Abstract: Large-scale fracturing technique is one of the important means to effectively develop shale oil. After large-scale fracturing, complex fracture networks will be formed around the wellbore. The inversion of fracture parameters after fracturing is the key to fracturing performance evaluation and parameter optimization for hydrocarbon development. However, it is difficult for the existing mathematic and well test models to meet the inversion needs of complex fracture network in shale oil. For this reason, the paper investigates the characterization of complex fracture networks in shale oil fractured horizontal wells, establishes semi-analytical well test models for multi-mode fracture network of shale oil, including volume fracturing model, compound fracturing model, and discrete fracture network model. The semi-analytical well test model of multi-mode fracture network is solved using point source method, semi-analytical method and Laplace transformation. Moreover, efforts are made to perform numerical verification, divide flow phases and analyze the characteristics of flow section. Based on the semi-analytical well test model established for multi-mode fracture network, a sensitivity analysis was performed on well test characteristic curve, and then a well test curve fitting method was established. Supported by the production history fitting method, the scheme for parameter evaluation of shale oil multi-mode fracture network was initially developed based on well test theory. The fracture network parameter evaluation method was actually applied in the shale oil fractured horizontal wells JA and JB in Jimsar. An evaluation was performed on fracture network parameters, including fracture network geometries, half length of primary and secondary fractures, hydraulic conductivities of primary and secondary fractures, storage coefficient before and after crack closure, and fracture closure time. In addition, the accuracy and practicality of the evaluation method of complex fracture network parameters were proved by field applications.

Key words: shale oil, fractured horizontal well, fracture network, well test analysis, Jimsar

摘要： 大型压裂技术是高效开发页岩油的重要手段之一，经过大型压裂后井筒周围会形成复杂裂缝网络，压后裂缝参数反演是压裂效果评价和开发参数优化的关键，但目前的渗流和试井模型难以满足页岩油复杂缝网反演的需求。为此，研究了页岩油压裂水平井复杂缝网的表征问题，建立了页岩油多模式裂缝网络半解析试井模型，包括体积压裂模型、压裂复合模型及离散缝网模型，利用点源方法、半解析方法和拉普拉斯变换等求解了多模式裂缝网络半解析试井模型，并开展了数值验证，划分了流动阶段，分析了流动段特征。在建立的多模式裂缝网络半解析试井模型基础上，对试井特征曲线进行了敏感性分析，并建立了试井曲线拟合方法，辅以生产历史拟合法，初步形成了基于试井理论的页岩油多模式裂缝网络参数评价思路。采用建立的缝网参数评价方法对吉木萨尔页岩油压裂水平井JA井与JB井进行分析，评价了裂缝网络参数，包括缝网几何形态、主次裂缝半长、主次裂缝导流能力、裂缝闭合前存储系数、裂缝闭合后存储系数和裂缝闭合时间等，并通过实例应用证明了复杂缝网参数评价方法的可靠性和实用性。

关键词: 页岩油, 压裂水平井, 裂缝网络, 试井分析, 吉木萨尔