西藏阿翁错盆地古近系牛堡组上段烃源岩评价

摘要

A number of Cenozoic terrestrial basins with varying scales are located on the Bangong -Nujiang suture in Central Tibet .These basins are characterized by high TOC ,high quality sedimentary organic matter and moderate thermal maturity which have well oil and gas exploration foreground .The authors have focused on the section from Upper Niubao Member in Awengcuo basin and studied the organic matter abundance ,organic matter type and organic matter maturity of the hydrocarbon source rocks .The results have shown that the average organic carbon contents of the limestone (marlite and micrite ) are 0 . 53% ,and 0 .95% after recovered which means that high quality hydrocarbon source rocks have developed in Upper Niubao Member .The type of organic matter of limestone is mostly Ⅰ and Ⅱ 1 .The maturity of organic matter in Upper Niubao Member is not high ,representing almost in the stage of low maturity .The general evaluation of source rocks is medium in Upper Niubao Member of Awengcuo basin .%　　位于西藏中部的班公湖‐怒江缝合带上发育了许多规模不一的新生代陆相沉积盆地。这些陆相沉积盆地具有沉积有机质丰度高、类型好和热演化程度中等的特点，有很好的油气勘探前景。对西藏阿翁错盆地古近系牛堡组上段实测剖面烃源岩的有机质丰度、有机质类型、有机质成熟度等方面的研究显示，牛堡组上段烃源岩较好，灰岩（泥灰岩和泥晶灰岩）的有机碳平均质量分数为0．53％，经恢复后为0.95％，表现出较好烃源岩特征。灰岩有机质类型以Ⅰ型和Ⅱ1型为主。牛堡组上段灰岩有机质成熟度不高，主体处于低成熟阶段。总体评价阿翁错盆地牛堡组上段为中等烃源岩。