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塔里木盆地古城低凸起在下奥陶统鹰山组下段白云岩储层中发现重要的油气资源,而断裂作为油气运移的通道,起着重要的作用。通过对古城低凸起三维地震资料的精细解析,结合主要界面的最大负曲率属性分析,对主要断裂带的剖面特征、平面特征、活动期次、成因机制及对油气成藏的影响进行了详细研究。结果表明,古城低凸起在剖面上主要发育负花状构造和平行高陡断裂2种构造样式;平面上主要发育NW向、NE向和NNE向共3个方向的断裂。结合对不整合面、生长指数和上覆地层的变形特征等综合分析,厘定出断裂的活动主要有3期,包括加里东早期(中寒武世)、加里东中期(晚奥陶世早期)和加里东晚期—海西早期(志留纪—泥盆纪)。加里东中期发育的张扭断裂,主要受控于先存基底薄弱带和阿尔金山北缘发育的沟—弧—盆构造体系的影响;加里东晚期—海西早期发育的张扭断裂是在加里东中期的拉张断裂的基础上继承发育的,受控于右旋走滑的古城北断裂和左旋走滑的车尔臣断裂。断裂的发育对古城低凸起的油气成藏有着重要的作用,主要表现在2个方面:断裂作为重要的油气通道,控制油气垂向运移;断裂也是热液流体的通道,利于白云岩化,改善储层物性。
The low relief of the ancient city in the Tarim Basin found important oil and gas resources in dolomite reservoirs in the lower part of the Lower Yingshan Formation of the Lower Ordovician, and the fault plays an important role as a passage for oil and gas migration. Based on the detailed analysis of the low-relief 3D seismic data in the ancient city and the analysis of the maximum negative curvature of the main interface, the authors have detailedly analyzed the profile features, planar features, active periods, genesis mechanisms and the impact on hydrocarbon accumulation in the major fault zones the study. The results show that there are two tectonic styles of the low relief in the ancient city: negative-shaped structures and parallel high-steep faults in the profile; mainly three directions of NW, NE and NNE are developed on the plane. According to the comprehensive analysis of the unconformity, the growth index and the deformation characteristics of the overlying strata, there are mainly three phases of faults, including Caledonian (Middle Cambrian), Caledonian (Late Ordovician) And late Caledonian-Early Hercynian (Silurian-Devonian). Tension and torsional rupture developed during the Caledonian mid-term was mainly controlled by the pre-existing basal weak zone and the groove-arc-basin tectonic system developed on the northern edge of the Altun Mountains. In the Caledonian-Early Hercynian, Inherited and developed on the basis of the eastern-middle stretch-breaking faults, they are controlled by the ancient north fault of the right-lateral strike-slip and the Che’erchen fault of the left-lateral strike-slip. The development of faults plays an important role in the formation of low-salient hydrocarbon accumulation in the ancient city, mainly in two aspects: the fracture is an important oil and gas channel and controls the vertical migration of oil and gas; and the fracture is also the passage of hydrothermal fluids, which is favorable to the dolomitization , Improve reservoir physical properties.