深部储层流体识别方法在仁和场地区的应用

Application of deep reservoir fluids identification method in Renhechang area

仁和场地区位于米仓山构造带前缘,该区下组合成藏条件优越,但目的层埋藏深度超过8000 m.深部地震资料通常缺少大炮检距信息并且信噪比低,这给叠前地震反演和流体识别带来了巨大挑战.针对这一问题,本研究采用基于基追踪弹性阻抗反演的两项式深部储层流体识别方法,对仁和场地区进行流体识别的应用研究.研究表明:(1)基于模型约束的基追踪反演方法提高了反演的抗噪性,两项式的反演结果和常规三项式相比与测井和地质认识吻合度更高,说明该方法具有一定的实用性;(2)在利用岩石物理模型预测横波速度时考虑围压修正关系对模型进行优化,减小深层压力对预测精度的影响,有利于提高流体的识别精度;(3)反演流体项的计算中涉及到较多的岩石物理参数,因此针对实际工区开展一定的岩石物理实验是提高深部储层流体识别精度的关键环节.

Renhechang area is located on the front edge of the Micangshan structural belt,and the lower assemblages in this area have superior conditions for accumulation.But the buried depth of the target layer exceeds 8000 m.Deep seismic data usually lack large offset information and the data's signal-to-noise ratio is very low,which brings great challenges to prestack seismic inversion and fluid identification.To solve this problem,the binomial deep reservoir fluid identification method based on basis pursuit elastic impedance inversion is used in this study to explore the application of fluid identification in Renhechang area.The results show that:(1)The basis pursuit inversion method based on model constraint improves the noise resistance of inversion.From the perspective of logging and geological knowledge,the inversion results of binomial formula are more consistent than those of conventional trinomial formula,which shows that the method is practical;(2)It is suggested that the confining pressure correction relationship should be considered to optimize the model when using the petrophysical model to predict the shear wave velocity.This method can reduce the influence of deep pressure on the prediction accuracy and improve the fluid identification accuracy;(3)Many petrophysical parameters are involved in the calculation of the inversion fluid term.Therefore,carrying out certain petrophysical experiments for the actual work area is a key link to improve the accuracy of deep reservoir fluid identification.