摘要
复杂的裂缝网络给页岩气藏数值模拟研究带来巨大挑战.本文利用离散裂缝模型(DFM),分别建立微尺度模型和矿场尺度模型,研究了不同基质渗透率和裂缝开度对应条件下,不同类型裂缝对页岩气总产量的贡献率.研究结果表明:在量级约为(10–8~10–4)×10–3μm2的页岩气藏基质渗透率范围内,且存在SRV改造区的条件下,页岩气产量以SRV内人工裂缝的贡献为主,SRV内以及SRV外天然裂缝的贡献量相对较小.因此,综合考虑计算复杂度和计算精度,可通过构建基质-天然裂缝表观渗透率和连续介质模型的方法表征天然裂缝,采用离散介质模型中计算网格少、效率高的离散裂缝网络(DFN)模型表征人工裂缝.
The complex fracture network brings great challenge to the numerical simulation of shale gas reservoirs.Based on the discrete fracture model(DFM),micro scale model and field scale model are established to investigate the influence of fracture types on the reservoir performance when the correspondence of matrix permeability and fracture aperture is different.Results show that:because the magnitude of shale gas reservoir matrix permeability isthe SRV is a prerequisite for shale gas production,hydraulic fractures play an important role in the shale gas production while the contribution of natural fractures in and out the SRV is relatively small.Therefore,considering the computational complexity and precision,natural fractures can be characterized by matrix-natural fracture apparent permeability model and continuum model while the hydraulic fracture can be characterized by the discrete fracture network(DFN)with less computational grids and high efficient.
引文
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