准噶尔盆地石南地区静校正方法应用研究

Application of static correction method in Shinan area,Junggar basin.

1. 中国石油天然气股份有限公司新疆油田分公司勘探开发研究院地球物理研究所,新疆乌鲁木齐830011;2. 北京帕美智软件开发有限公司,北京100022

Geophysical Research Institute of Exploration and Development,Xinjiang Oilfield Company,CNPC,Urumchi 830011,China

相对一个排列,沙漠区小沙丘的高程起伏变化一般不足以引起中、长波长静校正问题,而大幅度起伏的沙梁和低、降速带纵横向速度和厚度的变化,才是引起中、长波长静校正问题的主要原因。准噶尔盆地腹部石南地区地表主要表现为条带沙梁和蜂窝状流动沙丘,近地表低、降速层带中存在高速夹层。采用了3种不同的静校正方法,分别为：近地表分层模型法,主要利用小折射和微测井资料,通过控制点间内插的方式建立模型；初至波折射静校正法,利用有效的折射波初至时间,通过给定的近地表初始速度构建模型；初至波层析反演静校正法,利用更加丰富的初至信息,包括直达波、回折波、折射波等,通过多次迭代,反演近地表速度模型。通过实际应用,研究分析了3种方法静校正效果存在差异的原因,认为层析反演静校正方法效果最好,短、长波长静校正问题都得到了很好的解决。

Generally speaking,for an array,the variation in elevation of small dunes in desert will not result in the problem of static correction for wavelength (both medium wave and long wave). However,the largely fluctuated sand ridges and the variation in velocity and thickness of both low velocity layer and decelera-ting velocity layer in vertical and horizontal direction are the main reason for the problem of static correction.In Shinan re-gion of Junggar basin,the surface mainly presents banded sand ridges and honeycomb-shaped active sand dunes and the high-speed interbed exists in low and decelerating velocity layers near the surface.Three static correction methods are used,which are 1) the near-surface hierarchical model method,being used to construet model by using short-refraction and micro-log data with interpolation in controlled points,2) the primary wave re-fraction static correction method,being used to construct model with given velocity (near surface) by using the effective first ar-rival time of refraction wave,and 3) the primary wave chroma-tography inversion static correction method,using the arrival information,including direct arrival wave,reflection wave,and refraction wave to inverse the near-surface velocity model by it-eration.The result of applying the three static methods in prac-tice shows that the chromatography inversion static correction method is the best one and can better solve the problem of static correction for both medium and long waves.