重磁位场数据空间重构及层状介质反演研究

发布时间：2017-12-26 21:07

本文关键词：重磁位场数据空间重构及层状介质反演研究　出处：《吉林大学》2017年博士论文　论文类型：学位论文

【摘要】：随着重磁位场探测数据精度的提高和体量的增大,重磁位场数据空间重构,能够充分挖掘实测数据所蕴含的地质-地球物理信息,为地球物理勘探和国防建设提供至关重要的解释依据;另外,由于观测范围的拓宽和解释深度的加深,重磁位场数据层状介质反演,对深部地质构造基础理论研究和中深部工业找油找矿具体实际应用有十分关键的指导作用。所以,重磁位场数据的空间重构处理方法和层状介质反演解释技术长期受到专业人士重视,一直是重磁位场处理与解释的经典应用方向和热点研究问题。但是,作为数据空间重构关键途径的向下延拓和作为层状介质反演主要方法的界面反演,却存在着许多亟需解决的问题。本文针对传统向下延拓方法的下延深度浅、下延不稳定、结果不准等问题,分别提出了基于微分方程数值解法的Milne下延法和Adams-Bashforth下延法,以获得更令人满意的重磁位场向下延拓结果;针对经典Oldenburg界面反演方法中存在的高频放大因子,引入新的迭代方式改善了Oldenburg反演的收敛性,为优化密度界面反演提供了新思路;针对经典Parker-Oldenburg正反演方法数值结果的不准确问题,本文利用Pade有理展开替代泰勒展开,为解决磁性界面正反演提出了新方法。因此,以上述方法技术为根本,本文开展如下研究:首先,由于延拓可以为辅助导航构建重磁位场数据库,其中上延可以突出深部异常,下延可以突出浅部异常。重力场向上延拓过程是稳定且收敛的,而其向下延拓不稳定且发散。为此,本文提出新的重力场向下延拓方法——Milne下延法。先利用重力场及其垂向一阶导数,基于求解微分方程数值解法的Milne格式,推导出重力场向下延拓Milne公式;并将新推导的Milne下延法应用于模型数据,理论模型试验结果及其误差曲线表明,相对于快速傅里叶变换下延法(FFT下延法)和积分迭代下延法,Milne下延法解决了下延深度浅、下延不稳定和结果不准确等问题。Milne下延法的下延结果准确,可完成5-10倍点距的大深度下延,无论数据中是否含有噪声,下延过程都十分稳定,且结果与真实值的相对误差小;为验证实效性,本文将提出的Milne下延法应用于加拿大Nechako盆地地区实测航空重力数据,得到有效且准确的下延结果,能够识别和圈定一些细小的异常特征,为milne下延法的进一步推广应用奠定基础。其次,针对重磁位场向下延拓所存在的同样不足,本文又给出了一种重力场向下延拓方法。首先,利用已知的重力场和重力垂向一阶导数,进行向上延拓,得到若干个高度上重力场及其垂向导数的上延值;然后,基于微分方程多步线性解法的adams-bashforth格式,给出向下延拓adams-bashforth法;最后,为了检验所推导的adams-bashforth下延法的应用效果,分别将其对模型数据和实测数据进行向下延拓。模型数据试验表明,与fft下延法和积分迭代下延法相比,本文三阶adams-bashforth法的下延过程稳定、下延深度大、边界损失小、抗噪声能力强、相对误差小、结果准确;加拿大nechako盆地地区航空实测数据试验表明,本文方法的重力场向下延拓结果稳定且准确,可以有效识别小尺度异常,恢复真实异常分布形态。同时还比较了四阶adams-bashforth下延法和八阶adams-bashforth下延法的向下延拓效果,模型试验和实际算例表明,高阶adams-bashforth下延法可以获得更好的下延结果。再者,oldenburg反演可以快速反算海量重磁位场数据,确定地下深部界面的起伏和沉积盆地地层的分布。但是,对于高精度的测量数据,作为经典层状介质反演方法的oldenburg反演方法存在着发散性等问题。针对经典oldenburg反演存在的这一问题,结合积分迭代下延方法,本文推导出收敛的、可用来优化界面几何形态的密度界面parker-oldenburg正反演改进方法。本文提出的改进迭代的parker-oldenburg正反演方法,在迭代过程中不需要低通滤波器或者其他压制高频技术。类比于将发散的向下延拓改写为收敛的向上延拓的积分迭代下延法的迭代方式,本文主要采用正演反复迭代的方式,避免直接反演指数放大因子。本文利用其他地质地球物理信息来确定反演初值,在迭代计算过程中不省略高阶项,从而保证了反演过程收敛且结果准确。利用模型重力数据,验证了该方法的优越性;将改进后的oldenburg反演方法应用于中国青藏高原地区,有效反演了该地区莫霍(moho)面深度起伏。最后,由于经典频率域(波数域)磁性层状介质正反演是利用泰勒(taylor)级数对指数函数展开,并进行傅里叶变换(fouriertransform)而实现,存在计算慢、精度低的问题。因此,本文提出基于pade有理展开替代泰勒级数展开的磁性界面正反演方法。通过数学分析知,在展开步长大、展开点邻域无界的情况下,泰勒级数展开不收敛,而对应的Pade有理展开收敛。与泰勒级数展开相比较,Pade有理展开收敛域更大更稳定、逼近更准确。因此,本文推导了Pade有理展开替代泰勒级数展开的磁性界面正反演表达式。模型试验验证了Pade有理展开磁性界面正反演方法的有效性。应用该方法对加拿大Matagami地区实测数据进行反演,得到了比较稳定、合理的地下磁性界面分布结果。
[Abstract]:With the increase of the gravity and magnetic field detection data to improve the accuracy and volume, the gravity and magnetic field data space reconstruction, can fully exploit the data contained in the geological - geophysical information and provide important basis for the interpretation of geophysical exploration and the construction of national defense; in addition, by observation and interpretation to broaden the range of depth, the gravity and magnetic field data inversion of layered medium, deep geological structure basic theory research and deep prospecting for oil industry specific application guidance is the key. Therefore, the reconstruction and processing technology of gravity and magnetic field data and layered media inversion technology have long been attached importance to by professionals. They have been the classic application directions and hot topics of gravity and magnetic field processing and interpretation. However, as the key way of data space reconstruction, the downward continuation and the interface inversion as the main inversion method of layered media still have many urgent problems to solve. According to the traditional method of downward continuation of the extension of shallow depth, extension of unstable and inaccurate results, are proposed. The numerical solution of differential equation Milne extension method and Adams-Bashforth. Based on this method, to obtain a more satisfactory potential field downward continuation results; for high frequency inversion method Oldenburg the classic interface in the amplification factor, improve the convergence of Oldenburg inversion iteration is introduced in new ways, provides a new idea for the optimization inversion of density interface; not accurate to solve the problem of classical Parker-Oldenburg inversion method of numerical results, this paper uses Pade rational expansion to replace Taylor, in order to solve the magnetic interface inversion method is proposed. Therefore, based on the above methods, the following research is carried out in this paper. First, because continuation can build a gravity and magnetic potential field database for auxiliary navigation, the upper part extension can highlight the deep anomaly, and the next extension can highlight the shallow anomaly. The upward continuation of the gravitational field is stable and convergent, while its downward continuation is unstable and divergent. To this end, a new downward continuation method of