吐哈盆地北部凹陷低渗透砂岩储层发育有4组高角度裂缝和一组近水平裂缝。高角度裂缝主要为构造成因的剪切裂缝，低角度裂缝包括成岩裂缝、顺层滑脱裂缝和近水平剪切裂缝3类。裂缝的发育程度受岩性、岩层厚度、构造部位等因素的控制。裂缝是低渗透储层的主要渗流通道，是控制其油气产能高低的主要因素。通过地质和数值模拟研究，该区NE和NW向高角度裂缝为在燕山早期近SN向水平挤压作用下形成的共轭剪切裂缝，近EW向高角度裂缝和近水平剪切裂缝为燕山晚期近SN向逆冲推覆作用下形成的共轭剪切裂缝，近SN向裂缝主要与晚期的近SN向不均匀挤压作用有关。

为了研究鄂尔多斯盆地上三叠统延长组特低渗透砂岩储层裂缝对开发的影响，利用地表露头、岩心、薄片、测井和实验等资料，对裂缝的成因类型、分布特征及其控制因素进行了分布，并对裂缝的渗流作用进行了讨论。研究区主要发育高角度构造裂缝以及水平层理缝、粒内缝和粒缘缝等成岩裂缝，粒内缝和粒缘缝是沟通储层基质粒间孔和粒内溶孔的重要通道，使特低渗透砂岩储层孔隙的连通性变好。裂缝的形成与分布受古构造应力场以及储层岩性、岩层厚度和岩层非均质性等内外因素的影响，现今应力场影响裂缝的保存状态与渗流作用. 在燕山期和喜马拉雅期构造作用下，该区分布有北东向、北西向、近东西向和近南北向4 组裂缝，但由于岩层非均质性的影响，在某一部位主要表现为两组近正交的裂缝分布型式。受现今应力场的影响，北东向裂缝的连通性好，张开度大，渗透率最高，开启压力最小，是该区的主渗流裂缝方向。随着油田开发，不同方向裂缝的渗透性还将发生动态变化。

为了探讨在平面上的岩层非均质性对不同方位裂缝发育的影响，以鄂尔多斯盆地上三叠统延长组特低渗透砂岩储层为例，进行了岩石单轴和三轴岩石力学试验及岩石声发射试验，结果证实在平面上不同方向岩石力学性质各向异性的存在，它们是影响该区不同时期不同组系裂缝发育差异的主要原因，岩层非均质性往往抑制了共轭剪切破裂中的一组裂缝的发育，鄂尔多斯盆地延长组主要为在2其裂缝。

The formation and distribution of fractures are controlled by paleotectonic stress field, and their preservative status and effects on development are dominated by the modern stress field. Since Triassic, it has experienced four tectonic movements and developed four sets of tectonic fractures in the extra low-permeability sandstone reservoir at the south of western Sichuan depression. The strikes of fractures are in the S-N, NE-SW, E-W, and NW-SE directions respectively. At the end of Triassic, under the horizontal compression tectonic stress field, for which the maximum principal stress direction was NW-SE, the fractures were well developed near the S-N faults and at the end of NE-SW faults, because of their stress concentration. At the end of Cretaceous, in the horizontal compression stress fields of the NE-SW direction, the stress was obviously lower near the NE-SW faults, thus, fractures mainly developed near the S-N faults. At the end of Neogene-Early Pleistocene, under the horizontal compression tectonic stress fields of E-W direction, stress concentrated near the NE-SW faults and fractures developed at these places, especially at the end of the NE-SE faults, the cross positions of NE-SW, and S-N faults. Therefore, fractures developed mostly near S-N faults and NE-SW faults. At the cross positions of the above two sets of faults, the degree of development of the fractures was the highest. Under the modern stress field of the NW-SE direction, the NW-SE fractures were mainly the seepage ones with tensional state, the best connectivity, the widest aperture, the highest permeability, and the minimum opening pressure.

由于缺少应力标志，沉积盆地覆盖区的古构造应力场定量恢复一直是个难题。为子探讨石磁化率各向异性在恢复沉积盆地古构造应力场的最大主应力方向方面的可行性，首先对岩石缓慢加压变形前后的磁化率各向异性的变变化进行了实验研究，受力以后岩石的磁化率各向异性参数H，P，q值都相应增大，最大和最小磁化率轴产状也有明显的变化，反映了浅层次的构造变形过程可对岩石磁组构产生明显的影响。然后，在塔里木盆地北部，将用最小磁化率主轴所求得的最大主压应力方位与用构造变形分析所求得的最大主压力方向进行了对比分析，二者结果基本一致。说明在构造变形较强的沉积覆盖区（Q1），用岩石的最小磁化率主轴方向来确定沉积盆地古构应力场的最大主压力方位是可行的。最后，还对该方法的适应范围和构造应力场的分期等相关问题进行了讨论。

