准噶尔盆地坳陷湖盆坡折带在非构造圈闭勘探中的应用

Significance of slope break zones in downwarped lake basins to exploration of non-structural traps in Junggar basin

刘豪 王英民

Liu Hao Wang Yingmin

准噶尔盆地西北缘地区,多级坡折带十分发育,对层序地层发育、地层超覆叠置、岩性纵向组合以及沉积体的纵横向展布具有重要的控制作用。多级坡折带对非构造圈闭的控制主要表现为:非构造圈闭紧邻多级坡折带发育,沿着坡折带呈串珠状展布;非构造圈闭在纵向上发育具有继承性的特点;非构造圈闭发育的类型随着坡折带所处的地理位置的不同而不同,靠近盆缘的坡折带以形成地层超覆和削截为主的非构造圈闭,向盆地方向,地层圈闭逐渐减少,以地层-岩性圈闭或岩性圈闭为主。多级坡折带的存在导致了在盆地的不同地理位置发生不同的沉积剥蚀响应,控制了构造圈闭的储、盖组合。另外,断裂坡折带中的断裂及挠曲坡折带处发育的裂缝,成为油气运移的通道,有利于油气运聚。由于坡折带的深部构造往往是早期的有利聚油构造,因此坡折带又是深部构造中聚集的油气再次垂向运移分配的有利聚集场所。

Multistage slope break zones which are well developed on the northwestern edge of Junggar basin significantly control the development of sequence stratigraphy, overlapping and superimposition of strata, vertical lithologic combinations and vertical and lateral distribution of sediments. The control of multistage slope break zones on non-structural traps are mainly represented as follows:1) Non-structural traps are developed closely near the multistages slope break zones, and distributed in beaded occurrence along the slope break zones. 2) The development of non-structural traps is vertically characterized by their inheritance. 3) The types of non-structural traps vary with the geographical positions of the slope break zones. Non-structural traps would mainly be developed as stratigraphic overlaps and truncations in the slope break zone near basin edges, stratigraphic traps would gradually decrease basinward and then mainly become stratigraphic-lithologic or lithologic traps. The existence of multistage slope break zones would correspondingly lead to various erosions and depositions at different geographical positions in the basin, and control the combination of reservoirs and seals in non-structural traps. In addition, fractures developed in faulted slope break zones and fissures developed in flexural slope break zones would act as migration pathways, and would be favorable to hydrocarbon migration and accumulation. The structures deeply buried in the slope break zones would often be advantageous to hydrocarbon accumulation, thus the slope break zones would also be the favorable sites for accumulation of hydrocarbons that migrate vertically upward and redistribute from the earlier hydrocarbon accumulations at depth.

10.11743/ogg20040410