Injection experiments and thermal recovery in corehole OH-1, Lake City,California     

Jason?R.?McKennaEmail author  Walter?R.?Benoit  Colin?B.?Goranson  David?D.?Blackwell 《Natural Resources Research》2004,13(4):241-253

Two injection tests, shallow and deep, followed by repeated temperature logging were performed in the Lake City, California OH-1 corehole, to delineate permeable zones, investigate the permeability of rocks adjacent to the wellbore, and to test the validity of maximum-reading thermometer (MRT) measurements collected during the drilling process that show lower than static temperatures above a depth of 2100 ft and significantly higher than static temperatures below a depth of about 2500 ft. The tests confirmed several permeable zones in OH-1. At about 300 ft, there is a strong zone of lateral flow, and at 947 ft there is a major outflow zone for injected fluid. Two other possible permeable flow zones were detected from the thermal recovery logs: one at about 1500 ft and another at about 2300 ft. The 2300 ft permeable zone seems to be an inflow zone, and the source of a probable downflow responsible for cooling the wellbore below about 2500 ft. The hotter MRT data obtained during drilling may be reconciled with the significantly lower static temperature logs if downflow from about 2300 ft is present.  相似文献   

Accounting for length- and depth-dependent diel variation in catchability of fish and invertebrates in an annual bottom-trawl survey   总被引：4，自引：0，他引：4  

Benoit  Hugues P; Swain  Douglas P 《ICES Journal of Marine Science》2003,60(6):1298-1317

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Rift propagation at craton margin.: Distribution of faulting and volcanism in the North Tanzanian Divergence (East Africa) during Neogene times   总被引：1，自引：0，他引：1  

B. Le Gall  P. Nonnotte  J. Rolet  M. Benoit  H. Guillou  M. Mousseau-Nonnotte  J. Albaric  J. Deverchre 《Tectonophysics》2008,448(1-4):1-19

A revised kinematic model is proposed for the Neogene tectono-magmatic development of the North Tanzanian Divergence where the axial valley in S Kenya splits southwards into a wide diverging pattern of block faulting in association with the disappearance of volcanism. Propagation of rifting along the S Kenya proto-rift during the last 8 Ma is first assumed to have operated by linkage of discrete magmatic cells as far S as the Ngorongoro–Kilimanjaro transverse volcanic belt that follows the margin of cratonic blocks in N Tanzania. Strain is believed to have nucleated throughout the thermally-weakened lithosphere in the transverse volcanic belt that might have later linked the S Kenya and N Tanzania rift segments with marked structural changes along-strike. The North Tanzanian Divergence is now regarded as a two-armed rift pattern involving: (1) a wide domain of tilted fault blocks to the W (Mbulu) that encompasses the Eyasi and Manyara fault systems, in direct continuation with the Natron northern trough. The reactivation of basement fabrics in the cold and intact Precambrian lithosphere in the Mbulu domain resulted in an oblique rift pattern that contrasts with the orthogonal extension that prevailed in the Magadi–Natron trough above a more attenuated lithosphere. (2) To the E, the Pangani horst-like range is thought to be a younger (< 1 Ma) structure that formed in response to the relocation of extension S of the Kilimanjaro magmatic center. A significant contrast in the mechanical behaviour of the stretched lithosphere in the North Tanzanian diverging rift is assumed to have occurred on both sides of the Masai cratonic block with a mid-crustal decoupling level to the W where asymmetrical fault-basin patterns are dominant (Magadi–Natron and Mbulu), whereas a component of dynamical uplift is suspected to have caused the topographic elevation of the Pangani range in relation with possible far-travelled mantle melts produced at depth further N.  相似文献   

Investigating possible links between the North Atlantic Oscillation and rainfall variability in Marrakech (Morocco)     

Imen?TurkiEmail author  Benoit?Laignel  Noureddine?Laftouhi  Zeneddine?Nouaceur  Zineb?Zamrane 《Arabian Journal of Geosciences》2016,9(3):243

