A method for stripping coal seam strong reflection and low-frequency shadow analysis
Zhang Zaijin1, Zhang Junhua1, Li Jun1, Zhang Hong2, Xia Hongmin2, Lei Tao3
1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China;
2. Exploration & Production Research Institute, SINOPEC, Beijing 100083, China;
3. North China Oilfield Branch Co., SINOPEC, Zhengzhou, Henan 450006, China
Abstract:Coal seams are characterized by low velocity and low density, which result in strong reflection on seismic sections. Hydrocarbon reflection information may be hidden in strong events, and low-frequency shadow will be covered up. This phenomenon makes hydrocarbon direct detection fail. In this paper, we propose a method for stripping coal seam strong reflection by wavelet-constrained matching pursuit. This method can efficiently strip strong reflection in 3D seismic data. We use generalized S transform(GST) to do time-frequency analysis and compare time-frequency characteristics before and after stripping coal seam strong reflection. Two parameters adjust window functions according to the feature of frequency distribution. Model and real data tests show that the proposed method achieves good results and abnormal shadow appears under a reservoir after stripping strong reflection of coal seams.
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