Analysis of a deformable fracture in permeable material     

Lawrence C. Murdoch  Leonid N. Germanovich 《国际地质力学数值与分析法杂志》2006,30(6):529-561

The response of deformable fractures to changes in fluid pressure controls phenomena ranging from the flow of fluids near wells to the propagation of hydraulic fractures. We developed an analysis designed to simulate fluid flows in the vicinity of asperity‐supported fractures at rest, or fully open fractures that might be propagating. Transitions between at‐rest and propagating fractures can also be simulated. This is accomplished by defining contact aperture as the aperture when asperities on a closing fracture first make contact. Locations on a fracture where the aperture is less than the contact aperture are loaded by both fluid pressure and effective stress, whereas locations where the aperture exceeds the contact aperture are loaded only by fluid pressure. Fluid pressure and effective stress on the fracture are determined as functions of time by solving equations of continuity in the fracture and matrix, and by matching the global displacements of the fracture walls to the local deformation of asperities. The resulting analysis is implemented in a numerical code that can simulate well tests or hydraulic fracturing operations. Aperture changes during hydraulic well tests can be measured in the field, and the results predicted using this analysis are similar to field observations. The hydraulic fracturing process can be simulated from the inflation of a pre‐existing crack, to the propagation of a fracture, and the closure of the fracture to rest on asperities or proppant. Two‐dimensional, multi‐phase fluid flow in the matrix is included to provide details that are obscured by simplifications of the leakoff process (Carter‐type assumptions) used in many hydraulic fracture models. Execution times are relatively short, so it is practical to implement this code with parameter estimation algorithms to facilitate interpretation of field data. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Mud volcano gas hydrates in the Gulf of Cadiz     

L. L. Mazurenko  V. A. Soloviev  I. Belenkaya  M. K. Ivanov  L. M. Pinheiro 《地学学报》2002,14(5):321-329

ABSTRACT This paper presents new geochemical data on gas-hydrate-bearing mud volcanoes discovered for the first time in the Gulf of Cadiz during cruises TTR9 and TTR10 of the R/V Professor Logachev in 1999–2000. The estimated gas hydrate content is 3–16% of sediment volume and 5–31% of pore space volume. Estimated values of the water isotopic composition for the Ginsburg mud volcano are very heavy for δ¹⁸O (up to +53‰) and light for δD (up to − 210‰). Gas released from the hydrates contains 81% of C₁ and 19% of C₂₊. The inferred source of the gas in the hydrates is enriched in C₂–C₆ (≤ 5%), indicating that the gas has a thermogenic origin. Gas hydrate of cubic structure II should be formed from a gas of such composition. It is interpreted that the composition of the mud volcano fluid corresponds to deep oil basins below the Gulf of Cadiz.  相似文献   

Verification of Remote Sensing Data for Determining the Nature of Hydrocarbons (a Case Study of the Barents Sea)     

Nemirovskaya  I. A.  Ivanov  A. Yu. 《Doklady Earth Sciences》2022,507(1):941-945

Doklady Earth Sciences - Using the remote sensing data obtained by the Sentinel-1A and Sentinel-1B satellites in the years 2016–2021, a local accumulation of oil slicks in the Barents Sea in...  相似文献   

Laboratory tests with interferometric optical fibre sensors to monitor shallow landslides triggered by rainfalls     

Longoni  Laura  Ivanov  Vladislav  Ferrario  Maddalena  Brunero  Marco  Papini  Monica  Arosio  Diego 《Landslides》2022,19(3):761-772

Optical fibre–based sensors have now established their place in the field of geohazard monitoring due to their sensitivity to strain and temperature changes. Progressive development in the technology leads to the availability of novel, accurate and durable sensors at a relatively limited cost. This creates room for original monitoring applications that have been, so far, impeded by the shortcomings of conventional monitoring tools. In this work, we explore the applicability of an interferometric optical fibre sensor as a vibration sensing tool at laboratory scale. We tested the ability of the sensor to identify precursors of instability in a downscaled model of a rainfall-induced landslide composed of granular material. We carried out four experimental tests which involved different sensor deployments and soil mixtures. The recorded signals were processed by means of a time–frequency analysis and we identified two frequency-domain parameters—the spectral centroid and band power—that could provide information on the development of instability. Their ratio yielded a unique parameter through which a precursory stage could be outlined by defining a threshold value based on the data collected at the beginning of the experiment. In our lab tests, precursors of instability were detected 2–3 min before a crack was observed at the surface. This may upscale to a lead time of about 20–30 min or more in the field, classifying our monitoring approach in between an alarm and a warning system. The work presented here can be considered a first promising step towards an innovative monitoring system and shows the potential of optical fibre sensing as a shallow landslide monitoring technique, encouraging further testing, especially in real-case studies.

