准静态孔缝介质广义裂隙弱度研究  

General fracture weaknesses for quasi-static porous fractured media

作　　者：薛姣[1] 顾汉明[1] 蔡成国[1] 

机构地区：[1]中国地质大学(武汉)地球物理与空间信息学院,湖北武汉430074

出　　处：《石油地球物理勘探》2015年第6期1146-1153,1033-1034,共8页Oil Geophysical Prospecting

基　　金：国家重大科技专项(2011ZX05000-023-004-001);国土资源部公益性行业科研专项(201211082-03);中央高校优秀青年教师基金项目(CUGL120208)等联合资助

摘　　要：基于地震低频条件下的等效介质理论,联合应用线性滑移模型和各向异性流体充填理论研究包含一组平行裂缝的含流体孔隙介质。由于不能简单地用法向和切向附加弱度表示Gurevich准静态孔缝介质模型中的裂缝,其柔度矩阵也无法用各向同性背景岩石的柔度加上法向和切向柔度来表示,因此本文提出用广义裂隙弱度表征Gurevich准静态等效介质中的含流体裂缝。广义裂隙弱度是各向同性背景介质岩石、裂隙和充填物的物性参数的函数,分析裂隙密度、充填流体和等径孔隙度对广义裂隙弱度的影响,为广义裂隙弱度指示裂隙发育程度和裂隙中流体的存在提供理论依据。同时,为了从地震数据中获取广义裂隙弱度信息,研究了基于Born近似的由广义裂隙弱度表达的反射系数公式,并进行了广义裂隙弱度反演敏感性研究。结果表明,广义裂隙弱度是更具有普遍意义的表征含流体裂隙的特征参数,可用于实现准静态孔缝模型地震数据的定量解释。Porous and fractured reservoirs can be studied using effective medium theory in seismic low frequency.Fluid saturated porous media with a set of aligned fractures,which is known as Gurevich's model,can be expressed by combing linear-slip model and anisotropic Gassmann's fluid substitution theory.Fractures in Gurevich's quasi-static porous fractured model cannot be simply characterized by normal and tangential weaknesses,and the compliance matrix for the saturated porous fractured medium cannot be represented by the sum of an isotropic matrix and an excess compliance matrix with normal and tangential components.So we propose to use general fracture weaknesses to characterize parallel fractures,which are filled with fluids and hydraulically connected with surrounded pores.We investigate the characterization of general fracture weaknesses and analyze effects of fracture density,fluid infill,and equant porosity on general fracture weaknesses.The investigation shows that general fracture weaknesses are related to the fracture density,fluid saturation,and hydraulic connection between fractures and equant pores.In order to estimate the general fracture weaknesses from seismic data,we express linear reflection coefficients with general fracture weaknesses using Born formula.To understand how the general fracture weaknesses affect PP-reflection coefficients,we investigate the sensitivity of reflection coefficients to general fracture weaknesses.The general fracture weakness turns out to be suitable to characterize saturated fractures with porous isotropic background,and to quantitatively interpret seismic data.

关 键 词：准静态等效介质 Gurevich模型 广义裂隙弱度Born近似 AVOA反演敏感性分析 

分 类 号：P631[天文地球—地质矿产勘探]