共查询到20条相似文献,搜索用时 15 毫秒
1.
HELMUT LINSSER 《Geophysical Prospecting》1970,18(1):119-133
The principle of optical pumping allows the design of magnetometers with high sensitivity. When mapping the field of the total magnetic force, it is no longer possible to make full use of the accuracy of the instruments because the accuracy of the reduction of the diurnal variation is limited. By simultaneously recording with two instruments in different altitudes, the vertical gradient can be measured which doe's not depend on the time variation of the magnetic field. Therefore, the gradiometer seems to be a more adequate tool for oil exploration than the magnetometer. It is investigated in this article whether the results of this gradiometer or the measurements of the total magnetic field by the high sensitive magnetometer are more useful in oil exploration. The article comes to the conclusion that for most problems of oil exploration the total magnetic field is a more valuable unit than the vertical gradient measured directly by the gradiometer. The total magnetic field allows a better investigation of the tectonics than the vertical gradient. The apparent advantages of the gradiometer claimed by its supporters are mainly based on inconsistent mathematical concepts. 相似文献
2.
本文对大地电磁阻抗相位资料的性质及其意义作了总结和评述。文中述及的阻抗相位资料正则化反演方法,是在文献〔1〕的基础上进行了改进,笔者就此给出了实际算例和概要分析 相似文献
3.
P. HUBRAL 《Geophysical Prospecting》1976,24(4):719-724
A satisfactory approximation to the travel time of a reflected wave is achieved by finding a ray, which originates in the source and emerges close enough to the receiver. The reason for this is, that the actual travel time function can be approximated in every emergence point of the wave by a time function which is entirely defined by seismic parameters along the ray connecting the source with the point of emergence. 相似文献
4.
物理大地测量学与地球物理学结合中的有关问题评注 总被引:2,自引:0,他引:2
本文依据大地重力学反问题的有关研究,对重力场边界扰动量的本征含义进行分析,由此揭示出它们在逼近地球实际重力场源过程中所具有的物理意义及存在的不足。然后进一步论及正常场源的非物理性上,并对其解决途径进行了探讨,最后对大地得力学反问题研究中的物理核--正交分解定理描述的场源量所具有的实际意义及其在地球物理反演中的具有的作用进行了分析和评注。 相似文献
5.
RAMESH P. SINGH 《Geophysical Prospecting》1985,33(3):369-376
In tectonically active regions electrical conductivity anisotropies are the dominating features. The importance of conductivity anisotropy in the interpretation of magnetotelluric data is well known. In the present study numerical results presented which show the effect of a substratum with inclined anisotropy on the magnetotelluric response. The pronounced change on the magnetotelluric response is found for the models in which the substratum underlies (i) conductive and (ii) resistive overburden. 相似文献
6.
本文从大地电磁扬的色散关系出发,阐述了进行大地电磁资料一维联合反演的物理意义。论证了对于以色散关系相联系的一对大地电磁响应函数,特别是阻抗实部和虚部视电阻率进行联合反演的必要性和可能的应用前景。对比研究了大地电磁阻抗各单参量及其联合反演的效果。结果表明,在加快反演迭代速度,限定反演解的非唯一性、保证反演迭代的稳定进行等方面,联合反演比单参量反演具有明显的优越性;在大多数情况下,阻抗实部视电阻率和阻抗虚部视电阻率联合反演的效果要比通常所采用的常规视电阻率和阻抗相位的联合反演效果好。实际大地电磁资料的试验表明,各种不同平均阻抗的利用和综合反演解释将有助于获得更为可靠的结果。 相似文献
7.
The telluric method of geophysical investigation is re-evaluated and several improvements are suggested. Besides the traditional Jacobian, several new parameters that bear information on the structure under investigation are proposed as sounding tools. These parameters are calculated for several two-dimensional models and plotted as pseudo-sections. The model results, calculated over a wide frequency band (10-4-10-2 Hz) suggest that these new parameters can give very detailed information about the subsurface structures. By way of example, we present experimental results obtained along two profiles across familiar structures. The interpretation of the results leads to two-dimensional models of the subsurface that are in good agreement with known geophysical and geological features of these two sections. 相似文献
8.
TH. KREY 《Geophysical Prospecting》1969,17(3):206-218
The paper presents a discussion of some of the noise features of the VIBROSEIS SYSTEM *** ** Trademark of Continental Oil Company.
and their bearing on the determination of the optimally weighted stack. 相似文献
and their bearing on the determination of the optimally weighted stack. 相似文献
9.
在用环域大地边值理论求解大地水准面的基础上对环域大地逆边值问题的解式作进一步研究.结果表明:①在线性化模式下,环域大地逆边值问题的解与确定大地水准面的传统的移去-恢复法解具有一致性;②在采用移去-恢复法时应注意,尽管移去过程中需调整地球质量,但不能调整参考正常重力场值;③若边界观测采用重力异常值,在采用移去-恢复法时应注意不能恢复移去物质对大地水准面的一阶项影响;④移去-恢复法的向下归算是环域大地逆边值问题解中的调和延拓的线性近似.本文既是对利用环域大地边值理论求解大地水准面的有效性的重要论证,也是对传统的确定大地水准面的移去-恢复法的数学证明. 相似文献
10.
