基于等效介质模型的裂缝参数AVOA反演  

Estimation of fracture parameters from P-wave AVOA data based on equivalent media theory

作　　者：薛姣[1,2] 顾汉明[1,2] 蔡成国[1,2] 李宗杰[3] 朱定[3] 

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 [2]地球内部多尺度成像湖北省重点实验室,湖北武汉430074 [3]中国石化西北油田分公司勘探开发研究院,新疆乌鲁木齐830011

出　　处：《石油地球物理勘探》2016年第6期1171-1179,1051-1052,共9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);湖北省"地球内部多尺度成像"重点实验室开放基金资助项目(SMIL-2016-02)联合资助

摘　　要：对于裂缝储层内部的垂直剖面,裂隙弱度差可能为负值,而裂隙弱度为非负值,裂隙弱度递推反演方法和假设反射界面之上为各向同性介质的反演方法所得到的反演结果与真实裂隙弱度有较大差异。为此,根据裂隙弱度差等于一阶差分矩阵与裂隙弱度的乘积推导出了反射振幅与裂隙弱度的直接关系式,并将裂隙弱度非负值约束条件加入裂隙弱度反演方程中,构建了裂隙弱度纵波AVOA反演方法。模型试算结果证明了改进的裂隙弱度直接反演方法的有效性。利用塔里木盆地麦盖提地区实际纵波AVOA数据实现了法向和切向裂隙弱度以及裂缝密度反演,裂缝参数反演结果表明该区裂缝基本呈条带状发育,裂缝发育强度与断裂带密切相关,裂缝储层预测结果与测井和钻井资料吻合。The contrasts of the fracture weakness may be positive or negative while the fracture weakness is nonnegative. Layer stripping is normally used to invert the fracture parameters of individual layers in sections. Otherwise, the upper layer of each interface is assumed to be isotropic to simplify inversion algorithms. Large errors in the final estimations of the fracture parameters may be introduced by layer stripping or inversion methods assuming that upper layer of each interface is isotropic. Thus, we propose in this paper a method for estimation of fracture parameters from P-wave AVOA data based on equivalent media theory. We express the contrasts of the fracture weakness as multiplication of the first order difference matrix with the fracture weakness itself, and express the reflected amplitude as a function of the fracture weakness, which can be used to estimate normal and tangential weakness. A priori information about the model can be added to the objective function as penalty term according to Bayesian theory. AVOA inversion results for a synthetic model show that the fracture weakness can be reliably estimated. Fracture weakness and fracture density are estimated from real seismic data in Markit area in the Tarim Basin. The AVOA inversion results are consistent with well and logging information, which means they can be used to determine fractured reservoir locations. © 2016, Editorial Department OIL GEOPHYSICAL PROSPECTING. All right reserved.

关 键 词：裂缝等效介质理论 裂隙弱度 裂缝密度 纵波AVOA 

分 类 号：P631[天文地球—地质矿产勘探]