| 软煤储层顶板水平井穿层工况下压裂缝扩展模型 |
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| 引用本文： | 王志荣,胡凯,杨杰,陈玲霞.软煤储层顶板水平井穿层工况下压裂缝扩展模型[J].煤田地质与勘探,2019,47(6):20-25. |
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| 作者姓名： | 王志荣 胡凯 杨杰 陈玲霞 |
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| 基金项目： | 国家自然科学基金项目（41272339）；河南省自然科学基金项目（182300410149） |
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| 摘 要： | 为了探索煤层顶板中水平井向目标层穿层压裂的裂缝扩展规律，以华北石炭-二叠纪煤田为例，运用断裂力学、损伤力学以及流体力学等经典理论并结合现场实测资料，开展了压裂缝延伸距离与压裂时间时空演化规律的建模与验证。首先，基于原生裂缝特性、渗透特性以及压裂射孔段附加应力等因素，提出了顶板水平井垂向造缝的起裂压力计算公式；其次，在考虑裂缝性煤岩体损伤效应的基础上，引入Dougill损伤因子，将该计算模型拓展为延伸压力计算模型；最后，基于改进的经典PKN裂缝模型和压裂液滤失理论，建立了连续穿层工况下压裂缝延伸距离与压裂施工时间的函数关系。实践验证表明，根据理论模型合理调配时间参数，可以控制穿层裂缝的延伸距离。
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| 关 键 词： | 碎软煤层 顶板水平井 穿层压裂 裂缝扩展模型 华北石炭-二叠纪煤田 |
| 收稿时间： | 2019-06-10 |
Extension model of fracturing cracks of translayer horizontal well in roof of soft coal reservoir |
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| Abstract: | In order to study the propagation rules of hydraulic fracturing crack formed by a horizontal well in roof to coal seam, taking the Permian-Carboniferous coal field in North China as an example, through the classical theory of fracture mechanics, damage mechanics and fluid mechanics, combined with field actual data, the modeling and verification of the space-time evolution law of the crack propagation distance and fracturing time were carried out. Firstly, considering the additional stress of perforation, the characteristics of primary fracture and the permeability characteristics of rock formation, the calculation formula of cracking pressure of vertical hydraulic fracture caused by horizontal well in roof was proposed; Then, considering the damage effect of fractured coal and rock mass, Dougill damage factor was introduced to extend the calculation model into the calculation model of extension pressure; Finally, based on the improved classical PKN model and fracturing fluid loss theory, the functional relationship between the crack propagation distance and fracturing construction time under continuous penetration conditions was established. The research results show that extension distance of the cracks can be controlled by accurately adjusting the time parameters according to above theoretical model. |
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