二氧化碳驱油的地震资料特征研究

Study on Seismic Data Characteristics of Reservoir after Carbon Dioxide Flooding

二氧化碳驱油作为三次采油的重要技术手段,提高采收率效果明显,具有重要的环保降排价值。但在二氧化碳驱油过程中,部分层位二氧化碳过早突破,一方面严重降低气驱的波及效率,另一方面油井气窜后,二氧化碳将对油井举升系统、地面工艺设备乃至井场环境造成严重影响等问题。常规的注采及油气水性质监测方法,仅能简单地监测二氧化碳驱油的效果和二氧化碳采出情况,驱油过程的精细监测成为薄弱环节,制约着二氧化碳驱油的进一步发展。二氧化碳驱油前后储层的地球物理性质发生的变化能在地震资料上表现出差异性。为此,从二氧化碳驱油前后地震正演模拟、敏感属性分析和时移地震差异等方面进行分析,为开展基于地震资料的二氧化碳驱油精细监测提供了依据。

As an important technique of the three oil extraction,carbon dioxide flooding has obvious effect on oil recovery,and has important environmental protection value. But in the CO_2 flooding process,some layers are broke by carbon dioxide early,which on the one hand severely reduces the gas drive spread efficiency,on the other hand,carbon dioxide will have some serious impact on oil well lifting system,surface process equipment and cause serious environmental problems such as well. The conventional CO_2 injection monitoring method such as tracer,oil gas water quality,only have a simple monitoring of carbon dioxide flooding effect and carbon dioxide production,fine monitoring of oil displacement process becomes a weak step,which restricts the further development of carbon dioxide flooding. The changes of the physical properties of the reservoir before and after the CO_2 flooding can show differences in the seismic data. To this end,the analysis of seismic forward modeling,sensitivity analysis and time shift difference between the before and after the carbon dioxide flooding are analyzed,which provides a basis for the development of the fine monitoring of carbon dioxide flooding based on seismic data.