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油气化探在鄂尔多斯盆地北部上古生界天然气勘探开发中显示出良好的应用前景和较好的经济效益，化探方法对寻找气藏具有明显的指向作用。针对目前方法较多、没有系统理论认识的情况，作者通过对油气化探方法分析原理和应用实践进行系统分析研究，总结出如下认识：①酸解烃方法是目前在鄂尔多斯盆地北部寻找上古生界气藏的最有利方法，但应用时应排除土壤碳酸盐含量的干扰；②野外合理采样、室内注重层位、岩性等数据的校正，可最大限度的排除干扰因素的影响；③盆地北部的地球化学背景场与其特殊的地貌有着紧密联系，总体表现为北高南低形态；④化探异常形态最有利的是复合环状和环中环状，异常整体分布呈北东—南西向，与主要目的层的储层展布特征基本一致；⑤油气化探在鄂尔多斯盆地北部的实践结果证明，它对寻找上古生界气藏具有明显的指向作用和较高的成功率。

EVALUATION OF OIL AND GAS GEOCHEMICAL EXPLORATION METHODS USED FOR NORTH E’ERDUOSI BASIN

The oil and gas geochemical exploration has shown up a good application prospect and fair economic benefit in Upper Paleozoic gas exploration and development in North E’erduosi Basin because the geochemical exploration methods are of evidently guiding effect on surveying gas reservoirs in the basin. Owing to the fact that there are many methods but no systematical theories at present， through thoroughly analyzing and investigating the principles and application results， the authors summarize the following viewpoints：① the acidolysis hydrocarbon method is the mostfavourable method in surveying Upper Paleozoic gas reservoirs in the basin currently but the interference of carbonate content in soil should be eliminated； ② the influence of interference factors may be eliminated to a maximum through reasonably sampling and paying much attention to the correction of the data on the horizon and lithology of the samples； ③ the geochemical background fields in the basin are closely related to the special morphologic characteristics which the terrain in the north is higher than that in the south in general； ④ the most favourable geochemical exploration anom alies are the complex circularities and the rings in circuit； and ⑤ the distribution of anomalies is identical with that of target zone basically， which shows a northeast southwest extent on the whole. The practical results indicated that the oil and gas geochmical exploration for the Upper Palezoic gas reservoirs in North E’erduosi Basin was of obviously guiding effect and relatively high success ratio.