论文详情
层间多次波的存在严重影响地震资料品质,造成合成地震记录与实际资料不匹配,对油气勘探开发造成许多负面影响。由于层间多次波来自表层以下的反射位置,因而与一次波差异小,且多源叠加造成多次波周期性特征复杂,目前还没有非常有效的压制方法可以借鉴。针对层间多次波“识别难,压制难”问题,在广泛技术调研的基础上,改变思路,提出了一种处理解释一体化的层间多次波识别与压制技术方案,以四川盆地高石梯—磨溪地区灯影组为例,介绍其实际应用效果。首先,研发了基于反射率法的多次波正演模拟技术,通过含与不含多次波正演模拟结果与实际资料对比分析,结合其它多种手段论证了高石梯—磨溪地区井震不匹配主要是由层间多次波造成的,并得到VSP资料的验证。其次,利用剥层法多次波正演模拟与周期性分析,明确了灯影组层间多次波主要来源于其上覆4组速度反转层。其后,在层间多次波模拟与来源层位指导下,通过多次波压制试验优选技术,建立了偏移前、偏移后和叠后分步组合迭代的多次波压制技术流程,并通过层控剩余速度分析与叠加速度优化,以及层控Radon变换解决了层间多次波与一次波速度差异小的瓶颈问题。最后,基于速度谱上速度展度,研发了多次波发育强度平面预测技术,形成了点、线、面完整的多次波压制处理质控技术,保障了在压制多次波的同时不伤及有效波。该技术方案在高石梯—磨溪地区已经得到规模化应用,落实了超深层地层结构,取得了显著地质效果;在GS1井区应用中提高了井震匹配程度,储层预测符合率提高了20%以上;在GS19井区应用中首次在灯影组内幕发现了大量弱“串珠”反射,它们是未来重要的资源接替区;在高石梯东地区应用中消除了台缘带假像,降低了井位部署风险。
The existence of interlayer multiples seriously affects the quality of seismic data,causes mismatch between synthetic and actual seismic data at well location,and has many negative effects on oil and gas exploration and development.At present,there is no very effective suppression method for the multiples.Based on extensive literature research,a new identification and suppression method,which integrates processing and interpretation is proposed.Firstly,the multiple wave forward modeling technology based on the reflectivity method was developed.The forward simulation results of models with and without multiples were compared and analyzed with actual seismic data.It has been proven that the well-seismic mismatches in this area,which was verified by VSP data,were mainly caused by interlayer multiples.Secondly,multiple forward modeling layer by layer and periodic analysis confirmed that four overlying velocity reverse layers were the main sources of multiple waves in Dengying Formation.Thereafter,under the guidance of multiple wave identification and source analysis,an iteration processing procedure with three steps of multiple wave suppression on CDP and CRP gather and stack data was established using optimal technology of multiple wave suppression through processing test.The bottleneck problem of small wave speed difference between the multiple waves and primary waves was solved by combination of horizon-constrained residual velocity analysis,stacking velocity optimization,and horizon-constrained Radon transform.Finally,based on the velocity spread on velocity spectrum,the plane prediction technology of multiple development intensity was developed,and a complete quality control procedure and technology of multiple waves suppression processing with well-seismic tie,seismic section and seismic slices was developed to ensure that the multiples are suppressed without damaging the effective wave.This technical scheme has been applied at scale in Gaoshiti-Moxi area of Sichuan basin with good effect,and the ultra-deep strata structure is defined more clearly.In particular,the well seismic matching degree was improved in the GS1 well area,and the reservoir prediction coincidence rate increased by more than 20%.A large number of weak bead reflections were found in the GS19 well area for the first time,and it is an important resource replacement area in the future.When the scheme was applied in the eastern part of Gaoshiti area,the false image of carbonate platform margin was eliminated and the risk of well location deployment was reduced.
中国石油天然气集团有限公司前瞻性基础性技术攻关课题(2021DJ3701)资助。