摘要：

时移地震成本较高且并非适用于所有类型的油气藏，因此在实施前开展充分的可行性分析非常重要。时移地震可行性分析的关键是油藏开发后的地层弹性参数预测，而影响地层弹性参数的因素十分复杂，油藏开采造成的地层温度、压力、岩石骨架等变化都会对其产生影响。为准确预测油藏开发对地层弹性参数的影响，实现时移地震可行性定量评价，本文以我国渤海湾盆地浅层疏松砂岩油藏为例，开展基于岩石物理建模的时移地震可行性分析方法研究。渤海湾盆地浅层疏松砂岩具有高孔隙、低胶结等特征，本研究根据目标地层的地质条件，将沉积和埋藏史研究与岩石物理建模相结合，建立沉积-埋藏史指导下的岩石物理模型，对疏松岩石的岩石物理特征进行描述。在岩石物理模型的基础上，对研究目标地层的岩石骨架和流体条件进行定量评价，并根据油藏开发动态预测地层弹性参数，基于地震正演对地震条件进行定量评价。针对研究目标储层厚度有限的情况，利用楔状模型正演研究分析储层厚度对时移地震响应的影响。最终，从油藏地质条件、岩石物理条件、地震条件3个方面对研究目标地层的时移地震可行性进行评价。结果显示，研究区的储层地质条件和岩石骨架条件都较好，流体性质是决定时移地震可行性的关键因素，轻质油油藏更利于时移地震观测。从几个研究目标中选取最利于开展时移地震研究的一个，对已有地震数据进行一致性处理，开展时移地震分析，证明时移地震可行性分析的结果比较可靠。研究结果可为渤海湾盆地类似的浅层疏松砂岩时移地震可行性分析提供参考。

关键词: 岩石物理模型, 时移地震, 岩石物理建模, 渤海湾盆地, 疏松砂岩

Abstract:

Under high operational costs and selective applicability constraints, time-lapse (4D) seismic monitoring requires a rigorous feasibility assessment before implementation. The critical aspect of this analysis involves predicting post-production changes in formation elastic parameters, which are influenced by complex factors including reservoir temperature variations, pore pressure changes, and alterations in rock frame properties during hydrocarbon production. To achieve a quantitative evaluation of time-lapse seismic feasibility, a methodological framework based on rock physics modeling has been established, using several shallow, unconsolidated sandstone reservoirs in the Bohai Bay Basin as representative examples. The targeted sandstones exhibit high porosity and weak cementation, requiring specialized modeling approaches. Based on the geological background of the target areas, sedimentary environment analysis and burial history reconstruction are integrated with rock physics techniques to build geologically constrained models. These models facilitate the quantitative description of petrophysical characteristics under varying burial and diagenetic conditions. Based on the constructed rock physics models, evaluations of rock frame stiffness and pore fluid properties are conducted, and elastic parameter variations caused by reservoir production are predicted. Forward seismic modeling is then applied to assess the detectability of time-lapse seismic signals under different acquisition scenarios. Given the limited thickness of the target reservoirs, wedge-shaped model simulations are employed to analyze the sensitivity of time-lapse seismic responses to changes in formation thickness. The overall feasibility of time-lapse seismic application is assessed from three dimensions: geological conditions, rock physical properties, and seismic detectability. Results indicate that most studied reservoirs exhibit favorable geological frameworks and competent rock skeletons. However, the nature of the pore fluids, especially hydrocarbon composition and phase behavior, emerges as the critical factor influencing the effectiveness of time-lapse seismic monitoring. Light oil reservoirs show greater potential for successful monitoring due to more significant impedance contrasts. Among the studied cases, the reservoir exhibiting the highest suitability for time-lapse seismic monitoring is selected for further analysis using existing seismic datasets. Time-lapse seismic data matching processing and 4D response evaluation are performed to validate the reliability of the feasibility assessment framework. The findings demonstrate that the proposed approach can provide robust support for evaluating the feasibility of time-lapse seismic monitoring in shallow, unconsolidated sandstone reservoirs in the Bohai Bay Basin. These insights contribute valuable guidance for future applications of 4D seismic in similar geological settings, offering meaningful implications for both petroleum geology and reservoir engineering disciplines.

Key words: rock physics model, time-lapse seismic, rock physics modeling, Bohai Bay Basin, unconsolidated sandstones

中图分类号: 

• P618.13

• TE132