| Abstract:Nowadays, the basin deep volcanic rocks have become a hot field of oil and gas exploration, it is crucial for volcanic oil and gas exploration to obtain the gravity and magnetic anomalies caused by volcanic rocks and their distribution by potential field separation and boundary identification . In this paper, all kinds of potential field separation methods are firstly classified into two categories according to their separation ability, i.e. dichotomous and multi-division method, and the origin, development and current situation of multi-division potential field methods which are capable of extracting gravity and magnetic anomalies of basin deep volcanic rocks are discussed in detail. As the result, the matched filtering method doesn’t have the desirable effect of potential separation because of the probable spectral overlap among different field sources in vertical direction. Wavelet analysis mothed can effective separate the potential field of the field sources with different buried depth and determine their buried depth by wavelet multi-scale decomposition and power spectrum analysis. Because of the equivalent relation between the cutting radius and the central depth of the abnormal body, the interpolation cutting method can realize the stratified separation of potential field with specific geological significance. Therefore, the wavelet multi-scale analysis and the interpolation cutting methods are more effective in the potential field separation comparing with the matched filtering. Secondly, the boundary detection methods of local anomalies are classified and compared. It is considered that the direct derivative calculation methods can effectively determine the boundary of shallow field sources, but it is not sensitive to that of the deep field source. While the derivative ratio calculation methods can normalize the anomalies caused by the deep and shallow field sources to the same level, so as to realize the accurate boundary identification both of the deep and shallow field sources. Therefore, derivative ratio calculation methods are the preferred choice for basin deep volcanic rock boundary detection. In addition, the influences of the analytic singularity of derivative ratio calculation methods and the noises introduced in derivative calculation on the accuracy of boundary recognition and the solutions are discussed. |
