水力压裂分布式光纤传感联合监测技术研究进展

Joint application of distributed optical fiber sensing technologies for hydraulic fracturing monitoring

水力压裂分布式光纤传感监测技术已成为非常规储层开发的重要技术之一,为使业界进一步明确和了解不同类型传感技术的物理机理、技术特性和理论模型,促进该技术更加快速有效地推广和应用,本文针对分布式温度传感(DTS)、分布式声波传感(DAS)和基于瑞利频移的分布式应变传感(DSS-RFS)3种技术在水力压裂监测中的应用情况,从不同传感技术的物理机理和主流安装方式出发,系统地总结分析了各类传感技术现场应用的典型案例和技术特点,以及对应的监测解释理论模型的研究现状。最后结合水力压裂监测矿场实验的最新实例,总结了未来开展水力压裂分布式光纤联合监测的技术思路。研究结果表明:(1)水力压裂分布式光纤传感联合监测技术能够在压裂工艺设计、裂缝扩展反演、邻井干扰监测和压后效果评价等诸多方面提供重要的实时数据和解释结果,不同类型传感器所对应的理论模型有不同程度的发展;(2) DTS本井温度监测是水力压裂光纤监测和评价的重要组成部分同时具有一定程度的多解性,DAS邻井应变率监测和DSS-RFS本井应变监测能够直接反馈裂缝扩展和裂缝演化过程中的相关应变,今后将成为水力压裂裂缝评价的重点发展领域;(3)分布式光纤传感技术在未来的有效应用除了需要发展更加准确高效的机理模型外,同时也有赖于大数据处理和深度学习算法与之高度融合,从而实现监测过程的数据筛选、模式识别和关键参数的快速反演。结论认为,科学有效地设计和采用多种分布式光纤传感对水力压裂过程和压后生产过程进行联合监测和数据分析解释,可在很大程度上实现压裂液/支撑剂分布、暂堵转向、级间干扰、压裂冲击和裂缝形态的解释分析,以及压后生产剖面反演和裂缝有效性分析,为分布式光纤传感技术在我国非常规资源开发中的应用提供了技术参考。

Distributed optical fiber sensing for hydraulic fracturing monitoring is an important technology in the development of unconventional reservoirs. However, the physical mechanisms, technical features and theoretical models of different distributed optical fiber sensing technologies have not been fully understood. In this paper, the typical application cases and technical features of three major optical fiber sensing technologies, i.e. distributed temperature sensing(DTS), distributed acoustic sensing(DAS), and distributed strain sensing via Rayleigh frequency shift(DSS–RFS), are analyzed systematically, and the research status of the corresponding monitoring and interpretation theoretical models is presented. Furthermore, based on the learnings from hydraulic fracturing test sites,a joint application of distributed optical fiber sensing technologies for hydraulic fracturing monitoring is proposed. It is indicated that the joint application of distributed optical fiber sensing technologies for hydraulic fracturing monitoring can provide critical realtime data and interpretation results in terms of fracturing design, fracture propagation inversion, offset well monitoring, and post-frac evaluation, and the corresponding theoretical models have been advanced to different extents. The DTS well temperature monitoring is an important part of the optical fiber monitoring and evaluation of hydraulic fracturing, and provides somewhat ambiguous results. The DAS offset well strain rate monitoring and DSS–RFS well strain monitoring can directly reflect the strains during fracture propagation and evolution, and will be the focus in the evaluation of hydraulic fractures. The effective application of distributed optical fiber sensing technologies in the future will require more accurate and efficient mechanism models and also an organic integration with big data processing and deep learning to enable the data screening, pattern recognition and fast inversion of key parameters during monitoring. It is concluded that the scientific and effective design and application of multiple distributed optical fiber technologies for monitoring and data analysis/interpretation during and after hydraulic fracturing can adequately realize the interpretation/analysis of fracturing fluid/proppant distribution, temporary plugging and diversion, interstage interference, frac-hit, and fracture morphology, as well as the postfracturing production profile inversion and fracture effectiveness analysis. The research provides technical reference for the application of distributed optical fiber sensing technologies in the development of unconventional resources in China.