduction direction of the Pacific plate. The Huizhou Movement has significant influence and control on the Paleogene hydrocarbon-generating sags and the development of hydrocarbon source rocks, sedimentary system and deep high-quality reservoir, hydrocarbon migration and accumulation in the Pearl River Mouth Basin.

The Paleogene geological framework and evolution process in the central anticline zone in the Lufeng 13 sag in Pearl River Mouth Basin is well analyzed through seismic data and drilling data, and control of tectonic evolution on hydrocarbon accumulation is also discussed. The results show that the central anticline zone in the Lufeng 13 sag develops the upper deformation layer and lower deformation layer. The “arched graben system” is developed in the upper deformation layer, and the magmatic diapir structure and flowing deformation of plastic strata is developed in the lower deformation layer. The evolution process of the central anticline zone can be divided into four stages, i.e. fault block uplifting stage, prototype stage, strengthening stage and finalization stage. The geological framework and tectonic evolution of the central anticline zone control Paleogene hydrocarbon accumulation. The Paleogene two-layer geological framework is favorable for development of structural traps and composite traps; the paleostructure highs are the direction of hydrocarbon migration, and the gravitational gliding faults are the main carrier bed for vertical hydrocarbon migration; the tectonic uplift is a key factor for reservoir diagenesis improvement and preservation of primary pores, and also controls distribution of high-quality reservoirs. Keywords: Geological framework, Upper and lower deformation layers, Gravitational gliding faults, Hydrocarbon migration and accumulation, Carrier bed, The central anticline zone, Lufeng sag

A systematic geochemical analysis of samples from newly drilled wells in the Lufeng Sag, Pearl River Mouth Basin has been carried out to characterize source rock quality, determine organic matter input and reconstruct the depositional environment of the Enping and Wenchang formations. Total organic carbon (TOC) content ranges from 0.46 to 1.57 wt% in the Enping formation, and from 0.53 to 6.10 wt% in the Wenchang formation. Kerogen types I-II were identified in the Wenchang formation samples, while kerogen types II-III were identified in the Enping formation samples. Maturity parameters suggest marginally mature to mature levels for most samples with higher maturity for the Wenchang formation samples. Biomarker assemblage and trace element ratios of the Wenchang and Enping formations are distinctively different, indicating predominantly aquatic origin organic matter input under suboixc-anoxic water conditions for the Wenchang formation and more allochthonous terrestrial organic matter input under oxic water conditions for the Enping formation. Moderate to high primary productivity and temperature drove water stratification, together with weak detrital material dilution led to the enrichment of organic matter in the Wenchang formation. While the low primary productivity, poor preservation conditions and high dilution led to the relatively poor source rock quality in the Enping formation.

For the first time, we have applied the idea of a source-to-sink balance to study the ancient geomorphology of an uplift in a continental basin. By assessing the differential subsidence and denudation in the context of a source-to-sink system's volume balance, we have established a set of methods to restore the uplift geomorphology. We use the latest 3D seismic data over the Huizhou-Lufeng uplift, Pearl River Mouth Basin, South China Sea. By identifying the catchment and sedimentary boundaries, we have divided first-order, second-order, and third-order source-to-sink systems and subordination between them. The results showed that there are 3 s-order systems and three third-order source-to-sink systems recorded in the unique first-order systems of the eastern Huizhou-Lufeng uplift. The restored geomorphology of the Huizhou-Lufeng uplift in the Lower Wenchang Formation shows that the ancient height (h0) and the dip angle (α0) of each source area are generally much larger than those in the present day in the three third-order source-to-sink systems. These recovered landforms are related to the development of relatively sand-dominated delta systems. The three second-order source-to-sink systems have a larger ancient height (h0), but the ancient dip angle (α0) increment is smaller than today, likely related to the development of interbedded sandstone and mudstone delta systems. Our restoration of the geomorphology in this region may guide the assessment of reservoir properties and scales in the Pearl River Mouth Basin, in large part because our source-to-sink method explains the distribution of various sediment types in the region.

A multiple-anchored fluorescent probe ((((hexane-1,6-diylbis(2,7-bis(4-formyl)-phenyl)-9H-fluorine-9,9-diyl))-bis(hexane-6,1-diyl))-bis(9H-carbazole-9,3,6-triyl))-tetrakis(benzene-4,1-diyl))-tetraformyl-(8FP-2F) with eight aldehyde groups was designed and synthesized. The molecule has four branches and highly twisted structure. Furthermore, it tends to self-assemble into nanospheres, which is beneficial for gaseous analyte penetration and high fluorescence quantum efficiency. Among gaseous analytes, detection of aniline vapor is extraordinarily important in the control of environmental issues and human diseases. Herein, 8FP-2F was introduced to detect aniline vapor with distinguished sensitivity and selectivity via simple Schiff base reaction at room temperature. After exposure to saturate aniline vapor, the 89% fluorescence of 8FP-2F was quenched in 50 s and the detection limit was as low as 3 ppb. Further study showed the suitable HOMO/LUMO energy levels and matched orbital symmetry between probe and aniline molecules ensured chemical reaction and PET process work together. The synergistic effect resulted in a significant sensing performance and fluorescence quenching toward aniline vapor. Moreover, the multiple active sites structure of 8FP-2F means it could be applied for constructing many interesting structures and highly efficient organic optoelectronic functional materials.