gravity field, Milne down method, is proposed in this paper. The first use of gravity field and vertical derivative, numerical solution of differential equation based on Milne format, derived from the gravity field downward continuation of the Milne formula; and a new derivation of the Milne extension method is applied to the model data, the results of theoretical model test and error curve shows that relative to the fast Fourier transform method (FFT. Under the extension method) and integral iteration continuation method, Milne extension method to solve the extension of shallow depth, extension of unstable and inaccurate result etc.. The Milne extension method and the extension is accurate, large depth can be completed 5-10 times from the extension, whether the data in the presence of noise, under the extension process are very stable, and the results and the real value of the relative error is small; in order to verify the effectiveness of the application of the extension method, this paper will put forward the Milne to take airborne gravity the measured data in the Nechako basin, effective and accurate results can be extended, abnormal feature recognition and delineation of some small, lay the foundation for further application of Milne extension method. Secondly, a downward continuation method of gravity field is given in this paper in view of the same shortcomings in the downward continuation of the gravity and magnetic field. First of all, using gravity field and gravity vertical to a known derivative of upward continuation of gravity field and vertical, get some height to the derivative of the extended value; then, the differential equation of multi step linear method based on Adams-Bashforth format, given the downward continuation Adams-Bashforth method; finally, to test the effect of the the derivation of the Adams-Bashforth extension method, respectively. The downward continuation of model data and measured data. The data shows that the model test, and the FFT extension method and integral iteration continuation method compared to the three order Adams-Bashforth method under the extension process is stable, decurrent depth, boundary loss, anti noise ability, small relative error, accurate results; tests for aviation data region of Canada nechako basin, gravity method the downward continuation of the stable and accurate, can effectively identify the small scale anomalies, abnormal distribution of real recovery. At the same time, we also compare the downward continuation effect of the four order Adams-Bashforth downward continuation method and the eight order Adams-Bashforth downward continuation method. Model tests and practical examples show that the higher order Adams-Bashforth downward continuation method can get better lower delay results. Furthermore, Oldenburg inversion can quickly calculate the data of massive gravity and magnetic field, determine the undulation of the deep underground interface and the distribution of sedimentary basin strata. However, for the high precision measurement data, the Oldenburg inversion method, as the classical inversion method of the classical layered medium, has the divergence and so on. Aiming at the problem of classical Oldenburg inversion, combined with the integral iteration downward continuation method, this paper deduces a convergent and improved parker-oldenburg interface method which can be used to optimize interface geometry. The improved iterative parker-oldenburg forward and inverse algorithm proposed in this paper does not require low pass filters or other suppression of high frequency techniques during the iterative process. It is analogous to rewriting the downward continuation of divergence into the iterative iteration method of the integral iteration for upward convergence of convergence. In this paper, we use forward iteration and iterative method to avoid direct inversion of exponential amplification factor. In this paper, we use other geophysics information to determine the initial value of inversion, and do not omit the higher-order terms in the iterative calculation process, so as to ensure the inversion process is convergent and the result is accurate. The superiority of the method is verified by using the model gravity data. The improved Oldenburg inversion method is applied to the Qinghai Tibet Plateau and effectively retrieved the depth fluctuation of Moho (Moho) surface in this area. Finally, due to the classical frequency domain (wavenumber domain), the forward and inversion of magnetic layered media is achieved by using Taylor (Taylor) series to expand the exponential function and perform Fourier transform (Fouriertransform), which is slow and precise.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P631

【相似文献】