面向碳酸盐岩缝洞型储层的高密度全方位三维地震采集技术及应用效果

塔里木盆地奥陶系碳酸盐岩储层以溶蚀孔洞和裂缝为主，储层非均质性强，内幕地震资料信噪比低，常规三维地震资料观测方位角较窄，面元较大，覆盖次数低，存在缝洞体成像横向偏移归位不足、小缝洞体识别和裂缝预测精度低等问题。针对碳酸盐岩缝洞型储层的特点，详细分析了面元大小、覆盖次数和横纵比等主要观测参数对缝洞储层成像和油藏精细描述的影响，在塔北哈拉哈塘地区设计并首次实施了高密度全方位三维地震勘探，道密度达100×10⁴道/km²。通过实际应用改善了缝洞储层的成像效果，显著提高了小尺度缝洞储层的识别精度和裂缝预测精度。

The Ordovician carbonate reservoirs in Tarim Basin are strong heterogeneous with dissolved caves,holes and fractures,and the seismic data are usually with low S/N.Conventional 3D seismic data are narrow-azimuth with large bin size and low fold.As a result,some problems appeared,such as inadequate lateral migration,low-accuracy for small fracture-caves identification and fracture prediction.Aiming at the above characteristics of the carbonate reservoirs,we gave a detailed analysis on the impact of main geometry parameters (including bin size,fold and aspect ratio) on the imaging of fracture-cave reservoir and fine characterization.A high-density full-azimuth 3D seismic acquisition with trace density reaching to as much as 100×10⁴ traces per square kilometers was carried out in Northern Tarim Basin based on the analysis.The results show great improvement in imaging the fractured-cavernous reservoirs in any direction.Much more small caves are identified and the fracture prediction accuracy is improved considerably.