共查询到20条相似文献,搜索用时 62 毫秒
1.
Low-mature gases and typical low-mature gas fields in China 总被引:2,自引:0,他引:2
No natural gas pool of industrial importance could be formed at the low-evolution stage of organic matter. In the 1980s, on the basis of the development in exploration practice, the hypotheses of bio-thermo-catalytic transitional zone gases and early thermogenic gases were proposed. The lower-limit Ro values for the formation and accumulation of natural gases of industrial importance have been expanded to 0.3%―0.4%. In the light of the two-stage model established on the basis of carbon isotope fractionation in coal-type natural gases, the upper-limit Ro values have been set at 0.8%―1.0%. In terms of the geological practice in the low-mature gas zones and China's main coal-type gas fields, it is feasible and proper to set the upper-limit Ro value of low-mature gases at 0.8%. Supper-large gas fields such as the Urengoy gas field in western Siberian Basin should belong to low-mature gas fields, of which the natural gas reserves account for more than 20% of the global proven reserves, providing strong evidence for the significance of such a type of resources. The proven natural gas reserves in the Turpan-Hami Basin of China have almost reached 1000 × 108 m3. The main source rocks in this area are the Jurassic Xishanyao Formation, which occurs as a suite of coal series strata. The corresponding thermal evolution indices (Ro ) are mainly within the range of about 0.4%―0.8%, the δ 13C1 values of methane vary between-44‰ and-39‰ (correspondingly Ro =0.6%―0.8%), and those of ethane are within the range of-29‰―-26‰, indicating that natural gases in the Turpan-Hami Basin should be designated to coal-type low-mature gases. The light hydrocarbon evolution indices of natural gases also fall within the area of low evolution while the precursor type of light hydrocarbons also shows the characteristics of the coal-type. The geological background, carbon isotopic composition and light hydrocarbon index all provide strong evidence suggesting that the proven natural gases in the Turpan-Hami Basin are low-mature gases. In China a gas field with the gas reserves reaching 300 ×108 m3 can be defined as a large gas field, and thus the proven low-mature gases in the Turpan-Hami Basin are equivalent to the reserves of three large gas fields. Its existence is of great significance in research on and exploration of low-mature gases in China. 相似文献
2.
The Tuoku region in northern Tarim Basin of China is a key area for studying oil/gas reservoir rocks. The magnetic and mineralogical
parameters of well cuttings from two wells, well S7, situated on oil/gas field, and well S6, at an oil/water interface, were measured. The two wells are located in the same structure with similar strata and types
of lithology, but well S6 is a showing well of oil and gas 5 km northwest of well S7. The purpose of this paper is to evaluate the possibility and distribution of secondary magnetic alteration that may have
occurred due to hydrocarbon migration above an oil/gas accumulation. It is concluded that the magnetism of well cuttings from
major strata in well S7, including source rocks, oil reservoir rocks and cap rocks, and in Quaternary (Q) soil is higher than that from well S6. The Cambrian oil-bearing strata and cap rocks have even higher magnetism in well S7. The shape and parameters of magnetic hysteresis loops indicate that soft (H
c<20 mT,H
s<0.3 T) ferrimagnetic components dominate the magnetic carriers within the strongly magnetic strata of well S7, whereas a mixed paramagnetic and ferrimagnetic distribution occurs in well S6 (for example, low coecivityH
c and nonsaturating magnetized character). Analysis of heavy minerals shows that the contents of iron oxide (magnetite, maghemite
and hematite) in well S7 are often higher than those in well S6. The magnetite content in samples of cuttings from Cambrian rocks can reach 9.7% in oil-bearing strata in well S7, and in strata Ekm and N1j are 1.215% and1.498%, respectively. Typical spherical magnetite grains are found within the main source rocks and the soils
in well S7. By analysis of surface microtexture and of trace element contents, we infer that the spherical magnetite is composed of
aggregates of ultrafine particles that are probably authigenic magnetite formed in a hydrocarbon halo background.
