三分量微测井方法在转换波静校正中的应用

转换波静校正一直是制约多波多分量勘探的瓶颈。与常规微测井相比,三分量微测井技术在获取纵波信息的同时也能接收横波信息,从而可以准确计算出纵、横波速度及低(降)速带分层结构,得到各检波点处静校正量,解决转换波静校正问题。以沁水盆地二维三分量地震勘探中的某条测线为例,详细介绍了井中激发、地面三分量检波器接收微测井施工设计、处理及解释方法,认为井中激发、地面三分量检波器接收方法在水平分量上可以记录到可靠的横波信息,频谱分析可见垂直分量主频高、频带宽,两个水平分量频带和主频都低于垂直分量;地面三分量检波器可以不受地表条件影响灵活安置,其“背对背”安置方式可以压制高频噪声;横波是续至波,叠加于其它波的背景之中,初至走时不易直接拾取,需通过偏振分析进一步处理。经三分量微测井校正后的时间剖面上同相轴连续性明显改善,静校正效果更为理想。

 The static correction of a converted wave is a bottleneck in multi-wave and multi-component exploration.Compared with conventional micro-logging,the three-component micro-logging technology is able to retrieve information on both P-waves and S-waves.Using this technology,the velocity of these waves can be accurately calculated,the layered structure of the low-velocity zone can be identified,and the static correction at the detection point can be calculated,thereby resolving the issues in the static correction of the converted wave.Taking a survey line in the Qinshui Basin as a case study,the method for designing,processing,and interpreting borehole excitation and ground three-component micro-logging data from geophones was illustrated.The results showed that the proposed method can produce reliable records of the horizontal component of transverse waves.Furthermore,the frequency spectrum analysis pointed out that the vertical component was characterized by a higher dominant frequency and a wider frequency band compared with those of the two horizontal components.The placement of three-component geophone was not affected by the surface conditions.Nonetheless,the back-to-back arrangement best suppressed high-frequency noise.The S-wave was identified as a continuation wave,which was superimposed on other waves.However,directly retrieving the travel time of the first arrival remains to be difficult,thus further processing by polarization analysis is needed.The continuity of the time section after the three-component micro-logging correction was improved significantly,and an ideal static correction effect was achieved.

国家自然科学基金(41374131)和山西省煤基重点科技攻关项目(MQ2014-01)共同资助。