对比千米桥潜山异常高温气藏产水特征及封闭条件下汽、水相态模拟实验结果,分析鄂尔多斯盆地上古生界气藏形成过程和形成条件.镜质体反射率、磷灰石裂变径迹、包裹体均一温度测定表明,晚侏罗世—早白垩世鄂尔多斯盆地上古生界具有异常高的古地温场.异常高温促使煤系有机质快速熟化、生成大量天然气,同时地层水汽化,天然气与蒸汽互溶并逐渐积累产生异常高压；气(汽)相流体在异常高压推动下向封存箱内的上部地层扩散运移,降低下部异常高温地层的压力,加速地层水汽化并重新积聚压力,如此循环反复,气(汽)相流体逐渐渗透到封存箱的各个部位,封存箱内温度、压力趋于平衡,从而形成盆地级的高温高压气藏.晚白垩世—古近纪的抬升剥蚀导致上古生界温度、压力下降,蒸汽液化使气藏中的蒸汽和天然气浓度降低,从而形成了盆地级的低压气藏.%The forming process and conditions of Upper Paleozoic gas reservoir in Ordos Basin was analyzed by comparing the water producing characteristics of abnormally high temperature gas reservoir in the Qianmiqiao buried hill with the simulated experiment results of gas/water phases under sealed conditions. The test results of vitrinite reflectance, apatite fission track and inclusion homogenization temperature indicate that the Upper Paleozoic in the Ordos Basin had an abnormally high geothermal field during the Late Jurassic to Early Cretaceous. Driven by the abnormally high temperature, the organic matter matured rapidly to generate a lot of natural gas; meanwhile, the formation water vaporized, with intersoluble gas and vapor to accumulate and generate abnormally high pressure. The gas (vapor) phase fluid migrated towards the upper formation within the compartment under abnormally high pressure, which lowered the pressure in the lower abnormally high temperature formation, sped up the vaporization of formation water and resulted in the accumulation of pressure for a new round of migration. In this circular way, the gas (vapor) phase fluid diffused to every part of the compartment, with inner temperature and pressure being balanced. The high temperature and high pressure gas reservoir at basin level was formed. The uplift and erosion during the Late Cretaceous-Paleogene led to the drop of the temperature and pressure of the Upper Paleozoic. The liquefaction of vapor lowered the vapor and gas concentration. Thus the basin level low-pressure gas reservoir was formed.
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