三维MT在库车坳陷新近系沉积相研究中的应用

Application of 3D MT in researching of sedimentary facies of the Neogene in Kuche Depression

在野外露头观察和测井解释成果的基础上,对测得的岩石电阻率值进行校正,界定出新近系不同岩性的电阻率值范围,通过对三维MT资料进行预处理(去噪、编辑与平滑和静态位移校正)和三维反演处理,使三维MT数据准确地反映研究地区岩石的电阻率,然后将三维MT与三维地震数据体叠合,进行电震同台解释,建立构造模型,最终在建立的地层格架内对沉积相分布进行精细地识别,该方法解决井间相带变化和地震相特征不明显带来的研究困难。研究结果表明:库车坳陷新近系的吉迪克组和康村组从山前到盆地中心依次为扇三角洲和湖泊,康村组扇三角洲规模更大;库车组山前地带主要为冲积扇沉积,南部为冲积平原沉积,从西部到东部,冲积扇规模呈现出由小变大的趋势。

Based on the observation of field outcrop and well logging interpretation, resistivity value of rock was corrected, and the resistivity value range of different rocks of Kuche formation was ensured to make the electrical data reflect intuitively different lithofacies. Through pretreatment of 3D MT data, such as de-noising, editing and smothong, and static shift correction, and 3-D inversion treatment, reflected more accurately the resistivity of sediments from study area. And then stratigraphic framework was then established by corrected 3D MT profile congruent to seismic profile. Finally, sedimentary facies in Neogene were recognized and researched finely in stratigraphic framework. And the problems that sedimentary facies belt changed among wells and unconspicuous characteristics of seismic facies were solved. The results show that from piedmont to the basin center fan dalta and lake develop during the periods of Jidike and Kangcun, and the scale of fan dalta is larger in Kangcun Formation. In Kuche Formation, alluvial fans are mainly distributed in piedmont of northern Kuche Depression, and alluvial plains are the main facies in south. The scales of alluvial fans shift from small to large from west to east.