水平井分段压裂注液过程中温度分布预测

Temperature distribution prediction of horizontal wells during fracturing treatment

近年来,光纤分布式温度传感器(DTS)越来越多地用于水平井压裂动态监测,拟解决在水平井分段压裂过程中普遍面临的人工裂缝起裂位置不明、压裂液去向未知、裂缝扩展形态不清、压裂效果难以评价等技术难题,而温度预测模型是基于DTS监测进行压裂诊断的基础,但目前定量预测水平井压裂过程中的温度分布仍是一项巨大挑战。在考虑多种微量热效应的基础之上,建立了一套水平井分段压裂温度分布预测模型,并完成模型耦合求解,采用建立的温度模型,分别模拟了一口水平井常规压裂和分段多簇压裂时的温度分布,分析了水平井分段压裂过程中温度分布特征,明确了压裂液排量、地层滤失系数、裂缝宽度及裂缝高度对温度分布的影响规律。该研究成果为实现基于DTS监测诊断压裂动态、识别裂缝起裂、分析压裂液去向提供了理论支撑,对于压裂水平井改造效果评价和压裂设计优化具有重要意义。

In recent years, optical fiber distributed temperature sensor system(DTS) has been increasingly used in horizontal well fracturing dynamic monitoring, aiming to solve the technical problems commonly faced in the process of horizontal well fracturing, such as artificial fracture initiation location unknown, fracturing fluid whereabouts unknown, fracture propagation morphology unclear, fracturing effect difficult to evaluate. The temperature prediction model is the basis of fracturing diagnosis based on DTS monitoring, but it is still a great challenge to predict quantitatively the temperature distribution in the fracturing process of horizontal wells. Considering the basis of a variety of trace heating effect, this paper established a set of horizontal well staged fracturing temperature distribution prediction model and completes the solution coupling model. The established temperature model was used to simulate the temperature distribution of conventional fracturing and multistage fracturing in a horizontal well, and the temperature distribution characteristics in the process of multistage fracturing were analyzed. The effects of fracturing fluid displacement, formation filtration coefficient, fracture width and fracture height on temperature distribution were determined. The research results provide theoretical support for the realization of DTS based monitoring and diagnosis of fracturing performance, identification of fracture initiation and analysis of fracturing fluid direction, which is of great significance for the evaluation of fracturing effect and fracturing design optimization of fractured horizontal wells.