藏北比如盆地油气地表地球化学勘探

The characteristics of surface geochemical exploration of hydrocarbon in Biru basin, northern Tibet.

青藏高原是我国唯一没有进行大规模油气勘探的空白区 ,比如盆地的油气勘探程度更低。根据实际探测资料和试验数据 ,探讨地表地球化学勘探方法在青藏高原烃源岩大量出露地表的特殊条件下的有效性。研究表明 ,对于强风化的地表样品和灰岩裸露区 ,最有效的化探指标为甲烷和重烃浓度 ,其次为荧光和紫外光 ,而常用的蚀变碳酸盐指标应用效果不佳。比如盆地地表土壤中检测到的烃类主要来源于地下烃类的微渗漏 ,受生物活动的影响较小 ,化探结果能较真实地反映地下油气信息。比如盆地内有机质以高成熟和过成熟为主 ,主要处于生气阶段 ,地表地球化学异常较高 ,盆地中部异常最显著 ,凯蒙呷拉蒙地区具有一定的含油气远景 ,为油气勘探的有利区带。图 3表

The Qinghai Tibet Plateau is the only blank space of petroleum exploration in a large scale. Biru basin is much less explored. In this paper, according to the actually tested data and experiment results, the authors probed the efficiency for applying the surface geochemical exploration in Qinghai Tibet Plateau, especially under the conditions of hydrocarbon source rocks being widely exposed. The research results indicate that, in the samples being strongly weathered or from the exposed limestone area, methane and heavy hydrocarbon content indices are of most valid, and then the fluorescence spectrum and ultraviolet spectrum indices, but altered carbonate index is not valid. In Biru basin, the hydrocarbons being detected in soil are mainly sourced from underground hydrocarbons by micro leakage, and they are less affected by biological activity, which shows that geochemical results can really reflect the hydrocarbon information underground. The organic matter are high mature or overmature and at the gas generating stage. In Biru basin, there occurs high surface geochemical abnormality, especially in the center of the basin. Kemenxialamen area is the hydrocarbon prospect area.