Inspired by the wide application of whispering gallery mode (WGM) resonance in the field of photonics, a robust sensing platform made of a hollow-shell silica microsphere was proposed and employed for the detection of low vapour pressure explosives such as nitrate ester and hexogen (RDX). The fluorescent sensory materials were synthesized by the organo-functionalization of intact hollow silica microspheres with two rationally designed pyrene derivatives as sensing units. The sensing films of fluorescent microspheres (NPC-Py-SiO2 and TPA-Py-SiO2) made by solid phase transfer method displayed 92% quenching efficiency towards ethylene glycol dinitrate (EGDN) and an 80% sensing response to nitroglycerin (NG) within 300 seconds. In addition, the quenching efficiency and fluorescent intensity of the dye-functionalized microspheres were greatly enhanced by over 900% and 300% compared with their corresponding fluorophores (NPC-Py and TPA-Py), along with superior stability for practical use. Furthermore, the amplified fluorescent intensity and sensitivity were in accordance with theoretical simulation, which proved the WGM resonance of closely stacked silica microspheres. This study enlarged the application of resonant cavities based on size-controlled and functionalized microspheres by a facile preparation method, providing an agile sensing platform for trace explosives and other chemical species with excellent performance.

Sarin is a nerve agent that is usually used in terrorist attacks. Diethyl chlorophosphate (DCP) has a similar reactivity to sarin, but lacks high toxicity, so DCP is a good model compound for sarin detection. Terpyridine is a common functional unit used in coordination compounds, but not used in toxic gas detection. In this contribution, multiple terpyridine units were introduced into the periphery of hyperbranched conjugated polymers with pyrene as the core and fluorene as connecting units for highly efficient DCP detection, which utilized the excellent properties of hyperbranched polymers including high functional group density, efficient energy transfer from the core to the periphery units, etc. As compared with linear small molecular probes, terpyridine end capped hyperbranched polymers showed much better photostability and sensitivity to DCP vapor. The fluorescence was almost completely quenched under saturated DCP vapor within 3 s and the emission peak red-shifted from 468 nm to 554 nm. A concentration of 65 ppt DCP with a quenching efficiency of 3.6% could be detected, which is far better than the results estimated by others. Therefore, multiple terpyridine end capped hyperbranched polymers are a very promising probe for nerve agent detection whatever in the sensitivity or response rate.

Interpretation of seismic data from the Lufeng Sag of the Pearl River Mouth Basin (PRMB) in the northern part of South China Sea shows that different intersection patterns developed in the cover units above basement normal faults. A series of analogue models are used to investigate the intersection patterns and deformation in the sedimentary cover sequences above a basement horst bounded by two non-parallel faults. Modelling results show that during their upward propagation, the basement faults may intersect within the cover sequences and form a graben above the basement horst. Length and width of the graben increase with cover thickness. The strike and dip intersection points are controlled directly by the thickness of the cover sequences, dip and strike of the basement faults, and width of the basement horst. The intersection point migrates along the axis of the graben toward the wide end of the basement horst, when the cover sequence thickens. In contrast, it migrates toward the narrow end of the basement horst, where both fault dip and angle of strike difference increase. The intersection point moves upward with increasing width of the basement horst crest. Model profiles also indicate that in the presence of a ductile layer between the cover and basement such intersection patterns do not form. Interpretation of seismic data and model results show that the intersection pattern developed in the Lufeng Sag is a result of propagation of basement faults into cover units during different extension stages of the basin. Results of this study can be applied to many other sedimentary basins where such fault intersection patterns are likely to form when non-parallel conjugate basement faults are active during sedimentation.

The well LF35-1-1 in the eastern Pearl River Mouth basin (PRMB) of the northern South China Sea revealed unmetamorphosed Middle-Late Jurassic neritic-bathyal sediments and Cretaceous fluvial-lacustrine sediments. Three tectonic movements were identified in Late Jurassic to Early Cretaceous, late Early Cretaceous, and Late Cretaceous to Paleocene, respectively. The Late Jurassic marine facies mainly contain the hydrocarbon source and reservoir-seal assemblages, providing a main exploration target.

To study the deep dynamic mechanism leading to the difference in rifting pattern and basin structure from shelf to oceanic basin in passive continental margin, we constructed long geological sections across the shelf, slope and oceanic basin using new seismic data. Integrated gravity-magnetic inversion and interpretation of these sections were made with the advanced dissection method. Results show that the basement composition changes from intermediate-acid intrusive rocks in the shelf to intermediate-basic rocks in the slope. The Moho surface shoals gradually from 31 km in the shelf to 22.5 km in the uplift and then 19 km in the slope and finally to 13 km in the oceanic basin. The crust thickness also decreases gradually from 30 km in the northern fault belt to 9 km in the oceanic basin. The crustal stretching factor increases from the shelf toward the oceanic basin, with the strongest extension under the sags and the oceanic basin. The intensity of mantle upwelling controlled the style of basin structures from shelf to oceanic basin. In the Zhu 1 depression on the shelf, the crust is nearly normal, the brittle and cold upper crust mainly controlled the fault development; so the combinative grabens with single symmetric graben are characteristic. In the slope, the crust thinned with a large stretching factor, affected by the mantle upwelling. The ductile deformation controlled the faults, so there developed an asymmetric complex graben in the Baiyun (白云) sag.

Service-Oriented Computing (SOC) is emerging as a new promising computing paradigm. Web service discovery is one of the key issues in SOC. Web service discovery usually provide UDDI as a standard registry which features only keyword-based matches that often give poor performance. Currently approaches for semantic service discovery are mostly limited to the matching of their inputs/outputs possibly enhanced with some ontological knowledge. Recent works have demonstrated that this approach is not sufficient to discover relevant services. In this paper, we argue that in many situations, the service discovery should be based on the specification of service behavior. The idea behind this is to develop matching techniques that operates on behavior models and allow delivery of partial matches. We give the relative definition of our formal model based on Petri nets and WF-nets and propose the transformation from the OWL-S process model into a formal model we defined. And then we define behavior equivalence notion based on our formal model and detail the semantic web service matchmaking algorithm based on that notion.