﻿ 折射波共检波点叠加技术在活动断层上断点探测中的应用
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 大地测量与地球动力学  2020, Vol. 40 Issue (6): 640-645  DOI: 10.14075/j.jgg.2020.06.018

### 引用本文

ZHI Min, PEI Gendi. Application of Refractive Common-Receiver Stack Technology in Detecting Upper Breakpoints of Active Faults[J]. Journal of Geodesy and Geodynamics, 2020, 40(6): 640-645.

### Foundation support

Science and Technology Innovation Fund of Xi'an Research Institute, China Coal Technology and Engineering Group Co Ltd, No.2015XAYQN06.

### 第一作者简介

ZHI Min, assistant researcher, majors in processing and interpretation of seismic data, E-mail:zhiminccri@163.com.

### 文章历史

1. 中煤科工集团西安研究院有限公司，西安市锦业一路82号，710077

1 方法原理 1.1 折射波时距曲线

 图 1 二层速度结构折射波路径及时距曲线 Fig. 1 Refraction path and time-distance curve of 2 layers velocity structure
 $T(X) = \frac{X}{{{V_2}}} + \frac{{{H_S}{\rm{cos}}{\theta _C}}}{{{V_1}}} + \frac{{{H_R}{\rm{cos}}{\theta _C}}}{{{V_1}}}$ (1)

1.2 折射波滑行速度求取

 图 2 差数时间法计算折射层速度 Fig. 2 Refraction layer velocity calculated by difference time method
 ${{T_A}({X_{AC}}) = \frac{{{X_{AC}}}}{{{V_2}}} + \frac{{{H_A}{\rm{cos}}{\theta _C}}}{{{V_1}}} + \frac{{{H_C}{\rm{cos}}{\theta _C}}}{{{V_1}}}}$ (2)
 ${{T_B}({X_{BC}}) = \frac{{{X_{BC}}}}{{{V_2}}} + \frac{{{H_B}{\rm{cos}}{\theta _C}}}{{{V_1}}} + \frac{{{H_C}{\rm{cos}}{\theta _C}}}{{{V_1}}}}$ (3)

 $\begin{array}{*{20}{c}} {{T_A}({X_{AC}}) - {T_B}({X_{BC}}) = }\\ {\frac{{{X_{AC}} - {X_{BC}}}}{{{V_2}}} + \frac{{({H_A} - {H_B}){\rm{cos}}{\theta _C}}}{{{V_1}}}} \end{array}$ (4)

 ${\rm{d}}{T^\prime }({X_C}) = \frac{{{\rm{d}}{X_{AC}} - {\rm{d}}{X_{BC}}}}{{{V_2}}}$ (5)

 ${V_2} = 2\frac{{{\rm{d}}{X_{AC}}}}{{{\rm{d}}{T^\prime }({X_C})}}$ (6)

1.3 炮点延迟时间求取

 $T_0^S + T_0^R = T(X) - \frac{X}{{{V_2}}}$ (7)

1.4 折射界面深度确定方法

 ${T_0}(x) = \frac{{{H_R}(X){\rm{cos}}{\theta _C}}}{{{V_1}}}$ (8)

 ${H_R}(X) = \frac{{{T_0}(X){V_1}}}{{{\rm{cos}}{\theta _C}}} = \frac{{{T_0}(X){V_1}{V_2}}}{{\sqrt {V_2^2 - V_1^2} }}$ (9)

2 模型研究

 图 3 断层速度模型 Fig. 3 Fault velocity model

 图 4 速度模型的典型单炮记录 Fig. 4 Typical shot record of velocity model

 图 5 差数时间法分析折射层速度 Fig. 5 Refraction layer velocity analyzed by differential time method

 图 6 折射层速度在水平方向的变化 Fig. 6 Variation of refractive layer velocity in horizontal direction

 图 7 炮点延迟时间曲线 Fig. 7 Delay time curve of shot point

 图 8 共中心点与共检波点域折射波叠加剖面 Fig. 8 Refractive wave stack profiles in common mid-point domain and common-receiver domain

 图 9 利用近炮点初至时间计算低速层速度 Fig. 9 Velocity calculation of low velocity layer based on near shotpoint arrival time

 图 10 低速层速度曲线 Fig. 10 Velocity curve of low velocity layer

 图 11 时深转换获得基岩深度曲线 Fig. 11 Bedrock depth curve obtained by time-depth conversion

 图 12 时深转换的深度误差 Fig. 12 Depth error of time-depth conversion
3 应用实例

 图 13 测线上的典型单炮记录 Fig. 13 Typical shot record on the line

 图 14 二维测线共中心点反射波叠加剖面 Fig. 14 Reflection wave stacking profile of 2D line in common midpoint domain

 图 15 二维测线共中心点与共接收点折射波叠加剖面 Fig. 15 Refractive wave stacking profiles of 2D line in commonmidpoint domain and common-receiver domain

 图 16 二维剖面对应的工程地质剖面 Fig. 16 Engineering geological profile corresponding to 2D profile

 图 17 二维测线低速层速度求取 Fig. 17 Velocity calculation of low velocity layer of 2D line
4 结语

1) 在共接收点域，可以应用消除炮检距及炮点延迟时间的方法将折射波及断点绕射波校正到同一时间，通过叠加技术可进一步提高折射波及断点绕射波信噪比。

2) 差数时间法不依赖于测线地形和低速层速度，可以获得较准确的折射波速度；采用直达波初至时间线性拟合方法可以得到较准确的低速层速度，应用该速度作时深转换精度较高。

3) 共检波点折射波叠加方法可以得到横向分辨率和信噪比较高的叠加剖面，剖面上折射波和断点绕射波形态清晰，可以较可靠地反映埋深较浅的活动断层上断点的空间位置，结合反射地震剖面及钻孔资料可以较准确地判定活动断层的浅部形态。

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Application of Refractive Common-Receiver Stack Technology in Detecting Upper Breakpoints of Active Faults
ZHI Min1     PEI Gendi1
1. Xi'an Research Institute, China Coal Technology and Engineering Group Co Ltd, 82 First-Jinye Road, Xi'an 710077, China
Abstract: Based on the refraction time-distance curve equation, we anayze the principle of common-receiver refraction stack imaging technology. The refraction wave of the 2D fault model is stacked in common midpoint domain and common-receiver domain respectively, and the actual 2D seismic data of Hexi corridor is processed comparatively. The results of model and practical application show that the common-receiver domain profile has higher lateral resolution than the common midpoint domain. This method, in combination with other data, can accurately determine the spatial location of fault points on active faults.
Key words: active faults; upper breakpoints; common-receiver; refractive wave stack