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本文提出在用时距关系作速度分析时,为了消除界面曲率对时距关系的影响,减少系统的干扰因素,采用计算大量点的速度数据进行统计分析来削弱随机干扰的影响,从而提高计算速度的精度。文中提出一种曲界面反射波时距关系计算的正演方法,它是设计任意曲界面反射波速度计算方法的基础。圆弧法求速度是把相邻两炮点t_0道反射点之间的一段界面用一段圆弧去拟合。文中推导了用相邻两炮点的时距信息,同时计算这段界面曲率及界面以上介质速度的公式。趋势动校正是对流行的正常时差动校正的改进。它具有较高的精度和校正时不要求动校正速度两个优点,从而能够较准确地将共炮点时距场转换为自激自收的法线反射时距场。反趋势动校正根据共炮点时距场与法线反射时距场,可换算出剖面上任意点激发在适当的任意炮检距接收时应得的反射时间,从而建立一套完整的时距场体系。综合地利用这套时距场体系,就可以导出如文中所介绍的反射点法、绕射点法、圆弧法及其它新的计算速度的方法。
In order to reduce the influence of interfacial curvature on the time-distance relationship and to reduce the interference factor of the system, this paper proposes a statistical analysis to calculate the velocity data of a large number of points to weaken the influence of random interference to improve the calculation speed Accuracy. In this paper, a forward method for calculating the time-distance relationship of reflected waves in a curved surface is proposed, which is the basis of the method for calculating the reflected wave velocity at an arbitrary curved surface. Arc method is to seek the speed of the adjacent two shots point t_0 reflection point between a section of the interface with a section of the arc to fit. In this paper, we derive the time-distance information of two neighboring shots and calculate the curvature of the interface and the velocity of the medium above the interface simultaneously. Trend movement correction is the improvement of the popular normal time difference correction. It has two advantages of high precision and not requiring dynamic correction when calibrating, so that it can accurately convert the common shot point time-span field to the self-excitation normal-reflection time-distance field. Anti-Trend Movement Correction Based on the distance field from the normal shot and the normal reflection time field, the reflection time that any point in the section can excite when receiving at any appropriate offset can be calculated, so as to establish a complete time span Field system. By comprehensively using the time-distance field system, we can derive the reflection point method, diffraction point method, arc method and other new methods of calculating velocity as introduced in the article.