A New Rapid Method for Measuring the Vertical Head Profile          下载免费PDF全文

Carl Keller 《Ground water》2017,55(2):244-254

This study describes a new technique for measuring the head profile in a geologic formation. The technique provides rapid, low cost information on the depth of water‐producing zones and aquitards in heterogeneous aquifers, yielding estimates of hydraulic heads in each zone while identifying any potential for cross contamination between zones. The measurements can be performed in a typical borehole in just a few hours. The procedure uses both the continuous transmissivity profile obtained by the installation (eversion) of a flexible borehole liner into an open borehole and the subsequent removal (inversion) of the same liner from the borehole. The method is possible because of the continuous transmissivity profile (T profile described by Keller et al. 2014) obtained by measuring the rate of liner eversion under a constant driving head. The hydraulic heads of producing zones are measured using the reverse head profile (RHP) method (patent no. 9,008,971) based on a stepwise inversion of the borehole liner. As each interval of the borehole is uncovered by inversion of the liner, the head beneath the liner is allowed to equilibrate to a steady‐state value. The individual hydraulic heads contributing to each measurement are calculated using the measured transmissivity for each zone. Application of the RHP method to a sedimentary bedrock borehole in New Jersey verified that it reproduced the head distribution obtained the same day in the same borehole instrumented with a multilevel sampling system.  相似文献   

Is there a relationship between abyssal scleractinian corals and the global oceanic conveyor belt?     

N. B. Keller  N. S. Oskina  T. A. Savilova 《Oceanology》2017,57(4):552-557

The investigation data on Scleractinia of the abyssal zone have been generalized. Based on an analysis of maps of the distribution pattern of these corals, it can be concluded that there is a close correlation between the spread of their species and the position of the ocean currents that form the global oceanic conveyor belt. The maps were compiled from published and our own data collected on expeditions of the Shirshov Institute of Oceanology of the Russian Academy of Sciences. We analyzed data on 106 stations. The location of the global oceanic conveyor belt was shown in the maps. The distribution pattern of abyssal coral species confirms our assumption that there are two possible ways of origin of abyssal fauna. We suppose that the genera Fungiacyathus and Leptopenus are ancient and have evolved in deep oceanic layers, while the species D. parvulus obviously originated from shallow-water ancestors and then migrated deep into the abyssal zone as a result of the transition to neotenic development.  相似文献   

New Method for Continuous Transmissivity Profiling in Fractured Rock   总被引：2，自引：0，他引：2  

Carl E. Keller  John A. Cherry  Beth L. Parker 《Ground water》2014,52(3):352-367

A new method is presented to search for hydraulically transmissive features in open boreholes in bedrock. A flexible borehole liner made of a watertight, nylon fabric is filled with water to create a constant driving head to evert (reverse of invert) the liner down the hole so that the liner pushes the borehole water out into transmissive fractures or other permeable features. The descent rate is governed by the bulk transmissivity of the remaining permeable features below the liner. Initially, the liner descent rate or velocity is a measure of transmissivity (T) of the entire hole. As the everting liner passes and seals each permeable feature, changes in the liner velocity indicate the position of each feature and an estimate of T using the Thiem equation for steady radial flow. This method has been performed in boreholes with diameters ranging from 96 to 330 mm. Profiling commonly takes a few hours in holes 200‐ to 300‐m long. After arrival of the liner at the bottom of the hole, the liner acts as a seal preventing borehole cross connection between transmissive features at different depths. Liner removal allows the hole to be used for other purposes. The T values determined using this method in a dolostone aquifer were found to be similar to the values from injection tests using conventional straddle packers. This method is not a replacement for straddle‐packer hydraulic testing of specific zones where greater accuracy is desired; however, it is effective and efficient for scanning entire holes for transmissive features.  相似文献   

Initial results and progress of the Mississippi delta sediment pore water pressure experiment     

Richard H. Bennett  William R. Bryant  Wayne A. Dunlap  George H. Keller 《Marine Georesources & Geotechnology》2013,31(4):327-335

