开发后期井震结合致密含钙砂体识别方法

Identification method of tight calcareous sandstone by well-seismic combination in the later stage of development

致密含钙砂岩可以形成岩性遮挡,是油田开发后期剩余油分布的有利目标。针对仅仅基于井资料无法准确预测横向井间致密砂岩分布的难题,文中以测井曲线为基础,高密度地震资料为井间约束,采用序贯高斯模拟算法,井震联合识别致密含钙砂岩,并将研究成果应用于松辽盆地典型区块致密含钙砂岩的精确表征中。研究结果表明:研究区致密砂岩纵波阻抗大于8.0×10^7 kg·m^-3·m·s^-1;纵波阻抗变差函数垂向、主方向和次方向变程分别为5,1000,600 m;SⅡ-12层致密含钙砂岩整体厚度介于0.5~1.0 m,整体上具有北厚南薄的特征;表征结果与后验井符合较好,显示了该方法较好的应用效果。井震结合致密砂体识别方法适用于开发后期油田的致密含钙砂岩精细描述。

Tight calcareous sandstone can form lithologic shelter,which is the favorable target for remaining oil distribution in the later stage of oilfield development.Aiming at the problem that single well data can not accurately predict the distribution of tight sandstone between wells laterally,based on the well logging curve and constrained by the high-density seismic data between wells,the tight calcareous sandstones were identified by using sequential Gauss simulation algorithm and well-seismic combination.The research results were applied to accurately characterize tight calcareous sandstone in typical blocks of Songliao basin.The results show that the value of P-wave impedance of tight sandstone is more than 8.0×10^7 kg·m^3·m·s^-1 in the study area.The vertical,main and secondary ranges of P-wave impedance variogram are 5,1000 and 600 m respectively.The overall thickness of tight calcareous sandstone of layer SⅡ-12 is 0.5-1m with the characteristics of thick in the north and thin in the south,which is in good agreement with the later test well and shows that the new method has good application effect.The identification method of tight sand body by well-seismic combination is suitable for the fine description of calcareous sandstone in the later stage of development.