页岩气层小微尺度断缝精细预测方法

    A fine-scale prediction method for small-scale faults and fractures in shale gas reservoirs

    • 摘要: 页岩地层原始发育的小微尺度断缝(断距小于10 m的断层和裂缝)对水平井段优质储层钻遇率、改造体积、产能均有较大的影响,对其开展精细预测尤为重要,但目前单一的方法很难准确识别和预测。本文结合四川盆地南部某地区龙马溪组页岩气层小微尺度断缝发育的情况,开展了模型组合正演模拟、响应机理和响应特征研究,提出预测+建模相融合表征的小微尺度断缝预测方法,并优选地震资料处理、小微尺度断缝预测、多尺度裂缝建模和融合表征技术开展研究。研究成果同研究区龙马溪组页岩气层水平井钻遇的小微尺度断层、地层漏失、井间压窜等地质异常情况吻合度较高,且同单井产能情况具有较好的正向关联性,证实了该方法预测小微尺度断缝的可行性,可为同类型层系小微尺度断缝的预测研究提供参考。

       

      Abstract: Small- and micro-scale faults fractures (fractures and faults with fault throw less than 10 m) that originally developed in shale strata have a significant impact on the probability of penetration, stimulation volume, and production capacity of high-quality reservoirs in horizontal well sections. Therefore, it is critical to conduct fine-scale fault and fracture prediction. However, any single method struggles to accurately identify and predict these faults and fractures. Based on the developmental conditions of small-and micro-scale faults and fractures in the shale gas reservoirs of the Longmaxi Formation in the southern Sichuan Basin, this study conducted forward modeling, response mechanism analysis, and characterization of fracture responses, developing a prediction method integrating predicting and modeling. Furthermore, this study preferentially investigated techniques including seismic data processing, small-scale fault and fracture prediction, multi-scale fracture modeling, and fusion characterization. The results of the proposed method were highly consistent with the geological anomalies including small and micro-scale faults, lost circulation, and inter-well pressure channeling observed during the drilling of horizontal wells in the shale gas reservoirs of the Longmaxi Formation. Furthermore, these results exhibit a strong positive correlation with the single-well production capacity. All these corroborate that it is feasible to use this method to predict small- and micro-scale faults and fractures. This study can serve as a reference for predicting small-scale faults and fractures in other strata of the same type.

       

    /

    返回文章
    返回