共查询到19条相似文献，搜索用时 328 毫秒
1.
电磁随钻测量（简称EM-MWD）是现代石油钻井中的一项新技术,在国内各大油田的定向钻井中正在推广应用,但使用过程中仍存在石油地层电阻率低,电磁波信号衰减严重、测量深度受限等问题。据此特点,提出了研究设计小直径化EM-MWD系统,将其用于地层电阻率高,钻深浅的固体矿床钻探的设想,以便扬长避短,为电磁随钻测量开辟新的应用领域。分析了电磁随钻测量技术应用于固体矿床勘探的技术要求及可行性,提出了进一步研究工作的建议。 相似文献
2.
垂直磁偶极子电磁频率测深法,原名为地面电磁波法(Melos)。此法系法国地调局在六十年代于原大地电磁测深法的基础上,利用1954年Wait推导的垂直磁偶极子场强的公式,经过数学上的变换,建立了“中区场”测量的电磁频率测深法。通过探测地层的深度和电阻率来达到探矿的目的。 相似文献
3.
钻孔电磁波法的正常场公式是进行各种钻孔电磁波探测理论研究和资料解释的基础，因此有必要将其建立在近代天线理论之上。通过对钻孔电磁波法中的基本电磁系统的分析讨论，证明了关于绝缘天线的广义传输线理论在钻孔电磁探测和电磁波测井中的可应用性，并给出了在一般条件下的基于广义传输线理论的钻孔电磁波法正常场公式。通过与经典的正常场公式的定性对比发现，基于广义传输线理论的正常场公式既包含了天线本身绝缘层的作用，又考虑了钻孔的影响。因此，本文提出的公式能提供更多的关于围岩和钻孔流体的电磁性质的信息，应能成为跨孔电磁成像和电磁 相似文献
4.
双频组合波电磁测深视电阻率是利用双频电磁波进行地电探测的一种新方法。本文通过对各种典型地电模型视电阻率曲线分析,进一步证明了该视电阻率是进行近区频域电磁测深的一种行之有效的方法,它是电磁响应的单值函数,能客观反映地电断面的电性变化规律。具有压制背景场、突出地电异常的功能。它所表现的对地层的分辨能力和各种特性符合测评的要求。 相似文献
5.
探地雷达应用中的几个基本问题 总被引：13，自引：0，他引：13
本文讨论了探地雷达(GPR)应用中的四个基本问题:(1)电磁波在地层中传播的波阻抗;(2)电磁波在地层分界面上场强的反射系数与透射系数;(3)电磁波在地层中的传播速度和反射波相位;(4)GPR的探测深度。为GPR的资料解释工作提供一定的理论依据和方法,也会促进资料解释的研究和发展。 相似文献
6.
7.
利用微波侦测地下水位与河川变化 总被引：1，自引：0，他引：1
论文探讨藉由电磁波照射地表,从反射讯号中去判断地下水水位与土石流移动观测之可行性,期能提供一新的土石流预警方法.电磁波在土壤中的行为受土壤的介电系数所控制.我们首先以地下水模式仿真出地层中的含水量分布状况,同时搜集过去关于土壤介电系数的实验资料和模型,将其运用于层状介质法来仿真电磁波照射在不同含水量剖面下之反射波,以建立含水量分布与反射讯号间的对比模块.最后则是以砂箱实验,量测含水量剖面后,藉由天线与网络分析仪来发射电磁波与记录反射波.由理论计算与实验测量结果之比较可知所选择的土壤介电系数模型可以仿真简单潮湿土壤的电磁行为;而由实验量测可知电磁波至少可以打进50cm的微湿砂子.若以雷达扫瞄河道,可对土石流或洪水前锋的速度作准确之估计. 相似文献
8.
对极低频电磁波技术的理论进行讨论,首先根据研究对象和问题建立地质模型和相应的数学模型,然后根据电磁场理论选择了相适宜的计算方法,推导出水平长直导线接地源电离层、空气层和层状大地相互耦合频域电磁场响应的一般表达式。这些表达式将电磁响应和电离层的电导率等参数有机联系在一起,为极低频电磁波技术的正演计算以及极低频电磁波技术在资源探测应用中的可行性分析奠定基础。对理论地电模型的计算表明,由于电离层的存在使得电磁波在地面与电离层之间来回多次反射,从而改变了电磁响应曲线的形态。 相似文献
9.
10.
《物探化探计算技术》2021,(1)
为解决煤矿工作面底板注浆钻孔间遗留隐伏构造的探查和注浆效果评价两大问题,弄清孔间电磁波透视在数据冗余度不足条件下的成像精度,采用全空间偶极子电磁波传播公式计算电磁响应数值。讨论孔中电磁波透视施工所采取的施工方式,数据整理方法与常规电磁波方式的异同,通过模拟揭示了电磁波孔中透视取得良好效果的可能性。模拟结果表明,在透视数据冗余度缺乏的情况下,孔间透视依旧能取得良好的效果。 相似文献
11.
12.
