深水地震资料联合去多次波技术——以南海北部荔湾深水气田为例

珠江口盆地荔湾地区为南海北部深水油气重要勘探区。该区地震资料上多次波异常发育且复杂多样,单一的多次波压制方法有着明显的局限性。为此,在调查荔湾地区多次波特点的基础上,针对性地采取了多项技术组合应用的联合去多次波技术:①海底相关多次波为地震资料处理中多次波衰减的主要对象,可用基于波动方程的3DSRME技术来压制,理论和实际应用均表明3DSRME较之2DSRME更具技术优势;②拉冬域去多次波技术处理流程位于3DSRME之后,主要压制海底相关多次波以外的长周期多次波;③对于剩余的绕射多次波主要利用AVO预测法压制,基本思想是分离多次波与有效波,利用多次波与有效波的频率和能量差异进行压制。最后,从压制多次波效果和保幅性两个方面对联合去多次波技术进行了评价,认为该技术多次波压制效果明显,能够做到相对保幅处理。该技术为荔湾深水气田群的地震资料精细解释、AVO分析和叠前反演提供了优质的基础数据。

A portfolio of demultiple technologies in deepwater seismic data processing:A case study of the Liwan gas reservoirs in northern South China Sea

Liwan is an important deepwater exploration area in the northern South China Sea. Multiples are common and complex in seismic data acquired in this area, thus a single multiple rejection approach is not very effective in processing these seismic data. Based on a study of the multiple characteristics of seismic data acquired in this area, a portfolio of demultiple technologies was proposed. (1) Seafloor associated multiples are the major target for multiple attenuation in seismic data processing and can be rejected by using the wave equation based 3D SRME technology. Both theoretical studies and application practices show that 3D SRME is superior than 2D SRME. (2) The Radon antimultiple processing flow follows after 3D SRME and mainly attenuates long period multiples except seafloor associated multiples. (3) The remaining diffracted multiples are attenuated mainly through AVO prediction. The basic principle is to attenuate multiples through separating effective waves from multiples according to their differences in frequency and energy. The portfolio of demultiple technologies was of high performance and also preserved amplitude processing. Its application in Liwan deepwater gas reservoirs provided quality data for fine seismic interpretation, AVO analysis and pre stack inversion.