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    基于岩石物理模板的地震属性优选方法研究

    Seismic attribute selection method based on rock physical quantity models

    • 摘要: 随着地震属性技术的蓬勃发展,属性的种类迅速增加,属性优选方法有必要随之改进。目前地震属性优选方法主要有三大类,即专家经验法、数学分析法和地震正演模拟法。这三类方法分别存在主观性强、大量依赖已知样点、没有明确的地质意义及计算量大等不足。更重要的是,很少有利用属性直接分析储层物性变化特征的研究。特别是对于致密砂岩油气藏来说,其最大孔隙度只有8%,储层与围岩难以区分,在工区探井数量少时,利用属性分析方法描述储层较为困难。针对性地提出了建立符合致密砂岩储层特征的岩石物理模型,改变储层物性参数来系统性优选属性的方法。该方法通过测试不同的孔隙度和含水饱和度参数,对岩石物理模型进行正演并求取地震属性,把这些属性按皮尔逊相关系数进行系统聚类,优选出每一类中与储层物性参数的相关系数绝对值最大的一种或两种属性,用于表征储层物性变化。方法应用于 H 工区,建立了 H 工区致密储层岩石物理模型,并对高孔砂体进行了识别。结果表明,利用该方法优选出的地震属性很好地反映了储层孔隙度的变化。

       

      Abstract: The seismic attribute technology is experiencing rapid development, and the attributes are becoming rich in types. It is very necessary to improve the attribute selection methods accordingly. Currently, the seismic attribute selection technologies mainly include three categories: expert experience method, mathematical analysis method, and seismic forward modeling simulation method. They respectively have the shortcomings of strong subjectivity, heavy reliance on known sample points, lack of clear geological significance, and large computational volume. Moreover, attributes have barely used directly to analyze the characteristics of the changes in reservoirs’ physical properties. Especially in the case of tight sandstone oil and gas reservoirs, the maximum porosity is 8%, and it is difficult to distinguish the reservoir from the surrounding rocks. In addition, there are a few exploration wells in the area. Therefore, this paper proposed a method to establish a rock physics model that conforms to the characteristics of tight sandstone reservoirs for optimizing attributes. The method tested different porosity and water saturation parameters through the established rock physics model, performed forward modeling on the model, and obtained seismic attributes. These attributes were systematically clustered using Pearson correlation coefficients, and one or two attributes with the absolute value of the correlation coefficient in the reservoirs’ physical property parameters being the largest in each category were selected for optimization. This method effectively characterized the changes in the physical properties of the target layer in the study area. The method was applied to the H area, and a rock physics model of the tight reservoir in the H area was established, with high-porosity sand bodies identified. The results show that the seismic attributes selected by this method well reflect the changes in reservoir porosity.

       

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