VSP激发方式选择分析

为满足实际生产对VSP资料的更高要求，除了加快采集设备和处理软件的更新外，激发方式也是一个不容忽视的重要问题。在川渝地区，长期以来都采用“水炮”作为震源来采集VSP资料，并且认为“水炮”激发方便、资料一致性较好，是VSP资料采集的理想震源，但是在川中、川中-川南过渡带上用水炮采集的VSP资料往往出现主频低、频带窄、波组不齐全的问题，在很大程度上影响了VSP技术的应用效果和推广。以BQ205井VSP测井为例，对“井炮”和“水炮”激发采集的VSP资料从子波一致性、能量的稳定性、分辨率的高低等方面进行了对比分析，认为在低降速带较厚的地区，“井炮”激发采集的VSP资料比“水炮”激发的子波一致性要好、能量的稳定性更优、抗低频的能力更强、分辨率更高。这一结论对四川盆地VSP资料采集及其推广应用具有指导意义。

A shooting method optimized to acquire the vertical seismic profile (VSP) data with good quality

In order to improve the quality of VSP data, shooting methods should be optimized in addition to the updating acquisition equipments and processing software. The "shooting in water" is believed to be an ideal seismic source for VSP data acquisition because of its convenience and high consistency, and that is why it has been widely applied in Sichuan and Chongqing gas fields. However, in the area of the central Sichuan Basin and the transition belt between the central and southern Sichuan Basin, the VSP data acquired by "shooting in water" usually present the following characters such as low main-frequency, narrow frequency band, and incomplete wave group, etc. Therefore, taking the well BQ 205 as an example, a comparison study was performed on the VSP data acquired by the methods of "shooting in water" and that by "shooting without water" in respect of wavelet consistency, energy stability and resolution. The results showed that the VSP data acquired by "shooting without water" method have better wavelet consistency, higher energy stability, stronger low-frequency resistance and higher resolution, therefore, providing reference for the VSP data acquisition in the Sichuan Basin.