羌塘盆地羌资5井二叠系展金组烃源岩基本特征

Basic Characteristics of Permian Zhanjin Source Rock in Well Qiangzi-5 in Qiangtang Basin

前人对羌塘盆地的烃源岩研究资料主要来源于中生界地表露头,少见古生界的。对羌资5井二叠系展金组烃源岩的钻井岩心研究表明,其有机碳含量高,平均值达到1.15%,属于好烃源岩。干酪根显微组分主要为Ⅲ型,其次为Ⅱ2型;有机质主要来自于海相低等水生生物,热演化已达到成熟阶段。烃源岩具较好的生气能力。认为井下烃源岩样品虽显示其处于有机质演化成熟阶段,但因受后期构造抬升的影响,推测二叠系深部未知的烃源岩可能尚处于高成熟—过成熟阶段。羌塘盆地二叠系具有较好的勘探前景,油气勘探可向深部古生界开展。

Most of information about the source rocks was commonly taken from the analysis data of Mesozoic strata outcrops but hardly any from Paleozoic strata in Qiangtang Basin in the past because of virgin exploration. Analysis samples are from a group of drilled cores of Permian Zhanjin source rock from Wel Qiangzi-5 that was solely dril ed in the plateau basin recently. The result of organic geochemical analysis shows that Zhanjin source rock belongs to the rank“good”for high TOC values （the average 1.15%） and good kerogen types of dominant Type- Ⅲ and seldom Type- Ⅱ2. Organic matter general y derived from marine low-grade aquatic organism and thermal y evolved into mature stage, which means good gas-generating capacity of the source rocks. The core samples from the well have demonstrated organic matter being mature;but even so, affected on late tec-tonic uplifting, the unknown Permian source rocks that are deeply buried probably are high mature or over mature. It is implied that the deeply-buried Permian source rocks are of good prospective for oil and gas exploration in the basin.