【作者】 孙洁；

【导师】 徐凯军；

【作者基本信息】 中国石油大学(华东) ， 地质资源与地质工程， 2017， 硕士

【摘要】 重力梯度张量相对于重力数据具有更高的分辨率,包含多个分量,可以提供更为丰富的异常源信息。地震勘探纵向分辨率高,分层能力好,在火成岩、膏岩体比较发育的地区和复杂地表条件下,地震资料品质差,对异常体的识别存在一定的困难。火成岩和盐岩体的密度和速度与围岩存在明显差异,据此,可以通过重力数据和地震资料的联合反演,得到异常体的密度和速度差异,更好的反映地下构造特征,识别地下异常体。目前国内重震同步联合反演存在的几个问题,一是速度密度关系,联合反演普遍根据岩石物理模型,采用经验公式法确定固定的密度和速度关系,不能很好地反映地下地质真实情况;二是重震同步联合反演多是反演地质界面,少有属性参数反演。基于上述问题,本文采用了交叉梯度函数,将速度和密度进行耦合,根据结构相似性进行约束,构建目标函数,采用拉格朗日乘子反演方法,进行重力梯度张量和地震联合反演,得到地下介质的速度和密度。首先,网格采用矩形可变大小网格剖分,目标区进行精细剖分;然后,采用时间域有限差分进行地震正演,解析法进行重力梯度张量正演;最后,选取交叉梯度函数作为目标函数的约束条件,将目标函数和约束条件转化为线性等式约束的一个最小极值问题,通过拉格朗日乘子进行求解。通过模型试算,对反演算法进行了测试,结果表明联合反演的效果比单独反演好。选取冲绳海槽地区的重力和地震数据,将联合反演算法运用到实际资料,推断火成岩体分布,根据重磁震综合解释断面图,验证了方法的实用性和有效性。更多还原

【Abstract】 The gravitational gradient tensor has a higher resolution relative to the gravitational data,and contains multiple components that can provide more abundant source information.Seismic exploration has high longitudinal resolution and good stratification ability.Under the condition of igneous rock and gypsum rock,the quality of seismic data is poor and the identification of abnormal body is difficult.The density and velocity of the igneous rock and the salt rock are obviously different from those of the surrounding rock.According to the joint inversion of the gravity data and the seismic data,the density and velocity of the anomalous body can be distinguished,which can better reflect the underground structure,Abnormal bodyAt present,there are several problems in the simultaneous inversion of the heavy earthquake in China.First,the velocity density relationship,the joint inversion is based on the physical model of the rock.The empirical formula is used to determine the fixed density and velocity relationship,which can not reflect the true situation of underground geological;Second,the joint synchronization of heavy earthquake inversion is inversion of geological interface,few attribute parameters inversion.Based on the above problem,this paper uses the cross gradient function to couple the velocity and density,and restrain it according to the similarity of the structure.The objective function is constructed and the Lagrangian multiplier inversion method is used to carry out the gravitational gradient tensor and seismic joint inversion,Get the speed and density of underground media.Firstly,the grid is divided into rectangular size and the target area is subdivided.Then,the time domain finite difference is used to carry out the seismic forward modeling and the analytic method to carry out gravity gradient tensor forward.Finally,the cross gradient function is chosen as the objective function The objective function and the constraint condition are transformed into a minimum extremum problem of linear equality constraint,and the Lagrangian multiplier is used to solve the problem.The inversion algorithm is tested by the model trial.The results show that the effect of joint inversion is better than that of single inversion.The gravity and seismic data of the Okinawa Trough area are selected,and the combined inversion algorithm is applied to the actual data.Combined with the geological knowledge and logging data,the distribution of the igneous rock is deduced to verify the practicability and effectiveness of the method.更多还原