鄂尔多斯盆地南部旬-宜探区延长组长7烃源岩特征及评价

The evaluation and characteristics of Chang7#hydrocarbon source rock in Xun-Yi exploration area,South Ordos Basin

为综合评价鄂尔多斯盆地旬—宜探区三叠系长7烃源岩特征,通过岩石热解、干酪根镜检、镜质体反射率及可溶有机质族组分等分析测试,结合烃源岩分布特征对其进行研究。结果表明:长7烃源岩有机质(TOC)丰度高,平均值为7.37%,生烃潜量(S_(1)+S_(2))平均值为26.50 mg/g,综合评价为好烃源岩;有机质类型较好,主要为Ⅱ_(1)~Ⅱ_(2)型;最高热解峰温Tmax主要在440℃~453℃之间,镜质体反射率Ro平均值为0.78%,热演化程度适中,已达到成熟阶段和排烃门限。平面上,延长组长7烃源岩全区分布,累计厚度大,平均厚45 m;纵向上,长73页岩最发育,累计厚度为20~30 m,为油气的形成提供了丰富的物质基础。本项研究为建立鄂尔多斯盆地整体的烃源岩特征与评价体系以及加快该区下一步油气勘探进程提供了科学依据。

In order to comprehensively evaluate the characteristics of the Triassic Chang 7 source rock in the Xun-Yi exploration area of the Ordos Basin,through analysis and testing of rock pyrolysis,kerogen microscopy,vitrinite reflectance and soluble organic matter group components,combined with hydrocarbon The source rock distribution characteristics are studied.The results show that:Chang 7 source rock has a high abundance of organic matter(TOC),with an average value of 7.37%,and an average value of hydrocarbon generation potential(S_(1)+S_(2))of 26.50 mg/g.It is comprehensively evaluated as a good source rock;the organic matter type is relatively high.Good,mainlyⅡ_(1)-Ⅱ_(2);the highest pyrolysis peak temperature Tmax is mainly between 440℃-453℃,the average value of vitrinite reflectance Ro is 0.78%,the degree of thermal evolution is moderate,and it has reached the mature stage and the threshold of hydrocarbon expulsion..On the plane,the Yanchang Formation Chang 7 source rocks are distributed throughout the area,with a large cumulative thickness,with an average thickness of 45 m;vertically,the Chang 73 shale is the most developed,with a cumulative thickness of 20-30 m,which provides abundant material for the formation of oil and gas.Foundation.This study not only fills the gaps in the characteristics and evaluation of source rocks in this area,but also has important guiding significance for the next step of oil and gas exploration in the study area.