Project supported by the National Natural Science Foundation of China and the Geological Industry Foundation of China (Grant
No. 49374216) and Foundation of the State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation of China (Grant No.
9608). 相似文献
3.
By measuring carbon and hydrogen isotope compositions for C1, C2 and C3 of 74 gas samples, natural gases from the Tarim Basin can be divided into six groups on the basis of their origins: (1) coal-type gas derived from coal measures; (2) coal-type gas generated from the T-J lacustrine mudstones; (3) oil-type gas derived from the Cambrian and low Ordovician marine source rocks; (4) oil-type gas from the source rocks deposited in the marine-transitional facies; (5) mixing gas between gas derived from the Carboniferous transitional source rocks and the Mesozoic humic gas, and (6) mixing gases of thermal genetic gas and little deep gas in the Southwest depression of the Tarim Basin. The δ D values of methane in natural gases originating from different type kerogens are affected by both palaeo-environments of the source rock formation (kerogen types) and thermal maturity, with sedimentary environment (kerogen type) as the main controlling factor. Under the similar thermal maturity, the hydrogen isotope composition of methane is more enriched in deuterium in marine environments than lacustrine one. With the increase of thermal maturity and the increase of carbon atomic numbers of gaseous alkanes, the hydrogen isotopes become enriched in deuterium. The δ D values of ethane and propane (δ D2, δ D3) are controlled mainly by thermal maturity and to a lesser degree by sedimentary environment of the source rock formation. The partial reversal of hydrogen isotopes for gaseous alkanes would be related to the microbial oxidation, mixing of sapropelic and humic gases and / or mixing of gases from similar kerogen sources with various thermal maturities. In the oil-type gas, the sulfate reduction reaction would result in the reversed order of δ D1 and δ D2 (e.g. δ D1>δ D2). 相似文献
4.
Sushil Chandra Das Gupta 《Pure and Applied Geophysics》1959,43(1):45-74
Summary Coda waves viz. the tail portion of an earthquake record have been observed and analysed byCarder, Macelwane and others. They showed that the periods of such waves increase with the increase of epicentral distances.Carder observed that these waves have very little transverse component so that these may be considered as of the type of Rayleigh waves. RecentlyOmote showed that the Coda waves contain three periodsT
1,T
2,T
3 of whichT
1 increases with epi-central distances as observed by previous observers. ButT
2,T
3 remain constant for all earthquakes from different epicentral distances.Omote tried to explain this phenomenon by considering that the surface of the earth consists of several layers andT
2,T
3 are free oscillation periods of the surface layers.T
1 period has been explained bySezawa and also byJeffreys which has been shown byGutenberg. The author has attempted to explain the periodsT
2,T
3 by considering passage of cracks at the focal region. The Rayleigh wave character of Coda waves and low velocity of such waves have been explained. 相似文献
5.
The source parameters of the M
W
= 7.6 Olyutorskii earthquake were estimated using the moments of the slip rate function with degrees 1 and 2. The moments
were estimated from broadband P-wave records at 52 stations of the worldwide network. The first step was to find a function S(t) for each station; this function is an apparent source time function, i.e., the P-wave slip as radiated by the source toward a station under consideration. The method of empirical Green’s functions was used
to estimate S(t). The next step was to calculate the moments of S(t) of degrees 1 and 2 over time and to set up relevant equations to be solved by least squares for the unknown source moments.
The horizontal linear source was used as a nonparametric model for calculating the source moments. Haskell’s parametric model
was used for further interpretation of the source moments. The resulting estimates are as follows: the source centroid was
13–25 km southwest of the epicenter, the source was 105–120 km long, the source strike was 222°–228°, the rupture velocity
was 2.7–3.0 km/s, and the total radiation duration was 24–27 s. These estimates indicate a bilateral rupture dominated by
a southwestward sense of rupture propagation. The source characteristics are consistent with the aftershock area geometry
and with the focal mechanism, as well as with surface breakage as observed by geologists in the field. 相似文献
6.
