CRP Gather Optimization Processing and Its Application in Thin Dolomite Reservoir Prediction in Hechuan Area, Sichuan Basin

At Hechuan area of central Sichuan Basin, in view of the serious overlap of wave impedance between thin-layer dolomite reservoir and surrounding rock and the difficulty in distinguishing, it is necessary to introduce pre-stack data information to carry out pre-stack reservoir prediction. The pre-stack elastic parameter inversion retains the characteristics of seismic reflection amplitude changing with offset or incident angle, namely AVO characteristics, revealing the physical properties and oil and gas properties of underground reservoir. However, after conventional processing, the input pre-stack CRP gathers of the Hechuan area still have problems such as low signal-to-noise ratio, low resolution, poor frequency consistency of seismic traces with different offsets, weak energy of near and far channels, and poor lateral continuity, which lead to the fact that the actual gathers can not well reflect the AVO characteristics of underground media, and there is a large deviation. However, the prediction of thin layer dolomite reservoir puts forward higher accuracy requirements for pre-stack elastic parameter inversion, in order to meet the requirements, The AVO characteristics of the gathers need to be restored, so the pre-stack CRP gathers need to be optimized. For this reason, the pre-stack gathers of the Lower Permian in Central Sichuan Hechuan area are optimized by using a set of technical processes includes radon de-noising, spectrum balance technology and elimination fitting amplitude compensation technology. The optimized gathers are improved in terms of signal to noise ratio, resolution and AVO fidelity after comparison, and the processed data are applied to the subsequent pre-stack AVO inversion in Sichuan Hechuan area, The prediction effect of thin dolomite reservoir has been improved and the reliability is stronger.