Abstract

This report describes the instrumentation, initial results, and progress of an experiment designed to measure and monitor submarine sediment pore water and hydrostatic pressures in a selected area of the Mississippi Delta. The experiment also is intended to monitor significant pressure perturbations during active storm periods. Initial analysis of the data revealed excess pore water pressures in the silty clay sediment at selected depths below the mudline. Continuous monitoring of the pore water and hydrostatic pressures was expected to reveal important information regarding sediment pore water pressure variations as a function of the geological processes active in the Mississippi Delta.  相似文献   

Comparison of surface and borehole locations of induced seismicity   总被引：1，自引：0，他引：1  

Leo Eisner  B. J. Hulsey  Peter Duncan  Dana Jurick  Heigl Werner  William Keller 《Geophysical Prospecting》2010,58(5):809-820

Monitoring of induced microseismic events has become an important tool in hydraulic fracture diagnostics and understanding fractured reservoirs in general. We compare microseismic event and their uncertainties using data sets obtained with surface and downhole arrays of receivers. We first model the uncertainties to understand the effect of different acquisition geometries on location accuracy. For a vertical array of receivers in a single monitoring borehole, we find that the largest part of the final location uncertainty is related to estimation of the backazimuth. This is followed by uncertainty in the vertical position and radial distance from the receivers. For surface monitoring, the largest uncertainty lies in the vertical position due to the use of only a single phase (usually P‐wave) in the estimation of the event location. In surface monitoring results, lateral positions are estimated robustly and are not sensitive to the velocity model. In this case study, we compare event location solutions from two catalogues of microseismic events; one from a downhole array and the second from a surface array of 1C geophone. Our results show that origin time can be reliably used to find matching events between the downhole and surface catalogues. The locations of the corresponding events display a systematic shift consistent with a poorly calibrated velocity model for downhole dataset. For this case study, locations derived from surface monitoring have less scatter in both vertical and horizontal directions.  相似文献   

A new approach in determining the age of deep-water species of scleractinia using temperature ranges of their habitation     

N. B. Keller  N. S. Os’kina  S. D. Nikolaev 《Doklady Earth Sciences》2009,425(1):264-268

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Chemical composition of nyerereite and gregoryite from natrocarbonatites of Oldoinyo Lengai volcano,Tanzania     

A. N. Zaitsev  J. Keller  J. Spratt  T. E. Jeffries  V. V. Sharygin 《Geology of Ore Deposits》2009,51(7):608-616

Alkali carbonates nyerereite, ideally Na₂Ca(CO₃)₂ and gregoryite, ideally Na₂CO₃, are the major minerals in natrocarbonatite lavas from Oldoinyo Lengai volcano, northern Tanzania. They occur as pheno- and microphenocrysts in groundmass consisting of fluorite and sylvite; nyerereite typically forms prismatic crystals and gregoryite occurs as round, oval crystals. Both minerals are characterized by relatively high contents of various minor elements. Raman spectroscopy data indicate the presence of sulfur and phosphorous as (SO₄)²⁻ and (PO₄)³⁻ groups. Microprobe analyses show variable composition of both nyerereite and gregoryite. Nyerereite contains 6.1–8.7 wt % K₂O, with subordinate amounts of SrO (1.7–3.3 wt %), BaO (0.3–1.6 wt %), SO₃ (0.8–1.5 wt %), P₂O₅ (0.2–0.8 wt %) and Cl (0.1–0.35 wt %). Gregoryite contains 5.0–11.9 wt % CaO, 3.4–5.8 wt % SO₃, 1.3–4.6 wt % P₂O₅, 0.6–1.0 wt % SrO, 0.1–0.6 wt % BaO and 0.3–0.7 wt % Cl. The content of F is below detection limits in nyerereite and gregoryite. Laser ablation ICP-MS analyses show that REE, Mn, Mg, Rb and Li are typical trace elements in these minerals. Nyerereite is enriched in REE (up to 1080 ppm) and Rb (up to 140 ppm), while gregoryite contains more Mg (up to 367 ppm) and Li (up to 241 ppm) as compared with nyerereite.  相似文献   

Paleowind velocity and paleocurrents of pluvial Lake Manly,Death Valley,USA     

Jeffrey R. Knott  Joanna M. Fantozzi  Kelly M. Ferguson  Summer E. Keller  Khadija Nadimi  Carolyn A. Rath  Jennifer M. Tarnowski  Michelle L. Vitale 《Quaternary Research》2012,78(2):363-372

