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在野外地质调查基础上,系统分析了柴达木盆地石炭系烃源岩分布以及地球化学特征,并从有机质丰度、类型和成熟度方面对烃源岩进行了综合评价。研究认为:柴达木盆地石炭系烃源岩广泛分布在全盆地大部分地区。柴北缘烃源岩厚度大、分布广,厚度中心主要位于欧龙布鲁克山一带,最大残余厚度达900 m;柴南缘厚度次之,沿盆地边缘呈带状展布,在格尔木—乌图美仁—甘森一带厚度在400~500 m之间,盆地西北及东南角厚度较小。石炭系主要发育暗色泥岩、碳酸盐岩和煤3种类型烃源岩。暗色泥岩有机质丰度均值为1.28%,有机质类型主要为Ⅲ型与Ⅱ2型,处于成熟—高成熟阶段,为中等—好的烃源岩;碳酸盐岩有机质丰度较低,平均值为0.37%,有机质类型为Ⅱ1—Ⅱ2型,综合评价为差烃源岩;石炭系煤岩则为良好的气源岩。总体而言,柴达木盆地石炭系分布广泛,具有较好的油气勘探远景。
Based on the field geological survey, the distribution and geochemical characteristics of Carboniferous source rocks in the Qaidam Basin were systematically analyzed. Comprehensive evaluation of source rocks was carried out based on the abundance, type and maturity of organic matter. The study shows that: Carboniferous source rocks in the Qaidam Basin are widely distributed in most parts of the basin. The source rocks in the northern margin of Qaidam have a large thickness and a wide distribution. The center of thickness is mainly located in the area of Oolong Brook, with a maximum residual thickness of 900 m. The thickness of the south margin of the Qaidam basin is second, followed by bands along the margin of the basin. - The thickness of Gansen ranges from 400 m to 500 m, while the thickness of northwestern and southeastern corners of the basin is small. The Carboniferous mainly develops three types of source rocks, dark mudstone, carbonate rock and coal. The average abundance of organic matter in dark mudstone is 1.28%, and the organic matter types are mainly type Ⅲ and type Ⅱ2, which are middle-good source rocks at mature-high maturity stage. The organic matter abundance of carbonate rocks is lower with an average of 0.37 %, And the type of organic matter is type Ⅱ1-Ⅱ2, the comprehensive evaluation is poor source rock; Carboniferous coal rock is good source rock. In general, the Carboniferous in the Qaidam Basin is widely distributed and has good prospect of oil and gas exploration.