利用DCT法计算重力归一化总梯度

Using DCT to Calculate Normalized Full Gradient of Gravity Anomalies

利用重力归一化总梯度方法可以寻找场源位置,通过"两高夹一低"的典型场特征可以检测油气构造,传统的方法主要采用的是别列兹金法(即傅立叶级数法)和傅立叶变换法。利用DCT法计算重力归一化总梯度是最新研究方法。从理论上给出了基于DCT的重力异常转换公式,进而研究了无限长水平圆柱体、三度体非含油气球冠以及储油球冠模型GH场特征。模型实验证实:随着地质体埋深的增大,谐波数会逐渐减小,GH场奇点极大值向下移动,且呈现线性衰减的特征;储油球冠GH场等值线表现出明显的"两高夹一低"的储油气藏典型标志;用DCT法计算的GH场具有优良的稳定性,而且能够增加向下延拓的计算深度。

Normalized full gradient of gravity anomalies can be used to find the location of source and inspect hydrocarbon structure because of its characteristic of ＂one less value between two high values＂. Traditionally, B. M. DepeaKnH method and Fourier transform were used primarily, but using DCT to calculate normalized full gradient of gravity anomalies was a new method. The authors presented gravity anomalies conversion formula based on DCT, in succession studied GH field characteristics of these mod- els that include infinite horizontal cylinder, symmetrical-density sphere-coronal and asymmetric-density oil storage sphere-coronal. These experiments had proved that the more was the depth, the smaller was the harmonic wave member, at the same time the singular point Maximum moved downwards and had linear attenuation. GH field contour line of asymmetric-density oil storage sphere-coronal had presented typical characteristic of ＂one less value between two high values＂. GH field calculated by DCT has excel- lent stability and could enhanced the depth of downward continuation.