Reddy , I. K., D. Rankin , 1971, Magnetotelluric Effect of Dipping Anisotropies, Geophysical Prospecting 19, 84–97. A solution is obtained for the magnetotelluric effect in the case of multi-layered earth, each layer containing dipping anisotropy, with the strike of anisotropy oriented at an arbitrary angle to the measuring directions. A technique to compute tensor impedances and tensor apparent resistivities is presented and the importance of anisotropies in magnetotelluric interpretation is discussed. 相似文献
11.
本研究做为电磁感应国际合作研究项目—EMSLAB计划的一部分,主要目的在于确定东太平洋年轻的海洋板块——Juan de Fuca板块及其周围地区岩石圈和软流圈的电性结构。 在对海底观测的大地电磁资料定性和定量分析的基础上,进行了二维数学模拟。在二维模型中,海洋地形和已知的表层构造被确定。通过改变模型的重要参数,评价响应函数和观测资料之间偏差的增加,检验模型的可靠性。结果表明,Juan de Fuca板块深部存在两个导电层,一个在40km,另一个在200km左右。这里岩石圈比其它较老板块的岩石圈薄 相似文献
12.
A new presentation for magnetotelluric data is proposed to be used together with the traditional representation. It is easily computed by applying the Bostick transform to all field data points. The result is an approximate depth-resistivity diagram which contains an indication of the data quality as well as the homogeneity of the subsurface. This resistivity section should be used in the interpretation of surveys in which accuracy is either not of prime concern or cannot be achieved. Since this mode of presentation is easily understood it can be used to familiarize earth scientists with the use of the MT method in exploration. 相似文献
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15.
H. G. MEYER 《Geophysical Prospecting》1991,39(8):1005-1014
The dynamic inversion of reflection seismic data is investigated with reference to the influence of noise on pseudo-impedance logs. Model traces are calculated with 0, 5, 15 and 50% noise, respectively. In solving the inversion problem, the algorithm of Marquardt and Levenberg is used in connection with singular value decomposition (SVD). The results are within a 1% error range so that there was no visible change in the logs. Further signal analysis show that there is no dependence on the phase content of the wavelet used if all other parameters of the model are known. 相似文献
16.
SUDHIR JAIN 《Geophysical Prospecting》1966,14(2):143-148
A simple method of magnetotelluric interpretation is derived using the property that the earth currents flow in horizontal sheets. It is shown that when the depth is taken as two-thirds of the Cagniard's depth of penetration (Cagniard, 1953), the mean resistivity-over the depth is the same as the apparent resistivity of the medium. From a mean resistivity versus depth of penetration plot, resistivity can be easily computed at all depths of the sounding. This method gives satisfactory results in a short time and makes it possible to interpret the soundings over media of several layers. However, the results are inaccurate near maximum and minimum points of the plot as well as in the zone of thin layers. 相似文献
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18.
A. K. GOODACRE 《Geophysical Prospecting》1973,21(1):66-69
The use of arctangents rather than arcsines in the expression for the gravitational attraction of a homogeneous rectangular prism reduces computational difficulties. Once a subroutine is available to compute one component of attraction in a Cartesian coordinate system, the other components may be obtained by cyclic permutation of the field point and body coordinate parameters. This technique also readily provides derivatives of the gravitational attraction and hence forms a compact method for the calculation of a magnetic anomaly due to a homogeneous rectangular magnetic prism. 相似文献
19.
The finite element method, here viewed as a special case of the Galerkin projective method, is applied to the modelling of magnetotelluric problems, and its adaptation to geological profiles is outlined. A novel method for obtaining surface field values, involving matrix representation of the normal derivative operator, is presented in detail. Results obtained by this method are compared with well-known infinite series solutions for the vertical fault and the outcropping dyke. Two profiles containing sulphide zones are also modelled, the results being compared with field data; satisfactory agreement is obtained. 相似文献
20.
N. DE VOOGD 《Geophysical Prospecting》1978,26(3):509-524
A finite realization of a discrete random noise process may be considered as a one-sided energy signal. Its phase property can then be described by means of the center position. The samples of such a realization are the components of a random signal vector and the center position is therefore a random variable. A statistical analysis shows that the expected value of the center position equals half the time duration of the realization. This implies that the Z-transform of the realization may be expected to have an equal number of poles and zeros inside and outside the unit circle. The standard deviation from the expected value of the center position is shown to depend on the time duration of the realization and on the autocorrelation of the process. It follows that, for processes that can be described by the convolution of a white series and a disturbance wavelet, the center position is independent of the phase property of the wavelet. A conclusion based on these results is that the homomorphic technique of wavelet estimation through cepstrum stacking must give questionable outcomes. Another conclusion is that the super-position of a realization of random noise on a minimum phase wavelet will in general give a mixed phase resulting signal. It is pointed out that schemes for the derivation of deconvolution filters do not take account of this phenomenon. 相似文献