Prediction of rockburst probability given seismic energy and factors defined by the expert method of hazard evaluation (MRG) 总被引:2,自引:0,他引:2
In this paper we suggest that conditional estimator/predictor of rockburst probability (and rockburst hazard, P
T
(t)) can be approximated with the formula P
T
(t) = P
1(θ
1)…P
N
(θ
N
)·P
dyn
T
(t), where P
dyn
T
(t) is a time-dependent probability of rockburst given only the predicted seismic energy parameters, while P
i
(θ
i
) are amplifying coefficients due to local geologic and mining conditions, as defined by the Expert Method of (rockburst)
Hazard Evaluation (MRG) known in the Polish mining industry. All the elements of the formula are (approximately) calculable
(on-line) and the resulting P
T
value satisfies inequalities 0 ≤ P
T
(t) ≤ 1. As a result, the hazard space (0–1) can be always divided into smaller subspaces (e.g., 0–10−5, 10−5–10−4, 10−4–10−3, 10−3–1), possibly named with symbols (e.g., A, B, C, D, …) called “hazard states” — which saves the prediction users from worrying of probabilities. The estimator P
T
can be interpreted as a formal statement of (reformulated) Comprehensive Method of Rockburst State of Hazard Evaluation,
well known in Polish mining industry. The estimator P
T
is natural, logically consistent and physically interpretable. Due to full formalization, it can be easily generalized, incorporating
relevant information from other sources/methods. 相似文献
7.
In order to estimate the recurrence intervals for large earthquakes occurring in eastern Anatolia, this region enclosed within
the coordinates of 36∘–42∘N, 35∘–45∘E has been separated into nine seismogenic sources on the basis of certain seismological and geomorphological criteria, and
a regional time- and magnitude-predictable model has been applied for these sources. This model implies that the magnitude
of the preceding main shock which is the largest earthquake during a seismic excitation in a seismogenic source governs the
time of occurrence and the magnitude of the expected main shock in this source. The data belonging to both the instrumental
period (MS≥ 5.5) until 2003 and the historical period (I0≥ 9.0 corresponding to MS≥ 7.0) before 1900 have been used in the analysis. The interevent time between successive main shocks with magnitude equal
to or larger than a certain minimum magnitude threshold were considered in each of the nine source regions within the study
area. These interevent times as well as the magnitudes of the main shocks have been used to determine the following relations:
fwawhere Tt is the interevent time measured in years, Mmin is the surface wave magnitude of the smallest main shock considered, Mp is the magnitude of the preceding main shock, Mf is magnitude of the following main shock, and M0 is the released seismic moment per year in each source. Multiple correlation coefficient and standard deviation have been
computed as 0.50 and 0.28, respectively for the first relation. The corresponding values for the second relation are 0.64
and 0.32, respectively. It was found that the magnitude of the following main shock Mf does not depend on the preceding interevent time Tt. This case is an interesting property for earthquake prediction since it provides the ability to predict the time of occurrence
of the next strong earthquake. On the other hand, a strong negative dependence of Mf on Mp was found. This result indicates that a large main shock is followed by a smaller magnitude one and vice versa. On the basis
of the first one of the relations above and taking into account the occurrence time and magnitude of the last main shock,
the probabilities of occurrence P(Δ t) of main shocks in each seismogenic source of the east Anatolia during the next 10, 20, 30, 40 and 50 years for earthquakes
with magnitudes equal 6.0 and 7.0 were determined. The second of these relations has been used to estimate the magnitude of
the expected main shock. According to the time- and magnitude-predictable model, it is expected that a strong and a large
earthquake can occur in seismogenic Source 2 (Erzincan) with the highest probabilities of P10 = 66% (Mf = 6.9 and Tt = 12 years) and P10 = 44% (Mf = 7.3 and Tt = 24 years) during the future decade, respectively. 相似文献
8.