Pluvial lake deposits are found throughout western North America and are frequently used to reconstruct regional paleoclimate. In Death Valley, California, USA, we apply the beach particle technique (BPT) of Adams (2003), Sedimentology, 50, 565–577 and Adams (2004), Sedimentology, 51, 671–673 to Lake Manly deposits at the Beatty Junction Bar Complex (BJBC), Desolation Canyon, and Manly Terraces and calculate paleowind velocities of 14–27 m/s. These wind velocities are within the range of present-day wind velocities recorded in the surrounding area. Sedimentary structures and clast provenance at Desolation Canyon and the Manly Terraces indicate sediment transport from north to south. Lake level, based on the elevation of constructional features, indicates that the hill west of the BJBC was an island and that the BJBC spits formed during simple lake regression. The data are consistent with the hypothesis that the present wind regime (velocity and direction) formed the pluvial Lake Manly features.  相似文献   

Deccan volcanism linked to the Cretaceous-Tertiary boundary mass extinction: New evidence from ONGC wells in the Krishna-Godavari Basin     

G. Keller  P. K. Bhowmick  H. Upadhyay  A. Dave  A. N. Reddy  B. C. Jaiprakash  T. Adatte 《Journal of the Geological Society of India》2011,78(5):399-428

A scientific challenge is to assess the role of Deccan volcanism in the Cretaceous-Tertiary boundary (KTB) mass extinction. Here we report on the stratigraphy and biologic effects of Deccan volcanism in eleven deep wells from the Krishna-Godavari (K-G) Basin, Andhra Pradesh, India. In these wells, two phases of Deccan volcanism record the world’s largest and longest lava mega-flows interbedded in marine sediments in the K-G Basin about 1500 km from the main Deccan volcanic province. The main phase-2 eruptions (∼80% of total Deccan Traps) began in C29r and ended at or near the KTB, an interval that spans planktic foraminiferal zones CF1–CF2 and most of the nannofossil Micula prinsii zone, and is correlative with the rapid global warming and subsequent cooling near the end of the Maastrichtian. The mass extinction began in phase-2 preceding the first of four mega-flows. Planktic foraminifera suffered a 50% drop in species richness. Survivors suffered another 50% drop after the first mega-flow, leaving just 7 to 8 survivor species. No recovery occurred between the next three mega-flows and the mass extinction was complete with the last phase-2 mega-flow at the KTB. The mass extinction was likely the consequence of rapid and massive volcanic CO₂ and SO₂ gas emissions, leading to high continental weathering rates, global warming, cooling, acid rains, ocean acidification and a carbon crisis in the marine environment.  相似文献   

Stratigraphy of the Cenomanian–Turonian Oceanic Anoxic Event OAE2 in shallow shelf sequences of NE Egypt     

Ahmed El-Sabbagh  Abdel Aziz Tantawy  Gerta Keller  Hassan Khozyem  Jorge Spangenberg  Thierry Adatte  Brian Gertsch 《Cretaceous Research》2011,32(6):705-722

Two shallow water late Cenomanian to early Turonian sequences of NE Egypt have been investigated to evaluate the response to OAE2. Age control based on calcareous nannoplankton, planktic foraminifera and ammonite biostratigraphies integrated with δ¹³C stratigraphy is relatively good despite low diversity and sporadic occurrences. Planktic and benthic foraminiferal faunas are characterized by dysoxic, brackish and mesotrophic conditions, as indicated by low species diversity, low oxygen and low salinity tolerant planktic and benthic species, along with oyster-rich limestone layers. In these subtidal to inner neritic environments the OAE2 δ¹³C excursion appears comparable and coeval to that of open marine environments. However, in contrast to open marine environments where anoxic conditions begin after the first δ¹³C peak and end at or near the Cenomanian–Turonian boundary, in shallow coastal environments anoxic conditions do not appear until the early Turonian. This delay in anoxia appears to be related to the sea-level transgression that reached its maximum in the early Turonian, as observed in shallow water sections from Egypt to Morocco.  相似文献