页岩可压性指数评价新方法及应用

A New Method for Evaluating Shale Fracability Index and Its Application

脆性指数是评价页岩可压性的基础,国外的脆性指数研究只局限于近井筒参数。为了更全面地表征页岩的可压性,以压裂施工参数为基础,从能量的角度提出了一种新的页岩脆性指数综合评价方法,并建立了地质参数与工程参数有机结合的可压性指数综合模型;同时应用归一化方法,建立了利用等效支撑剂量与等效压裂液量的比值表征可压性指数的新模型。实例计算表明,采用该方法计算的脆性指数及可压性指数与压后产气效果关联度较强,能够准确反映裂缝的延伸性,其值大小可作为优选压裂段簇位置的依据,并具有较高的可信度和现场实用性。建议在现场推广应用,以促进国内页岩气的勘探开发效果及水平。

Brittleness evaluation is the basis for shale fracability evaluation ,and the brittleness index research has been limited to near-wellbore zone in foreign studies .In order to fully describe the shale fraca-bility ,a new integrated method of shale brittleness index evaluation was proposed in view of energy based on fracturing parameters .A comprehensive model of shale fracability index was established taking into ac-count both geology and engineering parameters .Moreover ,the normalization method was adopted to estab-lish a new model of shale fracability index which was evaluated by the ratio of equivalent proppant volume to equivalent fracturing fluid volume .Field application showed that the calculated shale brittleness index is highly correlated to fracability index and post-frac gas production ,and may be used to determine the pre-ferred fraturing position for each stage ;the new method is reliable and practicable .It can be recommended for promoting shale gas exploration and development in China .