Prof. Sydney Chapman 《Pure and Applied Geophysics》1951,19(3-4):151-158
Summary Evidence is adduced indicating that geomagnetic disturbance at Huancayo isnormal, that is, comparable with that shown elsewhere in similar latitudes —as contrasted with the remarkable Huancayoabnormality, in the horizontal magnetic force, of the quiet-day solar and lunar daily variations, and in theS
q augmentation (solar flare effect). the normality of magnetic disturbance at Huancayo is manifested by the disturbance daily variationS
D, and by the storm-effectD
st and its associated changes of daily mean (D
m) and the non-cyclic variation; it is not stated whether or not the irregular part,D
i, is normal. The normality ofD
st seems natural according to theChapman-Ferraro theory of magnetic storms, but the normality ofS
D is less easy to explain.Prof.Sydney Chapman, Research Associate, California Institute of Technology, under Signal Corps Project No. 24-172 B; on leave (from April 1950 to March 1951) from Oxford University, Queen's College,Oxford, England. 相似文献
9.
IntroductionThecrustaltectonicmovementisacomplicatedevolutionprocesswithtimeandspace.Spatially,themovementofcrustaltectoniciscloselyrelatedtotheinter-movementandinteractionofmulti-leveledcrustalblocksinacertainregionandtheirborderfaults.Temporally,themovementiscloselyrelatedtothatofmulti-leveledcrustalblocksandtimesequencedevelopmentofinteraction.Anearthquakeoccurrenceistheresultofsuddenruptureofcrustmediaundertheactionoftectonicstressfield,isalsoacomplicatedprocessinnercrust.Duetotheobviousi… 相似文献
10.
Characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific 总被引:1,自引:0,他引:1
Based on the daily turbulent heat fluxes and related meteorological variables datasets (1985–2006) from Objectively Analyzed
air-sea Fluxes (OAFlux) Project of Woods Hole Oceanographic Institution (WHOI), characteristics of low-frequency oscillation
intensity of air-sea turbulent heat fluxes over the northwest Pacific are analyzed by linear perturbation method and correlation
analysis. It can be concluded that: 1) the distribution of low-frequency oscillation intensity of latent heat flux (LHF) over
the northwest Pacific is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea humidity gradient
(Δq′) as well as mean air-sea humidity gradient (), while the distribution of low-frequency oscillation intensity of sensible heat flux (SHF) is mainly affected by that of
low-frequency oscillation intensity of anomalous air-sea temperature gradient (ΔT′). 2) The low-frequency oscillation of turbulent heat fluxes over the northwest Pacific is the strongest in winter and the
weakest in summer. And the seasonal transition of low-frequency oscillation intensity of LHF is jointly influenced by those
of low-frequency oscillation intensity of Δq′, low-frequency oscillation intensity of anomalous wind speed (U′), and mean wind speed (Ū), while the seasonal transition of low-frequency oscillation intensity of SHF is mainly influenced by those of low-frequency
oscillation intensity of ΔT′ and Ū. 3) Over the tropical west Pacific and sea areas north of 20°N, the low-frequency oscillation of LHF (SHF) is mainly influenced
by atmospheric variables q
a
′ (T
a
′) and U′, indicating an oceanic response to overlying atmospheric forcing. In contrast, over the tropical eastern and central Pacific
south of 20°N, q
s
′ (T
s
′) also greatly influences the low-frequency oscillation of LHF (SHF).
Supported by National Natural Science Foundation of China (Grant No. 40675028) and National Basic Research Program of China
(Grant No. 2006CB403600) 相似文献
11.
