致密砂岩微观孔隙特征评价是致密油气地质评价的核心研究工作。基于恒速压汞、铸体薄片、X-射线衍射等测试分析,对吐哈盆地水西沟群致密砂岩开展微观孔隙特征评价工作。研究表明:靶区致密储层岩石类型以岩屑长石砂岩和长石岩屑砂岩为主,不稳定矿物含量高是导致微观孔隙结构复杂的主要原因;致密储层的物性与矿物组成有密切关系,石英由于其脆性而易形成微裂缝,对储层的渗透率贡献明显,对孔隙度影响不大;黏土矿物由于其可塑性及遇水膨胀的特性,对孔隙度和渗透率影响明显,均呈负相关;长石由于其不稳定性,在溶蚀作用下形成高岭石,但在致密储层复杂孔喉体系的背景下,流体的迂回程度高,造成高岭石多在原地沉淀,堵塞孔隙和喉道,与孔渗存在明显的负相关;基于毛管压力曲线,可把致密储层的孔喉结构划为3类,分别为粗喉道所控制的高孔区、中喉道控制的中孔区和细喉道控制的低孔区;同常规储层相比,致密储层具有排替压力高、进汞饱和度低、喉道半径小、孔喉比高、结构系数高等特点。该评价方法和思路,为吐哈盆地,乃至我国其他盆地的致密油气勘探提供科学依据。 The microscopic pore characterization of tight sandstone is the core research work of the tight oil and gas geological evaluation. Based on the testing and analysis of constant velocity mercury injection, thin cast film and X-ray diffraction, the micro-pore characteristics of tight sandstone of Shuixigou Group in Turpan-Hami Basin were evaluated. The results show that the rock type of the tight reservoir in the target area is mainly feldspar feldspathic sandstone and feldspathic lithic sandstone, and the high content of unstable minerals is the main reason leading to the complex microscopic pore structure. The physical properties and the mineral composition of the tight reservoirs are close Because of its brittleness and susceptible to the formation of microcracks, which contribute significantly to the permeability of the reservoir and have little effect on the porosity. Due to its plasticity and water swelling properties, clay minerals have obvious effects on porosity and permeability The feldspar formed kaolinite under the action of dissolution due to its instability. However, in the background of complex pore-throats in tight reservoirs, the degree of bypassing of fluid is high, resulting in the precipitation and clogging of kaolinite in situ The pores and throats are significantly negatively correlated with pore infiltration. Based on the capillary pressure curve, the pore-throat structures of tight reservoirs can be divided into three types, namely the high-pore area controlled by the coarse throat, the middle throat controlled Mesoporous area and fine throat control. Compared with conventional reservoirs, tight reservoirs are characterized by high displacement pressure, low mercury saturation, small throat radius, high pore-to-throat ratio and high structural coefficient. The evaluation method and ideas provide a scientific basis for the tight oil and gas exploration in the Turpan-Hami Basin and other basins in China.