Research and application of interval velocity inversion for VSP data by layer-by-layer recursion algorithm
Tian-Zhu LUO1, Ming-Shun HU1,2(), Di HAN1, Yi-Qiang REN1
1. School of Resource and Geosciences,China University of Mining and Technology,Xuzhou 221116,China 2. State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China
The use of VSP data to accurately acquire formation velocities plays an important role in time-depth conversion and migration imaging of seismic data.Due to factors such as changes in receive and excitation conditions,near-source dynamic interference,and first arrival time pick-up errors,the first arrival time of VSP data often contains a certain degree of random interference.The authors studied the error characteristics of inverting interval velocity for VSP data with different offsets by layer-by-layer recursion algorithm when VSP data have random noise at the first arrival time and only deep data are received.Some conclusions have been reached:①The larger the offset,the smaller the inversion velocity error of the corresponding data;②When the data is only recorded from the deep level,the smaller the offset,the closer the inversion result to the actual formation velocity.For this reason,the first arrival time should be smoothed before being inverted by layer-by-layer recursion algorithm,and then the average of inversion results is taken from multi offset VSP data as the final interval velocity.This method can improve the inversion accuracy of the interval velocity.By using this research conclusion,good results were obtained in the processing of marine Walkaway-VSP data.
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Tian-Zhu LUO, Ming-Shun HU, Di HAN, Yi-Qiang REN. Research and application of interval velocity inversion for VSP data by layer-by-layer recursion algorithm. Geophysical and Geochemical Exploration, 2019, 43(3): 608-617.
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