You-Kuan Zhang Jie Lin 《Stochastic Environmental Research and Risk Assessment (SERRA)》1998,12(2):117-140
Transport of non-ergodic solute plumes by steady-state groundwater flow with a uniform mean velocity, μ, were simulated with Monte Carlo approach in a two-dimensional heterogeneous and statistically isotropic aquifer whose transmissivity,
T, is log-normally distributed with an exponential covariance. The ensemble averages of the second spatial moments of the plume
about its center of mass, <S
i
i
(t)>, and the plume centroid covariance, R
i
i
(t) (i=1,2), were simulated for the variance of Y=log T, σ
Y
2=0.1, 0.5 and 1.0 and line sources normal or parallel to μ of three dimensionless lengths, 1, 5, and 10. For σ
Y
2=0.1, all simulated <S
i
i
(t)>−S
i
i
(0) and R
i
i
(t) agree well with the first-order theoretical values, where S
i
i
(0) are the initial values of S
i
i
(t). For σ
Y
2=0.5 and 1.0 and the line sources normal to μ, the simulated longitudinal moments, <S
11(t)>−S
11(0) and R
11(t), agree well with the first-order theoretical results but the simulated transverse moments <S
22(t)>−S
22(0) and R
22(t) are significantly larger than the first-order values. For the same two larger values of σ
Y
2 but the line sources parallel to μ, the simulated <S
11(t)>−S
11(0) are larger than but the simulated R
11 are smaller than the first-order values, and both simulated <S
22(t)>−S
22(0) and R
22(t) stay larger than the first-order values. For a fixed value of σ
Y
2, the summations of <S
i
i
(t)>−S
i
i
(0) and R
i
i
, i.e., X
i
i
(i=1,2), remain almost the same no matter what kind of source simulated. The simulated X
11 are in good agreement with the first-order theory but the simulated X
22 are significantly larger than the first-order values. The simulated X
22, however, are in excellent agreement with a previous modeling result and both of them are very close to the values derived
using Corrsin's conjecture. It is found that the transverse moments may be significantly underestimated if less accurate hydraulic
head solutions are used and that the decreasing of <S
22(t)>−S
22(0) with time or a negative effective dispersivity, defined as , may happen in the case of a line source parallel to μ where σ
Y
2 is small. 相似文献
12.
Transport of non-ergodic solute plumes by steady-state groundwater flow with a uniform mean velocity, μ, were simulated with Monte Carlo approach in a two-dimensional heterogeneous and statistically isotropic aquifer whose transmissivity,
T, is log-normally distributed with an exponential covariance. The ensemble averages of the second spatial moments of the plume
about its center of mass, <S
i
i
(t)>, and the plume centroid covariance, R
i
i
(t) (i=1,2), were simulated for the variance of Y=log T, σ
Y
2=0.1, 0.5 and 1.0 and line sources normal or parallel to μ of three dimensionless lengths, 1, 5, and 10. For σ
Y
2=0.1, all simulated <S
i
i
(t)>−S
i
i
(0) and R
i
i
(t) agree well with the first-order theoretical values, where S
i
i
(0) are the initial values of S
i
i
(t). For σ
Y
2=0.5 and 1.0 and the line sources normal to μ, the simulated longitudinal moments, <S
11(t)>−S
11(0) and R
11(t), agree well with the first-order theoretical results but the simulated transverse moments <S
22(t)>−S
22(0) and R
22(t) are significantly larger than the first-order values. For the same two larger values of σ
Y
2 but the line sources parallel to μ, the simulated <S
11(t)>−S
11(0) are larger than but the simulated R
11 are smaller than the first-order values, and both simulated <S
22(t)>−S
22(0) and R
22(t) stay larger than the first-order values. For a fixed value of σ
Y
2, the summations of <S
i
i
(t)>−S
i
i
(0) and R
i
i
, i.e., X
i
i
(i=1,2), remain almost the same no matter what kind of source simulated. The simulated X
11 are in good agreement with the first-order theory but the simulated X
22 are significantly larger than the first-order values. The simulated X
22, however, are in excellent agreement with a previous modeling result and both of them are very close to the values derived
using Corrsin's conjecture. It is found that the transverse moments may be significantly underestimated if less accurate hydraulic
head solutions are used and that the decreasing of <S
22(t)>−S
22(0) with time or a negative effective dispersivity, defined as , may happen in the case of a line source parallel to μ where σ
Y
2 is small. 相似文献
13.
