利用波速、密度和体积模量估计微裂隙岩体的渗透率演化  

Using Velocities、Density and Bulk Modulus to Predict the Permeability Evolution of Microfractured Rocks

作　　者：喻洪平(译)[1] YU Hongping(China Railway Eryuan Engineering Group Co.,Ltd.,Chengdu 610031,China)

机构地区：[1]中铁二院工程集团有限责任公司,四川成都610031

出　　处：《四川建材》2021年第6期93-97,99,共6页Sichuan Building Materials

摘　　要：热致裂隙会引起储层岩石渗透率的显著增加,利用弹性波速、密度和弹性模量的改变预测裂隙引起的渗透率的变化。对Westerly花岗岩样进行了250℃、450℃、650℃和850℃的热处理,温度的升高引起了各向同性均布裂隙的长度、隙宽和密度的增加。采用去离子水作为孔隙流体,测试了10、30、50 MPa有效应力下的渗透率。对同一批岩样,在类似的有效应力水平下,渗透率与纵波与横波速度、体密度和静态体积模量有关。裂隙密度的演化采用Kachanov模型计算,随着有效应力的增加,裂隙闭合引起裂隙密度和渗透率的下降,但其他参数增加。热处理引起了渗透率和裂隙密度的系统性增加以及其他参数的减小。对干、饱和条件,渗透率和其他参数之间存在高相关系数经验关系式,并随有效应力而变化。大致来说,可以利用弹性波速、密度和弹性模量来预测各向同性破裂引起的渗透率的改变。然而,仍需要可靠的方法来提高这些用于建模和描述渗透率的实验室测量数据。Thermal fracturing in reservoir rocks can cause significant increase in permeability.The change in permeability due to fracturing was predicted using the change in elastic wave velocity,density,and elastic moduli.Westerly granite samples were thermally treated to 250,450,650 and 850℃.Increasing the temperature produces an increase in fracture length,aperture and density that is isotropically distributed.The permeability was measured at 10,30 and 50 MPa effective pressure using deionized water as the pore fluid.The permeability was correlated to P-and S-wave velocities,bulk density,and static bulk modulus that were measured at similar effective pressures on the same suite of samples.Kachanov’s(Elastic solids with many cracks and related problems,in:John,Theodore(eds)Advances in applied mechanics,Elsevier,pp 259-445,1994)model was used to calculate the evolution of fracture density.Closure of fracture,due to increasing effective pressure,caused the permeability and fracture density to decrease,and the other parameters to increase.Thermal treatment caused a systematic increase in permeability and fracture density,and a decrease in the other parameters.Empirical relationships with high correlation coefficient exist between permeability and the other parameters for both dry and saturated conditions,which vary with effective pressure.Overall,we conclude that the elastic wave velocity,density and bulk modulus can be used to predict the change in permeability due to isotropic fracturing.However,a reliable method would be required to upscale these laboratory measurements for modelling and describing the permeability within a granitic reservoir.

关 键 词：渗透率 热致裂隙 纵波和横波波速 密度 体积模量 地热系统 

分 类 号：P642.3[天文地球—工程地质学]