四川东部高陡构造时深转换方法研究

RESEARCH ON TIME-DEPTH CONVERSION METHOD OF THE HIGH-STEEP STRUCTURES IN EAST SICHUAN

四川东部高陡构造由于地表和地下两翼地层陡峭、断层发育以及由此产生的断层上下两盘地层速度横向的变化,造成在时间剖面上的反射复杂,甚至有构造假象的存在,由时间域向深度域的转换是一个重要环节。正确的时深转换处理是搞准地腹构造形态的关键。层速度时深转换处理的效果,主要取决于所建立的时深转换速度模型的正确及合理性。通过层速度时深转换方法的改进,较好地解决了多年来高陡构造大断层上、下盘,因速度突变而造成时深转换之后的深度误差和构造形态的畸变,大大提高了钻探符合率。该方法操作容易,实用性强,在四川东部DTC构造带上的MYB、XJG和WQJ构造带上已见到较好的效果。

The lateral interval velocity changes of both hanging walls and lower walls of the faults in the high-steep structures in East Sichuan always happened because of their precipitous two flanks and developed faults, which often made the reflection on time section very complex, and even created a false structural appearance. There fore the conversion from time-domain to depth-domain is an important step, and the correct time-depth conversion processing is the key of determining accurately subsurface structural shape. The effectiveness of interval velocity time-depth conversion processing is mainly dependent on the correctness and rationality of the built velocity model of time-depth conversion. The problems with the depth error and structural shape distortion of the hanging wall and lower wall of large fault in the high-steep structure, which was caused by velocity mutation and has existed for many years, were well resolved by means of the improvement of time-depth conversion method, thus raising greatly drilling success ratio. This method is possessed of strong operability and practicability and a good result has been obtained by applying it to the MYB and XJG structures of DTC structural belt and the WQJ structural belt in East Sichuan.