基于空间约束的裂缝密度反演方法

Inversion method of fracture density based on spatial constraints

常规利用法向弱度、切向弱度间接预测裂缝密度的方法存在较大误差。为此,提出一种针对碳酸盐岩(HTI介质)裂缝密度直接反演的方法。在振幅随炮检距和方位角变化(AVAZ)反演的基础上,引入反距离加权插值法(IDW)以优化传统各向异性全变分(ATV)多道反演的横向差分算子,充分利用相邻多个地震道之间的相关性,提高反演算法的横向连续性和稳定性;将横向约束、低频约束及稀疏约束共同用于构建反演目标函数,采用交替方向乘子法(ADMM)优化求解。利用裂缝密度直接反演和反距离加权插值的优点,先对Marmousi II模型测试,验证了该方法的有效性和抗噪性;再将该方法应用于塔里木盆地YM区块的实际数据,验证了该方法的可行性。该方法对裂缝密度预测结果更准确、可靠,可在类似地区推广应用。

Due to the large error in conventional indirect prediction of fracture density using normal weakness and tangential weakness,this paper proposes a direct inversion method for fracture density in carbonate rocks(HTI medium).Based on the inversion of amplitudes varying with offset and azimuth(AVAZ),the paper in⁃troduces an inverse distance weighted method to optimize the transverse difference operator of traditional aniso⁃tropic total variationa(l ATV)multichannel inversion.The method fully utilizes the correlation between adja⁃cent seismic tracks to further improve the horizontal continuity and stability of the inversion algorithm.Lateral constraints,low⁃frequency constraints,and sparse constraints are applied to construct the inversion objective function,and the alternate direction multiplier method(ADMM)is adopted to optimize the inversion objective function.With the two advantages of direct inversion of fracture density and inverse distance weighted interpola⁃tion,model tests are conducted on the Marmousi II model to verify the effectiveness and noise resistance of the proposed method.Then,the paper further verifies the practical feasibility of the proposed method by applying it to the actual data of carbonate rocks in YM block,Tarim Basin.The proposed method is more accurate and reli⁃able for predicting fracture density and can be widely applied in similar areas.