火山岩压敏性的定量综合评价及其对气井产能影响

摘要

Previous evaluations on stress-sensitivity of volcanic rocks are limited to qualitative analysis,and the influence factors of the stress-sensitivity are not comprehensive.Basing on the results of stress-sensitivity experi-ment on volcanic rocks and the theory of stress-deformation,this paper has established a relatively comprehen-sive quantitative evaluation method.This paper has analyzed the factors that affect the stress-sensitivity of vol-canic rocks,finding that fracture development situation and pore structure are the key factors.The result of stress-sensitivity experiments is highly consistent with the result of quantitative comprehensive evaluation on stress-sensitivity of volcanic rocks with the 0. 94 of linear fitting R2 ,verifying the high reliability of this evalua-tion method.All the influence factors of stress-sensitivity are fracture type,fracture filling situation,permeabili-ty,the ratio of porosity to permeability,fracture number,fracture width,porosity,clay mineral content and depth in descending order.In addition,the volcanic gas well productivity equation with stress-sensitivity is es-tablished,which can forecast gas well productivity with stress-sensitivity under different reservoir pressure.And the analysis result of the effect of stress-sensitivity on gas well productivity shows that the stronger the stress-sen-sitivity is,the more the gas well productivity losses under the same condition.%以往对于火山岩压敏性评价多限于定性分析且影响因素分析较片面，基于6块火山岩岩样的压力敏感性实验结果，结合岩石应力变形理论，建立了一种相对完善的定量化综合评价方法。分析了影响火山岩岩石压敏性的因素，其主控因素为裂缝发育情况和岩石孔隙结构。同时对影响岩石压敏性的影响因素进行了定量综合评价，其评价结果与实验结果的高度吻合（直线拟合R2为0．94），验证了该评价方法的可靠性。火山岩压敏性的各影响因素的影响因子由大到小依次为裂缝类型、裂缝充填情况、岩石渗透率、岩石孔渗比、裂缝条数、裂缝宽度、岩石孔隙度、黏土矿物含量和井深。此外，还建立了压敏条件下火山岩气井的产能方程，给出一种预测不同地层压力下火山岩气井产能的方法，分析了压敏性对火山岩气井产能的影响，其结果表明：岩石压敏性越强，地层压力下降越多，压敏性带来的附加产能损失越大。