3D-Imaging of 2D-Time Reverse Modeling
Published in
72nd EAGE Conference & Exhibition
Date of publication
14 July 2010
Abstract
Time reverse modeling has become an efficient tool to detect the origin of low-frequency (<10 Hz) seimic tremor signals. Examples of such signals are observed before volcanic eruptions or above hydrocarbon reservoirs. Technical expertise has mainly been developed for 2D application. However, effects from using three-component signals for 2D reverse modeling are still widely unknown. An example is reverse propagation of signals on a plane vertically below a seismometer array. In this case, reverse calculation is performed with the vertical and the horizontal component parallel to the array. The horizontal component perpendicular to the array is dropped. This causes partial loss of information on particle motion and directivity of the recorded waves. The concept of merging multiple 2D images to one 3D image is presented to meet problems arising from this loss. A synthetic study with a tremor-like source demonstrates how this source is imaged in different vertical planes. Planes within the distance of two wavelengths from the source render artificial focusing at the horizontally projected source location. However, these artificial focusing points are weak relative to the focusing at the corret location. A source seems to be locatable with 2D reverse modeling and successive analysis in a 3D image.