M
TSU
: Recovering Seismic Moments from Tsunameter Records 总被引:1,自引:0,他引:1
We define a new magnitude scale, MTSU, allowing the quantification of the seismic moment M0 of an earthquake based on recordings of its tsunami in the far field by ocean-bottom pressure sensors (``tsunameters') deployed
in ocean basins, far from continental or island shores which are known to affect profoundly and in a nonlinear fashion the
amplitude of the tsunami wave. The formula for MTSU, MTSU = log10 M0 − 20 = log10 X (ω) + CDTSU + CSTSU + C0, where X (ω) is the spectral amplitude of the tsunami, CDTSU a distance correction and CSTSU a source correction, is directly adapted from the mantle magnitude Mm introduced for seismic surface waves by Okal and Talandier. Like Mm, its corrections are fully justified theoretically based on the representation of a tsunami wave as a branch of the Earth's
normal modes. Even the locking constant C0, which may depend on the nature of the recording (surface amplitude of the tsunami or overpressure at the ocean floor) and
its units, is predicted theoretically. MTSU combines the power of a theoretically developed algorithm, with the robustness of a magnitude measurement that does not take
into account such parameters as focal geometry and exact depth, which may not be available under operational conditions in
the framework of tsunami warning. We verify the performance of the concept on simulations of the great 1946 Aleutian tsunami
at two virtual gauges, and then apply the algorithm to 24 records of 7 tsunamis at DART tsunameters during the years 1994–2003.
We find that MTSU generally recovers the seismic moment M0 within 0.2 logarithmic units, even under unfavorable conditions such as excessive focal depth and refraction of the tsunami
wave around continental masses. Finally, we apply the algorithm to the JASON satellite trace obtained over the Bay of Bengal
during the 2004 Sumatra tsunami, after transforming the trace into a time series through a simple ad hoc procedure. Results are surprisingly good, with most estimates of the moment being over 1029 dyn-cm, and thus identifying the source as an exceptionally large earthquake. 相似文献
14.
Fausto Grassa Giorgio Capasso Rocco Favara Salvatore Inguaggiato 《Pure and Applied Geophysics》2006,163(4):781-807
Hydrochemical (major and some minor constituents), stable isotope ( and , δ13CTDIC total dissolved inorganic carbon) and dissolved gas composition have been determined on 33 thermal discharges located throughout
Sicily (Italy) and its adjacent islands. On the basis of major ion contents, four main water types have been distinguished:
(1) a Na-Cl type; (2) a Ca-Mg > Na-SO4-Cl type; (3) a Ca-Mg-HCO3 type and (4) a Na-HCO3 type water. Most waters are meteoric in origin or resulting from mixing between meteoric water and heavy-isotope end members.
In some samples, δ18O values reflect the effects of equilibrium processes between thermal waters and rocks (positive 18O-shift) or thermal waters and CO2 (negative 18O-shift). Dissolved gas composition indicates the occurrence of gas/water interaction processes in thermal aquifers. N2/O2 ratios higher than air-saturated water (ASW), suggest the presence of geochemical processes responsible for dissolved oxygen
consumption. High CO2 contents (more than 3000 cc/litre STP) dissolved in the thermal waters indicate the presence of an external source of carbon
dioxide-rich gas. TDIC content and δ13CTDIC show very large ranges from 4.6 to 145.3 mmol/Kg and from –10.0‰ and 2.8‰, respectively. Calculated values indicate the significant
contribution from a deep source of carbon dioxide inorganic in origin. Interaction with Mediterranean magmatic CO2 characterized by heavier carbon isotope ratios ( value from -3 to 0‰ vs V-PDB (CAPASSO et al., 1997, GIAMMANCO et al., 1998; INGUAGGIATO et al., 2000) with respect to MORB value and/or input of CO2-derived from thermal decomposition of marine carbonates have been inferred. 相似文献
15.
