新疆准噶尔盆地西北缘克拉玛依−乌尔禾断裂带推覆体上盘构造样式及影响因素

    Structural patterns and influencing factors of the upper wall of the nappe in the Karamay-Wuerhe fault zone, northwestern Junggar Basin

    • 摘要: 准噶尔盆地西北缘克拉玛依−乌尔禾断裂带(克−乌断裂带)及其周缘发现了大量的油气藏,尤其是推覆体上盘伴随着勘探程度及地质认识不断深化,已呈现出“百里油区”的态势。然而,受多期构造活动及断裂带内部复杂的岩性组合影响,石炭系内幕地层构造样式展现出多种类型及复杂的空间展布样式,因此需要对构造样式及成因进一步探讨。综合地震和钻井资料,结合区域构造格局,梳理了准噶尔盆地西北缘克−乌断裂带上盘构造变形特征与影响因素;根据构造样式与推覆体内的岩性组合类型,将克−乌断裂带推覆体上盘划分出南段、中段和北段3个变形单元;明确了上盘石炭系5期主要构造阶段,分段恢复了推覆体上盘构造演化期次及样式。综合上述研究,认为克−乌断裂带上、下盘原始岩性组合关系是造成上盘石炭系内幕地层原始形变差异的主要因素,上盘石炭系内幕地层岩性组合差异是造成原生构造保存的主要因素。上述因素共同造成了圈闭条件沿克−乌断裂带自南向北变化。该研究为克−乌断裂带上盘油气勘探提供指导,同时也为类似条件地区的油气勘探提供借鉴。

       

      Abstract: Many oil and gas reservoirs have been discovered in the Karamay-Wuerhe (Ke-Wu) fault zone and its periphery in the northwestern margin of Junggar Basin. With the deepening of exploration level and geological understanding, the upper wall of nappe has already presented a situation of "Baili Oildom". However, due to the influence of multi-period tectonic activities and complex lithological assemblages inside the fault zone, the structural patterns show various types and complex spatial distribution patterns. Therefore, it is necessary to further explore the structural patterns and genesis. Based on seismic data, drilling data and regional tectonic framework, this study summarizes the structural deformation characteristics and influencing factors of the upper wall of the Ke-Wu fault zone in the northwestern margin of the Junggar Basin; the upper wall of the nappe of the Ke-Wu fault zone is divided into three deformation units: namely southern, central and northern segments; the five main tectonic stages of the Carboniferous strata on the upper side are clarified, and the stages and styles of tectonic evolution have been restored. In summary, the main factor for the difference in the original deformation of the Carboniferous inner strata is the original lithological assemblage relationship. And the difference of the lithologic assemblage in the upper wall is the main factor for the preservation of the original structure. The above factors together result in different trap conditions from south to north along the Ke-Wu fault zone. This study has guidance for future hydrocarbon exploration of the upper wall of the Ke-Wu fault zone and other similar areas.

       

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