山前冲积扇表层静校正对策

由于山前地表冲积扇的厚度和速度变化较大,利用传统的表层调查和静校正方法计算无法彻底解决“中长波长静校正量”问题。具体表现为小折射排列长度太小(当低速带厚度较大时,无法追踪到高速层顶界面)、小折射资料的解释算法不合适及微测井深度明显不够。通过对雁木西地区多条过井测线进行系统分析(内容包括采集方法、处理技术、速度建场及成图方法等),从采集、处理和解释入手对表层结构进行研究,采用大排列小观测折射及微测井观测,层析成像等技术,并利用初至波形成了一套完善的表层静校正技术,先后在雁木西和胜北地区应用,取得了很好的效果。

Strategy of near-surface static corrections in piedmont fluvial fans

Using ordinary near-surface survey and static corrections can't thoroughly solve the issue of "middle to long wavelength static corrections" because of large variation of thickness and velocity of piedmont near-surface fluvial fans. The concrete shows are that the spread length of shallow refraction is too short to trace the top interface of high-velocity bed when the thickness of low velocity layer is large, inadequate interpretation algorithm of shallow refraction data and insufficient depth of uphole survey. Through systematically analyzing multiple well-crossed lines in Yanmuxi area (the contents include acquisition methods, processing techniques, velocity-field-building methods and mapping methods),we studied near-surface structures starting from acquisition,processing and interpretation, adopted the techniques such as shallow refraction with longer spread and uphole survey as well as tomographic image etc. and used first breaks to form a set of complete near-surface static corrections technique. The above mentioned techniques have been used in Yanmuxi and Shengbei areas successively and good results have been achieved.