针对页岩储层水平井压裂开发中复杂缝网形态、纳微米孔隙—复杂缝网—井筒多尺度渗流规律认识不清等问题,开展了针对性的研究:①通过巴西劈裂实验,诱导压裂缝的产生;②通过X射线CT扫描,观测岩样内部压裂缝形态,测得压裂缝开度;③结合压裂缝形态描述和气体在基质—复杂缝网—井筒中的渗流机理,在多尺度统一渗流模型的基础上,建立考虑扩散、滑移及解吸的水平井单段压裂改造产能方程;④考虑多级压裂区干扰及水平井筒压降,建立页岩储层多级压裂水平井产能预测模型.研究结果表明:①压裂缝形态为复杂网状缝;②测得压裂缝开度为4.25～453.00 μm,平均为112.00 μm;③不同缝网形态下页岩气表现出不同非线性渗流规律;④随着重改造区裂缝密度、重/弱改造裂缝分布范围的增大,产气量逐渐增加,压裂段间缝网渗流区域发生干扰,产气量增加幅度减小;⑤模拟水平井筒长1 500 m、重度改造区缝网半长100 m时,压裂10级产能效果最好.结论认为,需要合理地控制压裂程度、优化裂缝参数,才能为页岩气压裂优化设计等提供技术支撑.%In this paper,a series of specific studies were carried out to investigate the complex form of fracture networks and figure out the multi-scale flowing laws of nano/micro pores-complex fracture networks-wellbore during the development of shale reservoirs by means of horizontal well fracturing.First,hydraulic fractures were induced by means of Brazilian splitting tests.Second,the forms of the hydraulic fractures inside the rock samples were observed by means of X-ray CT scanning to measure the opening of hydraulic fractures.Third,based on the multi-scale unified flowing model,morphological description of fractures and gas flowing mechanism in the matrixcomplex fracture network-wellbore,the productivity equation of single-stage horizontal well fracturing which includes diffusion,slipping and desorption was established.And fourthly,a productivity prediction model of horizontal well multi-stage fracturing in the shale reservoir was established considering the interference between the multi-stage fracturing zones and the pressure drop in the horizontal wellbore.The following results were obtained.First,hydraulic fractures are in the form of a complex network.Second,the measured opening of hydraulic fractures is in the range of 4.25-453 μm,averaging 112 μtm.Third,shale gas flowing e in different shapes of fracture networks follows different nonlinear flowing laws.Forth,as the fracture density in the strongly stimulated zones rises and the distribution range of the hydraulic fractures in strongly/weakly stimulated zones enlarges,gas production increases gradually.As the interference occurs in the flowing zones of fracture networks between fractured sections,the increasing amplitude of gas production rates decreases.Fifth,when the length of a simulated horizontal well is 1500 m and the half length of a fracture network in the strongly stimulated zone is 100 m,the productivity effect of stage 10 fracturing is the best.Therefore,it is necessary to control fracturing degree reasonably and optimize fracturing parameters,so as to provide a theoretical support for the optimization design of shale gas reservoir fracturing.
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