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利用叠后地震反演进行油气检测存在一定的局限性,因此提出了利用叠前地震反演预测民丰地区沙四段盐下砂砾岩体的含油气性。首先,通过岩石地球物理特征分析,求取目的层段的密度、纵波速度、横波速度和泊松比等参数;然后,通过正演模拟分析气层在叠前地震道集上的响应特征;最终,根据交会分析技术,对比了截距—梯度、速度—密度、拉梅常数—剪切模量和速度—泊松比等参数对油气检测的适用性,优选对研究区储层含油气性比较敏感的拉梅常数和泊松比作为反演参数。通过叠前地震反演,分析了敏感参数对气层的判识程度。应用结果表明,通过对叠前地震反演提取的拉梅常数和剪切模量2组参数进行交会解释,气层反射特征与丰深1井砂砾岩体实钻结果吻合较好,预测有利含气面积为109km2,天然气资源量为290×108m3。
Therefore, it is suggested that the prediction of oil and gas in the sand-gravel massif of the fourth member of Shahejie Formation in Minfeng area by means of pre-stack seismic inversion is proposed. Firstly, the parameters of density, P-wave velocity, S-wave velocity and Poisson’s ratio of the target interval are obtained through the analysis of the geophysical characteristics of the rock; and then the response characteristics of the gas layer on the pre-stack seismic trace are analyzed by forward modeling; finally, According to the rendezvous analysis technique, the applicability of parameters such as intercept - gradient, velocity - density, Lame constant - shear modulus and velocity - Poisson ratio to oil and gas detection is contrasted, which is more sensitive to oil and gas in the study area The Lame’s constant and Poisson’s ratio are used as inversion parameters. Through the prestack seismic inversion, the sensitivity of the parameters to the gas layer is analyzed. The application results show that the gas reflection characteristics are in good agreement with the actual drilling results of the glutenite body at Fengshen 1 well through the Lame constant and shear modulus parameters extracted from prestack seismic inversion. Gas area of 109km2, natural gas resources for 290 × 108m3.