鄂尔多斯盆地姬塬油田长6致密砂岩储层成因机理

鄂尔多斯盆地姬塬油田长6储层原油储量丰富，储层致密制约着油气的勘探开发潜力和评价精度.通过开展物性、粒度、铸体薄片、X衍射、扫描电镜、压汞等测试研究储层特征，以时间为主轴，综合成岩史、埋藏史、地热史、构造等因素，采用“成岩作用模拟”和“地质效应模拟”构建孔隙度演化模型及计算方法探讨致密储层成因机理.结果表明:储层经过较强的演化改造发育微-纳米孔喉系统，形成低孔特低孔-超低渗的致密砂岩储层.H53井长6段孔隙度演化史揭示了增孔和减孔因素对孔隙度及油气充注的影响；通过对比最大粒间孔面孔率、最大溶蚀面孔率、最大压实率、最大胶结率样品孔隙度演化路径和含油饱和度，查明了致密储层成因的差异及品质. 

Formation Mechanism of Chang 6 Tight Sandstone Reservoir in Jiyuan Oilfield,Ordos Basin

In order to further study the occurrence state and origin of geothermal resources in Guide basin, the hydrochemistry, hydrogen and oxygen isotope data from the study area are collected to analyze the geochemical properties and evolution of geothermal water and to calculate the geothermal reservoir temperature of high-temperature field. Hydrochemistry analysis of geothermal fluids show that the high-temperature thermal water is mainly of SO₄·Cl-Na type, and the low-temperature thermal water is mainly of SO₄-Na、SO₄·HCO₃-Na. There is a positive correlation between Li, F, Sr, As and Cl in Zhacangsi thermal field, which indicates the possible same origin, and the positive correlation between SiO₂ and Cl confirms the deep hot source of geothermal resources. The δD values range from-59‰ to-87‰, the δ18O values range from-8.6‰ to 12.2‰, and they are all distributed near the local meteoric water line, which suggests the thermal water in study area is recharged from the atmospheric precipitation mainly. The temperature and depths of geothermal reservoir of Zhacangsi thermal field are calculated using reasonable geothermometers. The Na-K-Mg equilibrium diagram reflects that the cold water mixing action occurred in Zhacangsi thermal field during the hot water rising process, the cold water mix proportions and the geothermal reservoir temperature before the cold water mixed are obtained using Si-enthalpy model. The geothermal reservoir temperature of Zhacangsi thermal field is about 133 ℃ calculated by multi mineral balance method and geothermometers, which is close to the shallow reservoir temperature, the depth of the thermal cycle is about 1 800 m; while the geothermal reservoir average temperature of Zhacangsi geothermal field is 222 ℃ before the cold water mixed and the cold water in geothermal fluid mixed with 60%-68% analyzed by Si-enthalpy model, which is close to the deep geothermal reservoir temperature, the depth of the thermal cycle is about 3 200 m. It is concluded that there are two geothermal reservoirs in Zhacangsi thermal field within the depth of 4 000 m This paper can facilitate further study of genetical mechanism of the high-temperature geothermal systems and provide guidance for exploration and drilling in the area.