基于地震复波的含气砂体识别技术与应用

松辽盆地南部伏龙泉气田属于复杂小断块,砂泥岩薄互层叠置发育,受构造和砂体双重控制,成藏上对断层—岩性时空配置要求高,一直以来含气砂体识别难度大。通过深入分析地质、地震资料,并结合大量动态数据,建立了地震复波与储层含气性之间的关键联系。通过井震结合建立地质模型,利用正演技术分析不同含气条件下地震波组特征,得出储层含气是复波出现的充分非必要条件,含气饱和度对地震响应的影响体现在密度的变化上,密度变化又导致阻抗界面的变化,含气性和砂泥岩薄互层是该区形成复波的主要原因。在运用地震复波进行含气砂体识别这一技术的支撑下,后续部署井钻井显示好、气层钻遇率较高,杜绝了低效井出现,为该区井位部署及井型设计提供了重要依据,也为松辽盆地南部深层及其他相似地质条件地区的天然气勘探开发提供了有益借鉴。

Identifying technique of the gas-bearing sandbody based on the seismic complex wave and its application

Fulongquan Gas Field in South Songliao Basin belongs to a complex small fault block, which is characterized by well-developed thin-overlaid sandstone and mudstone interbeds, and moreover double controlled by the structure and sandbody, high time-space arrangement and layout between the fault and lithology is required for the hydrocarbon accumulation, it has always been difficult to identify the gas-bearing sandbodies. Through in-depth analyses of the geological and seismic data, combined with a large number of the dynamic data, the key relationship between the seismic complex wave and reservoir gas-bearing property was established. The geological model was built by the well-seismic combination, with the help of forward modeling technique, the seismic wave-group characteristics under different gas-bearing conditions were analyzed, and then the obtained sufficient and unnecessary condition for the complex wave occurrence was reservoir gas-bearing attribute, the influence of the gas saturation on the seismic response is reflected in the change of the density, and furthermore the change leads to the change of the impedance interface, the gas-bearing property and interbeds are the main causes of the complex wave formation in this area. Supported by the technique of identifying the gas-bearing sandbodies by the seismic complex wave, the subsequent deployed wells show much better drilling performances and pretty higher gas-layer drilled rate, thus the occurrence of the inefficient well was eliminated and moreover the important basis was provided for the well location arrangement and well pattern design in this area, and furthermore the beneficial references were presented for the deep gas exploration and development in South Songliao Basin and other regions with the similar geological conditions.