tailieunhanh - Estimation of Sedimentary Basin Depth Using the Hybrid Technique for Gravity Data

In this paper, we present the rapid method for determining the depth distribution of a sedimentary basin by combining the FFT-based and space domain techniques in gravity data interpretation. The method is tested on two 3D synthetic models which density contrast is constant and exponential variation with depth. Then, the method is applied to determine the depth distribution of Nam Con Son sedimentary basin in Vietnam. The obtained results coincide well with theoretical models and seismic data. The computation speed of the method is much faster than that of space domain technique. | VNU Journal of Science: Mathematics – Physics, Vol. 33, No. 2 (2017) 48-52 Estimation of Sedimentary Basin Depth Using the Hybrid Technique for Gravity Data Pham Thanh Luan, Do Duc Thanh* VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam Received 17 April 2017 Revised 22 May 2017; Accepted 05 June 2017 Abstract: In this paper we present the rapid method for determining the depth distribution of a sedimentary basin by combining the FFT-based and space domain techniques in gravity data interpretation. The method is tested on two 3D synthetic models which density contrast is constant and exponential variation with depth. Then, the method is applied to determine the depth distribution of Nam Con Son sedimentary basin in Vietnam. The obtained results coincide well with theoretical models and seismic data. The computation speed of the method is much faster than that of space domain technique. Keywords: The hybrid technique, FFT-based technique, space domain technique, Nam Con Son basin. 1. Introduction According to Parker [1], the computation time of gravity effect caused by a two-dimensional uneven layer of material using a FFT-based technique is proportional to N ln(N), where N is the number of input and output points of model. For the same model, the computation time using a space domain technique is proportional to N2. The difference of computation time between two techniques is not so significant if the size of model is small. However, the number of calculations in the spacedomain technique increases rapidly compared to that in the FFT-based technique as the number of input and output points increases gradually. Based on the FFT-based technique, Oldenburg [2] deduced an inversion method to compute a density contrast layer from its gravity anomalies. However, this method requires a given mean depth of the interface [2, 3] and a low-pass filter to achieve convergence [2-6]. On the other hand, Bott [7] introduced another method using the .