多分量地震在致密气储层精细描述中的应用

Application of multi-component seismic technology in fine description of tight gas reservoirs

四川盆地川中秋林地区沙溪庙组河道砂岩具有期次多、砂体叠置的地质特征,精细刻画砂体及其叠置关系对水平井的部署至关重要。由于常规地震勘探方法难以取得理想效果,因此在研究区开展了多分量地震采集探索。研究表明:①沙溪庙组砂岩与泥岩的纵波速度基本相同,而横波速度差别大,因此利用转换波区分岩性具有较大优势。②纵波数据对砂体变化不敏感,地震波形难以反映砂体的叠置关系。转换波虽然主频低于纵波,但对岩性变化敏感,地震波形与砂体变化有很好的对应关系。③纵波叠前反演的横波速度精度较低,纵、横波联合反演的横波速度具有很高的预测精度,能够准确刻画砂体及其叠置关系。研究结果证明多分量地震在精细描述砂岩储层方面具有潜力,为沙溪庙组致密砂岩气藏精准、高效开发提供了数据基础。

The channel sandstone of Shaximiao Formation in Qiulin area of the central Sichuan Basin has the geological characteristics of multiple stages and superimposed sand bodies.The fine description of sand bodies and their superimposed relationships plays a crucial role in the deployment of horizontal wells.Since the conventional seismic exploration method is difficult to obtain the ideal effect,the multi-component seismic exploration has been carried out in the study area.The results show that:①The P wave velocity of sandstone and mudstone in Shaximiao Formation is basically the same,while the S wave velocity is highly different,so the converted wave has a great advantage in distinguishing lithology.②The P wave data are not sensitive to the change of sand bodies,and the seismic wave-form cannot reflect the superimposed relationship of sand bodies.Although the main frequency of the converted wave is lower than that of the P wave,it is sensitive to the change of lithology,and the seismic waveform has a good correspondence with the change of sand bodies.③The S wave velocity accuracy by the P wave pre-stack inversion is low,while the S wave velocity by joint PP-PS wave inversion has high prediction accuracy,which can accurately characterize the sand body and its superimposed relationship.The study shows that multi-component seismic technology has the potential to accurately describe sandstone reservoirs,which provides a data basis for accurate and efficient development of tight sandstone gas reservoirs in Shaximiao Formation.