Guchengxu Uplift in which commercial oil and gas have been drilled out in Ordovician marine carbonate rocks in some wells in recent years has become one of the exploration focus areas in Tarim basin. Two series of Ordovician hydrocarbon-bearing reservoirs have b een confirmed to be present in Guchengxu Uplift, one is the limestone at the top of Ordovician Yijianfang Formation and the other is the limy dolostone of internal Ordovician Yingshan Formation. The hydrocarbon is present mostly in dry-gas state with normal pressure and high temperature in Ordovician reservoirs but exceptionally, light oil with low content of sulfur and wax which is characteristic of condensate oil are drilled out in the top of Yijianfang Formation in Well SN-1. Combined with the analysis of hydrocarbon property, biomarkers and hydrocarbon inclusion characteristics, it is suggested that two periods of hydrocarbon emplacement experienced in this uplift. Emplacing oil derived from the Cambrian to lower Ordovician source rocks in the first period of emplacement that occurred during the late Caledonian to Early Hercynian movements, and emplacing over-mature dry gas were dominated in the second period of emplacement that occurred during Himalayan movement. The following gas emplacement resulted in forming pure gas or condensate gas reservoirs. Different ranks of oil/gas shows are present in the drilled wells in Guchengxu Uplift, and specially all of oil and gas yielded are with no water. It is generally considered that high-quality carbonate reservoirs are the key for hydrocarbon accumulation and the developing NE-trending faults play an important role in hydrocarbon accumulation.%古城墟隆起奥陶系海相碳酸盐岩地层近年来相继发现了一些出油气井，已经成为塔里木盆地的重点勘探目标区。目前已证实古城墟隆起存在奥陶系一间房组顶部灰岩与鹰山组内幕灰质白云岩两套含油气层系。奥陶系主要为正常压力、高温的干气气藏，但顺南1井一间房组顶部的原油属低硫、低蜡轻质油，表现出典型的凝析油特征。综合油气性质、生物标志化合物特征及烃包裹体发育特征，认为该区主要存在两期油气充注过程：第一期油气充注发生在加里东晚期-海西早期，以来自寒武系-下奥陶统烃源岩的原油为主；第二期油气充注发生在喜马拉雅期，以寒武系过成熟的干气为主，气侵改造导致该区以纯气藏和凝析气藏为主。古城墟隆起已钻井均见到不同级别的油气显示，并且不含水，初步研究认为优质的碳酸盐岩储层是油气成藏的最关键因素，同时北东向断裂对油气成藏有重要影响。
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