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Comparison of Atmospheric Circulation in the Area of Spitsbergen in 1920–1950 and in the Modern Warming Period     

P. N. Svyashchennikov  U. V. Prokhorova  B. V. Ivanov 《Russian Meteorology and Hydrology》2020,45(1):22-28

The results of studying the temporal variability of atmospheric circulation in the Western Arctic (the Norwegian and Barents seas) are presented. The daily dataset of Girs-Vangengeim E, W, and C circulation forms for the period of 1891–2016 is used to describe atmospheric circulation. Special attention is given to the estimation of differences in weather conditions during the modern period of warming (1985–2015) and in the period of the first Arctic warming (1920–1950). For the cold (November-March) and warm (April-October) seasons, the trends in the frequency of occurrence of the circulation forms are determined. The occurrence of the number of consecutive days with the same atmospheric circulation form which can be considered as a characteristic of weather stability during the analyzed period of warming, is computed for both seasons. The prevalence of the E circulation form during the warm season is typical of both periods. The modern period of warming in the study area, as compared to the period of the first warming, is characterized by an increase in the occurrence of the C circulation form with a short duration. It is found that the current climate regime is characterized by an increase in surface air temperature against a background of less stable weather conditions.  相似文献   

Estimation of the effect of protective piers on wind wave parameters in the Sevastopol Bay     

D. V. Alekseev  V. A. Ivanov  E. V. Ivancha  V. V. Fomin  L. V. Cherkesov 《Russian Meteorology and Hydrology》2013,38(4):248-255

An effectiveness of the storm wave attenuation by protective piers in the Sevastopol Bay of the Black Sea is studied on the basis of numerical simulation using the SWAN spectral model. Analyzed are the parameters of waves generated by winds of four main directions as well as by the southern cyclone during the storm on November 11, 2007. It is obtained that waves from the northwest part of the Black Sea penetrate most intensively into the Sevastopol Bay in case of western wind and, to a lesser degree, in case of northern and southern winds. A protective effect of the piers is observed in the west part of the bay only and the wave attenuation near the southern coast is more significant than near the northern one. The area of the southern coast directly behind the southern pier is completely protected from the storm waves and, as moving away from the pier, the danger of intensive wave effect on the coast is kept.  相似文献   

On equilibrium tides in fully convective planets and stars     

P. B. Ivanov  J. C. B. Papaloizou 《Monthly notices of the Royal Astronomical Society》2004,353(4):1161-1175

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POSSIBLE　HYDROGEOCHEMICAL　PRECONDITIONS　FOR　KASHIN－BECK　DISEASE　IN　TRANSBAIKALIA     

Zamana Leonid Vasilevich 《中国地理科学(英文版)》1995,5(2):185-192

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Reconstruction of Open Solar Magnetic Flux and Interplanetary Magnetic Field in the 20Th Century     

V. G. Ivanov  E. V. Miletsky 《Solar physics》2004,224(1-2):69-76

We reconstruct mean magnitudes of the open solar magnetic field since 1915 using α magnetic synoptic charts of the Sun. The obtained series allows estimation of the interplanetary magnetic field. They also confirm the known conclusion about the secular increase of the solar open magnetic flux in the first half of the 20th century.  相似文献   

On the maximum value of the cosmic abundance of oxygen and the oxygen yield     

Leonid S. Pilyugin  Trinh X. Thuan  José M. Vílchez 《Monthly notices of the Royal Astronomical Society》2007,376(1):353-360

We search for the maximum oxygen abundance in spiral galaxies. Because this maximum value is expected to occur in the centres of the most luminous galaxies, we have constructed the luminosity – central metallicity diagram for spiral galaxies, based on a large compilation of existing data on oxygen abundances of H  ii regions in spiral galaxies. We found that this diagram shows a plateau at high luminosities  (−22.3 ≲ M _B ≲−20.3)  , with a constant maximum value of the gas-phase oxygen abundance  12 + log (O/H) ∼ 8.87  . This provides strong evidence that the oxygen abundance in the centres of the most luminous metal-rich galaxies reaches the maximum attainable value of oxygen abundance. Since some fraction of the oxygen (about 0.08 dex) is expected to be locked into dust grains, the maximum value of the true gas + dust oxygen abundance in spiral galaxies is 12 + log(O/H) ∼ 8.95. This value is a factor of ∼2 higher than the recently estimated solar value. Based on the derived maximum oxygen abundance in galaxies, we found the oxygen yield to be about 0.0035, depending on the fraction of oxygen incorporated into dust grains.  相似文献