水平井分段体积压裂复杂裂缝形成机制研究现状与发展趋势

水平井分段体积压裂是油气储层中复杂裂缝网络形成的重要技术之一,准确了解复杂裂缝网络形成机制、预测复杂裂缝网络形态对非常规油气资源高效开发具有重要意义,同时也是水力压裂设计优化的理论基础。围绕非常规储层复杂裂缝形成机制,国内外学者根据"应力阴影"效应对水力裂缝同步扩展、水力压裂顺序对多裂缝动态延伸影响、层理面对水力裂缝纵向扩展遮挡效应和天然裂缝与水力裂缝交互动态等方面,分别建立了相应的水力压裂模型,并从数值模拟角度对其进行了定性分析。通过总结国内外研究现状,并从模型建立假设条件、数值模拟模型思想和模型局限性3方面对现有模型进行了剖析,并对未来研究方向提出了建议,研究结果可对未来水力压裂复杂裂缝形成机制研究提供借鉴。

Research status and development trend of the formation mechanism of complex fractures by staged volume fracturing in horizontal wells

Staged volume fracturing in horizontal wells is one of the important technologies for the formation of complex fracture networks in reservoirs. To accurately understand the formation mechanism of complex fracture networks and predict the patterns of complex fracture networks is of great significance to the efficient development of unconventional oil and gas resources, and provides a theoretical basis for the design optimization of hydraulic fracturing. Focusing on the formation mechanism of complex fractures in unconventional reservoirs, domestic and foreign scholars have established hydraulic fracturing models according to the impacts of "stress shadow effect" on the simultaneous propagation of hydraulic fractures and those of hydraulic fracturing sequence on the dynamic propagation of multiple fractures, the blocking effect of bedding plane on the longitudinal expansion of hydraulic fractures, and the interactive dynamics between natural fractures and hydraulic fractures; they conducted qualitative analysis from the perspective of numerical simulation. By summarizing the research status at home and abroad and analyzing the existing model in terms of the assumed conditions of model establishment, ideas of numerical simulation model and model limitations, this paper puts forward suggestions for future research directions, which can provide a reference for studying the formation mechanisms of complex fractures by hydraulic fracturing in the future.