伪时移地震在油田开发中后期剩余油分析中的应用

Application of pseudo-time-lapse seismic to residual oil analysis in the middle and late stages of oilfield development

时移地震在剩余油研究中具有显著优势,但需要前后两次或多次采集的地震数据在采集处理方面具有严格的一致性,因此限制了其推广应用。为了避开传统时移地震研究的不足,提出了伪时移地震概念。伪时移地震研究不再重点关注两次或多次地震资料的一致性,而是重点分析地震资料对地质油藏问题的响应特征。在分析过程中综合利用多种地震资料去伪存真,结合正演分析的结果,获得可靠准确的地质油藏认识,然后分析认识差异并了解油藏开发动态变化的规律,用于指导剩余油分析。渤海F油田目的层埋深较浅,为曲流河沉积,储层物性较好。该油田前、后采集的两套地震数据时间跨度为12年,在采集和处理方面均存在显著差异。将伪时移地震用于该油田的剩余油分析,通过分析前、后两次地震资料的地质油藏认识,可以较好地判断油藏因注水开发所导致的油水关系变化,这种认识比油藏数值模拟结果更具指导意义,据此可以明确剩余油富集区域,为井位部署和实施提供建议。

Residual oil analysis is important in the middle and late stages of oilfield development to maintain and increase the production.Time-lapse seismic has significant advantages in residual oil analysis,but it requires a strict consistency of adjoining two or more sets of seismic data in acquisition and processing,which limits its application.In order to overcome the shortcomings of traditional time-lapse seismic in residual oil analysis,this paper proposes the concept of pseudo-time-lapse seismic,which focuses on the responses of seismic data to geological reservoir problems instead of the consistency of seismic data.Firstly,using various data with pseudo-data eliminated,forward analysis is performed to get a reliable and accurate knowledge of geological reservoirs.Then,the differences in the knowledge of geological reservoirs obtained from analysis in two rounds are identified,and accordingly,the change patterns of reservoir development performance are determined to guide the residual oil analysis.In this paper,the pseudo-time-lapse seismic is applied to the analysis of residual oil in Bohai F Oilfield.In this oilfield,the target formation is shallow and composed of meandering river sediments,with good physical properties.The two sets of seismic data of the oilfield are acquired with 12 years apart,and they are apparently different in acquisition and processing.Identifying the differences in knowledge of geological reservoir from the two sets of seismic data allows for an effective diagnosis on the change of oil-water relationship caused by water flooding in the reservoir.The findings are more instructive than the results of reservoir numerical simulation,and can help further delineate the area with rich residual oil,providing a basis for well deployment.