基于CRP道集优化处理的叠前AVA同步反演技术的应用——以KL9构造区为例

叠前AVA同步反演技术广泛应用于储层预测及流体检测,但叠前道集作为叠前反演的主要输入数据,CRP道集质量对反演结果的影响较大。重点开展了CRP道集优化处理研究,对海底电缆(Ocean Bottom Cable,OBC)数据偏移后的CRP地震道集进行去噪、去多次波、振幅能量补偿、提高分辨率及道集精细拉平处理,得到高质量且相对保真的地震资料。在此基础上进行叠前AVA反演,得到一系列和储层、流体有关的纵横波速度比、泊松比和密度等弹性参数,进行储层及流体综合预测,形成了叠前处理、反演、解释一体化的技术流程。以渤海海域KL9构造区为例,针对CRP道集中存在的远、中、近道能量不均衡、信噪比低和道集未拉平等问题,应用叠前去噪、无速度道集拉平和远近道频谱能量补偿的道集优化处理技术,提高叠前CRP道集品质,开展AVA同步反演。实际应用结果表明,优化处理后道集的信噪比、分辨率、保真度有明显提高,以此为基础开展的叠前反演结果的精度较道集优化处理前显著提高。

Prestack amplitude-versus-angle (AVA) simultaneous inversion is widely used in reservoir prediction and fluid detection.Common-reflection-point (CRP) gathers are the main input data,and hence important for inversion results.This paper focuses on the optimization of CRP gathers.After migration of Ocean Bottom Cable(OBC) data,CRP seismic gathers were optimized by denoising,suppression of multiples,amplitude-energy compensation,improvement of the resolution,and fine-scale gather flattening,in order to obtain seismic data of high quality and fidelity.A prestack AVA inversion was then carried out,obtaining a series of elastic parameters (e.g.,velocity ratio of P and S waves,Poisson density) related to both the reservoir and the fluid.Based on these data,we conducted a comprehensive reservoir and fluid prediction.Moreover,we established an integrated flow of techniques,including prestack processing,inversion,and interpretation.We tested this integrated flow on field data from the KL9 tectonic region.The CRP gathers presented some problems (e.g.,trace energy imbalance,low signal-to-noise ratio (SNR),unflattened gathers).In order to improve the quality of CRP gathers and be able to carry out an AVA simultaneous inversion,we implemented a gather optimizing process,which included prestack denoising,gather flattening,and energy compensation for unbalanced trace energy.The results of this practical application test showed that the SNR,resolution,and fidelity of CRP gathers were improved.The accuracy of prestack inversion,based on the optimized CRP gathers,was also improved and could be used to effectively predict the thin reservoir and fluid properties of the KL9 region.

国家科技重大专项“渤海海域勘探新领域及关键技术研究”(2016ZX05024-003)资助。