塔北隆起南坡差异构造演化及其对油气成藏的控制

Differential Tectonic Evolution and Its Controlling on Hydrocarbon Accumulation in the South Slope of Tabei Uplift

塔北南坡构造演化具有阶段性和横向差异性,是该区油气在纵向上和平面上不均衡富集的主控因素。通过研究其内部各次级单元构造演化的时空差异,结合油源、储盖组合等油气地质条件,探讨了塔北南坡差异构造演化对三大油气成藏组合的控制作用。对于下古生界碳酸盐岩成藏组合,古构造格局决定了油气来源和运聚方向,储盖组合差异性则与碳酸盐岩多期次的抬升剥蚀和岩溶作用有关,阿克库勒、英买力和哈拉哈塘等地区成藏条件优越。构造活动对古生界海(陆)相碎屑岩成藏组合的控制作用体现在:差异抬升剥蚀限制了有利储层的分布范围和厚度,并影响其储集性能;而圈闭特征和保存条件决定了油气充注成藏的规模,如东河塘背斜圈闭,经历2期大规模油气充注。油源和断裂、输导砂体等运移条件是影响中—新生界陆相碎屑岩成藏组合差异性的主要因素,阿克库勒地区通源断裂—砂体输导体系下的运移效率较高。

The evolution of the south slope of Tabei Uplift was characterized by multiple epochs and hori- zontal differentiation, which determines vertically and laterally imbalances of hydrocarbon distribution. Based on an integrated analysis,temporal and spatial variation of sub-structural units and geological condi- tions as hydrocarbon source rocks and reservoir-cap assemblages, this paper discussed the controlling fac- tors of differential evolution on hydrocarbon accumulation of three petroleum bearing groups in the South Slope of Tabei Uplift. For the Lower-Paleozoic carbonates petroleum-bearing group, tectonic location and concave-convex structure determine oil source and migration direction respectively, and diversity of reser- voir-cap assemblages is related to multi-stage of uplifting, erosion and karstification. Akekule, Yingmaili and Halahatang have superior hydrocarbon accumulation condition and great geological configuration. For the Paleozoic petroleum-bearing clastic rock group,diverse uplift and denudation limit the distribution and thickness of favorable reservoir, and also affect their reservoir performance. Trap characteristics determine the size of the oil and gas infilling, for anticlinal trap of Donghetang Oilfield have experienced two oil and gas charging stages. Oil source and migration conditions such as fault and sand are the major factors which influence lateral imbalance of the Mesozoic-Cenozoic petroleum-bearing clastic rock group. Oil and gas of Akekule and Halahatang mainly come from the underlying Palaeozoic marine oil-bearing series,with a high migration efficiency of source rock-rooted faults and sandbody.