塔里木盆地结晶基底的反射地震调查

大型克拉通内部沉积盆地基底组构与盆地起源和油气聚集有密切关系.除了钻井岩心及周缘露头研究可提供盆地结晶基底类型证据外,反射地震信号记录了沉积盆地起源时期的有关大地构造作用信息,盆地基底组构可通过记录长度大的反射地震剖面研究.2007年中石化在塔里木盆地将1400 km的地震剖面接收记录从6 s加长到12 s,为研究克拉通盆地结晶基底的组构和类型提供了难得的第一手资料.这篇文章主要介绍这次调查的反射地震剖面,讨论深反射地震数据处理的关键技术,展示塔里木盆地巴楚—塔中地区的四条12 s反射地震剖面,并对反射剖面的散射模式作初步分析.本次调查表明,将地震剖面接收记录从6 s加长到12 s,采集处理的成本只增加了3％左右,但是可为研究克拉通盆地结晶基底和上地壳不均匀性提供很有价值的第一手资料.

Seismic reflection investigations of basement in Tarim basin

Basement characteristics of a large cratonic sedimentary basin are closely related to the origin of sedimentary basins and to the formation of oil/gas fields. Information about the basements can be obtained from deep drilling within or from outcrop sampling around the basins, as well as can be obtained from reflection records that contain some tectonic information about early-deposited strata in the sedimentary basins. However, basement study requires reflection investigation with longer-time recording windows. In 2007, we extended the reflection recording window from 6 s to 12 s, obtained the first-hand seismic records for the study of basement structures in the Tarim basin. This 12 s reflection investigation contains 4 lines with total profile lengths of 1400 km. This paper presents these seismic profiles in detail after a short discussion of data acquisition and processing techniques, and then analyzes scattering patterns correlated to different parts within the basement. The investigation increases the 3% cost for longer data records, while has provided much more useful first-hand data for understanding of early development of the cratonic sedimentary basin and heterogeneity of the upper crust.