Eighty-two-year rainfall time series have been studied together with climatic patterns of NAO using classical statistical methods. Then, the wavelet approach has been applied to show annual (1 year (1y)) and inter-annual (2–4 years (2-4y), 5–8 years (5-8y), and 8–16 years (8-16y)) modes distributed following four major discontinuities: 1945, 1960, 1975, and 1995. The 1y, 2-4y, and 5-8y powers show high energy during the wet period 1922–1930 and a low one in 1928–1938. After 1945, the annual mode highlights a high energy while the inter-annual modes present low energy. Between 1975 and 1995, powerful modes of 1 and 2–4 years are identified with low power of 5-8y and 8-16y modes. Since 1995, the low power of 5–8y decreases, while the 8-16y mode emphasizes a high variability. The coherence between NAO and Marrakech precipitation is strongly defined for low frequencies with a total contribution of 75 %. This coherence is in phase in the beginning and presents out phase signs since 1945. The change of phase can be associated to a decreasing of coherence especially around 1990. This finding is useful to understand the relationship between the hydrological variability and NAO climate patterns in the southern side of the Mediterranean Sea.  相似文献   

About the Determination of Quasi Steady State Storativity and Connectivity Matrix of Wells in 3D Heterogeneous Formations     

Benoit Noetinger 《Mathematical Geosciences》2016,48(6):641-662

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Experimental study of the ground motion on a large scale topographic hill at Kitherion (Greece)     

Benoit LeBrun  D. Hatzfeld  P.Y. Bard  M. Bouchon 《Journal of Seismology》1999,3(1):1-15

We present the results of an experiment about the effects on the seismic ground motion of a hill of large dimensions (6km long, 3km large and 700m high) near Corinth (Greece). We installed 7 seismometers across the hill, and analyzed the ground motion with different methods: the classical spectral ratios (CSR) and the horizontal to vertical spectral ratios calculated both on noise (HVNR) and earthquake data (RF). The amplification at the resonant frequency (around 0.7Hz) is low, as expected, but one of the two stations installed at the top exhibits large amplification (up to a factor of 10) at 3Hz. The comparison between the H/V results and the CSR ones suggests that the former method is able to point out the fundamental frequencies of a hill. Amplifications and spatial localization predicted by numerical 3D modeling are consistent with the experimental data only at frequencies lower than 1Hz.  相似文献   

Nature and biological composition of the New Caledonian outer barrier reef slopes     

Benoit Flamand  Guy Cabioch  Claude Payri  Bernard Pelletier 《Marine Geology》2008,250(3-4):157-179

The Grande Terre of New Caledonia is enclosed by one of the longest barrier reefs in the world. For the first time, the fore-reef slopes of this barrier reef have been sampled by dredging, from 40 to 320 m deep, in order to analyze their sedimentological and biological characteristics. The rocks and sediments can be divided into seven sedimentary facies: bindstones dominated by coralline algal crusts, bindstones dominated by foraminiferal crusts, bindstones dominated by bryozoan crusts, coral framestones, bindstones and interstratified packstones rich in skeletal debris, packstones/wackestones and grainstones rich in rock gravels. Radiocarbon dating performed on encrusting organisms (coralline algae and acervulinids) and corals provide ages relatively young. These ages confirm that the encrusting organisms are modern and the corals mainly dated of Holocene are reworked due to the instability of the fore-reef slopes, especially during storms. Because the biological assemblages are distributed according to a bathymetric range depending on light intensity, a model of distribution of modern encrusting calcareous organisms can be proposed from our observations and analyses. From the upper reef slopes to approximately 90 m, thick coralline algal crusts are dominant and distributed in three groups. Group C, the shallowest parts of the fore slopes, is mainly characterized by mastophorids (Hydrolithon reinboldii, H. cf. munitum, Lithoporella melobesoides, Aethesolithon cf. problematicum, Neogoniolithon sp. and undetermined species) and lithophylloids (Lithophyllum sp., L. pustulatum). Group B, composed of lithophylloids (Lithophyllum sp., L. cf. kotschyanum, L. cf. moluccence, L. pustulatum), Mesophyllum sp. and Peyssonnelia sp. occurs from 15 to 40 m. Group A, rich in Mesophyllum sp., M. cf. mesomorphum, Peyssonnelia sp. and Sporolithon sp. is characteristic of deep reef slopes up to 90 m. Below approximately 90 m, when the light intensity decreases, the encrusting foraminifera acervulinids progressively replace the coralline algal crusts. Such a model is particularly useful to interpret and reconstruct the past Quaternary reef environments rich in crusts of coralline algae and/or foraminifera.  相似文献   

Mapping surface water erosion potential in the Soummam watershed in Northeast Algeria with RUSLE model     

