缝洞型碳酸盐岩气藏多层合采供气能力实验

摘要

The CT scan,mercury intrusion test and commingled production physical simulation experiment of the cores of pore-type,cavity-type and fracture-cave reservoirs was conducted to study the effects of interlayer heterogeneity,drawdown pressure,water saturation and water invasion on gas supply capacity.The experimental results were verified by the radial numerical model of multilayer commingled production based on the Eclipse software.The experimental results showed that:the fracture-cavity type reservoir,with strong seepage capability,makes great contribution to gas production in the early stage,while the pore-type and cavity-type reservoirs with weak seepage capability,make more contribution to gas production in the middle and late stages;the absolute permeability of the reservoir affects its contribution to productivity,while the relative permeability of reservoir affects the total recovery;the "dynamic supply balance" state among various reservoirs can be achieved at a reasonable drawdown pressure;although the fracture-cavity reservoir is less affected by edge and bottom water,water breakthrough will first occur in this type reservoir and block other reservoirs,significantly reducing the commingled gas supply capacity and recovery.%在孔隙型、孔洞型和缝洞型岩心CT扫描、压汞资料分析储集层微观孔隙结构特征的基础上,建立多层合采物理模拟实验模型,研究了层间非均质性、生产压差、含水饱和度和水侵等因素对供气能力的影响,并采用Eclipse软件建立多层合采径向流模型对实验结果进行了验证.研究表明:缝洞型储集层渗流能力强,前期产气贡献大,孔洞型和孔隙型储集层渗流能力较弱,产气贡献主要体现在中后期;储集层渗透率的绝对大小影响自身的产能贡献率,相对大小影响多层合采总采收率;合理的生产压差下各类储集层之间可以达到“动态补给平衡”供气状态;缝洞型储集层产气能力受边底水影响较小,但会优先见水并封堵其他储集层,大幅降低合采供气能力与采收率.