低渗透储层中构造成因的裂缝包括剪切裂缝、扩张裂缝和拉张裂缝3种类型。剪切裂缝是在压应力作用下形成的，理论上以两组共轭剪切裂缝的形式出现，但岩层强烈的非均质性通常可以抑制其中一组发育，而只留下另一组。剪切裂缝以高角度缝为主，具有进入性分布特征。此外，还常见有两类低度角度剪切裂缝；一类为在泥质岩中发育的滑脱裂缝；另一类为在逆冲构造带中发育的近水平剪切裂缝。扩张裂缝和拉张裂缝都是垂直于最小主应力方向分布的，规模小，延伸短。但是扩张裂缝是在压力作用下形成的，因而常与剪切裂缝同时出现；而拉张裂缝的形成要求至少最小主应力是张应力，通常呈透镜状局部发育，并被沥青，方解石等脉体充填。除了岩层弯曲派生的拉张应力形成的纵张裂缝外，沉积盆地中拉张裂缝的形成通常有异常高压流体的参与，异常高压流体可以使逆冲构造带中的挤压力变为拉张应力，从而在挤压力环境中形成拉张裂缝。拉张裂缝是沉积盆地古异常高压流体存在和重要指示标志。

裂缝是低渗透储层流体流动的主要通道，控制了低渗透油气藏的渗流系统。低渗透储层裂缝的形成与流体密切相关，高流体压力引起岩石内部的有效正应力下降，导致岩石剪切破裂强度下降，使岩石容易产生裂缝。高孔隙流体压力还造成某一点的应力摩尔圆向左移动，可以使其最小主应力（Q3）由压应力状态变成拉张应力状态，从而在岩石中形成拉张裂缝。裂缝的渗透性受现今应力场的影响，通常与现今应力场最大主压应力近平行分布的裂缝呈拉张状态，连通性好，开度大，渗透率高，是主渗透裂缝方向。构造应力对沉积盆地流体流动的影响主要表现在三个方面：（1）构造应力导致的岩石变形，不仅提供了流体流动的通道，而且还改变了岩石的渗透性能；（2）在构造强烈活动时期，构造应力的快速变化是流体流动的重要驱动力；（3）岩石中应力状态影响多孔介质的有效应力，从而影响介质中的渗流场。当作用在合流体介质上的构造应力发生改变时，岩石孔隙体积变小，构造应力首先由岩石的骨架来承担；当岩石孔隙体积减小到一定程度时，构造应力由孔隙流体来承担，从而影响岩层渗流场的变化。

Through rock acoustic emission experiments and structural deformation analysis, the tectonic stages in Meso-Cenozoic in the Kuqa depression of the Tarim basin are firstly divided. Then, combining with rock magnetic fabric analysis and memory information, the distribution characteristics of tectonic stress field of every tectonic stage are quantificationally resumed. At the same time, according to the distribution relation of tectonic stress field of hydrocarbon formation stage by the finite element numerical simulation method and the known hydrocarbon reservoirs, the effects of tectonic stress field on hydrocarbon migration and accumulation are further analyzed. The Kuqa depression has mainly experienced six tectonic movements since Mesozoic. Except that the tectonic stress field of the Early Yanshan stage (208-135 Ma) showed northeast-southwest extensional stress field where the orientation of the maximum principal compressive stress (σ 1) was northwest-southeast, the others were compressive stress field where the orientations of the maximum principal compressive stress (σ 1) were near north-south. Along with the closure of the paleo-Tethys ocean, the Kuqa depression in the Indosinian stage (250-208 Ma) was in strong compressive circumstance with apparently big maximum principal stress (σ 1) magnitude. Due to the equilibrium adjustment of interior Eurasia, the Kuqa depression in the Early Yanshan stage (208-135 Ma) was in weak extensional circumstance with apparently small maximum principal stress (σ 1) magnitude. From the Late Yanshan stage (135-65 Ma) on, with a series of collision events occurring at the south edge of Eurasia, the Kuqa depression was in compressive circumstance again in which the maximum principal stress (σ 1) magnitude was from small to big in turn. The Late Himalayan stage (2.6-0.7 Ma) was the main tectonic deformation stage with the biggest principal compressive stress (σ 1) magnitude. Tectonic stress field plays a dominant role in hydrocarbon formation, it not only forms migration channels and trap structures for hydrocarbon accumulation, but also is the main drive power for hydrocarbon migration vertically along faults.

为了分析特低渗透砂岩储层高角度裂缝的压力敏感性特征，对鄂尔多斯盆地陇东地区延长组特低渗透砂岩储层基质岩样、含天然裂缝岩样和含人造裂缝岩样进行了对比实验。实验结果表明，特低渗透砂岩储层裂缝的压力敏感性十分明显，在无裂缝时基质岩块为中等程度敏感性，含裂缝时为压力敏感性。裂缝的开度越大，渗透率越高，其压力敏感性越强，裂缝渗透率的恢复程度越小。裂缝的压力敏感性特征对特低渗透砂岩油藏开发具有十分重要的意义。

根据构造变形解析和岩石记忆信息，库车前陆盆地的喜马拉雅运动可以划分为3期，它们对应的时间分别为渐新世末、上新世末和早更新世末，其构造挤压强度依次由弱变强，在喜马拉雅晚期达到高峰，是该区构造的主要变形期和定格期，也是该区异常高压形成和油气成藏的主要时期。中更新世以来为新构造运动阶段，主要表现为2-3次重要的抬升和相对较弱的褶皱逆冲变形，并对该区的油气藏主要起破坏作用。库车前陆盆地的构造变形从喜马拉雅早期开始发育，各构造带的发育时间从北往南依次由早变晚，它控制了该区断层相关褶皱、构造圈闭及其油气藏的带状分布规律。喜马拉雅晚期强烈的水平构造挤压是该区异常高压形成的主要因素，是该区油气形成分布的主要控制因素和驱动力，喜马拉雅运动对该区的油气藏有一定的破坏调整作用。