Youcef SAHLI  Elhadj MOKHTARI  Belkacem MERZOUK  Benoit LAIGNEL  Christophe VIAL  Khodir MADANI 《山地科学学报》2019,(7)

The present study aims to estimate the annual soil loss in the Soummam watershed in the northeast of Algeria, using the Revised Universal Soil Loss Equation(RUSLE), geographic information system(GIS), and remote sensing(RS). RUSLE model has been used for modelling the main factors involved in erosive phenomena. The Soummam watershed covers a surface area of 9108.45 km2 of irregular shape, northeast –southwest towards southeast. It is characterized by an altitude varying between 2 m in the northeast and 2308 m in the northwest. Results showed that the average erosivity factor(R) is 70.64(MJ·mm)/(ha·h·year) and the maximum value reaches 140(MJ·mm)/(ha·h·year), the average soil erodibility factor(K) is 0.016(t·h·ha)/(MJ·ha·mm) and maximum values reach 0.0204(t·h·ha)/(MJ·ha·mm) in the southeast regions of the watershed, the average slope length and steepness factor(LS) is 9.79 and the mean C factor is estimated to be 0.62. Thematic maps integration of different factors of RUSLE in GIS with their database, allowed with a rapid and efficient manner to highlight complexity and factors interdependence in the erosion risk analyses. The resulting map for soils losses, with an average erosion rate of 6.81 t/(ha·year) shows a low erosion(7.41 t/(ha·year)) which covers 73.46% of the total area of the basin, and a medium erosion(7.42 to 19.77 t/(ha·year)), which represents 17.66% of the area. Areas with extreme erosion risk exceeding 32.18 t/(ha·year) cover more than 3.54% of the basin area. The results can certainly aid in implementation of soil management and conservation practices to reduce the soil erosion in the Soummam watershed.  相似文献   

Estimating aquifer thickness using multiple pumping tests     

Jean-Christophe Maréchal  Jean-Michel Vouillamoz  M. S. Mohan Kumar  Benoit Dewandel 《Hydrogeology Journal》2010,18(8):1787-1796

A method to estimate aquifer thickness and hydraulic conductivity has been developed, consisting of multiple pumping tests. The method requires short-duration pumping cycles on an unconfined aquifer with significant seasonal water-table fluctuations. The interpretation of several pumping tests at a site in India under various initial conditions provides information on the change in hydrodynamic parameters in relation to the initial water-table level. The transmissivity linearly decreases compared with the initial water level, suggesting a homogeneous distribution of hydraulic conductivity with depth. The hydraulic conductivity is estimated from the slope of this linear relationship. The extrapolation of the relationship between transmissivity and water level provides an estimate of the aquifer thickness that is in good agreement with geophysical investigations. The hydraulically active part of the aquifer is located in both the shallow weathered and the underlying densely fractured zones of the crystalline basement. However, no significant relationship is found between the aquifer storage coefficient and initial water level. This new method contributes to filling the methodological gap between single pumping tests and hydraulic tomography, in providing information on the variation of the global transmissivity according to depth. It can be applied to any unconfined aquifer experiencing large seasonal water-table fluctuations and short pumping cycles.  相似文献   

Geochemical modelling of fluid–rock interactions in the context of the Soultz-sous-Forêts geothermal system     

Bertrand Fritz  Emmanuel Jacquot  Benoit Jacquemont  Armelle Baldeyrou-Bailly  Michel Rosener  Olivier Vidal 《Comptes Rendus Geoscience》2010,342(7-8):653-667

The development of the Enhanced Geothermal System (EGS) at Soultz-sous-Forêts (France) has given to scientists an interesting opportunity for the application of geochemical modelling of water–rock interactions, combining theoretical studies with field and experimental data. The main results of four successive and complementary studies are summarized: geochemical modelling of fluid–rock interactions with prediction of dissolution/precipitation of minerals, feed-back effects on the mineralogy and petrography of the rock (major role of silicates in the geological past and of carbonates in the near future of the exploitation), experimental control of the dynamics of silicates under thermal gradient and relation between the evolution of the petrophysics of the rocks and the heat and mass transfers. The thermal cycle of the fluid, between 200 °C and 65 °C in the geothermal loop, may be responsible for dissolution/precipitation of minerals which modify the porosity and permeability of the granite, as it happened in the geological past, in relation with hydrothermal circulations in the Rhine Graben.  相似文献