Carbon and hydrogen isotopic characteristics of natural gases from the Luliang and Baoshan basins in Yunnan Province, China 总被引:2,自引:1,他引:2
XU Yongchang LIU Wenhui SHEN Ping WANG Wanchun WANG Xiaofeng Tenger YAN Yaomin & LIU Ruobin . Lanzhou Center of Oil & Gas Resources Institute of Geology Geophsics Chinese Academy of Sciences Lanzhou China . Research Institute of Petroleum Exploration Production SINOPEC Beijing China . South Branch of Petroleum Exploration Production Company SINOPEC Kuming China 《中国科学D辑(英文版)》2006,49(9):938-946
The Luliang and Baoshan basins are two small ba- sins in Yunnan Province. In the recent ten years or so, there have been found a number of natural gas pools of commercial importance in the two basins. Although the gas pools are small in size, the natural … 相似文献
16.
Gerardo Severino Alessandro Santini Angelo Sommella 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(4):567-582
Average steady source flow in heterogeneous porous formations is modelled by regarding the hydraulic conductivity K(x) as a stationary random space function (RSF). As a consequence, the flow variables become RSFs as well, and we are interested into calculating their moments. This
problem has been intensively studied in the case of a Neumann type boundary condition at the source. However, there are many
applications (such as well-type flows) for which the required boundary condition is that of Dirichlet. In order to fulfill
such a requirement the strength of the source must be proportional to K(x), and therefore the source itself results a RSF. To solve flows driven by sources whose strength is spatially variable, we
have used a perturbation procedure similar to that developed by Indelman and Abramovich (Water Resour Res 30:3385–3393, 1994) to analyze flows generated by sources of deterministic strength. Due to the linearity of the mathematical problem, we have
focused on the explicit derivation of the mean head distribution G
d
(x) generated by a unit pulse. Such a distribution represents the fundamental solution to the average flow equations, and it
is termed as mean Green function. The function G
d
(x) is derived here at the second order of approximation in the variance σ2 of the fluctuation (where K
A
is the mean value of K(x)), for arbitrary correlation function ρ(x), and any dimensionality d of the flow domain. We represent G
d
(x) as product between the homogeneous Green function G
d
(0)(x) valid in a domain with constant K
A
, and a distortion term Ψ
d
(x) = 1 + σ2ψ
d
(x) which modifies G
d
(0)(x) to account for the medium heterogeneity. In the case of isotropic formations ψ
d
(x) is expressed via one quadrature. This quadrature can be analytically calculated after adopting specific (e.g.. exponential
and Gaussian) shape for ρ(x). These general results are subsequently used to investigate flow toward a partially-penetrating well in a semi-infinite
domain. Indeed, we construct a σ2-order approximation to the mean as well as variance of the head by replacing the well with a singular segment. It is shown
how the well-length combined with the medium heterogeneity affects the head distribution. We have introduced the concept of
equivalent conductivity
K
eq(r,z). The main result is the relationship where the characteristic function ψ(w)(r,z) adjusts the homogeneous conductivity K
A
to account for the impact of the heterogeneity. In this way, a procedure can be developed to identify the aquifer hydraulic
properties by means of field-scale head measurements. Finally, in the case of a fully penetrating well we have expressed the
equivalent conductivity in analytical form, and we have shown that (being the effective conductivity for mean uniform flow), in agreement with the numerical simulations of Firmani et al. (Water Resour
Res 42:W03422, 2006). 相似文献
17.
