塔里木盆地库车坳陷北部构造带地质结构与油气勘探领域

地质结构、构造演化及其与油气成藏的关系是制约塔里木盆地库车坳陷北部构造带油气勘探进程的重要因素.以地震剖面为基础,结合区域构造背景、露头地层特征以及钻井资料,对北部构造带3个构造段(吐格尔明、迪北吐孜、巴什)的地质结构进行了详细解剖,恢复了构造演化史,并分析了变形特征,最后在构造演化与油气成藏关系的基础上,讨论了北部构...

Geological structures and petroleum exploration fields of the northern tectonic belt in the Kuqa depression, Tarim basin

Geological structures, tectonic evolution and their relationships with hydrocarbon accumulation are significant factors that limit the hydrocarbon exploration of the northern tectonic belt in the Kuqa depression, Tarim basin. Based on seismic sections and combined with regional tectonic background, strata characteristic of outcrops and well drilling data, the geological structures, tectonic evolution and deformation features of three tectonic sections (i.e., the Tugerming, the Dibei- Tuzi and the Bashi sections) of the northern tectonic belt were systematically analyzed, and the potential exploration fields of the northern tectonic belt were discussed on the basis of relationship between tectonic evolution and hydrocarbon accumulation. The results show that the Tugerming section is an anticline controlled by a paleo- uplift and basement- involved faults. The Dibei- Tuzi and the Bashi sections both develop deep and shallow deformation systems, where the deep deformation system is a fold belt dominated by basement- involved thrust faults, and the shallow deformation system is a relatively simple fault- fold system. The tectonic activities of the Tugerming, the Dibei- Tuzi and the Bashi sections dated from the Cretaceous- early Paleogene, middle Neogene and late Neogene, respectively, and were all finalized in the Late Kuqa Period of Neogene- Quaternary. At the Jidike- Kangcun period of Neogene (23~5 Ma), the Dibei- Tuzi and the Tugerming sections developed paleo- oil reservoirs, while the Bashi section developed oil- bearing belts with large area and low abundance. At the Kuqa period of Neogene (5~2 Ma), early formed paleo- oil reservoirs were destroyed, but in some regions they were preserved, and in the meantime, some natural gas reservoirs or condensate gas reservoirs formed on various scales. In the Xiyu period of Quaternary (~2 Ma), previously formed gas reservoirs and residual paleo- oil reservoirs were massively adjusted and transformed, and the current accumulation pattern ultimately formed. The hydrocarbon exploration of the Tugerming section should keep away from the denuded area at the cores of anticlines. The north limb, south limb and west- east plunging crown develop fractured lithological oil- gas reservoirs, porous lithological oil- gas reservoirs and structural- lithological oil- gas reservoirs, respectively. The south Dibei slope of the Dibei- Tuzi section is a significant potential field for fractured tight sandstone oil- gas reservoir exploration, and the Yiqikelike oil field is an important practical field for the structural- lithological oil- gas reservoir exploration, while the Dibei- 2 well block and the Bashi- 1 monocline are the exploration fields with high risks. The Lower- Middle Jurassic of the Kelasu tectonic belt, to the south of Bashi section, can be considered as a reserve risk exploration field. The hydrocarbon exploration of the northern tectonic belt should give priority to Lower- Middle Jurassic, and consider shallow multi target formations to further broaden hydrocarbon exploration field.