Abstract The Baxian Sag is a mature exploration area. The exploitation of deep sedimentary formation is becoming increasingly important as the further development potential of shallow plays faces growing challenges. The discovery of the Niudong gas-condensate field from deep Precambrian reservoirs indicates that potentially significant hydrocarbon resources remain to be discovered in deeper stratigraphic units. This study was undertaken to better understand the generation and accumulation of hydrocarbons in deep reservoirs through integrated petroleum geochemistry, fluid inclusion analysis and source rock analysis. Geochemical parameters of condensate and gas suggest that condensate and gas in Precambrian reservoir have similar thermal maturity, and are directly derived from gas-prone source rock at high maturity levels. The regional structure section and hydrocarbon distribution indicate that gas-condensate in the ND1 well is more likely derived from lacustrine source rock in the Paleogene Shahejie Formation. Refined source kitchen analysis indicates that lacustrine source rocks in the Shahejie Formation display a high degree of heterogeneity, including organo-facies C, D/E and F. Differences in the nature and composition of the expelled petroleum exist between organo-facies due to variations in kerogen composition. The orderly spatial distributions of gas/oil ratio (GOR), API gravity and gas carbon isotopes denote that the various fronts expelled hydrocarbons at different maturity levels from different organo-facies. This reflects the dynamic scenario of petroleum migration and accumulation from kitchen to shallow reservoirs. The Precambrian reservoir in ND1 well has experienced multiple-charging with hydrocarbon expulsion at different maturity levels. While hydrocarbons of lower maturity have arrived into the shallower reservoirs, condensate and gas expelled at high maturation levels have efficiently accumulated in deeper prospects.

中文翻译：

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渤海湾盆地霸县凹陷前寒武系深层油气成藏

摘要 八县凹陷是一个成熟的勘探区。随着浅层油藏的进一步开发潜力面临越来越大的挑战，深层沉积地层的开发变得越来越重要。前寒武系深部储层牛东凝析气田的发现表明，在更深的地层单元中仍有潜在的重要油气资源有待发现。本研究旨在通过综合石油地球化学、流体包裹体分析和烃源岩分析，更好地了解深层油气藏的生成和聚集。凝析气和凝析气地球化学参数表明前寒武系储层中凝析气和天然气具有相似的热成熟度，并且直接来源于高成熟度的气源岩。区域构造剖面及油气分布表明ND1井凝析气更可能来源于古近系沙河街组湖相烃源岩。精细烃源厨房分析表明，沙河街组湖相烃源岩具有高度非均质性，包括有机相C、D/E和F。不同有机相之间存在不同性质和组成的差异在干酪根成分中。气油比（GOR）、API 重力和气碳同位素的有序空间分布表明，各个锋面从不同有机相排出了不同成熟度水平的油气。这反映了石油从厨房到浅层油藏的运移和聚集的动态情景。ND1井前寒武系储层经历了不同成熟度的多次充注和排烃。虽然较低成熟度的碳氢化合物已经到达较浅的储层，但在较高成熟度下排出的凝析油和天然气已有效地积聚在更深的远景中。