基于高密度地震资料的钙质层预测及应用

Prediction and application of calcareous layer based on high density seismic data

为进一步提高钙质砂岩的描述精度,提高剩余油挖潜效果,以大庆油田B2区块为例,基于高密度地震资料实现钙质砂岩的精准表征。主要步骤为:首先,基于钻井取心和测井曲线分析钙质砂岩的纵波阻抗曲线特征,确定钙质砂岩的纵波阻抗值域范围;其次,拟合研究区纵波阻抗变差函数,利用序贯高斯模拟算法计算出纵波阻抗初始模型;最后,通过模型正演与实测地震迭代,结合钙质砂岩纵波阻抗值域范围,实现井震结合钙质砂岩表征。研究表明,钙质砂岩表征结果与后验井符合较好,基于B2区块钙质砂岩的空间精准描述结果,设计并实施了水平井BS-3-2,日产油25 t。该方法具有较高的精度,适用于陆相油田钙质层的精准表征。

On the basis of high-density seismic data,Block B2 of Daqing oilfield is taken as an example to achieve accurate characterization of calcareous sandstone so as to further improve the calcareous sandstone description accuracy and improve the remaining oil potential efficiency.The main steps are as follows:Firstly,the compressional wave impedance range of calcareous sandstone is determined by analyzing the characteristics of the compressional wave impedance curve of calcareous sandstone based on drilling cores and logging curves.Secondly,the longitudinal wave impedance variation function in the study area is fitted,and the initial model of the longitudinal wave impedance is calculated by sequential Gaussian simulation algorithm.Finally,through model forward modeling and measured seismic iteration,combined with the range of compressional wave impedance of calcareous sandstone,the characterization of calcareous sandstone is realized.The study shows that the calcareous sandstone characterization results are in good agreement with the posterior well.Based on the spatial accurate description results of calcareous sandstone in Block B2,the horizontal Well BS-3-2 has designed and implemented,25 tons of oil is obtained per day.This method has high precision and is suitable for the accurate characterization of calcareous layers in continental oil field.