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统计鄂尔多斯盆地上古生界90余口钻井140多个含气层位压力测试数据,通过压力系数频数统计综合分析研究区上古生界不同含气层段的压力分布特征。研究表明:上古生界天然气藏压力随层位变浅而降低,同一气层体系内部由南向北压力逐渐降低。结合烃源岩演化、天然气组分对比、成藏与构造运动的时间耦合关系,综合分析认为:原生气藏于早白垩末期形成,烃供应不足初步造成两区块压力南北分异;q5次生气藏于晚白垩世形成,构造运动使神木地区原生气藏垂向泄露形成q5超低压次生气藏,也导致了气藏后期的调整逸散,进一步扩大了其与米脂地区原生气藏的压力差。
More than 140 pressure test data of more than 90 gas reservoirs in the Upper Paleozoic of the Ordos Basin were calculated. The pressure distribution characteristics of different gas-bearing intervals in the Upper Paleozoic of the study area were comprehensively analyzed by means of frequency coefficient statistics. The research shows that the pressure of the Upper Paleozoic natural gas reservoir decreases with the shallowing of the horizon, and the pressure in the same gas field gradually decreases from south to north. Based on the time coupling of hydrocarbon source rock evolution, natural gas composition, and hydrocarbon accumulation and tectonic movement, we conclude that: the primary gas pool formed at the end of Early Cretaceous, and the insufficient hydrocarbon supply initially caused the north-south pressure difference between the two blocks; During the Late Cretaceous, the tectonic movement led to the vertical leakage of primary gas reservoirs in the Shenmu area to form q5 ultra-low pressure secondary gas reservoirs, which also led to the adjustment and dissipation of gas reservoirs in the later period and further expanded the pressure on the primary gas reservoirs in the Mizhi area difference.