塔河油田四区奥陶系古岩溶流域的倒淌河及其成因研究

在现代岩溶区,由于构造运动、岩性差异以及地貌起伏等因素,常常出现水系袭夺现象,并随之伴生一系列反常的水文地貌现象,如分水岭迁移和破坏、袭夺肘、风峡、断头河和倒淌河等。基于三维地震资料,应用层拉平技术、精细相干分析技术及相关地震成图技术,对塔河油田四区中—下奥陶统顶部海西早期的岩溶古地貌和古水系进行了恢复识别,发现也存在类似的反常水文地貌现象。借鉴现代水系袭夺理论,证实了塔河油田四区东部岩溶流域早期为南向汇流结构,而后期由于构造运动引起西北部侵蚀基准面下降,并通过地下途径对邻近南向流域北缘进行逐步袭夺,形成了大型倒淌河,再现了本区岩溶古水系及流域的阶段性演化过程,从而为揭示塔河油田奥陶系古岩溶发育规律提供了重要的依据。

The Inverted River and Its Origin in Palaeo-karst Drainage Basin of Ordovician in Block 4, Tahe Oilfield

Because of structure movement, lithology diversity, morphologic prominence, etc, river system capture usually appears in modern karst drainage basin, accompanied by a series of peculiar hydrogeomorphic phenomenon like divide move- damage, capturing elbow, wind gap, beheaded river and inverted river, etc. Based on 3D seismic data, by applying flattening, accurate coherence analysis and seismic imaging, the karst palaeogeomorphology and palaeodrainage pattern are described and recognized, where the peculiar hydrogeomorphic phenomenon is discovered. In the light of the theory on modern river system capture, it had been south-confluence structure in the east of Block 4, Tahe Oilfield. Then, the base level of erosion had declined in the northwest, and the north border of south-confluence drainage basin was captured by underground way, so the inverted river was built-up. The evolutionary process of karst palaeodrainage pattern and drainage basin were reappeared, supplying a significant foundation for revealing Ordovician palaeo-karst built-up regular pattern for Tahe Oilfield.