地震分频多属性融合技术在裂缝预测中的综合应用——以川南页岩气区块宜A井区为例

Comprehensive Application of Seismic Frequency Division Multi-Attribute Fusion Technology in Fracture Prediction—Taking Yi A Well Area of Shale Gas Block in South Sichuan as an Example

摘要: 天然裂缝(简称裂缝)是页岩气开发效果的关键影响因素，建立可靠的多尺度裂缝模型对提高页岩储层钻遇率至关重要，同时系统表征不同尺度和类型的裂缝有利于识别优质储层并优化开发效果。然而，基于传统地震属性的裂缝预测方法仅能突出单一尺度的断裂，且不同裂缝属性的数学独立性使得识别综合裂缝系统面临挑战。本文提出一套改进的全尺度裂缝系统评估方案，其核心在于利用分频地震数据和多属性算法确定不同尺度裂缝的发育概率，融合不同尺度裂缝与断裂，形成可感知全尺度裂缝的综合裂缝系统。多尺度和多属性综合分析表征大尺度断层、小裂缝及裂缝破碎带的分布，获得的全尺度裂缝系统，有效提升了区域断裂和裂缝预测精度。研究区钻井N-02和N-03实钻资料验证了该方案对不同尺度裂缝发育方向预测的准确性与可靠性，可为页岩气水平井开发部署提供理论指导。

Abstract: Natural fractures (referred to as fractures) are the key factors affecting the development effect of shale gas. It is very important to establish a reliable multi-scale fracture model to improve the drilling rate of shale reservoirs, and at the same time, systematically characterizing fractures of different scales and types is conducive to identifying high-quality reservoirs and optimizing the development effect. However, the fracture prediction method based on traditional seismic attributes can only highlight single-scale fractures, and the mathematical independence of different fracture attributes makes it challenging to identify comprehensive fracture systems. In this paper, an improved full-scale fracture system evaluation scheme is proposed, the core of which is to determine the development probability of fractures of different scales by using frequency-divided seismic data and a multi-attribute algorithm, and to fuse fractures and fractures of different scales to form a comprehensive fracture system that can perceive full-scale fractures. Multi-scale and multi-attribute comprehensive analysis characterizes the distribution of large-scale faults, small fractures and fracture zones, and the obtained full-scale fracture system effectively improves the prediction accuracy of regional fractures and cracks. The actual drilling data from wells N-02 and N-03 in the study area verify the accuracy and reliability of the scheme in predicting the fracture development direction of different scales, which can provide theoretical guidance for the development and deployment of shale gas horizontal wells.