蜀南地区须家河组致密砂岩含气性综合预测

四川盆地蜀南地区上三叠统须家河组为一套砂泥岩互层的陆相碎屑岩沉积，砂岩发育，但岩性致密，物性较差，砂岩储层含气后的速度与页岩速度相差不大，在地震剖面上无明显的响应，因而采用常规波阻抗反演和含气检测技术不能有效解决该类含气储层识别问题和含气范围展布问题。根据钻、测井资料分析可知，该套致密含气砂岩储层具有低自然伽马、高孔隙度的测井响应特征，因此可采用自然伽马反演来区分须家河组砂、泥岩的岩性，利用孔隙度反演来剔除致密砂岩，采用含气特征曲线重构技术预测含气储层段，并利用有效的含气检测技术进行含气异常范围预测。通过开展致密含气砂岩储层的地震综合预测研究，获得了蜀南HBC地区储量计算的各类平面图，为落实该地区260×10⁸ m³天然气探明储量提供了重要依据。

Gas-bearing prediction on tight sandstone gas reservoirs of Xujiahe formation in south Sichuan basin

The Xujiahe formation in south Sichuan basin is featured by continental clastic sedimentary, thin sand mud interbed, and the well developed sandstone in this area, however, its lithology is tight and its physical properties is poor. In the case of gas bearing, the acoustic velocity difference between the sandstone and the shale is too little to make clear responses on seismic data, as a result, it is very difficult to conduct the gas bearing prediction and to analyze the gas bearing range distribution by means of conventional impedance inversion and hydrocarbon detection. According to log data, the tight sandstone reservoir has characteristics of low GR and relatively higher porosity. So the GR inversion method is performed to identify sandstones and mudstones, and the porosity inversion method is performed to weed out tight sandstones. This paper also reconstructs the characteristic curves of reservoirs and inverts those to predict gas bearing layers, and uses special hydrocarbon detection techniques to predict abnormal distribution of gas bearing reservoirs. Good results have been achieved by comprehensive study in the HBC area, south Sichuan basin, providing important evidences for the estimated proven recoverable gas reserves of 26 bcm in the area.