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CCS技术是目前公认的快速减缓温室效应的最有效方法,CO2地质封存是CCS技术最核心的问题之一,监测CO2地质封存的安全性贯穿于CO2注入过程中与封存以后。四维地震监测技术是监测CO2是否泄漏、证实CO2封存安全性最有效的技术手段。常规四维地震技术通过对比CO2注入前后及注入不同阶段2次或者多次三维地震纵波振幅差异与旅行时差异,确定CO2在地下分布。而纵波振幅或旅行时差异是CO2饱和度与孔隙压力的综合反映,单纯的纵波信息难以区分饱和度与压力信息。目前,四维多分量地震监测技术的潜力并未挖掘,由于横波速度对于压力敏感,利用四维转换波信息监测CO2地质封存,可以识别注入CO2的压力分布范围。对于各向异性介质的储层,对比一次地震观测PS1,PS2旅行时、振幅差异与2次地震采集之间PS1,PS2旅行时、振幅差异,还可以有效确定注入CO2前与注入期间储层裂隙、裂缝的变化,以及储层与盖层的应力状态。四维多分量地震资料结合岩石物理资料和全波列测井资料,可以更准确地确定可能的CO2泄漏风险区域,更加可靠地评估CO2地质封存的安全性。
CCS technology is currently recognized as the most effective method of rapid mitigation of greenhouse effect. Geological sequestration of CO2 is one of the core issues of CCS technology. Monitoring the safety of CO2 geological sequestration runs through CO2 injection and storage. Four-dimensional seismic monitoring technology is to monitor CO2 leak, CO2 storage safety confirmed the most effective technical means. The conventional four-dimensional seismic technique determines the distribution of CO2 in the underground by comparing the amplitude differences between two or more three-dimensional seismic waves before and after CO2 injection and at different stages of injection. However, the amplitude of P-wave or the travel time difference is a comprehensive reflection of CO2 saturation and pore pressure. It is difficult to distinguish the saturation and pressure information with the pure P-wave information. At present, the potential of four-dimensional multi-component seismic monitoring technology has not been explored. Since the shear wave velocity is sensitive to pressure, the four-dimensional converted wave information can be used to monitor the geological storage of CO2 to identify the pressure distribution range of CO2 injection. For the anisotropic reservoir, comparing the amplitudes of PS1 and PS2 travels between the seismic amplitude difference and the two seismic acquisitions during a seismic observation of PS1 and PS2, it is also possible to effectively determine the fracture fissures before and during CO2 injection , Changes in fractures, and the stress state of the reservoir and cover. The combination of four-dimensional multicomponent seismic data with petrophysical data and full-wave well logging data allows for a more accurate identification of possible CO2 leakage risk areas and more reliable assessment of CO2 geological storage safety.