大同侏罗纪煤田无线电波坑道透视特征 总被引：4，自引：2，他引：2
介绍了大同侏罗纪煤田煤系地球物理特征和煤层中地质小构造的电磁波透视特征,说明在大同侏罗纪煤田采用无线电波坑道透视技术,能够有效地探测出煤层中的各种地质小构造,较好地指导综采生产。 相似文献
13.
A standing wave in front of a seawall may reach a height more than twice of its incident component. When excess pore pressure occurs, it may even induce seabed instability, hence endangering the structure. This issue was studied previously using only linear wave theory. In this paper, standing‐wave theory to a second‐order approximation is applied, in order to demonstrate the differences between these two solutions. The spatial and temporal variations in the instantaneous pore pressure are first calculated, in addition to their vertical distributions. The effects of wave height, water depth and the degree of soil saturation on pore pressure distributions are then discussed, followed by the net pore pressure averaged over one wave cycle. The results suggest the existence of a residual pore pressure in the seabed and its net pore pressure can be used to estimate the wave‐induced liquefaction potential in a soil column. It also indicates that, in deep water, the second‐order solution predicts that a negative pore pressure at an antinode which may be greater than a positive pressure. Overall, the second‐order solution is found to agree better with the experimental results of the pore pressures available, compared to the linear solution. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
14.
Refinement in the Reflection Properties of Electromagnetic Waves at a Stratigraphic Interface 总被引：3，自引：0，他引：3
The travel time of electromagnetic waves in conductive strata has a quantitative relation to the conductivity, permittivity,
and permeability of the strata. Using these parameters, geologists can determine the lithology of rocks. But current logging
and exploration methods take the time between incidence and reflection as zero and do not take into account the effect of
the lateral shift delay when the electromagnetic wave is reflected on the interface of strata. In this article, the lateral
shift delay will be considered and a more accurate relationship between petrophysics and electromagnetic wave travel time
will be derived. The lateral shift delay of quasi-total reflection of inhomogeneous s-polarized electromagnetic waves (whose
electric field is perpendicular to the incident plane) caused by the Goos–H?nchen effect is derived using the phase shift
of the wave. The result fits both low and high frequency electromagnetic waves. But for geologists, the most valuable frequency
range is between 106 and 109 Hz (1 MHz–1 GHz, wavelengths between 0.1 and 100 m). A numerical example where the frequency equals to 1 GHz. shows three
discontinuous points at the critical angle of phase shift, the critical angle of attenuation and 90∘. When the incident angle equals one of these three angles, the lateral shift delay will become infinite. That is, the electromagnetic
wave will propagate along the interface. Even when the incident angle is close to one of them, the lateral shift delay is
very large. The results also indicate that the two critical angles have an important relation to conductivity and permittivity
of the two strata, and that the lateral shift delay has a relation to the incident angle. These results can be used to determine
the lithology of the strata and to divide the strata more effectively. It is suggested that this approach may prove useful
in electromagnetic logging analysis and, perhaps, in the design of logging instruments. 相似文献
15.
Fu-Ping Liu Rui-Zhong Li Jin-yao Li Hui-Guo Chen Chang-Chun Yang 《Mathematical Geosciences》2008,40(7):813-829
The group time delay (GTD) formulae of quasi-total reflection of inhomogeneous P-polarized electromagnetic waves (P-PEW, whose electric field parallels to the plane of incidence), caused by the Goos–Hänchen effect, is derived by the phase shift of the wave. A numerical example where the frequency equals to 1 GHz is given. The curves of calculating results show that there are three discontinuous points at the critical angle of phase shift vector, the critical angle of attenuation vector and 90○. When the angle of incidence is equal to one of these three angles, the GTD will become infinite, and the electromagnetic wave will propagate along the interface. The GTD will be very large, when the angle of incidence is close to one of these three angles. The results indicate that there is an important relationship between the two critical angles and the conductivity and permittivity of the two strata, and that the GTD has an important relationship with the angle of incidence. These results can be used to determine the lithology of the strata and to delimit the interfaces of strata more effectively. It is suggested that this research may prove useful in electromagnetic logging analysis and, perhaps, in the design of logging instruments. 相似文献
16.
17.
18.
在进行地热资源勘察中,地球物理方法是很重要的,尤其是在城市中。以郑州市老鸦陈地热田为例,利用超长电磁波技术进行城市地热资源的勘察。首先根据已有的钻孔,建立地层和热储异常解释的标志曲线;其次,根据郑州的地质条件,布置10个测点;最后,根据标志曲线,对各测点的地层、断层和热储异常进行解释。勘察结果表明,郑州地热田主要由三种类型：西南浅部基岩中的地热水、基岩顶面以上地热水、深部基岩中的地热水。 相似文献
19.
引出水平分层大地面上水平电偶极源及垂直磁偶极源的电磁场分量表达式,对式中核函数进行了变换,分析所含的波型及其与场区的关系,指出了TE型场、TM型场和TEM型场穿透地层的能力。根据波型与地层作用特点,优化电磁场分量,以提高频率电磁测深的探测效果。 相似文献