【作者】 邱登峰；

【导师】 毛小平；

【作者基本信息】 中国地质大学（北京） ， 油气田开发工程， 2009， 硕士

【摘要】 构造应力场是影响油气运移、聚集乃至保存和破坏的重要因素之一,不仅形成了油气运移的通道与油气聚集的圈闭,不连续状态的瞬间构造应力和连续状态的长期构造应力还为油气运移提供了驱动力。本文针对塔中隆起断裂特征及其演化史,以中下奥陶统灰岩为主要研究对象,应用大型有限元分析软件ANSYS运用接触算法模拟了中晚奥陶世、泥盆纪、三叠纪、新近纪的构造应力场,研究该区的应力分布特征,并应用到裂缝预测和油气运聚中来。对应于三期裂缝,塔中地区与裂缝形成和油气成藏有重要影响的四次构造运动为加里东晚期运动、海西早期运动、印支运动和喜山运动。将塔中隆起的构造演化史划分为四个阶段。通过对研究区内主要断裂构造解析,认为塔中隆起具有垂向分层、南北分带、东西分段的构造格局。在构造解析的基础上,建立了与四期构造运动对应的四个不同时代的地质模型,在不同时期,施加不同的边界条件。塔中地区发育的多期次断裂构造,对构造应力场有很强的扰动作用,通过反复试算,认为用接触算法能够较好地模拟断层的动力学特征,塔中地区多条断裂呈现压扭-走滑性质,采取减小摩擦系数、减小法向刚度、增大切向刚度、增大最大允许穿透值的方式来表现走滑断层。模拟过程中,首次将盆模软件TSM、建模软件Autocad与大型有限元分析软件Ansys结合起来,实现了三者之间的矢量信息转换。对中下奥陶统碳酸盐岩四个不同时代的构造应力场模拟结果显示,主压应力场受东部车尔臣—星星峡走滑断裂影响显著,在隆起区沿断裂带呈条带状低值分布,在不同时期塔中Ⅰ号断裂带无一例外地都位于主压应力场的最低区,反映了塔中断裂带尤其是塔中Ⅰ号断裂带是油气运移的有利指向区。主拉应力场沿断裂带呈条带状高值分布,在断裂的上盘是拉应力高值区,易形成张裂缝,在断裂走向发生变化和断裂的倾末端也是拉应力高值区,是张裂缝发育的重要构造部位。主拉应力场和剪应力场受车尔臣—星星峡走滑断裂的影响明显减弱。在模拟结果分析的基础上,预测油气运移的有利区带为塔中隆起北斜坡的塔中Ⅰ号断裂带,预测裂缝发育的有利区带为塔中Ⅰ号断裂带东段、塔中26井区、塔中45井区以及塔中2号断裂带倾末端与塔中5-48井断裂带交汇处。更多还原

【Abstract】 Tectonic stress field is one of the important factors which affect the oil and gas migration, accumulation, preservation and destruction. Moreover, tectonic stress field can form the channel of hydrocarbon migration and the trap of hydrocarbon accumulation. Instantaneous tectonic stress of discontinuous state and long-term tectonic stress of continuous state can also provide hydrocarbon migration with a driving force. In this paper, according to fracture characteristics of Tazhong uplift and its evolution, with middle-lower Ordovician limestone as main study object, large-scale finite element analysis software (ANSYS) was applied to simulate tectonic stress field of Late Ordovician, Devonian, Triassic and Neogene by contact algorithm. The research on the stress distribution characteristics of Tazhong area can apply to crack prediction and hydrocarbon migration and accumulation.Corresponding to the three phase crack, four tectonic movements-the late Caledonian movement, the early Hercynian movement, Indo-Chinese Movement and Himalayan Movement-seriously affected hydrocarbon formation and accumulation in Tazhong area. The tectonic evolution history of Tazhong uplift is divided into four stages. By analysis of the main fault structure in Tazhong area, Tazhong uplift has three structure situations including vertical stratification, north-south sub-zone and east-west subsection.On the base of structural analysis, four geological models in four different periods were established corresponding to four tectonic movements, and different boundary conditions were imposed according to different periods. Multi-stages fault structure of Tazhong area disturbed tectonic stress field strongly. By contrast and repeated calculation, the contact algorithm can simulate the dynamic characteristics of faults preferably. Due to multi-fraction have the character of pressure-twisting and strike-slip, reducing friction coefficient and normal stiffness, and increasing tangential stiffness and maximum value of allowable penetration were used to represent strike-slip faults. In the process of simulation, basin-model software TSM, modeling software AutoCAD and large-scale finite element analysis software Ansys were firstly combined to use and made a progress in conversion of vector information during three software.By simulating tectonic stress field of middle-lower Ordovician carbonate rocks in four different periods, principal compressive stress field, which was affected markedly by the eastern strike-slip fault named Cherchen-xingxingxia, presented strip-shape and low-value distribution along fault zone in uplift area. Tazhong 1st fault in different periods were all at the minimum value area of main press stress field, which reflected Tazhong fault zone, especially the 1st fault was a well directed area for hydrocarbon migration. The main tensile stress field was banded distribution of high-value along fault zone. The hanging wall of fault was the high-value area of tensile stress and easy to form a tensile crack. The change area of fracture trend and trip fracture were also the high-value area of tensile stress and important structure area developing tensile crack. The affection on main tensile stress and shear stress field was weakened from Cherchen-xingxingxia strike-slip fault.Based on the analysis of simulation, the favorable area of hydrocarbon migration was the 1st fracture in Tazhong uplift, while the favorable areas of crack developing were the east of 1st fault, Tazhong 26 well area, Tazhong 45 well area and the junction by the 2nd trip fault and Tazhong 5-48 well faults.更多还原