SONG YuCai HU WenXuan NI Pei DUAN ZhenHao & ZHANG XueFeng State Key Laboratory of Mineral Deposit Research Department of Earth Sciences Nanjing University Nanjing China Institute of Geology Geophysics Chinese Academy of Sciences Beijing China 《中国科学D辑(英文版)》2007,50(3):385-391
On the basis of Parry’s method (1986), an improved method was established to determine the molar volume (Vm) and compositions (X) of the NaCl-H2O-CO2 (NHC) system inclusion. To use this method, the determination of Vm-X only requires three microthermometric data of a NHC inclusion: partial homog-enization temperature (Th ,CO2), salinity (S) and total homogenization temperature (Th). Theoretically, four associated equations are needed containing four unknown parameters: X CO2, XNaCl, Vm and F (volume fraction of CO2 phase in total inclusion when occurring partial homogenization). When they are released, the Vm-X are determined. The former three equations, only correlated with Th ,CO2, S and F, have simplified expressions:XCO2=f1(Th,CO2,S,F),XNaCl=f2(Th,CO2,S,F),Vm=f3(Th,CO2,S,F). The last one is the thermodynamic relationship of X CO2, XNaCl, Vm and Th:f4(XCO2,XNaCl,Vm,Th)=0.Since the above four associated equations are complicated, it is necessary to adopt iterative technique to release them. The technique can be described by:(i) Freely input a F value (0≤F≤1),with Th ,CO2 and S, into the former three equations. As a result,X CO 2,XNaCl and the molar volume value recorded as Vm1 are derived. (ii) Input the X CO2 and XNaCl gotten in the step above into the last equation, and another molar volume value recorded as Vm2 is determined. (iii) If Vm1 is unequal to Vm2, the calculation will be restarted from “(i)”. The iteration is completed until Vm1 is equal to Vm2, which means that the four associated equations are released. Compared to Parry’s (1986) solution method, the improved method is more convenient to use, as well as more accurate to determine X CO 2. It is available for a NHC inlusion whose partial homogenization temperature is higher than clatherate melting temperature and there are no solid salt crystals in the inclusion at parital homogenization. 相似文献
18.
The sorption of AuCl4
−,AuCl2
− and Au(S2O3)3- on δ-MnO2 was investigated at pH2–11.6, 0.01 mol/L and 0.1 mol/L NaNO3 solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO2 are 0.18–0.21 and 0.28μmoL/m2 for AuCl4
− and Au(S2O3)2
3-, respectively, and the Au surface coverage is approximate to or lower than 1%. This adsorption of the two Au complexes decreases
as the solution pH increases, which conforms to the sorption regularity of the anion on δ-MnO2. The Au sorption decreases in the sequence of Au(S2O3)2
3- >AuCl4
− >AuC12
−. The intrinsic equilibrium constants (logK
int) of the three Au complexes are 1.17–2.7, much higher than those of Cu and Cd. The hydrolysis products of AuCl4
- are preferentially adsorbed by δ-MnO2 and the inner-sphere Au-surface complexes are formed on the surface.
Project supported by the National Studying-abroad Foundation, the National Natural Science Foundation of China (Grant No.
49573200) and the Australian Mining Industry. 相似文献
19.
The 0S2~0S54 spheroidal modes of Earth’s free oscillations, triggered by the great Sumatra-Andaman earthquake of 26 December 2004 are retrieved from VHZ data recorded by seven upgraded stations of China Digital Seismograph Network (CDSN). We compare these spheroidal modes with theoretical free oscillation spectra calculated from the Preliminary Reference Earth Model (PREM) and find a coincidence between their periods. Spectral splitting phenomenon is observed obviously in 0S2, 0S3, 0S4, 2S1 and 1S2 free oscillation modes. What is most noticeable is that the oscillation mode 2S1 is reported for the second time (the first time by Rosat et al) without any data stacking. We simulated the split singlet of 0S2 mode on seven CDSN stations based on general focal mechanism and seismic moment of the earthquake. The result shows that seismic moment of the earthquake can reach 1023 N.m. We also find that the recording of Earth’s free oscillations carries abundant information of source mechanism and earthquake location, which is applicable to the detailed study of source rupture parameters. 相似文献