准噶尔盆地南缘东段侏罗系头屯河组储层特征及物性控制因素

准噶尔盆地南缘（准南）下组合（侏罗—白垩系）油气资源丰富，其中准南东段侏罗系头屯河组是下组合重要的储层发育层位之一，但目前有关其储层特征及物性控制因素尚未有系统研究。综合利用取心井的钻测井、镜下薄片、扫描电镜、物性、压汞测试、镜质体反射率等资料，并结合区域地质背景及地层条件，对头屯河组储层基本特征、成岩演化及物性控制因素等进行了系统研究。准南东段头屯河组储层沉积水动力条件较强，储层内部杂基含量较低，整体具有低成分成熟度、高塑性岩屑含量及中等结构成熟度的岩石学特征；储层储集空间以粒间孔为主，平均孔隙度为11.6%，平均渗透率为5.7×10-3 μm2，整体属低孔低渗—中孔中渗储层，孔喉结构以中孔—大孔、粗喉道为特征，且孔喉分选相对较好；储层成岩作用以压实、胶结和溶蚀作用为主，但胶结物含量较低，溶蚀作用表现为酸性溶蚀，且储层整体成岩程度较低，主体处于早成岩A-B期，仅部分达到中成岩A期。头屯河组储层以压实减孔最为显著，并包含构造压实和埋藏压实两方面，此外碳酸盐及黏土矿物胶结使得储层物性进一步损失。尽管溶蚀增孔作用相对有限，但目前由于储层已开始进入中成岩阶段，地层酸性流体在深层将增强，使得溶蚀孔隙增加；早期缓慢埋藏—后期快速深埋和快速抬升的埋藏方式，加之地层超压的出现和地温梯度的持续降低，使得头屯河组储层物性得到有效保存。 

Reservoir characteristics and controlling factors of physical properties of Jurassic Toutunhe Formation in the eastern segment of the southern margin of Junggar Basin

The lower assemblage (from Jurassic to Cretaceous) on the southern margin of Junggar Basin is rich in oil and gas resources, and the Jurassic Toutunhe Formation in the eastern segment is an important horizon for reservoir development. However, no systematic study has been accomplished for its reservoir characteristics and controlling factors of physical properties. Based on the drilling and logging, microscopic observation of thin section, scanning electron microscopic observation, physical property and mercury injection test, vitrinite reflectance (R_o%) and other data including coring wells, combined with regional geological background and stratigraphic conditions, it was analyzed in this paper for the basic characteristics, diagenetic evolution and controlling factors of physical properties of Toutunhe Formation. The sedimentary hydrodynamic conditions of the Toutunhe Formation in the eastern segment of the southern Junggar Basin are relatively stronger, which makes the content of matrix inside the reservoirs relatively lower. It has the petrologic characteristics of low compositional maturity, high plastic debris content and medium structural maturity. The reservoir space is dominated by inter-granular pores, with an average porosity of 11.6% and an average permeability of 5.7×10-3 μm2. The whole reservoir belongs to low-porosity and low-permeability or medium-porosity and medium-permeability reservoir. Medium and large pores and coarse throats are dominant, relatively well sorted. Reservoir diagenesis is dominated by compaction, cementation and dissolution, but the content of cement is low. The dissolution effect is mainly acidic dissolution. The overall diagenesis degree of the reservoir is low, mainly in the early diagenetic stage A-B with some in the middle diagenetic stage A. Compaction effect, including both structural and burial ones, lead to the decrease of porosity in the Toutunhe Formation. In addition, the cementation of carbonate and clay minerals further reduces the physical properties of the reservoir. Although the effect of dissolution for porosity enhancement is relatively limited, the reservoir has begun to enter the middle diagenetic stage, the effect of formation acid fluid will strengthen in the deep layer, which will increase dissolution porosity. Due to the slow burial in the early stage, rapid deep burial and rapid uplift in the later stage, combined with the occurrence of formation overpressure and the continuous reduction of geothermal gradient, the physical properties of the Toutunhe Formation have been effectively preserved.